RE: [CAD_CAM_EDM_DRO] Re: Vacuum table

JJ,
Thanks for the Porex recommendation. I just ordered some samples of the
recommended vacuum table material and will say something when I've tested
it. The best part about this stuff is that it's specifically designed to
not let liquid through so, seemingly, it would work well under coolant.
However, this still needs to be tested.

For anybody interested, the material recommended for vacuum tables, a
large-pore polypropylene, is only available straight from Porex,
www.porex.com and they're very willing to provide samples as well as have
very informative pre-sales tech support.

Andrey

-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of John Johnson
Sent: Monday, August 15, 2005 9:11 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Re: Vacuum table

The company I work for uses Porex sheets as a consumable table surface.
The cutting tool is a "pizza wheel" blade, or a tangetial (drag) knife,
so the surfaces last quite a while. Might or might not be useful for
your application.

Another thought is to use that grippy plastic mesh like you use under a
hand router on top of a table with multiple holes. The mesh helps
disperse the vacuum.

For any type surface, keep some plastic film on hand. When a section
cuts through and is complete, throw some film over it to reseal that
area.

Regards,
JJ

On 14-Aug-2005, at 17:47, Denis Casserly wrote:

> I haven't tried it but from what I've read porous hold down boards are
> used by
> guys who cut out plywood frames for the furniture manufacturing
> industry.
> It's very inefficient - you need a huge vacuum pump to overcome the
> resistance to airflow through the MDF, so I think the table is zoned
> up with
> valves controlled with a local PLC which monitors the spindle position
> and
> closes off all the other zones, in order to keep the pump size down.
> The
> pumps are huge and expensive because they deal with a 4 by 8 sheet of
> board.
> There an outfit in Langley BC that sells routers using it (Pacific
> Technology
> or some name like that) You could also check out a website named '
> Woodweb' -
> that's where I first heard of it.
> cheers,
> Denis Casserly
>
> On August 14, 2005 03:21 pm, davegsc@... wrote:
>> A couple of years ago, I read somewhere that MDF is porous enough that
>> you can provide a vacuum right through it with a ShopVac - no need to
>> drill millions of holes in your bed.
>>
>> If that's true, that would make it easy to replace sacrificial
>> surfaces.
>>
>> Anyone tried this?
>>
>> Dave
>>
>>
>
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