Re: Using Vacuum to hold down sheet metal.

John,
I built a vacuum box from MDF to hold balsa sheets for my router. I
used 1/8 inch holes on 1 inch centers. Vacuum source is a shop vac.
The vacuum also holds the box to the alum table of the router (bottom
of the box is open). I cover unneeded holes with paper to maximize
vacuum against the balsa. For small parts, I have to use tape to
keep them from slipping out of place as the final cut is made, or
leave tabs which I later cut with a knife to separate the parts from
the sheet.

I am considering opening the holes to 5/32 or 3/16 to increase
holding force for the small parts, and I may decrease hole centering
to 1/2 inch.

If you use other than a shop vac as a vacuum source, be sure you have
a good filter between the box and the pump.

Regards,
John Champlain



--- In CAD_CAM_EDM_DRO@yahoogroups.com, John Dammeyer <johnd@...>
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
>