Sanding table in table saw extension - good idea?

[Bob Cooper]

I'm looking to see if anyone has tried something like this. I'm thinking of adding an extension table to my tablesaw (unisaw) and incorporating a home made sanding table into it. If i do this clearly i'm not planning on adding any kind of walls on any sides of it -- that may or may not be an issue.

Is this a bad idea? Any suggestions on how to make this work well. BTW this will feed into a 5HP Clearvue located beneath the shop fed by 6" pipe.

Here's a couple variations i'm considering

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[Shane Copps]

That is a very interesting idea- I'm very interested to see what is said.

[Alan Bienlein]

This is what I recently built to replace my existing out feed table. I got the furnace blower for free.

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[Bob Cooper]

nice...One thing i'd need to figure out would be hole configuration. I've got a 6" pipe going to the dust collector that i need to keep fed plus i want to make sure i have reasonable coverage over the area with holes. Thinking...

The more i think about it, the more difficult it seems to get something that works reasonably well. For example it would seem like i would need larger open area the further i get from the middle of the 6" duct -- either by making the holes larger or putting more of them in a given area.

[Alan Bienlein]

Here is a better shot of the top of mine. The number of holes that were originally in the top was about half of what you see in the picture. They are 3/4" dia. and have a 1/8" radius. It works as is for now but I know I'm going to need to add some more to make it more effective.
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[Jim Neeley]

It'd work although there'd be some trade-offs. For a sawing surface I want as slippery as possible but for sanding I'd like it to be non-slippery; almost silicone-covered. That's why I think of a saw & router table as better shared table matches.

Just my $0.02.. YMMV.

Jim

[Rick Potter]

Jim has a good thought about the slickness. How about making the sanding table just a bit lower, and make a Formica top for when it is used as an outfeed table? You could spray some of that bedliner stuff on the sanding surface, just be sure to get the kind that dries completely.

Rick Potter

[Bob Cooper]

Rick...actually that's an interesting idea. Either a bit lower or just a replaceable top. I'm still though thinking my biggest issue will be one of getting good suction. Also i'm not sure which of the two configurations would be most useful -- longer and skinny vs square. The former i think would more functional but distributing suction seems like it would be tougher.

[Bob Cooper]

Alan...your attachments didn't come thru.

[Alan Bienlein]

Alan...your attachments didn't come thru.

I reloaded them. Thanks.

[Loren DeShon]

I have a downdraft table integrated into a workbench that has a melamine top. The melamine is, of course, fairly slippery, so when I use the downdraft for sanding I put down a sheet of that tacky, sort-of-woven-look liner for toolboxes, like this:

http://www.amazon.com/Big-Horn-19410-16-Inch-7-Feet/dp/B002LVUWMW/ref=sr_1_sc_1?s=hi&ie=UTF8&qid=1390975725&sr=1-1-spell&keywords=tool+box+liner+matt

It's tacky enough to grip the melamine and the workpiece pretty well, and the holes allow it to pass the dust through. Works for me.

[Shane Copps]

I use a Shopsmith quite a bit in my shop. It has the adjustable table vs. the adjustable blade for height of the blade. I have been wanting to build an outfeed table for it. The idea of using the lowered table for sanding with removable top for the outfeed table has got me thinking about how to make the top adjustable to match the Shopsmith table. If you had router tables, saws, etc that are about the same height, this may be a multi-tool item.

Any ideas?

[Rick Potter]

I would look at the from the other side Shane. You probably don't change the height of your table very often, just find a height you like and build the outfeed table to that. If you need to lower the saw table for an occasional cut, just move the table or the SS temporarily.

Rick Potter

[Rick Hubbard]

In my previous shop I had my out feed table set up likes Alan's and it worked very well. There was enough suction so that whatever stock I was sanding would be held tight against the table.

[Alan Bienlein]

Just don't forget to turn it off when cutting sheet goods. I found out mine has excellent suction because once the sheet covered about 2/3's of the out feed table I couldn't push the sheet anymore to finish the cut. I thought it was caught on some thing till I remembered that I left the down draft table running. Doh!

[Michael W. Clark]

I haven't designed a downdraft before. I know when I have done slotted hoods, the velocity through the slot is at least twice the velocity as through the back of the hood (plenum). This ensures the air is distributed evenly across the slot. Typically shoot for 2000 FPM in the slot and 1000 FPM in the plenum. If you handle dust, you have to provide a way to clean out the plenum.

I would think you could approach it similarly on the downdraft table, but if you may need to add some baffles to force the air to split or make a bigger plenum like Alan's to help the air get distributed. Alan posted some flow numbers that may help give you an idea of how much CFM you have to work with if you don't know already.

[Rick Hubbard]

My overall satisfaction with the setup got to the point where I changed things when I moved to my current shop. The main problem I encountered with the outfeed table had nothing to do with the dust collection; instead it seemed like the table was always sagging because I would use it for a work surface (rather than using my bench). Anyway, now no more dust collection. Instead I have what is probably a completely sag-proof outfeed table constructed from 2 inch oak plank!

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[Alan Bienlein]

I haven't designed a downdraft before. I know when I have done slotted hoods, the velocity through the slot is at least twice the velocity as through the back of the hood (plenum). This ensures the air is distributed evenly across the slot. Typically shoot for 2000 FPM in the slot and 1000 FPM in the plenum. If you handle dust, you have to provide a way to clean out the plenum.

I would think you could approach it similarly on the downdraft table, but if you may need to add some baffles to force the air to split or make a bigger plenum like Alan's to help the air get distributed. Alan posted some flow numbers that may help give you an idea of how much CFM you have to work with if you don't know already.

The down draft isn't connected to my cyclone. I'm using a squirrel cage from a furnace for the down draft table. I purposely left the holes small in the center in the hopes of provoding more flow to the edges of the table.

[Michael W. Clark]

Hi Alan,
I referenced your thread because Bob said he is connected it to his cyclone. I know it is not a direct comparison, but at least give him a starting point. If a blower was used, it would eliminate the DC drop.