Official Luthiers Forum!

This might belong in the off topic area, but there's a lot more traffic here.

So before it gets moved....

Are any of you using downdraft tables with a regular "Shop Vac" style vacuums as opposed to a real dust collector?

Grizzly has some little ones on their site but they don't spec the min cfm etc.

My wife is in the middle of a round with Prednisone because she started making wood jewelry from my scraps & had a reaction to some Cocobolo.

Thanks,
Kevin Looker

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

I have this grizzly downdraft table and love it. It's not a small unit by any means, but it virtually eliminates most of the problems I've had with sanding dust. I'm sure a smaller version would do the same.

No, I am not.

With the small CFM that Shop Vacs move it is hard for me to believe they would do much good in that application - unless the down draft table was post card size.

I just went to Grizzly and looked. The smallest they had was 15" x 25" with a 4" hose connection. Frankly, even a 6" hose connection would struggle to work well on that size, but they are trying to move product. A shop vac would not work.

Could work fine for a small table - it's jewelry you wife is doing, not cabinetmaking. And I presume it's hand sanding, not machine sanding?
Simple and cheap to make one and try it - just get a bunch of holes, stick them together with scrap/6mm MDF or similar, hook'em up to the vacuum cleaner!
I ran a plastic tube (with more of those free holes) about 1/2 of the way across my unit and put a support/baffle in front of the end of the tube to even out the suction a bit.
Just a thought -
If it's a dedicated unit, an inline ducting fan and some flexible ducting would probably be cheaper than a shop-vac, and move more air.
Vent to outside - it's not just the dust, it's the fumes/vapours too

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I don't think one hooked to a shop vac would work real well. Just not enough cfm. I made one that's about 23" x 36" and is hooked to a 7" duct into my dust collector. It works quite well.

This is when it was under construction.

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Steve Smith
"Music is what feelings sound like"

Grizzly has a benchtop model with a 2-1/2" dust port but they don't list the min cfm to make the thing work.

I've worked with dust collectors on saws, jointers, & planers & it seems that it would take a lot of cfm to get even a small table top unit to work effectively.

Thanks for the replies so far.

Kevin Looker

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

I wouldn't call this off topic by any means.
Search the archives. There's lots of good info there. I know I put up a post a few years ago about my own home made dd table.

I don't know what your situation is, but if you're much like the rest of us, money is always an issue and you're looking to make something that works but doesn't cost a bunch of $$$

You can build a very functional dd table for very cheap. The main thing you want to do is get the dust out of the air and away from your breathing apparatus.

Cheap fix #1. Wear a mask whenever sanding. No worries about CFMs but you still have dust covering everything when you're done with the day.

#2 (this is similar to what I did for my first one) Make a workbench out of a double layer of 3/4" plywood. Drill a gazillion 1/4" holes in it in a 2'X2.5' square. Build a box underneath big to mount a couple high quality furnace filters and a box fan in.

turn fan on high. Suck air (and dust) through the holes, the filters and the fan. Refine as needed.

I ended up building a box big enough for a furnace blower (which can be picked up for nothing or next to nothing from just about any HVAC Co.) Further on down the road, I built a spray booth on the opposite wall from the dd table and positively pressurized the booth and exhausted the air out of the shop. This lets me spray nitro without blowing any fumes past the blower motor. If this doesn't make sense, just ask and I'll explain more.

Main thing is, if you have dust hurting you, your family or your house, you need to deal with it.
Get a fancy schmancy thing designed by engineers to do the trick, or build something yourself. But do something before the problem gets worse.

Dave

I guess I have two questions. How big is your shop vac, and how big a work surface do you need? I made my own downdraft table, and it works very well. It is simply an open top box made from 1/2" plywood with a rabbet cut in the inside of the top walls. Then i cut a piece of pegboard scrap to fit. Put a hole in the side, added a 4" pvc elbow to connect to the hose of the dust collector.

It is not that large, and I left a flange so I could clamp it to my work bench. It has plenty of air flow through the peg board holes, and works great. I imagine it could be scaled down to work with a shop vac. My shop vac is small, but my dad has a large one that sucks like a leaf blower. If you have a vac that size, no problem.

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Phil

http://www.oleninstruments.com

"Those who tilt at windmills are only considered insane by those who can't see the dragon."

I have a home made downdraft table I use which works pretty well in spite of the fact that my DC is nothing special. One thing I do is to block off sections of the table that are covered by the workpiece with cardboard. The remaining work surface sucks better.

You could do the same and maybe even make it more permanent. Let's say she's working on peices that are pretty much no larger than 12"x12" - make the table about 18x18" but only drill holes on the 3" at the rim.

p.s. I used peg board to save time drilling but the thing whistled like mad until I chamfered each and every single hole.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Funny, I started with peg board over 3/4" ply. Needed the ply to support the peg board or it would have collapsed, then I drilled about 500 3/8" holes in the ply to match up with the holes in the peg board. When I first tried it I put a top down to sand it and couldn't get the top back up - turns out I had made a pretty effective vacuum clamp. So had to drill another 500 holes in the peg board to open them up to 3/8" too. Now it works fine.

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Steve Smith
"Music is what feelings sound like"

Using mylar masks (or similar) to block off all but a few square inches around the work piece might increase the efficiency of the shop vac.

Yes, I added two "floor joists" to the box to help support the peg board. It's not super stiff but its enough to keep from breaking the peg board.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

If you have the space available and want something that can accommodate just about any job and also have the flexibility to roll around and be kept out of the way until needed, here is a link showing a downdraft table I built a few years ago with help from Craigslist (squirrel cage blower), Harbor Freight (locking casters), shelving from Lowe's (grating) and a sheet of 3/4" plywood that I had out in the shop. I think the whole thing came in for less than $200 including the filters and misc. electrical. I use it all the time not only for sanding but as a work surface when needed. I clean the filters with my shop vac regularly and replace them as needed. It has been a valuable and very utilitarian addition to my shop.



http://www.peterjosephguitars.com/Peter ... Table.html

I also built a four ft. high, folding, three-sided enclosure out of some 3/16" melamine paneling, 1 x 2 stiffeners and some old door hinges I had laying around that I stand into the socket holes in the grating and use it as a spray enclosure. Works great!!

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Peter

Thanks for all the detailed replies & photos .

This is sort of like buying a helmet - the initial cost is pretty small once you look at the big picture.

I think a custom built unit based around a furnace blower would work best. My wife is 5'2" & all the pre-made units would be too tall. I also like the idea of adding casters.

Kevin Looker

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

Kevin, I would not make the table any shorter than 36" net height with the casters; even a bit higher depending on your height, not your wife's. Build it with the intention that it is for you to use in your shop and keep in mind that a bench which is too low will inevitably cause a sore lower back from leaning over a bit too much. You can easily make a small plywood platform for your wife to stand on when she is using it. The wood platform will be easier on legs and feet also.

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Peter

The grizzly site has a number of downdraft tables. Look at the ones you like and then their parts diagrams. They are my first source for stealing home built machines.o

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No one appreciates the very special genius of your conversation as the dog does.
Christopher Morley

If you're going to build one, use some of this:
http://www.rockler.com/product.cfm?page=6580&site=ROCKLER

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

A DD table powered by a Shop Vac would have to be very small to work well at all. In the range of 12 x 12 inches....

I am of the opinion that even a reasonable size Dust Collection system (mine is 2.5 hp) doesn't pull enough air to make a DD table really effective. I prefer to use a dedicated squirell cage blower with pleated filters in front in 2 stages.
I drew up a plan that went into one of the DIY forums a while back, but I don't know if it's still there. I probably have the drawings still on a drive somewhere.

-C

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Freeborn Guitars
and home of BeauGuard©

Rockler happens to sell the table inserts in case you want to make your own...Mike
http://www.rockler.com/product.cfm?page=21488

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Another day, another dollar.