RE: [CAD_CAM_EDM_DRO] Using Vacuum to hold down sheet metal.

A warning given to me by a supplier of vacuum hold downs. MDF is porous -
seal it well

Keith


John Dammeyer wrote:

> I have some 0.050" thick sheet metal in which I want to drill/mill a
> number of holes along with a rectangular cut-out. The G-Code is done.
> Things look like they will end up in the right place.
>
> I was thinking of building a vacuum assembly to hold the metal down
> while milling. I've put in mechanical stops to prevent shifting but I
> was thinking if I built a box and connected the shop vac that I'd be
> able to use lots of little 1/8" holes through the MDF frame to suck
> down
> the metal.
>
> A bit of math tells me that the 7 square inches of a 3" diameter
> vacuum
> hose translates into about 575 holes 0.125" in diameter.
>
> But do I really need that many. I plan on only putting holes under
> the
> metal where the mill does not do any cutting so no leaks.
>
> Would this work? Is it better to use a vane type vacuum pump instead?
> The milling cycle for all the holes is about 00:05:45 so that would
> mean
> the shop vac would be straining for a fairly long time perhaps
> overheating.
>
> Suggestions?
>
> Thanks,
>
> John
>