Improving Table Saw Dust Collection

Advice on how to improve dust collection for a table saw, especially when using a zero-clearance throat plate next to the blade. January 8, 2010

As the new year hits us, I'm thinking about ways to improve my shop. I like using a homemade, zero clearance throat plate for my table saw (10" Jet) to prevent tear out on the bottom of the board. However, it seems to hinder dust collection. Has anyone ever drilled a series of holes (3/8", 1/2" or ?) in the throat plate to allow more sawdust to be drawn down through the sawdust collector? I know an above-the-table collector would be the best, but not in my budget. If anyone has tried this or any other method to increase the dust collection on the table saw, I'd be interested in hearing about your experiences.

Forum Responses
(Furniture Making Forum)
From contributor A:
Table saws should have at least a 5" piece of pipe for collection. Caulking the box with silicone usually helps a bit. Most of the air sneaks in around the tilt and up/down handles.

It definitely makes a difference when you use a standard plate with a 1/4" + slot. Kind of hard because the dust is blowing in your eyes exactly because you are using a zero clearance plate.

Another thing that will help is if you cut the plate much deeper - meaning if you typically are cutting 3/4" stock, run the blade up to cut 1 1/2". This will provide a slot in front of the blade, still giving zero side clearance.

From contributor R:
If your ZC plate is covered by the board as you rip, holes in it will also be covered, negating any effect of the holes.

I agree with contributor A that better results can be had by sealing the cabinet better. You'll find holes all around the area where the table sits on the cabinet. I've also used felt strips over the tilt slot, allowing the handle to move, but covering most of the open space.

Lastly, you mention dust collection above the saw. Dust flying above the board can be caused by the blade scraping the stock on the back side, flinging it as the back teeth clear the top of the board. Double check the fence/blade orientation.

Keeping the blade just cutting through the stock (set low) can reduce this. I have found that most blades have a sweet spot where they throw less dust than other blade heights.

From the original questioner:
Thanks for the advice. It makes sense to seal the cabinet. My saw is on wheels (small shop necessity) and I notice lots of dust every time I need to move it. Should be fairly simple to fabricate rubber shields where the wheels come out, especially on the tilt mechanism. I too figured that the holes would be covered by the board. As a former shop teacher, I was always taught to just have the teeth of the blade above the board, but sometimes I admit to leaving it higher when cutting different thicknesses of stock. All good things to do. With the economy the way it is, at least working on my equipment will keep me in the shop!

From contributor W:
I have my table saw (25+ years Unisaw) on wheels too, and noticed the sawdust pile also. I cut a plywood plate that sits on the base flange inside and sealed it with, of all things, duct tape. Duct tape is doing well sealing other slots and holes in the cabinet, except for the tilt slot. Thanks for the felt seal idea. I run a JET dust collector and it does okay, but I have to wait to upgrade, maybe to a cyclone.

From contributor A:
You should always show at least the full tooth of the blade. Putting the blade up a little higher to expose the gullets will allow the gullets to carry more of the chips back into the saw. What are you using for dust collection?

From contributor B:
Try covering the tilt slots with magnetic bumper stickers. That way you can remove and replace them when you need to tilt the blade and put it back at 90. Beats tape. I make my own throat plates and only have 1 finger hole to remove it. No sense in making other holes for dust or air since the wood you're cutting will be covering the holes as you cut it.

From contributor R:
Great idea! I don't have any bumper stickers hanging around, but at Staples you can buy magnetic stock for printing your own. I've got some of that hanging around. I think I'll try it out.

From contributor O:
Dust collection works via the principle of maintaining a constant velocity/volume of air flow through the system. If you seal all the openings in a closed base cabinet saw such as a Unisaw you are decreasing the air flow and the dust will simply drop out into the cabinet below as there is no air velocity to carry it to the collector, and probably more will be carried around the blade to be thrown into your face. Furthermore, this same dust will remain in the air (you breathe) instead of being pulled down in through the louvers in the door in the front of the saw (they are there for a reason) and the openings through the hand wheel adjustments. If you want to maximize the collection on a table saw, you will have to install a blade guard with an additional outlet over the blade. You might want to do a little research on this subject before you wrap that Unisaw in a cocoon of duct tape.

From contributor R:
I did not see any information on wrapping the saw in duct tape. I do know a few things about DC systems and how they work. I would never suggest trying to close off all flow through, but some simple addition will prove that a 4 inch outlet (as supplied by the saw manufacturer) simply cannot create a workable flow volume through all the air gaps in a Unisaw. Sealing a few of the larger ones can help create a more effective flow around the blade where it is needed. I have done this in several shops, with different DC systems and saws and had excellent results. Like most things in life, a proper balance must be struck.

From the original questioner:
Great - this generated a lot of discussion and ideas. Contributor A, I have an older Jet DC and I suspect it's not as efficient as it was when new. I've considered upgrading the bag to a smaller micron size, but not sure if the cost can be justified. I've had some problems with dust collection on my 15" Powermatic planer. In any case, thanks for all of the input and ideas. I see both sides of it - not completely sealing the box, since in order to suck the dust out you've got to have some air in there to begin with! Seems as if the bottom line is to have an above the blade sawdust collection port.

From contributor O:
Do yourself a favor and consider replacing the bag collector with a cyclone. It is not as expensive as you would think for a small shop, as you can pipe multiple machines to a relatively small collector (2-3hp) using blast gates to maintain efficiency. They take up less space, are quieter, easier to maintain and to empty. The cost is about the same or less than a comparable 4 bagger (there is no comparison when it comes to performance). The additional cost associated with these units is the pipe, which is quickly paid back in time and aggravation. In fairness I will guarantee you one major regret if you go this route - that you didn't do it sooner. I have one from Onieda and recommend them highly. Their units are high quality, and they will engineer the system for you down to the last hose clamp.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor A:
To improve airflow around the zero clearance plate and still maintain zero clearance, try opening up around the center of the slot and leaving zero clearance where the teeth enter the plate at the front and exit the plate at the rear.