DIY Vacuum Table - Questions.

[Mark Crenshaw]

I built this vacuum table yesterday to hold my guitar bodies in place while I do various routing operations. It has strong resistance to vertical lifting but the body slips sideways when moderate lateral pressure is a applied.

It's a basic box made of 3/4" MDF sealed internally with silicone caulk. It's internal volume is 22" x 17" x 3" or almost .65 CF. It uses a 2.5" collector fitting attached to a Delta 50-720 1HP dust collector rated at 650CFM.

As you can see, the only holes are in the table top within the perimeter of the body. My less than logical brain tells me this has the DC working well under it's capacity. Do I need additional venting to increase the airflow and thus the vacuum within the box?

http://www.crenshawweb.com/vac01.jpg

http://www.crenshawweb.com/vac02.jpg

http://www.crenshawweb.com/vac03.jpg

Peace,
Mark

[Jerome Stanek]

A dust collector will not pull enough suction for a vac table Hook up a shopvac to it and see if that will help. A dust collector moves a lot of air.

[David Christopher]

Mark, you need a rubber gasket around the outside border....and a shop vac will hold

[Mark Crenshaw]

A dust collector will not pull enough suction for a vac table Hook up a shopvac to it and see if that will help. A dust collector moves a lot of air.

Hi Jerome.

Thanks for the quick response.

So, I want to move less air? Or is it a matter of a tighter system with in the Shopvac vs the DC?

I've seen Shopvacs rated in the 100 to 150 CFM, 5 to 6 HP range. Is that more what I need?

Peace,
Mark

[Mark Crenshaw]

Mark, you need a rubber gasket around the outside border....and a shop vac will hold

Hi David.

Thanks for the quick response.

So then maybe something like this... instead of form fitting, I could create a zone under the guitar.

http://www.crenshawweb.com/vac04.jpg

[Gerry Grzadzinski]

You don't want to move a lot of air, you want to pull a vacuum. You only need a lot of cfm if you get a lot of leakage. As mentioned, you should havea seal to prevent leakage. Something like this.

http://www.veneersupplies.com/products/Vacuum-Templating-Gasket-Tape-38-x-116-x-100.html

Sounds like what you really need is just a few vacuum clamping jigs. Build yourself a Joe Woodworker vacuum system and you'll get much better results.

[Mitchell Andrus]

Hi Jerome.

Thanks for the quick response.

So, I want to move less air? Or is it a matter of a tighter system with in the Shopvac vs the DC?

I've seen Shopvacs rated in the 100 to 150 CFM, 5 to 6 HP range. Is that more what I need?

Peace,
Mark

No. A very tiny motor will draw a sufficient vacuum. A small shop vac will do because CFM is meaningless.

Think of it this way. If you can pull 1 pound per inch (atmospheric pressure is about 15 pounds per square inch) and multiply that by the area of the body (1 square foot), you would be putting 144 pounds of pressure on it.

Don't you remember the Oreck commercial where they showed a household vacuum sucking a bowling ball off the floor?

You don't want to use a DC. You need a vacuum and a rubber gasket - self adhesive weatherseal at Home Depot will do..
.

[Mark Crenshaw]

No. A very tiny motor will draw a sufficient vacuum. A small shop vac will do because CFM is meaningless.

Think of it this way. If you can pull 1 pound per inch (atmospheric pressure is about 15 pounds per square inch) and multiply that by the area of the body (1 square foot), you would be putting 144 pounds of pressure on it.

Don't you remember the Oreck commercial where they showed a household vacuum sucking a bowling ball off the floor?

You don't want to use a DC. You need a vacuum and a rubber gasket - self adhesive weatherseal at Home Depot will do..
.

Thanks! I was hoping to use what I already have in the shop but I seem to remember an old upright vacuum that got stuck in storage when we bought out Dyson bowling ball lifter. :D

Thanks again!

Peace,
Mark

[Mark Crenshaw]

You don't want to move a lot of air, you want to pull a vacuum. You only need a lot of cfm if you get a lot of leakage. As mentioned, you should havea seal to prevent leakage. Something like this.

http://www.veneersupplies.com/products/Vacuum-Templating-Gasket-Tape-38-x-116-x-100.html

Sounds like what you really need is just a few vacuum clamping jigs. Build yourself a Joe Woodworker vacuum system and you'll get much better results.


Thanks Gerry. I think on the right track now.

Problem solved in less than 15 mins. How did I ever get anything done without the internet? :D

Peace,
Mark