Vacuum hold down for small objects on a big table

[Stockbub4]

I have a 60 x 96 table. My current hold down is two Fein Vacuum, which work great if I cutting out sheets. My Problem comes when I want to cut or carve something small. Most of the puck videos I have seen the puck is holding the part, which in my case, I would cut into it. Some of the smaller parts that I am carving would be 24x 24 or smaller. Was thinking about the puck system, but how would that work. pucks would sit on my current table, hold a spoil board and piece would go on the top of that. My table is zoned, but I cannot get the hold down needed.

An example is I am cutting some initials for my wifes class at school. Letters are 5" and a scroll font. I currently screw down a piece of wood, cut it out and then unscrew. There is also the problem of the little pieces that get cut out along the way, like the middle of the P. Will a vacuum hold that piece in place or no too small.

If I build a temp table, do you have a favorite link on what or how you made your table.

THANKS BUBBA

21624

[feinddj]

I got a venturi vac pump for a hard vacuum hold down. It is sold for wood turning. I make custom vac plates that I screw down to my table.

[Burkhardt]

I use 4"x4" pods with high vacuum (usually 15-27" Hg depending on leakage) for smaller parts or 4" x 9" for somewhat bigger ones. I use a 3/4 hp GAST double piston pump (eBay $150)

If the entire part to cut is bigger I just let it suck to the pod. Works fine but occasionally I make a mistake and the bit cuts into the pod anyway. No big deal it takes me 5 minutes to machine a new pod.

If the parts are smaller I use a roughly cut piece of 1/4" MDF as "spoilboard" that is a little bigger than the pod, identify the area that is under the part to cut, seal that off with 3/16" weatherstrip and drill a few small holes in there for the vacuum to transfer. That works well but you need probably at least 10 square inches vacuum area for a 1/4" bit and maybe 3 square inches for an 1/8" bit. This rubber weather tape collapses under vacuum to less than 20/1000 thickness and seals well.

For such intricate slim designs as in your example it would be possible but tricky to prepare.

This is the larger pod, intended to be re-used many times:
https://lh3.googleusercontent.com/-Rq8_B1KAwtM/VAkyikt4U6I/AAAAAAAAFRs/4gwF3ftUAeI/w1137-h853-no/DSC02413.JPG

This is an example of the expendable "spoilboard" for smaller parts (after being used):
https://lh6.googleusercontent.com/-p3XeReOS-eU/VAkylADRHJI/AAAAAAAAFR0/OJryZGS0Jog/w1137-h853-no/DSC02414.JPG

[donek]

There are multiple solutions to your problem. The simplest is to use your existing hold down, cutting within 0.020in to 0.030in of the bottom of your material. Then use a laminate trim bit on a router table to separate out the parts.
http://www.homedepot.com/p/Diablo-3-8-in-x-1-4-in-Carbide-Flush-Trimmer-Router-Bit-DR64100/100660703
You caln also get them with a sharp point for ponching through thin materials.

[bleeth]

You may be best off using double sided tape to hold your parts down. A low volume high pressure pump loses hold quickly when cutting through parts and these letters do have a lot of cut-through.

Another method I have used for things like this is to lightly spray a board and the back of my object to be cut with contact cement. Not nearly as much as I would use if I were planning on permanent adhesion. Then the parts come off with careful prying and/or a little lacquer thinner.

[Joe Porter]

You can also pocket out the small internal areas and use a few well placed tabs for the monogram as a whole. As far as removing a tab, a pattern bit in a router table (bearing on top) will let you remove the tabs quickly and easily...joe

[Brady Watson]

Vacuum Film (http://www.talkshopbot.com/forum/showthread.php?t=11481)

-B

[shilala]

Mind ya, I don't use a vac table.
But my first thought was "Why not plastic and duct tape off the rest of the table and just leave a 2'x2' workspace?"
Seems easy enough?