Re: [CAD_CAM_EDM_DRO] Achieving flatness on a large gantry table

kdoney,

On all commercial CNC routers that I have seen, the last step in
manufacturing is to flatten the table top.

For example, on a Multicam machine which use a high density material for
their vacuum system. The use a large fly cutter to flatten the table top
prior to routing in the vacuum grid pattern.

For my router design, I use a sheet of MDF for my spoil board. I use a 1"
fly cutter to flatten the table top. Normally is does not take very much to
get it flat.

For users that use aluminum or slat wall you will need to cut strips of
material like sheet PVC and use double sided tape to attach the PVC to the
table top. Then you will need to take a thin pass using your fly cutter.

Flatting the top of the table is a normal procedure.

Bob Campbell
Bob@...
www.campbelldesigns.com
Breakout board
THC board sets
CNC router plans
Stepper Motors
VisualMill Basic

----- Original Message -----
From: "kdoney_63021" <kdoney_63021@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, December 21, 2004 3:11 PM
Subject: [CAD_CAM_EDM_DRO] Achieving flatness on a large gantry table


>
>
> I just checked my table for flatness and was appalled. Max .025"
> error over a foot at certain points. The gantry itself is within
> reasonable tolerance. I have THK slides, machined extrusions and ball
> screws. I checked it every step of the way and it looked great; until
> mounting the table. This is a moving table design from Bob Campbell's
> plans (a nice system). I first used standard extrusions clamped
> together, I then went to slat wall, then tried to wedge together
> machined t-slotted 6061 (not mic6). The errors occurred ar the flat
> joins. With over 30 square feet, you certainly can't buy mic6. Even
> if I could, I couldn't t-slot it. What would you suggest? I guess I
> just expected too much. This system is good for plasma or router but
> you certainly can't machine on it.
>
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