Unisaw Dust Collection

[Harvey Pascoe]

I know this topic has been hashed over many times but as I was looking through prior threads I did not see the solution that I devised to this difficult problem without cutting any new holes in the cabinet.

Mine is the model 36-812, 1994 model with the wide slot at the bottom of the dust chute on the right side under the door. What I did, as shown in the photo below, is take a 3" PVC pipe and cut it in half lenthwise, cap one end and then shim or sleeve the 3" pipe at the other end to accept the 4" hose. This then gets bolted over dust ejection slot by just drilling two holes.

How well does this work? Actually quite well, although not without a little personal assistance. Dust will begin to pile up in the corners and at one end of the collection port. I remedy this by using my air hose with the DC turned on and that pulls all the rest of it out. So, by this means I can get 95% of the dust out of the cabinet without ever opening the door. To make it function though I have to stuff a rag in the huge tilt wheel slot at the front.

If you don't have air, you'll have to make a small hoe, then open the door and pull accumulated dust down to the port where it then gets sucked out. Another weakness is that small cut offs and slivers will eventually jam the port so that I have to go in on hands and knees to clean it out.

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[David Cramer]

Probably not what you want to hear, but cutting the hole in the back was easy and I'm a moron! Seriously, it was simply tilting it back on an angle and leaning it against my outfeed table and then using a bi-metal hole saw. I have a 2hp Gorilla Cyclone Dust Collector and it does a great job.

David

[Bruce Wrenn]

Probably not what you want to hear, but cutting the hole in the back was easy and I'm a moron! Seriously, it was simply tilting it back on an angle and leaning it against my outfeed table and then using a bi-metal hole saw. I have a 2hp Gorilla Cyclone Dust Collector and it does a great job.

David

His dust chute empties out on SIDE (not back) same as mine does. A hole in the back would be useless.

[Harvey Pascoe]

Bruce, how did you do yours?

Has anyone figured out a way to close off the tilt slot other than stuffing it with a rag?

[Jerome Hanby]

Magnetic sheets from some craft store. You can cut the stuff to fit and it's easy to peel off and restick when you have to change the tilt.

I bought this, I guess bag id the closest description, to seal off the motor opening on my contractor saw. It basically seals around the opening edges then cinches around the belt guard and side of the motor closest to the saw. There is enough material to allow the motor to swing back and forth when you change the tilt. I haven't installed it yet, so Ican't speak to how effective it is, but something similar could work for the tilt slot on your saw...

Bruce, how did you do yours?

Has anyone figured out a way to close off the tilt slot other than stuffing it with a rag?

[jeff vanek]

Do you guys seal up all gaps inside the cabinet ?

[Kent A Bathurst]

I have the same design Unisaw. In those models "dust collection" was the punch line to a joke.

I have the OEM accessory sheet metal chute that is the functional equivalent of Harvey's. Then, I did a few other things that has made it work pretty well - not perfect, but it works fine for me:

1. Mag sheets on the tilt slot. Also on the back of the cabinet where the OEM mickey-mouse pawls and blade cover were mounted.
2. Foil tape [like for DC piping] used in small pieces to close off every hole in the cabinet metal - including wrapped around the power cord exit. There are a variety of holes punched in the cabinet for some reason I have never divined - accessories I don't have, perhaps? Find 'em and close 'em.
3. Critical - foam sealant from an aerosol can, sprayed under the table top to fill the wide-open gaps at the top of the cabinet's sides. It takes quite a bit, in multiple applications, and looks ugly, but who cares?
4. Foam sealant or foil tape to fill the gaps around the floor inside the cabinet.
5. Adhesive-backed weatherstripping on the cabinet around the door opening - big air sieve there.
6. Now - control the air flow by:
[a] Slots cut in the motor cover....3/8" x 5" is what I used....this directs air flow into the cabinet and across the motor. Keeps dust off the motor and the gearing. I made three slots - stacked vertically with about 2" between them, to follow the motor path when it is tilted. Mag sheets can close off parts of these if you think there is too much air coming in.
[b] a slot cut 1" above the floor in the cabinet side opposite the dust pickup chute. This lets air into the cabinet, and is directed across the cabinet floor toward the dust pickup - reduces the accumulation of dust in the cabinet corners.

As I said, not perfect, but I am very happy. A modest amount still collects in the bottom of the cabinet, but it never exceeds a small level. I only clean it out when I go hunting for dropped arbor nuts.

The basic point - as much as possible, stop all the air from entering the cabinet, and then YOU choose where to let the air in, in a manner that directs the air flow, and is "controllable" via the mag sheets.

[Eric DeSilva]

I've got a similar era Unisaw, and here's what I did for DC out of the side slot: http://www.sawmillcreek.org/showthre...ghlight=Unisaw

The box is heavy enough to just butt up against the saw cabinet and doesn't leak. On top of the saw, I also use a Shark guard on a Biesenmeyer arm (stock was with a 2.5" port) opened up to 4" and piped into the 6" DC duct. Since I've got suction out of the top and bottom, I haven't tried to seal up any of the various openings on the cabinet.

[Jerome Hanby]

I don't think you need to make the saw airtight, you need airflow. All the usual gaps that are pretty easy to fill/caulk are probably worth doing. Seems you could adjust whatever is blocking the tilt opening to give you enough airflow. I would think you might want it pretty tight with a "normal" insert, looser with a ZCI...

[David Cramer]

His dust chute empties out on SIDE (not back) same as mine does. A hole in the back would be useless.

Sorry, just saw this.

So did mine Bruce. You simply cover the side up, move the metal ramps so they aim to the back and cut out your hole so the bottom of it is at the bottom of the ramp. Easy enough. A hole in the back is where it should be Bruce and would not be useless as it is actually where they put them now and for good reason.

David

[Bruce Wrenn]

Sorry, just saw this.

A hole in the back is where it should be Bruce and would not be useless as it is actually where they put them now and for good reason.

David

When I taught school, my in the shop 1947 model had no chute or floor. But it did have a slotted front door, and a 4" hole in the back. Saw dust would build up to a certain point, and then it formed it's own ramp to outlet hole. If you turn ramp, you need to add corner ramps to direct saw dust to outlet port. Or just bite the bullet and design and build your own blade shroud.

[Jeffrey Makiel]

I have the same saw.

The issue is that the ramp inside the cabinet at the bottom is not sloped enough. Dust particles land on the ramp and gravity is not helping the dust get to the end of the ramp where the slotted dust collection port is.

The only way to get more dust into the slot is to use a lot of air flow from your dust collection system. More air flow means more capture distance. However, even a decent home dust collection system will not overcome this design flaw and dust will accumulate on the ramp.

Plugging up all the openings in your cabinet will make this problem worse. In order to pull a large amount of air out of the cabinet, you need to let air in. But, again, the ramp is so poorly sloped, that even a huge hole to let air into the cabinet won't help.

Eventually, dust builds up at the bottom and blocks the slot. As a result, the vacuum pressure inside the cabinet becomes weaker and dust starts to migrate out of the other holes in the cabinet. This is all because the ramp is not sloped enough. Plugging the holes is not the answer as it will starve the flow more and more dust will spit from the spinning blade. By plugging the holes, you are only addressing the symptom.

I see only two ways to address this issue...

1. Install an overblade dust hood with dust collection. The cabinet will still fill up, but a little less slowly. However the hood really helps keep the dust that is spinning off the blade from going everywhere.

2. Build a shroud around the blade inside the cabinet saw with duct hooked directly to it. One of our SMC'ers did that. It is similar to what newer saws now offer. However, this retrofit appeared to be beyond my skill level.

Other than that, I reach in by hand and scoop the chips out followed by the old air hose while the dust collector is running. Not fun.

Jeff

[Jerome Hanby]

2. Build a shroud around the blade inside the cabinet saw with duct hooked directly to it. One of our SMC'ers did that. It is similar to what newer saws now offer. However, this retrofit appeared to be beyond my skill level.

Other than that, I reach in by hand and scoop the chips out followed by the old air hose while the dust collector is running. Not fun.

Jeff

Seems like I recall reading that thread )or maybe it was on the old woodworking machine site) and the shroud project didn't turn out too well. Am I remembering this incorrectly?

[Harvey Pascoe]

I have the same saw.


Eventually, dust builds up at the bottom and blocks the slot. As a result, the vacuum pressure inside the cabinet becomes weaker and dust starts to migrate out of the other holes in the cabinet. This is all because the ramp is not sloped enough. Plugging the holes is not the answer as it will starve the flow more and more dust will spit from the spinning blade. By plugging the holes, you are only addressing the symptom.

I see only two ways to address this issue...

1. Install an overblade dust hood with dust collection. The cabinet will still fill up, but a little less slowly. However the hood really helps keep the dust that is spinning off the blade from going everywhere.

2. Build a shroud around the blade inside the cabinet saw with duct hooked directly to it. One of our SMC'ers did that. It is similar to what newer saws now offer. However, this retrofit appeared to be beyond my skill level.

Other than that, I reach in by hand and scoop the chips out followed by the old air hose while the dust collector is running. Not fun.

Jeff

I don't have that problem. The wind created by the blade stirs the dust on the base enough that the side suction pulls it out. As I said earlier I do get drifts piling up in the corners but I just turn on the DC and give it a squirt from my air hose and its gone. Yes, the front end of the slot does fill up but the rear end doesn't, so that seems to make no difference and I don't bother to clear it anymore. Oh, and the one place the dust isn't easily removed from is the bottom of the motor cover, so anytime I have to open it, I'm greeted by an avalanche of dust on the floor.

[Kent A Bathurst]

Jeffrey - We simply disagree on these points. My remediation steps as posted above are based on 6 years of putting up with the dust, 4-6 hours of "I ain't taking this anymore" actions, and 7 years of "Hallejulah". I suspect that you may be confusing "close the holes" with "manage the airflow into the cabinet".

The issue is that the ramp inside the cabinet at the bottom is not sloped enough. Dust particles land on the ramp and gravity is not helping the dust get to the end of the ramp where the slotted dust collection port is.
> Gravity ain't in the game. Directing the airflow is the game - the entire game. If you are relying on gravity to manage the dust in your TS, or anywhere else in the shop, it will be disappointing.

Plugging up all the openings in your cabinet will make this problem worse. In order to pull a large amount of air out of the cabinet, you need to let air in. But, again, the ramp is so poorly sloped, that even a huge hole to let air into the cabinet won't help.
> Plugging all the holes means that the air that is not coming in at all of the widely-scattered OEM holes and gaps.
> This means that YOU can now put holes/slots in the cabinet to [a] allow enough air to enter, but [b] not too much air, [c] at the appropriate locations to direct the airflow in a manner that moves the dust where you want it to go.
> You don't want a "huge hole". The cabinet is nothing BUT a huge hole already. You want holes/slots that direct the airflow, and that can be easily managed with tape or mag sheets.

Eventually, dust builds up at the bottom and blocks the slot.
> No, it won't, if you do it correctly. I do get some build-up, but it reaches a certain level, and does not block the slot.

Plugging the holes is not the answer as it will starve the flow more and more dust will spit from the spinning blade. By plugging the holes, you are only addressing the symptom.
> No, sorry...you are not "only addressing the symptom", you are treating the disease: meaning, there are many entry points for airflow that do absolutely nothing to move the dust where you want the dust to go. To get the dust to go where you want it to go, you have to direct the airflow. To do this, you must stop air from entering in all the extraneous openings.