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View Full Version : My exhausted, exhausting question, only for other "big bed" epilog owners, please?



Barb Macdonald
01-11-2008, 10:49 AM
Hi all
I am still having issues with not enough exhaust to my epilog legend ext 60 watt machine. 2'x 3' bed. Big machine, for me anyway..
I'm not "handy", just efficient, and detail-driven.....
Currently I have a "peerless pressure blower (pw-12-220volt) rated for 860cfm at 6" static pressure. Roof-mounted. (You wouldn't believe what the first contractor sold me). This was the second contractors' attempt.
20' spiral ducting and fittings. The ducting splits into two at the machine.
It was JUST enough, and now it isn't enough, I think.. Maybe the fans of the impeller are getting bogged down with debris? I have cleaned everywhere I can reach, but I have a grubby shop, with a dog or two usually in attendance.
I've noticed smoke going up, before it thinks about going back.
What do ya think?

Abigail (my machine) also missed her alignment on a piece of agate I was rastering, bottom line only, not the top line. I sent the job twice, for increased depth, and she missed alignment on the bottom line ONLY, the piece had NOT moved, or the top line would have been out too.... grrrrrrrr

any and all thoughts appreciated.

Have a nice weekend
THE CREEK RULES!!!!!!!!!!!

barb

Joe Pelonio
01-11-2008, 11:06 AM
When I clean mine, I use a blowgun on an air compressor at about 75 lbs. I regularly blow the debris out of the "plenum" area of my laser with the fan on and can see it all going out, but once a year take the whole thing apart and clean it. Perhaps one of the wand type blowguns would help you reach in.

I got one like this for about $10.

Bruce Volden
01-11-2008, 11:23 AM
Another thought, have you caulked or sealed anywhere to make your shop tighter and more energy efficient???? I did this and it decreased the "draw" of my exhaust. What happened was, there wasn't an adequate supply of make up air coming into the shop with the exhaust fan on, and it created a vacuum (?) on the entire shop. You should be able to prove this by opening a door-slightly-and observing the smoke path. Churn is the term that comes to mind when this happens. That's something else to think on as if you don't have enough huh??

Bruce

Mike Null
01-11-2008, 11:43 AM
How many "els" do you have in the line. Every one of those decreases the efficiency of the blower.

Why does it split at the back of the machine? Do you have 2 ducts there?

What size is the duct from the blower to the machine? If the blower is a 6 or 8" housing and you reduce it to 4" right out of the blower you have also reduced the effectiveness of the blower.

Garry McKinney
01-11-2008, 12:03 PM
Barb ,
I am not an expert, But how high is the lift? The height to your blower from the machine? 850 sounds low to me . Was that with a 4" or a 5 inch hose connection ?

I am running a 16 inch wheel with a 5 inch intake producing 2400 cfm .

Garry

Neal Schlee
01-11-2008, 12:05 PM
Barb, Some manufacturer's of these type of exhaust fans installed a screen on the intake of the fan, (usually some type of expanded metal) this is to keep large debris from entering and damaging the impellor.
Try removing the ducting at the intake and if your fan has a screen you can easily scrape off the buildup. Of course this is not any fun with a roof mounted fan. You may want to consider removing the screen as the chance of anything large being ingested into the fan is nil when used as a engraver exhaust fan. The impellor should be inspected and cleaned on a regular basis too.

Neal

James Stokes
01-11-2008, 12:52 PM
With my Epilog I am using a 1650 cubic inch exaust. I tried a couple smaller units but they did not do the job.
As for cleaning a friend of mine takes his exaust off every couple months and throughs a couple hand fulls of sand through the tube, he says the sand breaks every thing loose and keeps it clean, sounds logical to me but I have not tried it.

Barb Macdonald
01-11-2008, 2:13 PM
I took the front "grate" off of the machine, and noticed that my smoke test improved dramatically. The Grate on the front of my machine has a debris trap behind the grate. If I take the grate off, cover the 13"x 39" gap with furnace filter material, what harm am I doing? (Other than exposing myself to invisible laser radiation)
Two 4" ports coming out of the machine, even though the spec sheet on the epilog web-site says 6".
6" ducting to the roof, so that isn't helping.... And hasn't helped, from the beginning, I suspect. I tried to download the PDF on the epilog website of the "exhaust specifications", 'puter crashed. I thought I'd saved the PDF, as I sent it to my first bone-headed contractor, but I cannot find it right now. It's what I used for showing the contractors what I needed. Big mistake, I guess..
I'm always cleaning the belts, and after cleaning like crazy today, I noticed a lot of build-up on the INSIDE of the belts, which is how grunge can mess things up to the x-travel. So, I used a q-tip and some windex and some paper towel, to try and clean the inside of the belts.
Tired of cleaning, I wanna burn:)
And I'm still waiting on a call back from any intelligent contractor I can find.
What is a "plenum"?
Gotta run, thanks for the input
Barb

Garry McKinney
01-11-2008, 2:24 PM
I don't know about the grate, But I can tell you , that I take both 4, turm them to a 5 " T" and the suction will lock a 24 x 36 1/8 in plywood down to where you can't get it off the platform without breaking it.

Smoke from vectoring cutting a .75 maple piece never reaches the cross bar.

I think the cfm's are just low.

Garry

Neal Schlee
01-11-2008, 3:25 PM
I've done the same for cleaning pipe and impellor, but I use kitty litter.

Neal

Larry Bratton
01-11-2008, 8:55 PM
How many "els" do you have in the line. Every one of those decreases the efficiency of the blower.

Why does it split at the back of the machine? Do you have 2 ducts there?

What size is the duct from the blower to the machine? If the blower is a 6 or 8" housing and you reduce it to 4" right out of the blower you have also reduced the effectiveness of the blower.
Mike:
EXTS have two ducts.

Richard Rumancik
01-11-2008, 9:12 PM
Hi all
Currently I have a "peerless pressure blower (pw-12-220volt) rated for 860cfm at 6" static pressure. 20' spiral ducting and fittings. The ducting splits into two at the machine.
It was JUST enough, and now it isn't enough. I've noticed smoke going up, before it thinks about going back.barb

Barb

Do you have an Epilog Legend EXT 9000? I looked in the "EXT 9000" pdf manual and it says "All Epilog 8000 laser systems require an exhaust fan that is rated at a minimum of 400 CFM at 6" of static pressure . . ."

I'm not sure if the "8000" is a typo in the 9000 manual or what. In any event I'm led to believe that Epilog thinks 400 CFM is enough for that unit. You should be getting more that 400.

1. Your blower seems to have a 3 hp motor on it. This is a heavy-duty air system. Lots of people seems to be getting by with much less than 3 hp. It should have enough capacity.

2. You seemed to be saying that at the "beginning" (right after installation?) it was "just enough" air. But it has become less, such that the smoke is not fully being pulled out? If so there is something seriously wrong.

3. I don't think that the spiral ducting is a problem UNLESS it has collapsed for some reason. Can you see it or is it hidden? If above a ceiling I think it needs to be inspected. If it got damaged, or collapsed because of a blockage in the duct, it might be causing a severe restriction.

4. I would use smooth tube whever possible and flexible ducting only where necessary. But flex duct is probably okay as long as it is not pinched somewhere. Espeically if you have 6" dia.

5. Do you have "gates" on your laser exhaust to restrict flow? If so close, the gates down to a "minimum" level and make sure the duct is not collapsing from the vacuum created.

6. Thie blower is a direct drive - I think you need to determine that the motor is actually getting up to proper speed. Can you verify that it is running at 3500 rpm? Someone needs to go to the roof and determine if it seems to be operating properly.

7. Take the duct apart before it splits into the "Y" at the laser and ensure that you are getting good suction there. As you probably don't have access to measuring equipment you'll just have to gauge if it "seems right" at this point.

8. Follow the system end to end. I don't think your system is plugged with a little dust. But maybe it has sucked a piece of paper into an intake? In the laser itself or up the vent? Make sure the ducting is all the way.

9. Any chance that there is some "winter" in your blower exhaust duct on the roof (frost or snow?)

10. The fact that the front grate seems to be "choking" the airflow tends to tell me that you have more flow than needed. But if so, it doesn't explain why the smoke is not exhausting properly . . .this part is puzzling.

Richard Rumancik
01-11-2008, 9:19 PM
Some manufacturer's of these type of exhaust fans installed a screen on the intake of the fan . . . You may want to consider removing the screen as the chance of anything large being ingested into the fan is nil when used as a engraver exhaust fan.

I am not sure about removing it - maybe it could be relocated to a more convenient place however. I have had paper and film get sucked up my exhaust tube and other people have mentioned it - it just depends on what you are cutting. The screen could be relocated next to the laser at the "Y" junction.

Stephen Beckham
01-12-2008, 8:50 AM
Barb,

I know you said you only wanted people with knowledge - I just wanted to offer that we just got our "March 2008" Wood Magazine in and it has a nice layout of some Dust Collector tests they ran. Not too far off from our needs of fume extractors.

They have a few points of interests of how to increase airflow and test systems.

Bill Cunningham
01-12-2008, 9:16 PM
I know you said 'spiral ducting' I am assuming you have installed 'metal' ducting, because the silver plastic stuff has a liner which 'will' collapse inside from the suction, and block the flow almost completely...

Dennis Solomon
01-13-2008, 11:13 AM
1)your duct work should be the same size all the way through it should be the size of your blower port.
2) The closer the blower is to the unit the stronger the draw will be and everything should be sealed!

Tim Jasper
01-13-2008, 10:33 PM
On mine, I had the same problem. We installed a dust collector fan and the X axis was still getting dirty. We talked to Steve Cortesy and he said to open the lid a little bit. We installed about 3/4 of an inch of magnets under the magnet interlocks to allow more air to flow over the top and that fixed the problem. It still has plenty of downdraft to hold down any of the materials we have had to work.

Hope this helps.

Tim

Peck Sidara
01-14-2008, 12:26 PM
Barb,

Straight tubing is better than spiraling/flex tubing as the contours/ribs can hinder airflow IMHO. Use the flex/spiraling tubing as little as possible and make sure you seal off all connecting points using duct tape or HVAC tape. Additionally, try to remove as many kinks or turns as much as possible.

HTH,

Chip Peterson
01-14-2008, 1:09 PM
Since I have been sucking (pun intended) so much information from this terrific forum, I'd like to take the opportunity to add something back.

There is a spiral ducting that is much more benifical than straight tubing in a dust/fume collector situation. Spiral ducting should not be confused with flexible ducting (although it does have sprials in it).

Spiral ducting is expensive but worth the price if efficiency is critical.

An example of industrial sprial ducting can be found here : http://www.novaflex.com/productcart/pc/viewPrd.asp?idcategory=45&idproduct=467 ( I have no affiliation )

When I installed my dust collection system for my woodworking shop, I feel that I became a quasi-expert due to all my research (much like all the laser research I am currently involved in!!)

Barb Macdonald
01-14-2008, 6:32 PM
Thanks so much to everyone for all the great replies. I've been sifting down, I wanted to reply to everyone, but my fingers do start complaining..

I do have straight tubing, and only a short bit of (very expensive, no it doesn't collapse) spiral ducting connecting the blower to the two ports. The two ports ARE 4", my ducting is 6". The two 4" ports, with 6" spiral ducting join at a "T" behind the machine. Well sealed. No leaks.

Check out the specs, Peck, that's what was asked for, that's what I did. I have a 9000 series machine, epilog legend ext 60watt, 2'x 3' bed. The blower is on the roof, 20' up, unblocked by anything. Sounds like a 747 when I fire it up. Draws great, right up to where the two ducts go into the machine, then all seems lost.
I pulled the front grate off (I said this already), but didn't dare laser anything, bit cowardly I am, although the draw was greatly improved without the front grate. (I used a cigarette's smoke for my test) The idea of lifting up the cover a bit makes sense, do you just build up a bit more magnet layer between the cover and the slot it sits in? You're still risking laser exposure??
I totally agree that I don't have nearly the CFM, even though I think I'm within epilog specs.
I don't know if epilog changed the specs, when they made the big EXT. Or I got a manual that ran out of correct spec pages, and gave me specs for a smaller machine. I don't know!!
I was told by my tech rep here in Canada that a piece of paper should be held by the blower to the front grate of the machine, in order for there to be enough "suck". (The things I have to type:) )
I'm afraid that's the "litmus test/gold standard" I used.
Everything gets dirty, very quickly, so I think the gold standard isn't enough, at all.
I cleaned the heck out of Abigail (my machine) on Friday, and did a full days work today, hooray!
Noticed that the backs of the x-carriage belts get really dirty, too. Cleaned 'em. Had to remove the x-motor to clean the metal belt spindle of gunk, just recently, it was causing raster-vector alignment issues.
Until I get this exhaust issue resolved, I know I'm leaving too much gunk behind, which sure slows down the production cycle! And increases the list of things to do cycle....
I just wish I'd had better specs from epilog, to start.
The first contractor guy? I did show them the epilog specs. They put in a little weenie office ventilation fan, no wait, Up-Side DOWN. Yes, folks, really, blowing towards the machine.... They actually started drilling a hole in the back of Abigail, until I pointed out the two ports. Had to pay 'em and then fire 'em. What did I know? They gave me a quote, yup, I signed it.
The second contractor guy, at least read the specs, and put the blower up and on very well. They did do what the epilog specs asked for (see my litmus test).
I've read posts where the cleaning ritual is monthly. Mine is two-days with plastics, and daily with wood.
Thanks again to all, you're a great bunch of folks, couldn't be burning without ya'
!

I'm still all agog over my duck boxes, made some in 0.125 alder from LaserBits, oooh, great Christmas gifts....
THE CREEK RULES!!!
Barb

Rob Bosworth
01-15-2008, 11:16 AM
Barb, I've been experiencing the same thing. I have a 36 EXT 60 watt machine in my shop. It came with a T duct assy. We were watching it yesterday, and the smoke was doing the exact same thing as yours. Building up on the belts and left side of the machine. I finally jerked the T off the machine and added a second 1 hp. blower. We are finally seeing some of the debris and smoke being pulled to the back of the machine. We are also only seeing this as a problem when you are cutting something thin, where the table is above the round exhaust ports. It seems it has a little better exhausting capabilities when the table is down lower.

Today I am tearing the machine apart. We are getting it ready to ship, so I've decided I am going to rip into it and see if it has some type of restriction in the airflow. (I am also going to look for the air assist tube that dissapeared into the machine.) If I find anything, I will let you know. It just might be a weak design of a system that requires a tremendous amount of air flow.

Other than the exhausting, the 36 EXT is a fabulous machine. HUGE and really really fast. Now, if we could just get the effluents out of the cabinet of the machine, we wouldn't have to tear the X axis cover off all the time to clean the encoder strip.

Peck Sidara
01-15-2008, 4:51 PM
Barb,

The EXT requires 800CFM at 6" of static pressure. Your Peerless system is rated at 860CFM at 6" of static pressure but it is really drawing that much air? Only a HVAC guy could tell you that.

Your set-up sounds good and I don't believe there's anything hindering the flow. Perhaps it's just the blower that isn't pulling enough air thru.

The EXT is a very large machine and needs alot of exhaust power to remove all the smoke, dust & debris. The exhaust system is definitely a key part of a good working machine. Here's something you can try:

the front panel has a bunch of vents which draws air in, try taping off the lower 1/2 to 2/3 of the vents allowing air to only flow thru the top 1/2 or 1/3. By doing this, I think the air that's being drawn air is forced in at a faster rate of speed, providing more flow. Should be simple, use some 2" masking tape or paper and regular masking tape and test.

if that doesn't help, then we'll probably have to try a larger blower.

Barb Macdonald
01-15-2008, 5:24 PM
the published exhaust specs for the machine are inadequate. That's got to be hard on epilog sales people.
I couldn't understand why my best tech help/sales guy EVER, Master Mike Clarke, wouldn't get involved with the exhaust question, at all. He sold me the machine, set-it up, but no recommendations, nothing. Shoulda set off the alarm bells then, but to be fair, it ain't what he does best:)

"Do you have an Epilog Legend EXT 9000? I looked in the "EXT 9000" pdf manual and it says "All Epilog 8000 laser systems require an exhaust fan that is rated at a minimum of 400 CFM at 6" of static pressure . . ."

Yes, all that said, Abigail is working as she should, but maybe, just maybe the specifications in the manual should be revised/revamped. I do hate throwing good money after bad. I'd have spent more initially, if that's what the specifications had called for. Why give a minimum specification?
I spent (not including the first contractor bone-head guy) about $3.5k, including the hole in the roof. I could have spent the money much more wisely, if I'd been a member of the Creek sooner! CONTRIBUTE!!!!! Best $ I've ever spent..

I did block off the front of the grate, but it doesn't do that much. I'll try taping just the bottom of the grate, as an interim fix. Thanks for the suggestion, Peck.

Thanks again, to all, for the very helpful replies. I'm waiting on a call-back, from Mr. second contractor guy. Fingers crossed. I think I need to spend more$, on a bigger blower. Strike that, I KNOW!

"Other than the exhausting, the 36 EXT is a fabulous machine. HUGE and really really fast. Now, if we could just get the effluents out of the cabinet of the machine, we wouldn't have to tear the X axis cover off all the time to clean the encoder strip."

I second that!!

Barb

Mike Mackenzie
01-15-2008, 6:19 PM
Barb,

One other thing to check Make sure that the rotation of the motor is correct.

The motors can be wired to run either clockwise or counter clockwise. either way will act like it is pulling but one direction is much better than the other.

Rob Bosworth
01-16-2008, 10:20 AM
Barb, I went and installed a 2007 36 EXT 60 watt unit today. I took the 2006 model out and replaced it with a 2007 model. The new machine has 6" exhaust ports on the back instead of the 4" that the 2006 model had on it. The newer machine seemed to draw a little better than the older machine. We are using two 650 CFM @ 6" of static pressure exhaust blowers on the machine now.

A private (and I will admit a selfish) note to anyone being told to tape up something on your laser engraving system. Please do not use duct tape or filament tape. Both of those tapes leave a lot of residue behind when the tape is finally removed. As a refurbisher of used laser engraving system, removing tape residue takes a long time. Rather than using tape, why not try using a large flex magnet to cover something up.

Richard Rumancik
01-17-2008, 12:15 PM
I've been pondering what Barb and other users have mentioned in this thread . . .


The EXT requires 800CFM at 6" of static pressure. Your Peerless system is rated at 860CFM at 6" of static pressure but it is really drawing that much air? Only a HVAC guy could tell you that.
I am not sure of your train of thought here, Peck. I don’t think you are doubting the Peerless specifications, though. Peerless is saying that the PW-12 will draw 860 cfm at 6”. This test will likely have been done at the factory with a minimal amount of inlet duct attached. Any tube, ells, filters, screens etc that are added to the inlet of a blower will reduce the flow somewhat from what the manufacturer indicates. Since Barb is using only 20' of ducting with minimal transitions, no reducers, etc. then it is likely that she is getting 90-95% of the blower’s capability at the Y. I think that in selecting this blower she has probably met the Epilog requirements.

Is she actually getting 800 through the laser? Maybe not, but the Epilog spec does not say the laser needs 800 cfm through the box. That would be unfair. It says (per your posting) that you need a blower capable of 800 cfm at 6” water connected to the laser, which is what she has. Epilog needs to spec the capability of the blower system up to the point of connection to the laser; the user has to keep in mind there are some losses depending on how far the ducting runs etc. But what happens to the airflow rate after the laser system is connected is beyond the control of the customer and should have been accounted for in the Epilog spec. I assume it was.


One other thing to check Make sure that the rotation of the motor is correct.
Good thinking; it could happen that the blower is running opposite direction. In which case it will still blow but not properly. I was originally going to mention the possibility of belt slippage but as this is a direct drive unit that can’t be an issue. I suppose it is conceivable the impeller coupling could be loose.

I know you said 'spiral ducting' . . . the silver plastic stuff has a liner which 'will' collapse inside from the suction, and block the flow almost completely...

I do have straight tubing, and only a short bit of (very expensive, no it doesn't collapse) spiral ducting connecting the blower to the two ports. The two ports ARE 4", my ducting is 6". The two 4" ports, with 6" spiral ducting join at a "T" behind the machine. Well sealed.

Barb – I think you have what is called “flexible” ducting from the laser to the Y – have you double checked that it is rated for vacuum, and the liner is not collapsing inside as Bill suggested? You said it “doesn’t collapse”, but the liner collapse he is talking about might not be visible from the outside. If in doubt maybe you could you try some 4” dust collection hose and see if it helps? Spiral ducting is a smooth-wall ducting made of a flat band of sheet metal coiled into a tube, not to be confused with flexible ducting which has a "spiral" spring-like wire running through it. But if you have conventional smooth-wall duct going to the roof this is fine.

Various members have given Barb some ideas to make sure that the blower itself is working properly. I would suggest that she get an HVAC guy to do a rough test to see what the flow measures at the Y. (This could be estimated by attaching the blower hose to a short piece of rectangular duct and measuring the air velocity with an anemometer.) Let’s assume that Barb checks everything people have brainstormed and finds that the blower is operating properly to the Peerless specs.


The EXT is a very large machine and needs alot of exhaust power to remove all the smoke, dust & debris.
Is the laser generating twice as much smoke as a typical 30 or 45 watt laser due to power and speed? It's possible, due to increased speed. But Barb has a 3 hp blower. Many members on this forum running smaller lasers seem to be getting away with 1 hp (and a few hundred cfm) and some much less. I have a 1/2 hp 250 cfm blower and seem to have more air than I need on a 30 watt. (I often throttle it back). Even though there will be more smoke generated with 60 watt, it would seem to me that the 3 hp/860 cfm system Barb has should be in the ballpark.

This is assuming that the airflow through the laser enclosure itself has been optimized, and that the front grill can really handle the airflow that is being expected (or is required) for proper flow.


try taping off the lower 1/2 to 2/3 of the vents allowing air to only flow thru the top 1/2 or 1/3. By doing this, I think the air that's being drawn air is forced in at a faster rate of speed, providing more flow. Should be simple, use some 2" masking tape or paper and regular masking tape and test.

I took the front "grate" off of the machine, and noticed that my smoke test improved dramatically.

If there is an excess amount of grille area on the front, then blocking off the bottom holes might help direct some air over the top of the table. Taping vents might help direct the air toward the top, but if the inlet area is reduced too much it will ultimately reduce total flow. Higher velocity does not mean higher flow, if you just reduce area to get it. (CFM = average velocity x area)

A more powerful blower will help overcome a high resistance (impedance) to airflow into the laser enclosure but it's possible that the enclosure does not have enough inlet area to deliver the needed air through it. Or the air is going in the wrong place. I would certainly exhaust other options first before spending another $1000+ to upgrade the blower unit.

Barb, I know you are convinced you need a bigger blower but I suggest you stall on changing the blower and determine if there isn’t another solution. I think you really need to have Epilog engineering do some work on this issue, as it seems to be more than a blower-selection issue or installation issue.

Let’s look at it from this point of view: I don’t have the exact volume of the Epilog enclosure but let’s suppose it is 4' x 3' x 2' = 24 cubic feet. It might be less. But even if Barb’s system can exhaust only 720 cfm, this represents 30 full air changes per minute. Every two seconds, all of the air in the box should be removed (ideally). I would have thought this would be adequate . . . but if the air is by-passing the location that the smoke is actually being generated, (i.e. going UNDER the table), then there is a problem which a bigger blower will not remedy.


I've noticed smoke going up, before it thinks about going back.

On mine, I had the same problem. . . .We installed about 3/4 of an inch of magnets under the magnet interlocks to allow more air to flow over the top and that fixed the problem.

Barb, I've been experiencing the same thing. . . . the smoke was doing the exact same thing as yours. We are also only seeing this as a problem when you are cutting something thin, where the table is above the round exhaust ports. It seems it has a little better exhausting capabilities when the table is down lower.

It seems that the problem is a result of dead air space in the laser enclosure at the point of cutting, especially when the table is up, and so the volume of contaminated air is not evacuating properly. If the smoke is “indecisive” as Barb observes, then it tells me the smoky air is not in a defined flow path. If the table becomes a divider that separates the top half of the laser volume from the bottom, and there are only exhaust vents at the bottom, then that would explain why the smoky air at the top is not clearing properly (and explains why opening the lid helps.)

A suitable solution might be found by:
changing/modifying the front grille
adding holes to the top door, or adjacent to the door (maybe only open the holes when table is up?)
adding some baffles to direct air
adding some smaller exhaust ports above the table that connect to the “Y” (or to the lower volume of the table)
adding a baffle in front of the two exhaust holes so they draw more air from the top
putting "legs" (or equivalent spacer) between the laser table and vector cutting table, so that the main table is lower when cutting thin materials

Not having an EXT I can’t say how practical any of these ideas is as a retrofit. Some could be difficult mods. But maybe they can help generate a solution.

Peck, I assume Epilog wants to sell lots of these lasers, so I don’t think you want to make this an expensive unit to own. Large, noisy, and expensive roof-mounted blowers, that use lots of energy will really limit the number of people that can consider this laser system. Some people won’t even have the power available to run a 5 hp blower. Not sure what it does to the heating bill. Barb already has a 747 on her roof, she probably doesn’t want a Concorde. If Barb has to upgrade to the PW-14 5-hp unit, then potential customers will see this as the “minimum”. Why not challenge the engineers to find out what is causing the problem and maybe you can show Barb that the blower she has is fine. Nobody wants to hack into their new laser, but maybe Epilog can come up with an appropriate fix, even if it means supplying new grilles or lids, or appropriate retrofit parts.

Another point: when laser system designs are developed with such high cfm requirements, it might be a good idea to provide BOTH intake and exhaust connections. This would allow users the option to supply cooler unheated air for smoke evacuation as opposed to evacuating room air. It also reduces the risk of chimney backdraft in fuel-heated buildings.

Barb Macdonald
01-18-2008, 7:31 PM
Quoting Richard's learned reply in italics
It seems that the problem is a result of dead air space in the laser enclosure at the point of cutting, especially when the table is up, and so the volume of contaminated air is not evacuating properly. If the smoke is “indecisive” as Barb observes, then it tells me the smoky air is not in a defined flow path. If the table becomes a divider that separates the top half of the laser volume from the bottom, and there are only exhaust vents at the bottom, then that would explain why the smoky air at the top is not clearing properly (and explains why opening the lid helps.)

A suitable solution might be found by:
changing/modifying the front grille
adding holes to the top door, or adjacent to the door (maybe only open the holes when table is up?)
adding some baffles to direct air
adding some smaller exhaust ports above the table that connect to the “Y” (or to the lower volume of the table)
adding a baffle in front of the two exhaust holes so they draw more air from the top
putting "legs" (or equivalent spacer) between the laser table and vector cutting table, so that the main table is lower when cutting thin materials

Not having an EXT I can’t say how practical any of these ideas is as a retrofit. Some could be difficult mods. But maybe they can help generate a solution.

Peck, I assume Epilog wants to sell lots of these lasers, so I don’t think you want to make this an expensive unit to own. Large, noisy, and expensive roof-mounted blowers, that use lots of energy will really limit the number of people that can consider this laser system. Some people won’t even have the power available to run a 5 hp blower. Not sure what it does to the heating bill. Barb already has a 747 on her roof, she probably doesn’t want a Concorde. If Barb has to upgrade to the PW-14 5-hp unit, then potential customers will see this as the “minimum”. Why not challenge the engineers to find out what is causing the problem and maybe you can show Barb that the blower she has is fine. Nobody wants to hack into their new laser, but maybe Epilog can come up with an appropriate fix, even if it means supplying new grilles or lids, or appropriate retrofit parts.

Another point: when laser system designs are developed with such high cfm requirements, it might be a good idea to provide BOTH intake and exhaust connections. This would allow users the option to supply cooler unheated air for smoke evacuation as opposed to evacuating room air. It also reduces the risk of chimney backdraft in fuel-heated buildings.

Barb here, and I took the liberty of cutting pasting the above to my (I hope), HVAC guy. If he ever calls me. He's a great reference from a great reference of my husbands, and the great reference promises/says he'll call. Fingers crossed.
I also, and I hope this is ok, sent my username and password to great squared reference too. I didn't know if he'd be able to get into the site without it. I can't see how an HVAC guy would be on here, but that's probably not a good assumption, given how many clever people there are on this forum. I just hope he's not sound asleep, by the time he's finished!! I need great-squared to care, for my Abigail:) I hope he'll read it, I've got the weekend to plan for a promotional sales call next week, and I've got some nice wood/plastic inlay work starting to come to fruition. I need to be making lots of smoke! I'd like to finally get this thing fixed. I have zero problem with cleaning stuff. I just don't have enough hours in a day.

First great Reference said maybe I needed some specialized air-flow/engineering done. $$$$$$, not what I need to be doing in this economy. I appreciated very much the comment about the Concorde, LOL.
My older dog has always hated our air compressor, the addition of the 747 has been hard on her. My 14 monthPuppy could care less, of course:) She grew up with the noise!
Made a bunch of IPI plastics room tags today, love how the vectored edges aren't schtickey. Have to clean, again, the lenses, they get dirty so quick with this stuff:(
Oh, I have some sort of all black rigid plastic spiral ducting, it does not collapse, it has a spiral wire wrapping around it, I'd see it collapse, really!!
I have been doing lots of thin stuff, most of my business plans are with thinner materials, for signs etc. I will try lowering the table and fitting something FLAT underneath, to build up the material, and lower the bed.
I'd need to know more about where to drill holes in the machine, but I have a lot to think about here, and you're quite right, I'm no hacker...

Thanks to all for their suggestions, I got just the kind of feedback I was hoping for
CONTRIBUTE to the CREEK

I initially loved the idea of fitting a saddle (and other large/odd-shaped items of course) into the humungous bed of my machine, but I was hoping to do lots and lots more of my main business first. (My saddle is retired to a good home anyway)
Much of the subsequent technical issues I've had with the machine could be traced directly/immediately/easilyreallywhenithinkaboutit to dirt-build-up.

Any comments to add, Peck?
:)
Can I exchange the machine for a 2007?
:)
(again)
Retrofits sound GREAT
:)

Optimism is what you make of it.
I'm always hoping:)
barbmacdonald
"Hope is the thing with feathers, that perches in the soul, and sings the tune, without the words, and never stops at all"
Happy past the middle of January!!!!!!!!!!!!!!
Here's to the CREEK
and here's to the birds..
And i WILL press send...

Richard Rumancik
01-18-2008, 11:32 PM
I have been doing lots of thin stuff, most of my business plans are with thinner materials, for signs etc. I will try lowering the table and fitting something FLAT underneath, to build up the material, and lower the bed.

I'd need to know more about where to drill holes in the machine, but I have a lot to think about here, and you're quite right, I'm no hacker...

Barb, if you want to follow this route I suggest that you make some kind of box frame which will sit on your table and allow you to place your vector table on top of it. (I assume you are using a vector table). The box frame could have solid sides but the front and back should be mostly open, so the air can "pass through" from your front vents and into the exhaust. This will hopefully pull some smoke downwards and into the exhaust. I can't promise it will completely clear any smoke generated above, however. If your vector table has a full sheet of material on it, it is effectively blocking the openings in the honeycomb.

(I actually use a box frame all the time on my LaserPro with my own metal grid. I rarely use the vector table that came with the laser. The smoke does not exhaust properly from the vector table as it is a closed frame all around and sits very close to the main table. I built mine for a somewhat different reason, but the same concept may help solve your problem. I clamp the box frame rigidly to the main table so it always registers the same.)

There may be a way of helping clear smoke above, when you are using sheets of plastic or wood that are not a full 24" high. Your bed is 36 x 24; if you limited sheets to say 36 x 18 you could locate them 6" away from the back leaving 6" of holes open in the honeycomb. Nothing says you have to put the material in the "upper left" corner. By leaving some open holes, even a few inches, it might encourage the air to go down through the honeycomb into the exhaust ports.

From what Rob said, I got the impression that when the table is up, the gap at the back to the exhaust ducts is narrow. So by moving the material you are giving the smoke a chance to go down and out.

(Just make sure you actually place the material in the laser correctly.)

Don't start hacking into your metal or plastic work until you have done more experiments and got some more feedback. Hopefully you can get some Epilog suggestions, as they have machines to test with. I was hoping maybe they would hack theirs and then help you solve your problem.

Scott Shepherd
01-19-2008, 9:13 AM
You shouldn't have to hack anything or make any modifications to your machine. There are probably 1000's of similiar machines out there and the users appear quite satisfied with their air flow. Just from reading this thread, I think there are a couple of people who have nailed it in reference to possibly the motor turning backwards, as well as the negative air flow created by turning the blower on. A HVAC guy can put the air flow checker thingy (can't recall the right name for it) right on the front of your machine and tell you real quick if it's drawing enough air. It's a simple test that only takes minutes and shouldn't cost you more than a 30 minute service call.

Have you tried leaving a door open (I know it's cold out there) a little and checking it to see if there is increased air flow with the door open? You building might just be too tight to be sucking all that air out. Also, does it do better when you first turn it on and then seconds (or minutes) later, it goes back to being poor air flow? Can you tell? Or is it the same from the time you hit the button all the way through the cycle?

Just thinking out loud.

Richard Rumancik
01-19-2008, 9:28 PM
You shouldn't have to hack anything or make any modifications to your machine. There are probably 1000's of similiar machines out there and the users appear quite satisfied with their air flow.
I don't think anyone has reported in this thread that their EXT was exhausting well, so I won't assume quite yet that all the other EXT owners don't have a problem.

Rob tested the 2007 machine and thought it was "a little better" than the older unit but keep in mind that he has two 650 cfm blowers on it which is 50% more air than spec. Also, note that Epilog changed the intake ports to 6" from 4". It seems that a problem was identified with the original configuration, and this was one approach to alleviate the problem. So what about the 2006 units like Barb's? It will probably not be possible to change them to have 6" ports, so a different mod may be needed. (And the 6" ports alone may not be the full solution.)

Scott Shepherd
01-20-2008, 9:57 AM
Richard, my point is that you shouldn't have to cut up your machine to make it work. If you do, then a phone call to Epilog needs to be made and they can resolve their mistakes free of charge, in my opinion.

Perhaps the 850CFM is the wrong number. Perhaps it's 1000CFM. Before I cut up my cabinet of spent hours modifying any machine parts, I'd try out a larger CFM blower. Also, I'd certainly have the room tested and make sure there wasn't negative air pressure. We only have a little 650CFM unit and we're in a commercial office space that's probably 30,000 sq ft on our floor alone. We had a tech come in and tell us that pulling that kind of air out of the building could be a problem.

So I would imagine a smaller space, like a 2,000 sq. ft office and a 850CFM blower causing some issues that certainly need to be considered in the equation. Might not be the issue, but needs to be considered.

I don't pretend to have the answer, but one of the first calls I'd have is to Epilog and their sales rep would be standing there watching it happen. There's no reason at all that this should have to be figured out or re-engineered by the end users, paying large amounts of dollars to have various contractors come in and evaluate it.

Ryan Sprole
01-20-2008, 10:22 AM
Barb,

I have plenty of EXT's out in the field and none have been experiencing your problems. Are you using the air assist? in some cases you may want to reduce the airflow so it doesn't blow the smoke all over the place. The EXT has a vacuum table that incorporates the vector grid by use of the exhaust. I've had clients tape off the exhaust inlets to use 100% of the down force. say when your cutting veneers or balsa. I also agree that opening a window a bit or door can help. And lastly it's best to have a blower mounted outside because blower units tend to seep some smoke and smell. I hope this helps.
Creek on!

Ryan

Richard Rumancik
01-20-2008, 2:12 PM
Richard, my point is that you shouldn't have to cut up your machine to make it work. If you do, then a phone call to Epilog needs to be made and they can resolve their mistakes free of charge, in my opinion.
I agree 100%. I think I expressed that too, in different words. Maybe I was too hasty in discussing possible "mods". Some of these ideas were directed towards Epilog. I am hoping they will do any mods if it comes to that. Proping a lid open is not a long-term solution, in my opinion. It is an experiment, which may identify a design problem and ultimately a solution. I would not be satisfied if I was told to do that permanently.


. . . one of the first calls I'd have is to Epilog and their sales rep would be standing there watching it happen. There's no reason at all that this should have to be figured out or re-engineered by the end users, paying large amounts of dollars to have various contractors come in and evaluate it.
Scott, I think we are pretty much in agreement.

I will point out that "testing" a higher cfm blower is not necessarily an inexpensive thing. I was thinking about how I would do this, if I was in her situation. Rent a blower? Buy the blower? Get the HVAC guy in for a day? The electrician for a day? Rig it temporarily, or just install it and hope? In my case, I could do quite a bit of work myself but I think Barb needs assistance which means paying for contractors. She has $3500 in it already – I feel for her.

I think she DOES need to find out how many cfm is going up the pipe in the laser room, then report back to Epilog.


I don't pretend to have the answer . . . .
. . . and I hope no one thought that I pretend to have the answer, either. Just trying to help by brainstorming. I will let a few others (including Epilog) contribute to this thread and see what develops.

Barb Macdonald
01-20-2008, 6:01 PM
I do use air assist, not when I'm rastering, only when vectoring. The smoke "hangs", when rastering. The air assist works just jim-dandy-fine. I understand, and have tried, most of the fixes suggested. My blower is outside, 20' up. (I feel a blank stare coming) I haven't yet ripped the whole back off the machine, at once. That'll be next. I've done alignments, and such, I've been feeling pretty confident about running Abigail. I'm pretty good at deduction, and process of elimination. Really. I see anotherblankstare.
It's never been comforting in business, to hear that I'm mostly alone in my problems. I will only mention Dahlgren. Enough said.

The frustrating thing was (is) the blank looks I can get, when I hand over, and detail, my requirements to contractors. First contractor was well recommended. They did install the first one incorrectly, and upside down. I betcha they used a 400 cfm. (Can't remember now). It wouldn't surprise me, because I downloaded a PDF manual, before receipt of the machine, for the specifications required. So everything was (almost) all in place, when the machine was delivered. Remember the upside down? That's when that happened. I took the electrician to notice that. Then I got second contractor, have the machine, have the hard-copy manual for the machine in my hands, now. Hear what I'm saying? The both had those specs., I wonder? I'm going to look again, tomorrow. I did save a PDF, but do I still have the original? I think first contractor was on some other planet.
I phoned HVAC guy, the second, asking for a service call on the unit, as I was always dealing with dirt issues, about 6 months after they installed. The blower was fine, blowing as it should. As I mentioned, I have disconnected it at the T, and all is well, great suck, motor spinning correctly, central vac it ain't though, according to one property manager buddy who also promised a call from a contractor. That's what Property Manager guy suggested, a central vac, right behind the unit. Nice:)
Remember litmus test?
I have lots of air moving around my unit, I'm in a older building, not well sealed, by any stretch of the imagination. Oh, it'll be cold tomorrow...It's zero Fahr. here:)
Maybe we're running low on air in my part of Toronto:)
(I'm not sure how to type a half-smile)

So, I await, assistance/phone-calls/anything at this point!!.
I appreciate all the thoughts, suggestions and comments, please, no offence has been meant, by anything I've said. I am trying to figure out how to improve efficiency. Period.
I am just now thinking, I could build a second level to my shop, and Abigail could live on the second floor mezzanine, therefore shortening the 20' of 6" tube, out. $$$$$$$$$$$$$$$
(oh, well)
Thanks to all, and for sure Richard. I think you've been helpful, and that's what the Creek is all about.
I agree, though. I hear feathers ruffling.
And, ayup, I have already figured out that you can put your material anywhere you want in the machine, it hasn't made much difference, other than the gook is easier to clean, nearer the middle of the table.
Enough said:)
Thanks for the luck, I'll need it!

Best

Barb

Barb Macdonald
01-21-2008, 1:40 PM
Barb,

The EXT requires 800CFM at 6" of static pressure. Your Peerless system is rated at 860CFM at 6" of static pressure but it is really drawing that much air? Only a HVAC guy could tell you that.

Your set-up sounds good and I don't believe there's anything hindering the flow. Perhaps it's just the blower that isn't pulling enough air thru.

The EXT is a very large machine and needs alot of exhaust power to remove all the smoke, dust & debris. The exhaust system is definitely a key part of a good working machine. Here's something you can try:

the front panel has a bunch of vents which draws air in, try taping off the lower 1/2 to 2/3 of the vents allowing air to only flow thru the top 1/2 or 1/3. By doing this, I think the air that's being drawn air is forced in at a faster rate of speed, providing more flow. Should be simple, use some 2" masking tape or paper and regular masking tape and test.

if that doesn't help, then we'll probably have to try a larger blower.

Peck, I have re-checked my manual, it says 400cfm. Not 800, 400. That was the manual supplied with the machine. That's what I showed to the first contractor. He supplied me with a 600cfm, and it wasn't nearly enough. (I just checked what I had, this is over a year ago now.)

I would appreciate a response back. The Laser is not the issue here, the specifications supplied by Epilog for exhausting the machine are. I also feel the fixes/work-arounds suggested in this thread are valid, but I would prefer not to hack into the machine. I would prefer to hear from Epilog.

Obviously, I do feel that there is an issue here, that Epilog should at least try to help me resolve. I have spoken to my HVAC guy, he's sending a retired engineer over this week, to help in figuring this out. Small $$$$, but still extra $$$$. I think Epilog is at least partly, if not wholly, responsible for the extra costs I'm incurring.

Yes, maybe I do need way more CFM, but should I have "known" this before purchase? Specifications are there to help the customer, correct?
I had a huge job for Abigail the moment she arrived. The lack of exhaust directly impacted how quickly the machine became dirty, which set off a whole host of problems, that do occur after lots of use, not minimal use.
(Please, no blank stares)

I have mentioned in this thread, that I've tried blocking the front grate, but the results are variable. I would like to remove the front grate altogether, as that does increase air flow to the back of the machine.

Thanks very much.

Barbara L. Macdonald, B.Sc., CFO

Peck Sidara
01-21-2008, 1:44 PM
Barb,

I'm currently talking to engineering to see what options are available. I didn't take into account how much time, money and effort you've already invested when I suggested a larger/higher flowing blower motor.

I'm confident we'll be able to increase the flow to keep Abigail cleaner and happier. I'll send you a PM with engineerings recommendations and will likely be sending a replacement panel.

For the time being, check to make sure the back exhaust ports & plenum is free and clear for air flow. This would require removing the 2 4" port extensions in the rear and going in with a flashlight. Let's also hold off on bringing someone in to check the air-flow etc.

I'll be in touch shortly.

Rob Bosworth
01-21-2008, 4:38 PM
I'm not sure that we can blame the exhausting problems on the design/ manufactures of these systems. They offer guidelines for exhausting, but there are too many variables that are hard to take into account.

I went back and took a look at our exhaust system for the Epilog 36 EXT 60 watt machine. The machine has two 4" dia. exhaust manifolds on the back of it. So we hooked up two 4" dia. galvanized ducts, which both had an elbow which then led directly to a 4" dia. Tee. We then ran from the Tee, through a sliding gate valve, through about 8 ft. of 4" dia. reinforced flex tubing (corregated on the interior and exterior), into the exhaust blower. Then we had another 5 ft. section of 4" dia. reinforced flex hose to a 6" elbow. That 6" elbow feeds into 10 ft. of 6" galvanized ducting up the wall of the shop to another elbow, then through the wall, and out through a grated exhaust cap. Sounded pretty straight forward and effecient to us.

Let's look at what we actually had. Let's start with a reprint from a Universal Owner's manual from their 1995 ULS 25E manual (24" X 12" range of motion 25 watts recommended ~ 250 cfm @6" of static pressure.)


DISTANCE BETWEEN BLOWER AND LASER
CFM RATING AT 6 INCHES STATIC PRESSURE
UP TO 10 FEET 235 @ 6 INCHES STATIC PRESSURE
11 - 20 FEET 410 @ 6 INCHES STATIC PRESSURE
21 - 30 FEET 535 @ 6 INCHES STATIC PRESSURE
31 - 40 FEET 625 @ 6 INCHES STATIC PRESSURE*

*reprint from 1995 ULS 25E Operator's Manual

These numbers represent an exhaust system running from the laser to the exhaust blower, and the exhaust blower exhausting directly out of the blower into the air. IT does not even take into account any exhaust running from the blower to the outside.

I also seem to remember from somehwere that each restriction in the air flow path can cut down pressure significantly. Something like 20% for each elbow and Tee.

So we start out with an exhaust bvlower that is capable of 650 cfm @ 6" of static pressure. Four elbows. One Tee. 13 ft. of corregated 4" dia reinforced plastic tubing. At least 12 more ft. of 6" dia. galvanized ducting after the blower. So if it is true that each elbow and Tee reduces airflow by 20%, we would be at 213 CFM @ 6" of static pressure without taking into account the length of run of ducting. So what do we have at the machine?

I recommended the new owner of the machine buy a 2 hp blower that is capable of 1600 cfm. at 6" of static pressure. The blower I recommended also had a Y at the inlet which should reduce the restrictions. The less smoke that swirls around in the cabinet, the better and more reliable his machine will run.

Barb Macdonald
01-21-2008, 5:35 PM
"They're just guidelines"
That's a line from my Favorite of all times Movies, arrrr Laddie, they're just guidelines, anyway.
The creek rules
And of course, Johnny Depp and Crew
Can I confess that I watched Pirates 3 all through the holidays?
Thank you, all.
Barb (och) Macdonald

Dave Fifield
01-22-2008, 2:59 PM
Interesting thread!

I have a 45W Epilog EXT (2007 model with 6" ports). I experience EXACTLY the same issues as stated above. I upgraded from a Mini 24. I used the same extractor (a 1HP, 914cfm beast - one of these http://www.pennstateind.com/store/dc5.html) on my EXT, with 4" ports (homemade) and a 4" Y connector and tube. I immediately noticed that smoke hung around for a lot longer than it ever did on my Mini 24. However, I shrugged it off, knowing that the EXT required a lot more suck than the Mini 24, and thought I'd do an upgrade on it eventually.

I've been using it as-is now for over a year, and I've noticed that the suck seems to be proportional to the Z-height of the work table. If I'm lasering a paintball marker using the 4" lens, the work table is down a good 6" to 8" from the top, and there's plenty of suck. However, if I'm vector cutting some veneer (for marquetry), using the 1.5" lens with the table all the way up almost, there's very little suck and smoke hangs around for ages.

In some ways, this is okay, since the last thing I want when cutting out tiny pieces of veneer is for the small pieces to disappear down the grid and zoom down the exhaust pipe! A friend of mine cured this by putting cut up womens tights (nylons) over the exit holes under the vector cutting grid. I will probably do this too if I upgrade my exhaust.

So, yes, as an EXT owner, I see the same issue, but I live with it as-is for right now. If anyone comes up with a suitable mod, I'll be sure to incorporate it (plus adding the nylons!).

Peck: Please let us ALL know if your engineering group comes up with something!!

Cheers,

Richard Rumancik
01-22-2008, 10:19 PM
I was glad to hear that Peck is trying to arrange assistance for Barb.

Very interesting comments and observations, Dave.

Your blower is probably not quite up to snuff for the Epilog EXT. The specs for your blower are:

Specifications:
Motor: 6.8 Amps @110V
914 CFM • 1HP
Max static pressure: 9.4"

The key is the word "Max" on static pressure. You probably don't have the static pressure you need. I'll attempt an analogy: A blower is analogous to a power supply – unfortunately, not an ideal power supply, because when you load down a power supply with a variable resistor it should maintain output voltage (up to the point that you overload it). A blower does not operate at constant pressure. It supplies maximum pressure (suction) with no flow. If you want some flow, the pressure (suction) drops. The “load” on a blower is anything that restricts or impedes flow – including items such as screens in front of the blower, the ducts themselves, bends, ells, Y’s, flexible tubing, the convoluted path through the laser, and finally the input grille (and maybe even the building envelope, as some have pointed out.) These are all analogous to many resistors in series.

The dust collector manufacturer says it can deliver 914 cfm, and can deliver a max. pressure of 9.4” of water pressure. But not at the same time.

Most blower manufacturers give a table of pressure vs flow, or else a curve. The dust collector spec gives you two points on the ends of the curve: 914 CFM at a very minimal pressure (probably less than 1", maybe even 1/4" water) and the other data point is 9.4" water at ZERO flow. Unfortunately this method often leads to confusion, as it is tempting to call it a 914 cfm blower.

Many of the laser manufacturers have settled on specifying a required flow at 6” of water. Not sure why they picked that number but at least it is somewhere "in the middle" of a likely operating point for a laser system.

But your comments still support the observations of Barb, Rob, and others.

A little aside. Some time ago, I wanted to kiss-cut some thin adhesive-backed material. I decided to make a "vacuum table" – basically a box that sits above the main table with holes in the top surface. The initial idea was to attach a shop vac for vacuum. The problems with this would be inconvenience and extra noise. So I came up with the idea of having an open back port on this box that aligned with an adapter I made, so that the laser exhaust blower would provide the suction. (I don't think I was the first to think of this.) It worked great!

Except that a vacuum hold-down uses vacuum (suction) at zero flow. So if I "stole" too much of my exhaust capacity to make the vacuum hold-down work, it would be at the expense of clearing any smoke. It is a balancing act; there is no free lunch. In my case, I was not generating much smoke, so it was not a major issue. But I could see how it could be a problem for veneer where some smoke is generated above the material.

What does this have to do with the Epilog? Maybe nothing – I can't say for sure as I don't have one to look at. But I am speculating that there might be a similar situation.

Barb Macdonald
01-23-2008, 7:51 AM
Barb,

I'm currently talking to engineering to see what options are available. I didn't take into account how much time, money and effort you've already invested when I suggested a larger/higher flowing blower motor.

I'm confident we'll be able to increase the flow to keep Abigail cleaner and happier. I'll send you a PM with engineerings recommendations and will likely be sending a replacement panel.

For the time being, check to make sure the back exhaust ports & plenum is free and clear for air flow. This would require removing the 2 4" port extensions in the rear and going in with a flashlight. Let's also hold off on bringing someone in to check the air-flow etc.

I'll be in touch shortly.

That's great news, Peck. I have already (a few weeks ago) removed and checked the 2 4" ports at the back. I still don't know what you mean by the plenum, sorry, duh? I've cleaned everywhere I can reach, the dead space behind the ports in the machine is dirty, but kinda hard to get at. I can see how I can clean it though, from one of the first replies to this thread. When I said I'd have to remove the entire back of the machine, I meant in order to do some studying.

I have put my HVAC guy on hold, Peck. He comes highly recommended, as I mentioned, he's a very busy guy.
Please advise, asap, as I do have a lot of wood inlay/production work to get out, as I mentioned. I would like to get this issue sorted out.
Please?
:)
Barb Macdonald

Richard Rumancik
01-24-2008, 10:54 PM
I'm not sure that we can blame the exhausting problems on the design/ manufactures of these systems. They offer guidelines for exhausting, but there are too many variables that are hard to take into account.

I think you have a valid point, Rob, and have presented some interesting info. Yes, there are quite a few variables and people here are using a lot of different blowers and different configurations with "varying" results.

At the same time it would be nice if the manufacturers put some resources into coming up with some technical assistance in blower selection, so each customer doesn't have to take a night course in HVAC. It seems that ULS made an attempt in 1995 to at least try to educate customers regarding losses in the ducting. (Do they still have this info in the current manuals?) I think a few more pages of material and some example installations would be quite worthwhile. It would be better if the laser systems engineers came up with some more comprehensive info so their customers don't have to to learn all this (or have to pay someone), or else use trial-and-error approaches to blower selection.

The best guideline I found was from New Hermes

http://www.gravograph.com/usa/Support/pdf/Engraving-305/Laser%20Exhaust%20Requirements.pdf

for the Gravograph - a name which doesn't come up in the forum very much. Something like this but perhaps more complete would be valuable. They don't do a good job of dealing with elbows etc. - I think the way this is normally handled is by converting elbows into "equivalent" length of tube eg. resistance of one 90 deg elbow = 12 feet of tube etc.

I went back to my old LaserPro info to trace where I got my blower info - and I can't actually find anything in the GCC literature that stated the necessary airflow.


I recommended the new owner of the machine buy a 2 hp blower that is capable of 1600 cfm. at 6" of static pressure.
You may be correct on the needed flow for the EXT, but I am not sure you will get this with a 2 hp motor. If you really need 1600 cfm at 6" then you are probably talking 5 hp. If Barb can only get 840-860 cfm free-flow at 6" with a 3 hp motor, then it is not likely that a competitor could design a 1600 cfm/6" blower with only a 2 hp motor. They are all using similar designs. (There are some differences in impellers etc but this will not radically affect the hp requirements.) I think the dust collector manufacturers tend to quote the "endpoints" of the blower curve, as I suggested to Dave.

It can be confusing and time-consuming, and this is why I would like to see the manufacturers provide more assistance. To be fair to Barb, she DID ask her Epilog rep for help before she installed her blower, and all that was provided was a spec (which unfortunately in her case was outdated and applied to a different machine).

Bart Walchuk
01-25-2008, 12:00 PM
The problem has to do with Static Pressure and the location of the blower. The blower has to be at roughly the same height as the Engraver, give or take a few feet, as you elevate the blower or hose you are now dealing with Static Pressure. The higher you go the more static pressure or resistance. If I try to push my exhaust up 10 feet the air will move, but the particles are to heavy to travel to that height and will accumulate and restrict air flow hence no exhaust.
Just like a vacuum will not pick up to a ten foot height.

Hope this helps. Bart

Barb Macdonald
01-25-2008, 1:00 PM
Thanks Bart
That confirms one of my suspicions. I did wonder about how high the exhaust fan is up in the air. But you know, I was told this was fine.
Peck is sending some parts for me to try, but I have a bad feeling... That maybe the Laser should be in my office... with the exhaust closer to the machine.... too. Need to relocate hole, blower, machine (in the office which is NOT where I wanted it, it's kinda loud when you're on the phone with customers...).
I have a south facing, (thank goodness for sunshine=free heat) industrial unit, I'm in the centre of a long skinny building, my unit is 33'x100'. The office space is 33'x 12'. The office exterior roof height is different from the Industrial unit exterior roof height. The Laser sits on the other side of the wall from the office. Won't fit through THAT door.
$$$$$$$$$$$$$$$$$$$$
Sales are a bit slow, this would be the good time, to get this OVER with...
I need to go make lots of promo stuff!!!!

Oh, gosh.
I think I'll go burn something:)
Hang the smoke!
(I mean I'll watch smoke hang)

Today, I've already managed to screw up two beautiful maple pen cases, but I learned ALOT), and after all they're samples:)
I have been using BeesWax and it works great:)
I still don't see why ya shouldn't use it? (Other than the fact that bees are having a tough time?) I like bees!
Is Carnauba Wax similar? Sorry, off topic


Have a great weekend
Winter's half over:)

"Hope is the thing with feathers, that perches in the soul, and sings the tune without the words, and never stops at all."

THE CREEK RULES!
CONTRIBUTE!!

Bill Cunningham
01-26-2008, 9:16 PM
I have had a can ofCarnauba wax (same can) for 40 years.. It obviously goes a long way.. I use it mostly for wooden belt buckles..Keep it sealed, and it lasts forever..:D

http://en.wikipedia.org/wiki/Carnauba_wax

Richard Rumancik
01-27-2008, 8:43 PM
The problem has to do with Static Pressure and the location of the blower. The blower has to be at roughly the same height as the Engraver, give or take a few feet, as you elevate the blower or hose you are now dealing with Static Pressure. The higher you go the more static pressure or resistance. If I try to push my exhaust up 10 feet the air will move, but the particles are to heavy to travel to that height and will accumulate and restrict air flow hence no exhaust.
Just like a vacuum will not pick up to a ten foot height.

You are quite correct that the loss of static pressure due to height should be accounted for in the design. When Barb's HVAC guy said it was not an issue he was probably thinking in terms of having 100% margin already above spec, so he may have felt the 20' elevation difference was adequately accommodated. But if she needs twice what she thought, then every loss will make things worse.

However, the laser exhaust system is really for smoke and airborne contamination, and not heavy particles such as sawdust. You would not want to elevate a dust collector in a wood shop, as you need to move much heavier particles and gravity will work against you. But when exhausting smoke you might lose .3" water due to the height of the blower. An HVAC expert could provide a more accurate number. But I have a suspicion that if Barb moved the blower to the same elevation as the laser, she may find that the improvement is not significant or noticeable.

Roof mounting (or a roof exhaust, which is equivalent) is desirable for other reasons, such as the fact that it dissipates the exhaust air higher up. It is not uncommon for industrial blowers, laboratory exhaust systems, and restaurant blowers to exhaust to the roof.

Rob Bosworth
01-28-2008, 10:29 AM
BArb, have you ever tried Johnson Paste Wax. It comes in a big yekkow can. I use it many finished wood products. Smear some on finished wood, do your lasering, then wipe off the excess smoke and tars with a damp cloth. After cleaning, I wipe it again with a cleean dry rag and your product is finished. A can of Johnson Paste Wax will last a LONG time.