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Picture of Vacuum Clamping Table for Homebrew CNC
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 I've always wanted a CNC machine so I started building a "woodpunk" CNC about 2.5 years ago. The original Idea was for me to build a temporary table for it then use the CNC to create this table. But due to the time restraints in order to win an awesome ShopBot, I asked my bosses at QuickCrate if I could use their CNC machine; they graciously agreed. 

I noticed most of the Homebrew CNC machines I looked at (and was modeling my machine after) were just brad nailing or screwing pieces to their tables. But what if you need to work on all sides of the material and have no place or way to nail or glue? Like Acrylic?You could even make a larger one of these for the ShopBot. You have to upgrade to a better vacuum pump. I don't think a shop-vac could power an awesome sized table as the ShopBot's 48x96. You would just have to take this idea and beef it up tremendously to get it on par with the ShopBot,.

Okay let's get going!!!!
 
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Step 1: Assemble the Table

Step 2: Machine the Table

This Part was a lot of fun. I pulled the measurements off of a commercial vacuum table for the grid pattern and the hole sizes etc.

Step 3: Make the Legs

Step 4: Attach the Pump Fitting

Step 5: Hook up the vacuum

Picture of Hook up the vacuum
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Okay all I had right now was a 1.2hp shop vac and I think it gave me sufficient pull to machine a part. A surprising amount of pull. 
In the Video you will see I took a piece of MDF and drilled holes in it and gasketed around it with adhesive gasket, drilled holes for  air. In the video it is really hard to see but I have to put a lot of force on it to pull it off the table. and I beat the crap out of it. In theory the amount of suction should be equal even if the whole table is holding down a part. It should just take slightly longer for the vacuum to form. But there a lot of factors that can increase or decrease a vacuum, IT WORKS!! so enjoy! 
 What would it mean to me to have a ShopBot? It would literally change my life, I could do more projects in half the time. And know I am using my time to it's fullest. I hope to one day get a degree in mechanical engineering, and this cold be a stepping stone to do so. It would be a blessing!
Wouldn't the nose on the fitting at the very tip block the route through the side channel, to some degree?
Why did you find it necessary to sand between coats of polyurethane? If applied properly, it shouldn't be necessary; the only reason I can think to need to sand is if you have bubbles on top, and with proper application technique (this is beyond the directions on the can), you can coat it without getting a single bubble anywhere.
pdbrecher3 years ago
instead of using gaskets and marbles, you can instead use clear plastic film to cover the workpiece and the entire table at once, when it stars to pull a vacuum, just press it down until it starts to seal
rickharris3 years ago
I tried this in the past and found it choked with saw dust after a short while - Your mileage may be different.
Consider increasing your holding force AND eliminating the clogging.

Find your marbles, wherever you lost them.
Play some Chinese checkers on your vacuum table.
remove all the marbles to their bag.

Place your workpiece on the table.
Fill any exposed holes with marbles.
Turn on the vacuum, and enjoy your non-clogging table!
THAT is a really neat idea.
HandyLandy (author)  ironsmiter3 years ago
Neat!
HandyLandy (author)  rickharris3 years ago
I am going to dedicate a shop vac solely to this. My boss at quickcrate suggested covering up the air intakes of a floor blower fan, and attaching a hose to the table and the other end of the hose to an opening you make in whatever you use to cover the air intakes of the blower. I hope that makes sense. :(