Strong acrylic smell on small rastor and vector? [Archive]

Keith Upton

01-17-2014, 8:42 PM

Hello everyone,

My first post here but I've gained a lot of information from everyone posting their experiences... so thank you!

I just picked up my Epilog Mini 24 (60w) a couple of weeks ago and start cutting and engraving various materials. One of them is clear acrylic. Whenever I engrave or cut this, I get a pretty strong odor in the office. Enough to have to vent the air out the window with a three head window fan. My laser is exhausted separately with an inline 6" 440CFM fan and 4" silicon ducting with about 5 feet total run. My question is, should I be getting that much of a smell from engraving and cutting a 4.25 inch circle (screen shot of the item attached)? I'm thinking I should not be. If that is the case, is it that I don't have enough air moving through the exhaust system to pull it out of the laser fast enough? I'm pretty sure the odor is coming from the 6 laser tube cooling fans on top of the Epilog. I know it's not coming from any leaks in my exhaust system.

280130

Thank you for any help or advice,

Keith

Mark Sipes

01-17-2014, 9:22 PM

I had a problem with my exhaust going into my neighbors place of business 50 ft away. Could not figure how the odor ( burning walnut) was making it that far and still being so strong. My laser vents to the outside via an inline fan with a 4 ft run so the smoke was venting out of my business out the dryer flap vent. Well the smoke was shooting straight down to the ground into a crawl space access and over to the neighbors business heater/ac fan unit........a simple cover deflected the down draft and problem solved.........

I would buy a can of smoke ( smoke detector tester) and power up the laser and fans at normal and track the smoke and see where the air is flowing.....might be surprised to see where the leaks are.....
.
.

Dan Hintz

01-17-2014, 9:44 PM

Where is the fan in relation to the output?

It should be:
Laser --> Duct --> Fan|Outside

You should be pulling air into the outside environment, never pushing... and your fan itself could be leaking, so check that.

Jerome Stanek

01-18-2014, 6:58 AM

Where are you exhausting the laser through the wall or out a window. If you put the fan right at the exhaust point and draw the smoke and odor it would be better

Mike Lassiter

01-18-2014, 7:43 AM

You also need to consider where the air that you are exhausting out of the room or house is being drawn back in from. If you have air going out it must be replaced somewhere. Is it possible air is leaking around a window by the exhaust outlet and being sucked back into the room or building?

Keith Upton

01-18-2014, 8:39 AM

Thanks for the replies everyone. My exhaust is set up like this:

Laser --> Duct --> Fan --> Duct -->|Outside via window

I know that is not ideal at all, and I have some parts on order that will allow me to set it up as Dan suggests (Laser --> Duct --> Fan|Outside via window).

I've leak tested everything on the output side of the fan (soapy water method) and there are no leaks there. I also sealed the fan itself. Right out of the box it was not air tight at all. I exhaust out the window that is next to the laser. I put a 3/4 board with a 4" hole in the window and sealed it with weather stripping. I have to compress/force the sides and bottom down into the window opening, so no leak back there. The window just closes down on top of the board, so there could possibly be some leak back there of odor, but I don't think it's that.

When I smell around the window, before the smell gets strong in the room, I don't smell anything there. I do smell the odor right away when I smell at the laser tube fans on top of the machine.

My return air is just coming from the house in general. I don't have another window in the office that I open up while my lasering... as the only other one is right next to the exhaust window and I did not want to pull that air back into the room. Sometimes I close the one office door to help keep the smell out of the rest of the house, but perhaps that is adding to the odor problem by not allowing enough return air into the room?

I have borrowed my friend's anemometer and measured the CFMs coming from the fan alone and at the end of my exhaust run. I'm losing just over half my CFMs with the current run (one of the reasons I've ordered new exhaust parts to let me remove pretty much all of the silicone flex hose). I plan on running two 90° coming out of the laser into the fan, then straight out the window (fan reducer will connect directly to the opening in the window).

When I laser other smokey materials, I can see the smoke being pulled out of the laser chamber, but I would not say it's getting removed super fast.

So, barring any exhaust leaks or the bad air getting pulled back in the room as part of the flow cycle (both of which I will test and address again), would higher exhaust flow reduce odor around the laser? I mean, you guys that have yours setup and running production stuff, can you smell strong odors while you are cutting?

Keith Upton

01-18-2014, 8:44 AM

I would buy a can of smoke (smoke detector tester) and power up the laser and fans at normal and track the smoke and see where the air is flowing.....might be surprised to see where the leaks are.....
.
.

Mark, where can you find those cans of smoke? I did not see them listed on Lowe's or the HD websites.

Mike Lassiter

01-18-2014, 9:00 AM

Another thought - you said you are loosing 1/2 of fans rated cfm if I understood right. Maybe need to consider air tightness of building and fan trying to pull more out than building leakage letting back in. I know this may sound odd but try cracking a window to allow air in. If air cannot enter building the fan is effectively starved for air. For fan to remove 400 cfm for several minutes of running time that much air must be available for it to move. Think of your car or lawnmower with stopped up air filter.

Joe Pelonio

01-18-2014, 9:28 AM

I have a similar setup with about 4'duct, then fan, then 3' duct and out, with no fume problems.
My fan is 800 cfm and I always crack a window to allow it to come in to replace what goes out.
Another thing that helps is leave the fan running and wait 10-30 seconds before opening the top to remove the items to ensure that the last of the fumes have been extracted.

Keith Upton

01-18-2014, 9:59 AM

Thanks Mike and Joe. I'll try opening a window in an adjacent room and see if that helps with the flow (I'll measure it with the anemometer to see the difference). I also try and wait a few seconds to let all the fumes get pulled out before opening up the laser.

Dan Hintz

01-18-2014, 10:49 AM

Another thing that helps is leave the fan running and wait 10-30 seconds before opening the top to remove the items to ensure that the last of the fumes have been extracted.

That was going to be my next suggestion... annoying when you're trying to crank through a number of items, but if you want to cut down on smell, you gotta do what you gotta do.

Keith Upton

01-20-2014, 2:03 PM

Well, looks like MLK day is going to delay my exhaust parts another day :(

Joe Hillmann

01-20-2014, 2:52 PM

Does it start to smell when you are cutting or once you open the laser and take the parts out. There are many materials that will hang on to the smokey smell after they are taken out of the laser and will stink the place up from a few hours to even days after it is engraved.

Keith Upton

01-20-2014, 5:26 PM

Chuck Stone

01-20-2014, 8:31 PM

Another thought - you said you are loosing 1/2 of fans rated cfm if I understood right.

You can lose that just by using flexible duct. 90° turns, blast gates, dryer vent flaps.. they
all suck down the cfm, probably more than anyone realizes.

Keith Upton

01-20-2014, 8:52 PM

Well, my short 6-4 reducers did show up this evening. I've put some silicone around them and attached to my blower. They should be dry when I come home from work tomorrow and I can start hooking everything back up and see what I get. I'll be removing about 8 feet of flex tubing (though it's silicon, so the inside walls are almost completely smooth on the straight sections) and lots of sweeping bend. I'll still have to have two 90° elbows, but at least those will be metal and a lot smoother.

Mike Null

01-21-2014, 6:10 AM

The 90 degree L's are extremely inefficient. If you could use adjustable joints instead you can gain some efficiency.

Keith Upton

01-21-2014, 6:41 AM

I already have two of the adjustable joints, but how would they be more efficient? They are still going to have to be 90° bends right?

Tony saunders

01-21-2014, 7:09 AM

I already have two of the adjustable joints, but how would they be more efficient? They are still going to have to be 90° bends right?

Hi Keith,

I have been having an ongoing saga with the out-to-air exhaust venting with my Trotec 400! - and I'm not alone it seems.

I found through trial and error how my exhaust system went from unusable to quite good (not perfect but it now works!) - by eliminating several small factors rather than thinking that it was possible to make one significant change. ( Jason Lefton on here has been leading the charge on this as it seems that the Trotec 400 has a chaotic airflow when using certain table configurations - but that's an aside)

I reduced corners and lengths between laser -> exhaust fan -> output and made any turns as gentle as possible.

I used two 45 degree connectors to replace a 90 degree one and it made a lot of difference. It made an abrupt turn into a curve and improved flow.

I can make it better yet once I replace a couple of flexible bits with proper, smooth metal piping.

Little by little it's improved when any hard turn was removed - even if it added slightly to the lengths.

HTH

Tony

Keith Upton

01-21-2014, 9:34 AM

Thanks Tony. Knowing that length is better than hard bends is good to know. I might be able to do two near back to back 45° turns instead of a single 90° if that would help. I could also look at putting a slight (less than 10°) bend between the fan and window (right now the plan is to have the fan connected right to the window opening). That might add a few inches of length on the output side, but free up a couple of degrees on the intake side.

Tim Bateson

01-21-2014, 11:55 AM

My new shop is several times further away from my fan than it use to be. I now have a massive reduction in fumes & smoke. The difference - I believe, is I moved from flexible tubing to rigid PVC pipes. Quieter too.

Keith Upton

01-21-2014, 12:33 PM

So would two 45° PVC joints work better than two of the adjustable metal ones?

Mike Lassiter

01-21-2014, 1:30 PM

Straight pipe flow is best. Any change of direction will affect flow to some degree. Metal pipe preferred as it will avoid static electric buildup. Metal connected to metal blower housing which in turn to motor which should be grounded to electric power source. I don't know just how important static buildup is, but know Penn State sales ground wire for duct work. I have flexible plastic (6" diameter) that connects my metal ductwork to blower and 3 4" ones attached to laser then metal ductwork. Never seemed to cause a problem (yet anyway).
Smooth inside ductwork walls and minimum bends will give you best air flow. Air is like water in regards to flow. Neither likes direction change and will have "some" flow loss in everything - even straight pipe.

Tim Bateson

01-21-2014, 3:25 PM

Here are a couple shots of my new pipe. The bottom elbow was accidentally put in upside down - the bottom is a clean-out. I have much better air flow now than I did with flexable pipe - even when the fan was just above the laser. The current tubing run is 15 feet between the laser & the fan. All joints are glued - except the clean-out. Joint between the laser & the PVS is wrapped with Heating Duct Tape. * Note - this is not "duct tape". That heavy gray "duct tape" has 100's of uses, but heating & pipe duct work is NOT one of it's uses. This is a thin metallic looking plastic - Very Sticky & will not dry/harden when it is heated or cooled.
280407280408

Keith Upton

01-21-2014, 3:41 PM

And what type/rating of fan are you using Tim?

Tim Bateson

01-21-2014, 4:33 PM

I can't say for sure, but looks a lot like this one: http://www.harborfreight.com/1-hp-mini-dust-collector-94029.html

Dan Hintz

01-21-2014, 7:11 PM

I can't say for sure, but looks a lot like this one: http://www.harborfreight.com/1-hp-mini-dust-collector-94029.html

Loud sucker, ain't it...

Tim Bateson

01-21-2014, 7:14 PM

Loud sucker, ain't it...
It use to be. Moved my shop to another part of the basement & left the blower where it was. I have a light on the blower switch so I don't forget it's on.

Chuck Stone

01-21-2014, 8:12 PM

I don't know just how important static buildup is, but know Penn State sales ground wire for duct work.

I don't think that's anything we need to worry about.. that's more for sawdust collection,
which can build up in the pipes if the airflow isn't sufficient. And without moving enough
air, there's a much better chance of hitting that 'sweet spot' where the ratio of dust to
air is just right and can be ignited by a spark.

Keith Upton

01-21-2014, 9:38 PM

Well, I was not able to get any of the 4" PVC piping to work. There is just not enough room to route it in the space I have. I can get two of the adjustable metal elbows to work connecting them at odd angles to each other, using the silicone flex tubing to span the 1" gap between them. It was already dark by the time I got that setup, so no CFM readings or testing.... maybe tomorrow.

I can't say for sure, but looks a lot like this one: http://www.harborfreight.com/1-hp-mini-dust-collector-94029.html

Thanks. I think that L configuration for the inlet and outlet openings would be much better for my confined space, but I'd have to have a quite one as it has to sit in the office right behind the laser with me :(

Speaking of noise and fans, what makes the inline fans so quite compared to these others? Is it the type of motors used?

Keith Upton

01-23-2014, 10:14 AM

Okay, since the 4" PVC did not work out for me, I went back to the original idea I had when first thinking about buying the laser. That was 4" silicone intake hosing used in the performance automotive industry:

http://www.wingsofwar.org/forums/attachment.php?attachmentid=120953&d=1390488456

They have about a 5mm wall thickness and are 9 ply (alternating plies of silicone and support layers). They have a tiny bit of flex to them, but not very much (you can get "hump" couplers that allow up to 20° of flex if you need it for alignment) . The inside is completely smooth. They a heat tolerance of -40° to 392° Fahrenheit. They can be cut with a razor blade. You can find bends of 30°, 45°, 60°, 90°, 135°, and 180°. I also picked up what is called T Bold clamps:

http://www.wingsofwar.org/forums/attachment.php?attachmentid=120954&d=1390488914

These will really allow you to tighen down on the hoses and you can actually see them squeezing into the silicone hoses (unlike the cheap worm clams that just tighten until they lose grip).

So, I redid my exhaust system using these parts last night. Here is the space I have to work with:

http://www.wingsofwar.org/forums/attachment.php?attachmentid=120930&d=1390477211

You can see the exhaust coming out the back of the laser and the window I have to exit out of right behind it... it's a pretty tight spot!

And here is the exhaust setup I went with:

http://www.wingsofwar.org/forums/attachment.php?attachmentid=120929&d=1390477209

The opening in the lower left is what attaches to the back of the laser and the outlet on the right is what connects to the window pipe (can be seen in the photo above, on the wood piece on the right of the photo).

The system fits in the space nicely and is actually even quieter than it was.... but I still have the smell!!

I also did some more anemometer readings last night. The fan claims to be rated at 440CFM, but with the 4"-6" reducers on it (nothing else), it was only putting out 239CFM (I'm pretty positive I did my conversions and math correct to go from inches to feet for the area). That seems really low for nothing but a set of reducers on it. I then attached it to my window insert and took another reading outside, that showed 179CFM. Finally hooked the whole system up to the laser and again took a reading outside, 172CFM this time. So, that crazy S bend coming from the laser to the fan only cost me 7CFM and the whole system only eats up 107CFM. I think that is pretty good.

This afternoon I plan on running to Harbor Freight and getting one of the noisy dust collector units. I'll take CFM rating on it and see what the results are.

One question for this post, is there any way that the odor could be escaping into the room via the air assist? I know the smell will be stronger when vector cutting, but sometimes it seems like I get a puff of odor when the air assist shuts off after cutting.

Mike Lassiter

01-23-2014, 10:30 AM

Keith you spent some money on those silicone hoses and clamps. My trade is diesel truck mechanic and very familiar with those. They are not cheap.

Keith Upton

01-23-2014, 10:58 AM

Keith you spent some money on those silicone hoses and clamps. My trade is diesel truck mechanic and very familiar with those. They are not cheap.

Yeah, they are not cheap. But the overall damage was not too bad. With everything for the hoses I'm at about $115. That would have been nothing if it got rid of my odor though. lol

Mike Lassiter

01-23-2014, 7:40 PM

Seeing a picture of your fan, I think it is a lot of the problem. I think it is an axial flow fan (air flows straight thru it, fan blades similar to a regular fan) if so as I understand these type fans have very limited static pressure ability. You need one (can' recall terminology) than pulls air in at center of fan and blows out 90 degrees to inlet. Most dust collector motor and fans are made that way I think. Harbor Freight has one.

This type can handle more static pressure than what I believe you have.

Keith Upton

01-23-2014, 9:31 PM

I picked up a HF dust collector (http://www.harborfreight.com/1-hp-mini-dust-collector-94029.html) today to try out...

http://www.wingsofwar.org/forums/attachment.php?attachmentid=120984&d=1390529928

It says it's rated at 914CFM, but when I measured it, it was only putting out around 588CFM. This new fan connected directly to my window "port" dropped down to 370CFM (363CFM if I closed the door to my office) and down to 312CFM once hooked up to my laser via the hoses above, but in this configuration:

http://www.wingsofwar.org/forums/attachment.php?attachmentid=120985&d=1390530510

I cut some more acrylic and I did not smell anything coming out of the heat fans on the top of the laser, but...

http://www.wingsofwar.org/forums/attachment.php?attachmentid=120986&d=1390530511

See those slits on the grey metal right in the middle, that is how the fan cools the motor. It blows air right out of the fan and into the room! How are you guys and gals using these types of fans if they can't be sealed off??

Mike Lassiter

01-23-2014, 9:42 PM

Most are rated free flow with no restrictions either side. Hardly how they are really used. I think there's something about the color of the fans being mentioned here before. I cannot recall if the red one is supposed to be recommended to be pretty good or not good. Perhaps someone else will chime in on that.

Keith Upton

01-23-2014, 10:12 PM

My measurement of 588 was with no attachments to the fan at all and not connected to any thing. I think all these fans are highly over rated on their CFM outputs.

john passek

01-23-2014, 11:01 PM

Hi Keith
I have a similar fan to your red one, I used a 90 right at the machines outlet then ran a 4" Flex hose about 6 ft out a window like you, it goes straight into the fan which is outside the window.
I have no issues with smelly exhaust air coming back into the shop and it seems to have enough pull for anything I cut or engrave, the shop is a lot quieter too which is good because it's in my basement.
Just a thought you might try if nothing else works.

Jerome Stanek

01-24-2014, 7:17 AM

I had the red one and it was so loud I took it back and got the green one.

Glen Monaghan

01-24-2014, 8:45 AM

When I used a fan similar to that, it was mounted in a box just outside the window rather than inside the room.

Keith Upton

01-24-2014, 9:35 AM

I had the red one and it was so loud I took it back and got the green one.

Jerome, is this the green HF DC (http://www.harborfreight.com/garage-shop/stationary-dust-collectors/13-gallon-industrial-portable-dust-collector-31810.html) you got? It's only rated at 660CFM, and with the readings I've been getting from these fans right out of the box, that's really going to be more like 300 something CFM. Not sure if that is going to be enough.

Jerome Stanek

01-24-2014, 12:28 PM

That was the one I had but it was hooked up to my CNC router and did a very good job of dust and chip removal.

Keith Upton

01-24-2014, 1:42 PM

So you never used it on your laser?

On another note, the wife as signed off on me swapping one of the girls with my office. This will give lots more room and make it so I can have the fan outside the house as it will be in the backyard. So, the problem might have solved it's self. lol

Keith Upton

01-25-2014, 7:00 PM

Okay, so I've moved rooms and now have the laser setup in the basement with a straight shot out the window to the fan in the window well...

http://www.wingsofwar.org/forums/attachment.php?attachmentid=121078&d=1390693054

http://www.wingsofwar.org/forums/attachment.php?attachmentid=121079&d=1390693056

Laser > 8" duct (3") > Window > 8" duct (3") > Fan

I did have to step down to a 3 inch pipe, but my reading at the exit of the fan is now 578CFM. I'm also able to feel air being sucked in for the first time at the front of the laser!

I just started engraving some BB and I still have a very strong burning odor in the room :(

I've uploaded a cell phone vid (http://wingsofwar.org/temp/LaserSmoke.MOV)where you can see how fast the smoke gets sucked out of the cutting area. You have to watch really close, above the ruler next to the word Glory at the top of the laser (left side of the vid).

Anyone have any thoughts on this?

Mike Lassiter

01-25-2014, 7:07 PM

With exhaust fan outside and sucking from inside there shouldn't be any air that can get out inside laser & room. Maybe try laying cigarette lite inside cabinet with unit on and exhaust off and see if cigarette smoke is getting draw by laser cooling fan thru a leak inside cabinet.

Chuck Stone

01-25-2014, 7:09 PM

I'm wondering if someone installed a fan backwards in the machine..

Keith Upton

01-25-2014, 7:23 PM

Now that that file is cutting, the smell is super strong and I was able to pin point it to this location...

http://www.wingsofwar.org/forums/attachment.php?attachmentid=121080&d=1390695741

Keith Upton

01-25-2014, 7:24 PM

Keith Upton

01-25-2014, 7:33 PM

So should the cutting chamber be completely sealed off from the lasers cooling fan area in the back? When I first had this odor problem, I called Epilog tech support and they said it was not a completely sealed area. Meaning that if the exhaust is not strong enough, some smoke/odor would come out the cooling vents. Does that sound right?

Matt Davis

01-25-2014, 9:39 PM

280802

If it helps, here is a look at the area in question with the rear cover removed. From what I could tell while changing my tube and other supporting parts the other day, it's reasonably well isolated from the engraving area.

Keith Upton

01-25-2014, 10:49 PM

Thanks Matt. So there were not direct openings from the engraving area to the back side? There has to be a "leak" in mine. I just can't imagine this much odor with that much exhaust flow being normal. I mean, when I when to the Epilog factory and we did some test cutting on acrylic and foam, there was not odor at all until we opened the lid and pulled the parts out.

Matt Davis

01-26-2014, 9:16 AM

It's pretty much a solid wall. The screw holes for mounting the tube do seem to go all the way through to the exhaust cavity, but obviously they're blocked by the screws themselves. I generally get a touch of smell when I'm cutting, especially extruded acrylic. But, I don't generally worry about it. My wife, on the other hand....that's a different story.

Keith Upton

01-26-2014, 10:01 AM

Thanks again. I'd not worry about a touch of smell either, but I have a lot of odor :(

Mike Lassiter

01-26-2014, 10:03 PM

Thinking out loud - what about hooking your first blower up to blow into the exhaust port with the back cover off and see if there is a leak. Cigarette smoke would locate a draft to help isolate problem area.

Keith Upton

01-27-2014, 9:53 AM

Thanks everyone for the help on this. I'll be calling Epilog this afternoon with I get home from work, but in the mean time could one of you guys with a Mini 24 please check these things for me...

With the laser turned on, but your exhaust system off:
Do the round cooling fans on top of the laser pull air into the laser tube area or push it out?
Do the slots on the back of the laser let air in or let air escape (in red in the photo below)?

http://www.wingsofwar.org/forums/attachment.php?attachmentid=121080&d=1390695741

With the laser turned on and your exhaust system running, does the airflow direction change for either the round top fans or the slots on the back of the laser?

With my laser on and no exhaust running, the top fans pull air into the laser tube area and the air escapes out the slots along the back. When I turn my exhaust system on, the top fans continue to pull air in, but the slots on the back also suck in air.

That tells me that my exhaust system is strong enough to pull air from outside the cabinet through the back (how I'm able to smell orders coming out there is beyond me) as well as the vents in the front door.

Tim Bateson

01-27-2014, 10:09 AM

...
With the laser turned on, but your exhaust system off:
Do the round cooling fans on top of the laser pull air into the laser tube area or push it out?
Do the slots on the back of the laser let air in or let air escape (in red in the photo below)?
...

Pull air in -I use a very breathable mash over these to filter dust.
The slots in the back do let the cooling fans exhaust.

Keith Upton

01-27-2014, 10:17 AM

Thanks Tim. Do the slots still exhaust the cooling fans when you have your exhaust system turned on, or does air get sucked in then?

Tim Bateson

01-27-2014, 10:27 AM

I'll check tonight, but I doubt it. You may have a weld crack somewhere in the exhaust internally (in the cooling fan/laser tube compartment). You may want to check with Epilog Support. A quick phone call may resolve or confirm an issue there.

Keith Upton

01-27-2014, 10:37 AM

My first call to them a week or so ago was "it's an exhaust issue, that's not our area". So I wanted to make sure I knew more about how it should be working for when I call them this afternoon. Thanks.

Mike Lassiter

01-27-2014, 11:39 AM

I bet you are fit to be tied! Going to be very aggravating to have gone thru all of this to find something in back wall of cabinet allowing cooling fans to pull fumes out of cutting area into room

Keith Upton

01-27-2014, 12:27 PM

I bet you are fit to be tied! Going to be very aggravating to have gone thru all of this to find something in back wall of cabinet allowing cooling fans to pull fumes out of cutting area into room

Yes, it will be very frustrating. But I'll have to look on the bright side, the wife suggested I switch my office to one of the rooms in the basement as a solution to this (straighter ducting and fan outside the house). This new room is about 75% larger ;) and I sorely need the space! But now the problems is going to be, I purchased the Mini 24 based on the limited space I had upstairs! Had I had more room, I would have looked at a larger laser. lol

Keith Upton

01-27-2014, 6:03 PM

Talked with Epilog this afternoon and told them that when my exhaust is running, that it is pulling air in from the laser tube venting slots on the back of the laser. They said it should not be doing that, but can't think of how it's happening. They agree that there could be a hole or crack someplace. I'll be pulling the back off this evening and looking for any signs of of a crack. In the mean time, they are checking their schedule to see when they can get it in for a repair. The good news is that I only live about 1.5 hours away from their factory and can just drive it up there. More to follow if I visually see any issues.

Mike Lassiter

01-27-2014, 6:08 PM

maybe you can trade it on a bigger one when you go. :)

Keith Upton

01-27-2014, 7:22 PM

lol, thought of that! But the saga continues. I pulled the back and side covers off and the cutting chamber is not sealed in any way from the electronic/tube area. So that theory is shot.

But I think I have over looked something. The seal around the wood I put into the window is airtight, but I don't think between the two pains of the window is when it's open. So, I'm thinking now that the exhaust system is sucking all the air/odor out of the laser, dumping it out into the window well and then sucking it right back in between the two window pains and into the room. I'm going to put a duct on the output of the fan and exhaust it away from the window area as much as I can and see if that helps/solves the issue.

Dan Hintz

01-27-2014, 7:29 PM

The seal around the wood I put into the window is airtight, but I don't think between the two pains of the window is when it's open. So, I'm thinking now that the exhaust system is sucking all the air/odor out of the laser, dumping it out into the window well and then sucking it right back in between the two window pains and into the room. I'm going to put a duct on the output of the fan and exhaust it away from the window area as much as I can and see if that helps/solves the issue.

If the window is all of the way up, it should "reseal", so to speak... but yeah, part way up and you have a 1/8-1/4" gap between seal and upper window panes (at least for most windows).

One way to test it is to apply some tape across the window top and temporarily seal it.

Keith Upton

01-27-2014, 7:37 PM

It's a side ways opening window, but same principle. And it's not open all the way, it's about 4.5" from being all the way open. Kind of mad at my self for not thinking to check that, for 20 years my job was to trouble shoot stuff. lol

This could have been the issue when I was running the blue fan upstairs as well (top opening window, not all the way open either). But hey, if this is what it finally turns out to me, at least I got a much larger room out of the deal :D

Mark Ross

01-27-2014, 8:54 PM

Keith Upton

01-28-2014, 11:36 AM

There was a post by some whiz bang wizard here a while ago, some magician named...if I am not wrong, Dan, who made a carbon scrubber. You should be able to find it. Acrylic (we cut it all day) is acrid. Consider building a scrubber. Or move out in the country, where the deer can't figger out the smell and you can shoot 'em lol. We moved and in our new building, we have Dan's scrubbers.

If it turns out to be the odor is just being sucked back into the room, a scrubber would indeed solve that issue. But this whole time I was under the impression that the leak was not in the exhaust system, so a scrubber would not have helped.

Assuming the odor is "suck back" (which I think it is) than my two options will be either building a scrubber and keeping everything down in the window well, or just running some hard pipe up and out the window well and connecting the fan there. the first option gets rid of the smell completely, but has an on going cost in materials and maintenance. The later one does not get rid of the smell, only moves it. The drawbacks here are the neighbors could complain about the smell and the noise could be louder. The pluses are no on going costs and it gets the exhaust pluming above ground so water going into the laser would not be a concern.

Dan Hintz

01-28-2014, 3:14 PM

There was a post by some whiz bang wizard here a while ago, some magician named...if I am not wrong, Dan, who made a carbon scrubber.
Since people keep asking about it and I never remember to keep the link around, I finally just posted it to my blog. I'm working on a new, improved version... slightly more costly (should be able to keep it <$400, shooting for <3), but easier to charge with new carbon and clean the filters.

If it turns out to be the odor is just being sucked back into the room, a scrubber would indeed solve that issue. But this whole time I was under the impression that the leak was not in the exhaust system, so a scrubber would not have helped.

Come winter time, I can't imagine being without the scrubber. It allows me to work in a warm environment without drafts and without a huge electric bill.

Tim Bateson

01-28-2014, 5:33 PM

...when my exhaust is running, that it is pulling air in from the laser tube venting slots on the back of the laser....

That sounds like the problem. If this is happening then you likely don't have enough pull inside the chamber to pull all of the smoke and smell away. Checked mine and it blows out from those vents when the cooling fans are running. With the laser off & blower on, there is no airflow at all from these vents.

Keith Upton

01-28-2014, 6:11 PM

Epilog tech was surprised I was pulling air in through the back vents, but if you pull the side covers off, there are huge openings in the side bulkheads that allow the cables and such to pass from the back of the laser around to the side. So it is in no way a sealed area. With that area completely open to the cutting camber, it makes sense that I'd be sucking air in through those slots as well. You should pull one of your side covers and see if you have those openings as well.... just out of curiosity.

On the main subject, I put weather stripping on both sides of the open window gaps, sealed those off with good old duck tape and ran some flex tubing from the fan up out of the window well and down the house a couple of feet. I've been engraving wood for 16 mins now and no a bit of odor!! I think I might have finally solved the problem. I also did a quick reading and I'm only getting ~350 CFM at the end of that run now. Seems to be enough, but I liked it better when I had a lot more flow. I'll most likely be doing hard pipe in the next day or so to replace that flow robbing flex tubing.

Keith Upton

01-28-2014, 7:38 PM

Well, I just cut and engraved some 1/8 Baltic Birch with no odor at all. I also cut and engraved the image that was in the first post with no odors. I'm now 6mins into more acrylic engraving with no odors. I think at this point it's safe to say my issue is solved!!

Thanks to everyone that have suggestions and offered help/advice. It all helped me work through this and increased my knowledge.

Joe Hillmann

01-28-2014, 9:21 PM

How are you measuring your CFM? Or more specifically where did you find the charts for the pitot tube/ annonmeter that go low enough to tell you the airspeed in your pipes? When I looked the only charts I could find were for airplanes and were for much higher speeds.

Keith Upton

01-28-2014, 10:48 PM

I'm using an Extech Instruments CFM/CMM Thermo Anemometer, Model AN100 (http://www.extech.com/instruments/product.asp?catid=1&prodid=2). You calculate the area of your duct and input that and it does everything else. I was taking my measurements with the Vane as flush to the duct opening as I could get it each time.

Mike Lassiter

02-01-2014, 3:53 PM

not sure I understand the root cause - but think you are saying you were pulling outside air back in around the piece you had made to go in the window opening to allow the exhaust to go outside. Duct taping around the window was what stopped you from getting the odor in the room?

Keith Upton

02-01-2014, 4:30 PM

Hi Mike,

It was not the wood adapter that I made and inserted into the window. That was sealed off good with weather stripping. The problem was that when you open a window part way, there is no longer a seal between the part of the window that slides, and the part that is stationary. There is a gap between those two parts with partially open. The exhaust system was pulling the stinky air that it had just pumped out of the room, back into the room from that gap. Once I found that, I sealed it off with weather stripping and covered that with duck tape to ensure it was as good a seal as I could get it. Is that clearer?

Mike Lassiter

02-01-2014, 4:54 PM

Yes. Keith that makes sense. You test you exhaust air flow with another window cracked to allow air back into the room and see if the cfm increased over what you reported?
If you are exhausting 400-500 cfm out it HAS to be replaced somewhere or you will start starving the blower for air to exhaust. That would aggravate fumes getting back in the house as it would be under negative pressure relative to the outside of the building.

Keith Upton

02-01-2014, 5:07 PM

Yes, I tested it with a different window open in the house. No change to CFM. I don't think I was starving it for air, I just think it was easy for it to pull the air from outside the window. Cold outside, warm inside, the air wanted to come back in anyways.

Mike Lassiter

02-01-2014, 5:23 PM

There are a lot of places for air to be drawn back into houses. Got a fireplace?, furnaces, over the range microwave that is vented outside ( they do have a damper that attaches on the back or top to prevent air coming back in, but it's not 100% effective) exhaust vents in bathrooms, clothes dryers, around doors and windows. Around receptacle and light switches on walls, thru holes cut in cabinets for drain and water pipes and even pull air back through the vent pipes on plumbing that go thru the roof. Very hard to make houses air tight, but not exactly good to have them that way either. We do need some fresh air in which I guess you get in a pretty tightly built house by entering and exiting doors.
Anyway, I can understand now that it wasn't the laser itself that was the problem at all, it was sitting very close to the window which was the real problem. Glad you got it figured out.