Hi All
Thanks for all the informative replies. I'll pursue the references.
Sounds like it's doable, but the time/effort spent on software development
will exceed the material savings. Unless of course, a few thousand were to
be made.
I would not use gears to drive the arms, but feedscrews, forming a triangle,
much like a mechanical shovel. I did not draw that all in as it was getting
real late.
Again, my target is an entry level CNC mill, for milling of plastics, PCB,
foam...
And it's a pity I'm on the other side of the planet(South Africa), because
I'd be happy to supply a prototype to someone who's keen on working on the
software, which is not my forte'
Thanks for the prices John. I'll look into it. Freight is always a killer.
Regards
Roland
On 05/12/2007, John Thornton <[EMAIL PROTECTED]> wrote:
>
> On 4 Dec 2007 at 16:51, [EMAIL PROTECTED] wrote:
>
> This is a very interesting and quite challenging project...
> The cost to drive each joint of the pivot mill would far exceed the cost
> of
> Dremil size slides. While the concept is sound the mechanics of the gears
> would be the killer. You are designing a robot. The gears would need to be
> planetary perhaps double reduction to get enough torque to drive the arms.
> Of course you can't buy them off the shelf they would have to be custom
> made or
> purchased from an OEM $$$$.
>
> I would make the first joint also be the Z axis drop the links to the Z
> that way your
> tool position is constant as the Z axis moves. If you do pursue this path
> please keep
> us posted as to your progress it is very interesting... and a challenging
> project...
>
> I would look at the options like using 80/20 with their slides and acme
> threaded
> rods and nuts if your not needing super tight precision. I'm building a
> plasma
> cutter with that as we speed and it is super simple to work with.
>
> For a load capacity of 315 lbs each from McMaster Carr you can get slides
> for $34 each and the rail is $0.09/mm and come in 500mm and 1000mm lengths
> So for $226 you would have 4 slides and 2 rails with about 16" of
> travel...
> Part# 9867K1 and 9867K11 for the rail if you want to look it up.
> 3/8" acme precision threaded rods are only $28 for 36" and the nuts $22
> Part# 95072A124 and 99030A326
>
> So for less than $600 you could have the the mechanics for a 16" x 16"
> table...
>
> And then there is always FleaBay that sometimes has bargains for rails and
> such...
> http://cgi.ebay.com/Wafer-Handler-Automation-Robot-21-arm-10-
> range_W0QQitemZ180186126744QQihZ008QQcategoryZ45044QQssPageNameZ
> WDVWQQrdZ1QQcmdZViewItem
>
> John
>
> > I believe that the greatest hurdle in constructing a small CNC machine
> > is the cost of the linear slides,
>
>
>
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