Re: [CAD_CAM_EDM_DRO] Re: Sanity check for homebrew CNC milling machine

I missed the original question.

A moving table design like the one at www.campbelldesigns.com is easier to
build and a lot less trouble than a gantry machine up to about 50" by 60".

If you need a 4' by 8' table that a gantry system will take up less room.
At 4' it is almost a wash. The moving table X axis will be 8' long, the
gantry table will be about 6' long.

Bob Campbell

----- Original Message -----
From: "jmkasunich" <jmkasunich@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Friday, October 10, 2003 7:02 AM
Subject: [CAD_CAM_EDM_DRO] Re: Sanity check for homebrew CNC milling machine


> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "bitnick78"
> <arvidpublic@h...> wrote:
>
> > This is a fixed bridge, moving table construction - not a
> > moving gantry machine. So the weight of the bridge will be
> > not be a problem - on the contrary, as it will help reduce
> > vibrations.
> >
> > Also, since I can make the length of the table longer than
> > the travel of the table, I can support the bars at the middle.
> > I could get even more travel without this extra support, but
> > I think it will be needed.
>
> Of course the design is up to you, but there are some
> significant advantages to a moving gantry machine compared
> to a moving table machine.
>
> For one, a moving table machine will use nearly twice the floor
> space compared to a moving gantry machine with the same work
> envelope.
>
> Also, you will _still_ have an unsupported rod rod length
> slightly longer than your travel distance. (The total
> rod length will be more than twice the travel distance.)
>
> With a moving table machine, rod length = travel length +
> distance between table bearings (table length). With a
> moving gantry machine, rod length = travel length + distance
> between gantry bearings (usually much less than table length).
>
> And finally, depending on the design and work materials,
> the table + workpiece may be much heavier than the gantry +
> cutterhead, which will require stronger motors or slower
> movement.
>
> Regards,
>
> John Kasunich
>
>
>
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