best design so far for a vac clamp

[woodman08]

This design is the best so far as with different o rings you get different hold down techiniques
with 4 of these hold downs ,you7 get a lot of vac power to hold a large surface area
Took about 40-45 minto make


http://youtu.be/rSQvrg2TKzE

included some tests too!

[phil_o]

Looks like an excellent design. Versatility is always a plus.

Phil

[woodman08]

this has gone very well ,it was difficult getting the supplies but its coming together nicely

[bob_s]

Stan
What are you using to create the vacuum for these?

[twelchPTM]

It is a very excellent design, it could even allow you to cut clean through the material with out hitting your spoilboard, or even profile the bottom edge of a piece!
Pods almost identical to this can be found on larger production cnc routers, the differences are instead of O-rings you use strips of gasketing and there is a spring loaded ball valve for the vacuum so even with multiple pops hooked up there is no bleedout from unused pods.

I considered trying to replicate these but haven't really had a need for it, my though however was to make them double sided so they would hold them selves to the spoilboard without clamps or mechanical fasteners.

[Brady Watson]

Stan,
Great job. It's nice when you can do a little R&D and come up with something that works!

Tom,
Yes, a number of CNCs use these types of pods. However, one style isn't necessarily better than another style all across the board. Pods are better for some things & universal type bleeders for others. Plastic lumber (solid - Veranda brand - not even sure if they still sell it) works well for these types of jigs. Playboard works well too.

Getting the pods to suck themselves down securely usually ends up in disappointment.

-B

[twelchPTM]

I wasn't trying to claim anything to be the best way to do anything, I haven't made myself any pods because I have yet to have a project that would remotely warrant the use.

The double sided pod Idea actually comes from a machine I saw at a granite shop and a machine that was being set up at a cabinet shop I used to work at, they both worked in a similar fashion.... once you loaded your part files the machine would project a laser outline on the table, you positioned you pods within the and or around the outline and they sucked down to the table. I imagine trying to do this with a bot would require a solid surface cutting table making it incompatible with an bleederboard style vacuum set-up.

I really wasn't trying to downplay the POD featured here just wanted to share my experience as it may potentially improve the idea.

[woodman08]

I actually have double sided vac clamps but i do find that the cnc table is a 1 in mdf and mdf does pass a bit but i do have them and they work fine but i would prefer to mount these latest ones to the sacraficial mdf board on the cnc table.
Now if your table is say a melamine then yes a double acting vac clamp would be ideal.
Some of these double acting ones have amach valve ,they don't suck down until you give it downward pressure .
Of all the testing we did the soft o rings are the best ,an adhesive gasket does distort after a few uses and the material can give but does not cause acuracey problems
The 4 clamps i have made could easily hold a large piece of plywood

[HelicopterJohn]

Hi Stan,

Your pods look really nice and look like they have plenty of holding power. I like the 3 O Ring idea to allow for mulitple clamping options. Thanks for sharing.

I have made some homemade fixtures from plexiglas and 1/4" gasketing material that I utilize when engraving LED Edge Lit Signage. I surfaced both the top and bottom of the fixtures prior to cutting the vacuum slots so that the material to be engraved is held as flat as possible. Plexiglas has a tendency of varied thickness and when engraving at shallow depths the artwork can be problematic. The downside to these fixtures is that they don't have the versility of your pod system. :)

Notice you are running Mach 3 and thought I would share the following information. I made a vacuum shoe with magnets that allow for use of different sized brushes for my Shopbot PRT and turn the dust collector on and off with a solid state relay or with a screen button I have on my customized screen set. I also have a solid state relay that turns on my vacuum pump which can also be controlled via a button on my customized screen set. If you would like to discuss you are welcome to send me a PM.

What Shopbot machine are you currently running?

John

[donclifton]

Buttons, what else have got on that Machbot?
Don

[bobmoore]

I designed mine the same as yours only larger. I use surgical tubes cut to length and but joined. You don't need to connect the ends as an Oring, just but them together in the fixture. The vacuum pods are a very flexible design and a small 1/3 horse vacuum pump can hold a part 2 feet x 4 feet. I have made them from maple and from corian.
Bob

[woodman08]

we found that after some sitting around the wood passes,so a coat of lacquer fixes that and though time some split a bit.
The corian sounds good but i have only seen 1/2 thick corian and thats tight ,i found 3/4 tight when you have to drill the hole to pull vac.
If i ever make more i would use 1 in thick plastic.
And that is interesting about not joining the o ring ,i have noticed some large companies just butting it---good thing to try
Corian machines nicely and is cheaper than the plastic.

[bobmoore]

Wood for sure is less stable but also more expendable for me. I glue up edge grain maple or ash and lacquer it. Stays pretty stable and of course you can resurface if needed once or twice. Never had one split yet if I stay away from heart grain. Corian can be glued face to face for more thickness. Machine in matching half rounds for your vacuum channels. What you add to fixture thickness you take away from z.
Bob

[Brady Watson]

FYI - Azek makes a glue now for their expanded PVC trim boards. It works pretty well.

Also, solid composite decking works really well for long molding type vac jigs.

-B

[woodman08]

I had thought of decking ,excellent idea
Also i found 8x8 sheets of dense rubber 1/4 thick adheive one side for 1.99 at a surplus store ,thi will make cheap pucks and with corian (surface seal)