Thanks,
That was a good suggestion, I picked up a 12" x 12" piece today at Halted, our local surplus outlet. Its not as stiff as I would like but it is open cell for air flow and may be ok with limited vacuum.
Craig
--- In Homebrew_PCBs@yahoogroups.com, John Tabberer <johntabb@...> wrote:
>
> Craig,
> have you considered the semi rigid black antistatic foam sheet as a spoiler sheet.
> That combines modest rigidity with permeability.
> Â
> Not sure how it would stand up to the levels of vaccuum that you typically apply on the vaccuum bed... might be worth a try.
> Â
> Â
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> Regards John
>
> --- On Thu, 17/2/11, designer_craig <cs6061@...> wrote:
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> From: designer_craig <cs6061@...>
> Subject: [Homebrew_PCBs] Re: PCB drilling vacuum table ??
> To: Homebrew_PCBs@yahoogroups.com
> Date: Thursday, 17 February, 2011, 5:48
>
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> Â
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> Well I did a little test and some more research. Seems the CNC bed routers used mainly in the cabinet industry use MDF for their vacuum tables. Note they fly cut off the surface layers on both sides to get better air flow. Some suggested they used ULDF (Ultra Low Density)-- one brand called Trupan seems popular. I slabed off about 1/4" thick piece on my band saw and hooked it up the shop vac for a little test. I could get it to hold a piece of .062 material but not good enough. But I am sure I was loosing vacuum along the edges. The term they use for this is Spoilboard.
>
> I finally realized I don't need the spoilboard for trace milling just for the drilling. So an aluminum, acrylic or UHMW poly vacuum table with air channels will work fine. For drilling where the Z depth is not as important there may be more options for the spoilboard. I could always put a presser collar on the quill and mechanically hold the boad from shifting.
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> Something like an 1/8" thick open cell polystyrene foam board would be ideal. But some thin MDF with vacuum holes may be what I end up with.
>
> Craig
>
> --- In Homebrew_PCBs@yahoogroups.com, "designer_craig" <cs6061@> wrote:
> >
> > I am about to build a vacuum table to hole down the blank stock when I cnc drill my boards. I am looking some low cost sacrificial material to use between the board and the vacuum table.
> >
> > The material needs to be thick enough so as not to drill into the vacuum table and be some what porous to allow air diffusion for a good vacuum grip.
> >
> > The ideal material would be something like 1/16" thick MDF. I have heard MDF is fairly porous. I have only seen MDF in 1/2 and 3/4" thickness. Possilble some sort of construciton paper or cardboard. Guess I need to do some experiments.
> >
> > Anyone got and good ideas?
> >
> > Craig
> >
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