The agony of Upgrading to 5" or 6" tool ports

[Scott Driemel]

Well, I spent a good hour looking at posts related and think I need to ask the gang for a more direct answer. We all buy machines that usually come with a 4" dust exhaust port. (Okay some of you did buy super deluxe machines that do come with larger, but I'm asking about us others who buy the regular sized ones) Without the repeat of "why do they do it" part when we know a 5" or 6" port is better, let's jump to what is the fix. ;)
There are lots of good discussions on where to go to buy hose, duct, gates, etc but I can't find any that actually go right to the root of my problem ... the actual tool port. A few threads on adapting scrap together items to create a new flange. (often invlolving a bit of welding)

But here's the crux of my question; Has anyone found a place to buy 5" or 6" ports that are easily retro-fitted to our usual brands of woodworking machinery? Realizing a larger hole may have to be cut on occasion to accomodate and a piece of weatherstripping or the like needs to be used (or silicone), so what have people used that's easy and reasonable to make or buy?

Although I can perform most type things in the shop, fabricating metal from scratch is not my strong suit. (especially metal) I'm again hoping, there is a place where hopefully someone can direct me to simply order on line, round or rectangular, 5" or 6" flanges (ports) than I can re-fit to my machines. Lots of recommendation threads about all the related equip for a DC system, just can't find one on actual store bought enlarged ports. I would have thought Oneida, Grizzly, Clearview, Laguna, Penn State, etc would have provided these as it is such a no-brainer to not choke down their systems with the stock tool ports (4" on most machines).
If anybody can direct me or give me an idea of making these which doesn't involve nuclear physics it'd be much oblidged.

[Erik Christensen]

i used the process that is described on bill penz's site on how to use heat to soften & mold PVC. I don't weld and the PVC was easily shaped with heat - it may not look pretty but it has worked without issue for 4+ years.

[John Lanciani]

Starter collars for ductwork are available in both 5" and 6" sizes from the BORGs. the tabbed end (bottom in pic) goes into the hole you cut in the cabinet and the tabs are bent over to secure it. Flex hose fits on the crimped end and you're in business.

Also, if you look at my post here; http://www.sawmillcreek.org/showthread.php?139804-Dust-collection-install&highlight= you might get a few ideas.



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[Brian W Smith]

Some general rambling here that may help?

To begin with,I hear you on this situation....we found the same thing(too small,or poorly designed machine ports).We simply make our own.....mostly 10 G.So start with a little researching on "gauge metal".Learn what thicknesses these are and try to qualify your requirements.Meaning,measure the thickness of the metal on the machines hood(where applicable,may not have one,or it's.....not right?)....now hit some gauge metal tables and try to put some numbers on it.

Next,if you're not going to make it.....how about modifying?Meaning,if you found a source for tubing...it's most likely going to be square ends.Are you capable/willing to do any fishmouthing(required if making round to round connections)?Remember,we're talking gauge metal here...not heavy wall pipe.

Now,if I couldn't find the perfect size over the counter....and you'll likely not,because of the nature of these fittings(they never seem to be the right ID/OD)....I'd find a sheet metal shop close to home.This most likely isn't going to be a typical HVAC joint.They deal with much thinner gauge material.Further,auto resto type places also don't work with thick enough material(generally).Try an old school roofing co......It's not about roofing,it's about all the associated fabrication that they're required to build.We're lucky here to have exactly that.

But theres still some work on your part.Lets say you came to my shop(AM NOT SOLICITING)....theres deffinately two prices.One,would be you show up with prints.Nuthin fancy,just the facts ma'm....thats the cheap price.If you showed up with just some vague description,requiring us to actually engage our brains....well,the price would reflect that.Just saying...the easier you make it on the fabricator the less problems there'll be.

Money is a wonderful thing....duh.Once you get a relationship going with a fabricator,and he sees theres some future biz in it....he'll most likely steer you in a helpful direction.Vs....a one-timer.So explain the situation and see if theres any interest?And remember to remind him "cash is king"......a lot of these jobs are so small,runnin it through the books is more trouble than it's worth.If he's not interested,maybe he can steer you to someone who is.

Another avenue....hit up your local pro welding/gas supplier.Catch them mid-week....and NO PHONE CALLS......go in,introduce yourself and see if one of their customers works with gauge metal and can roll you some fittings.The benny here,if you find the right "guy" is,they'll be able to Tig up your fittings.

Hope this helps.

[Eric DeSilva]

I upgraded a few machines and it wasn't hard at all. I used these: http://www.clearvuecyclones.com/supporting-products/38-blast-gate-6.html

They are well made and--more importantly--the screws holding the sides together can easily be removed to allow you to screw through the plate and attach it to something else. I used 1/4" plywood (but no reason you couldn't use sheet metal), cut a 6" hole, mounted the blast gate in the plywood, and then screwed the plywood to the opening of my machine. Provides a 6" attachment for ducting and gives you a blast gate at the machine. Both my jointer and table saw had the 4" duct in a plate that was easily removed, so if I ever want to return the machine to its original configuration for sale, it's a snap.

[Jim Andrew]

I used a piece of 3/4" ply and a piece of 6" 26 gauge pipe to upgrade the opening on the cabinet of my unisaw. It came with a 4" plastic fitting with a flat flange which screws to the cabinet. Just used the plastic one to trace the outside and holes onto the ply, then cut the hole for the 6" in the ply. Made the hole as snug as I could fit it into, and used screws to attach the pipe to the ply. Plan to pick up a 110 volt flux wire welder at Harbor Freight today, they have a parking lot sale and are selling the welder for 80$. Plan to use it to put a new 6" flange on my edge sander. A lot of dust escapes on it with just 4". You don't have to weld the flange solid, most of these tools just have 1/4 to 1/2" spots of weld in 3 or 4 places around the diameter. Will seal it with silicone.

[Brian Backner]

Someone is welcome to correct me if I am wrong, but I think you could simply use a 4" to 6" adapter and run your 6" piping to the machine. The reason I suggest this is that I've read that the restriction placed by this arrangement is inversely proportional to the length of the smaller diameter section. I think the actual formula is on Bill Pentz's site. So, you wouldn't be choked down fully to the 4" diameter's restrictions until something like four to six diameters away (so 16 to 24" worth of 4" ducting before going to the 6"). This also assumes that the original port opens up into the body of the machine, i.e., there isn't 24" of convoluted 4" duct inside the machine before it gets to the port.

Will this be as good as installing a 6" port? No, but it might be as good as going to a 5" installed port. If it were me, I'd give it a try before carving up a new-to-me machine.

Just my two cents. YMMV

Brian

[Jim O'Dell]

Actually, if you change the pipe diameter with a reducer, I believe you are limiting yourself to the flow of the smaller size, no matter how short or long the the piece is. But I could also be wrong on this.
I have changed one machine from 4" to 6". My Grizzly G0691 table saw. I used all PVC to do it. I marked and cut the hole in the access door. Lucky for me on this saw, it is a removable panel, but cutting the side out on a normal TS wouldn't be much harder. I used a jig saw with a metal cutting blade, then filed the hole to get the best fit. Painted the edges. I siliconed the joint. I had this coupled to a home made blast gate and made 4 pieces that I ran bolts through to secure it to the saw. The first picture is on the inside of the cabinet. 284189
The next 2 are from the outside. 284190284191 This was very simple to do. Hope it gives you an idea or two. On the piece of pipe from the blast gate to the saw I think I used a piece of coupler so that it covered any gaps between the metal and the pipe.
I wish there was a way to do this to the existing port on my bandsaw, but the factory 4" pipe is on the narrow edge of the saw, and there isn't enough room there, I need to figure out a way to build a shroud under the table to try to catch some there. My home built router table has 6" round to a 2X8 (IIRC) HVAC adapter and works very well. I even have 6" to the bottom of my contractor saw. Good luck and be sure to post what you come up with! Jim.

[Ty Williams]

The reason I suggest this is that I've read that the restriction placed by this arrangement is inversely proportional to the length of the smaller diameter section.


Actually, if you change the pipe diameter with a reducer, I believe you are limiting yourself to the flow of the smaller size, no matter how short or long the the piece is. But I could also be wrong on this.

You're both right, just under different conditions. :lol:

Under large pressure gradients air, being a gas, will compress when faced with a restriction and the throughput of the restriction depends on the restriction's diameter and length and some other things. At low pressure gradients air behaves like a liquid and is basically incompressible meaning that the diameter of the restriction alone determines the maximum flow.

Whole-shop dust collectors are very low pressure devices. Most of them seem to operate in the 4-6" of water region (by the time they reach the tool), which is damned near nothing. Because of this, the 4" restriction ring at the tool will effectively limit the entire run from the tool back to the DC to what can flow through that 4" ring. So, yeah, it's a flow killer in this scenario. Going to 6" tubing runs that terminate to 4" ports on the machine doesn't get you any significant increase in flow volume but it does drop the flow velocity in the 6" pipe (which could be good or bad).

[Jim Andrew]

Assuming you will get improved air flow through a 4" port by running 6" to it assumes that the air will compress through the 4" opening. My cyclone does not have the power to compress air in this way. I would need a much more powerful blower. It might be possible with a large enough motor and impeller. But my 2hp dust collector will not, and if I can eliminate blockage, the dc will be much more effective.

[Ole Anderson]

Each machine will have its own issues. I upgraded my Grizzly 1023 saw from 4" round hole to a 5" bell mouth by simply enlarging the 4" hole in the dust access door using a jigsaw with a metal cutting blade. No big deal. Machines with a 4" nipple will be more of a challenge. However if you can install a bell mouth nipple, you will enhance the flow characteristics by providing a smoother transition and reducing losses due to a sharp edge orifice. http://www.pennstateind.com/mm5/merchant.mvc?Screen=PROD&Product_Code=N-BELL05&showreviews=1&prodpage=1N- .

[Chris Parks]

Bell mouth is the key with a low pressure flow as the turbulence that blunt entry sets up will impact the flow. You need to remember that a second port of at least the same size as the extraction port will be needed to supply air to the cabinet. Bandsaws are critical with this requirement and it is the sole reason that everyone complains about the bandsaw cabinet filling up due to the dust extraction not working. It doesn't work because there is no way for the make up air to get into the cabinet.

[Ole Anderson]

You're both right, just under different conditions. :lol:

Under large pressure gradients air, being a gas, will compress when faced with a restriction and the throughput of the restriction depends on the restriction's diameter and length and some other things. At low pressure gradients air behaves like a liquid and is basically incompressible meaning that the diameter of the restriction alone determines the maximum flow.

Whole-shop dust collectors are very low pressure devices. Most of them seem to operate in the 4-6" of water region (by the time they reach the tool), which is damned near nothing. Because of this, the 4" restriction ring at the tool will effectively limit the entire run from the tool back to the DC to what can flow through that 4" ring. So, yeah, it's a flow killer in this scenario. Going to 6" tubing runs that terminate to 4" ports on the machine doesn't get you any significant increase in flow volume but it does drop the flow velocity in the 6" pipe (which could be good or bad).

Sorry, but I disagree. I keep seeing this repeated and it just isn't correct. The flow of air in the system is dependent on the SUM of the restrictions upstream of the tool. You must add in the loss in each pipe, fitting and orifice to determine the total restriction upstream of the dust collector itself. So if you use a 4" pipe instead of a 6" pipe because you believe the statement, you will have the higher loss in the 4" pipe under any flow conditions and higher pipe friction losses will cost you in cfm as you will slide down the fan curve of your collector unit. Now if that pipe is short, the difference could be so small as to not be noticeable. But someone believing the statement could construe it to mean that it applies to any length of pipe. Suppose for instance you run a 6" pipe to a 4" collection port which goes into a larger machine base, say a cabinet of a TS. The 4" collection port acts as an orifice, much like a nozzle on the end of a hose except in reverse. As with a hose, you wouldn't size the hose at 1/4" just because you have a 1/4" nozzle, you would go with a hose with a much larger hose cross section, usually 1/2" or 5/8" to minimize friction losses along the length of the hose. It is the same with a dust collection system except on a much larger scale. I am not saying that you shouldn't go with a 4" hose on a 4" port, just saying that you should incrementally enlarge the pipe as you go downstream toward the fan in order to maximize the flow in your system. Of course you have to be aware of keeping pipe velocity adequate to carry chips to the collector. But my 2 hp cyclone will produce enough flow with properly sized upstream pipes (4" vertical to 5" horizontal to 7" main) to pull 752 cfm through a 3.5" inside diameter blast gate with a velocity of 11,250 cfm. If I kept the upstream pipe at 3.5", flow at the blast gate would be drastically reduced.

Compressibility isn't particularly relevant. What is relevant is that at each change in diameter, whether an orifice or a pipe, you have a change in velocity. And friction loss is a very strong function of velocity.

[Ole Anderson]

You need to remember that a second port of at least the same size as the extraction port will be needed to supply air to the cabinet. Bandsaws are critical with this requirement and it is the sole reason that everyone complains about the bandsaw cabinet filling up due to the dust extraction not working. It doesn't work because there is no way for the make up air to get into the cabinet.

Again, sorry to be argumentative, but I take exception to this statement also. Yes you need make-up air, but to size the holes in your band saw or router cabinet (I see this all the time) to provide the same area as your inlet pipe, takes away from the function of collecting dust at its source in favor of keeping your cabinet clean. You need to keep velocity at its maximum near the cutting edge in order to catch particles being ejected at upwards of 100 mph on some machines. To do that you don't want to waste dust collection horsepower sucking in excess make-up air at a point other than near the tool. And my take on the goal of dust collection is to try to catch dust at its source to minimize it escaping into the air in your shop. Frankly, is it important to keep the inside of your cabinet clean as long as you don't impact the workings of your machine? I keep the inside of my router cabinet clean as I have an appropriately sized, yet small, slot to sweep air along the bottom to the hose outlet. My TS? Not so much as there are lots of square corners to trap sawdust and immaculate dust collection isn't something the engineers had in mind when they designed the saw. Same with my BS.

[Scott Driemel]

Hey & thx to all who've offered their 25 cents so far! If it makes any difference to what anyone might suggest, I'll give a bit more of my system. (Should have done that initially) I've just newly aquired a Grizz 3hp cyclone. Plan to run 6" mains, 6" drops, and then either 5" or 6" hose to my table saw, jointer, planer. (I'll prob be running more than this to the drill press, edge sander, router table, bandsaw etc) but specifically these machines are my mains. My unisaw is older in that it has the rectangular shoot (no port) where the sawdust just slides out onto the floor. My General 350 (also older) ... kinda like me ;) has no port at all on it. I'll try the metal HVAC shop approach & bring along my 6" spiral hose to see what they might be able to make. Just a shame no-one makes a 5" or 6" PVC "toilet flange" kinda thing that I could just sheet metal screw on after I enlarge or make a hole. That pic of the circular metal flange with the tabs looks pretty good. Maybe I'll print that & take it to the HVAC shop. Odd isn't it that my General (Canadian model) 350, doesn't have a port at all on it don't 'cha think?

[Eric DeSilva]

The oneida blast gate I referenced will screw on just like a flange... And I bet it would be cheaper than getting a metal shop to fab one up.

[Scott Driemel]

Hey just for anybody's info. I just found at Oneida a piece of kit called "Angle Ring with Collar". For a 6" version it's a little over $20. Looks like the thing I'm looking for to convert the machines. Hopefully this might help others who have been on the "quest" as well.

[Chris Parks]

Ole, you can disagree all you want but all my customers who have tried it (references available) have found that the above approach works.

[Ole Anderson]

Ole, you can disagree all you want but all my customers who have tried it (references available) have found that the above approach works. I am quite sure that it works well to keep the cabinet clean, but that was not the point that I was trying to make.

[Chris Parks]

No air velocity you can get will stop the ejection of chips from a cutter, it is not possible. What is possible and is the whole point of this problem is first you have to reduce the speed of the chip, that is trap it within the area of extraction and then you can remove it. In fact that is not the whole point either, the whole point is to trap and extract both the visible chips and the invisible dust that floats around us if not trapped. Of all the overhead collectors I have seen I still maintain that Alan Shaffer's is far and away the best at doing both and absolutely wins hands down.

[Ty Williams]

Sorry, but I disagree. I keep seeing this repeated and it just isn't correct. The flow of air in the system is dependent on the SUM of the restrictions upstream of the tool. You must add in the loss in each pipe, fitting and orifice to determine the total restriction upstream of the dust collector itself.
You're misunderstanding what I'm writing. My statements were ONLY related to the tool port, not the entire system. Youre absolutely right that the total flow through the system is determined by the sum of the losses in the system. However, you'll find this sum, at the very, very minimal pressures involved in home shop dust collection, are dominated by the narrowest point, regardless of length. So, effectively, you start out with whatever flow you can shove through the 4" port and then subtract the losses in the pipes all the way back to the impeller. If you're using 6" pipe, you'll find that the losses in the system are tiny compared to the restriction at the port. The system becomes dominated by the 4" port. If you increase the port to 6", you'll see a very significant increase in total flow because the 4" port was the most significant restriction.

In effect, if you're running 6" piping and terminating into a 4" port, you can safely ignore the contributions of the pipe and look solely at the port.

Of course, this is all physicist math where if it has the correct number of digits it's good enough.


Compressibility isn't particularly relevant.
It is at these very minimal pressures.

[Jim Andrew]

After considering the compression theory in dust collection I did some thinking about it. Appears that if you were going to try to compress air into a 4" port, the air would have to enter the port from a type of funnel shape, so that more air could be forced through the 4" opening. If you have a flat piece of metal, with a 4" hole in it, the flat shape of the opening would stop extra air from entering the port. Put some thought into that.

[Chris Parks]

There has been some work done in Oz after recognising that a bell mouth entry will increase the port flow.

[Ole Anderson]

After considering the compression theory in dust collection I did some thinking about it. Appears that if you were going to try to compress air into a 4" port, the air would have to enter the port from a type of funnel shape, so that more air could be forced through the 4" opening. If you have a flat piece of metal, with a 4" hole in it, the flat shape of the opening would stop extra air from entering the port. Put some thought into that. You are on the right track. The efficiency of a square edge orifice is generally considered to be about 61% whereas a rounded entrance like a bell mouth is around 97%. http://www.buschusa.com/fileadmin/Companies/USA/Pictures/Systems/Flow_Through_An_Orifice.pdf

[Jeff Duncan]

Late to the party but you can have most hvac duct suppliers make any fittings you need….you just have to pay for them! I have mine made but they are a bit pricey. Now if I were doing a home shop I think I'd more likely buy some light gauge sheet metal and a rivet tool and get-er-done! No need to weld when pop rivets will do the trick just fine.

good luck,
JeffD

[Jim Andrew]

If you really want to spot weld, they sell spot welders at Harbor Freight. I make simple fittings, just a couple weeks ago made a 5" square to 6" round fitting. My wide belt sander was driving me nuts, having a 5" round flange on top of a 5" square duct inside the machine. So I used a dremel tool to cut the welds on the flange, and found the inside of the hole in the top of the sander was 4 1/2". Took my jigsaw with a metal cutting blade and trimmed out the hole square, matching the duct, had to file some to make it match evenly, then made a fitting from a piece of 8" pipe about 12" long. I used caulk and pop rivets to attach it to the top of the sander. When I figured the square inches of the 4 1/2" opening, which is 15.9, versus the square inches of a 5" square, which is 25, seemed I had no choice but to proceed with the change. The difference to 6" equals 28.269, so this is a big upgrade in the change. Just wish these machine companies would see fit to use 6" on as many machines as possible, especially sanders.

[Lee Schierer]

Don't forget that to get air out of a piece of equipment you also have to let air in. You need as many square inches of inlet as you have outlet, otherwise a larger diameter outlet is meaningless. You also have to have enough cfm capacity of your blower to overcome the losses and still maintain adequate linear feet per minute of airflow in the duct to keep particles suspended and moving along the pipe.