Re: Homemade mill (was Very small miller/engraver)

wow, you guys are thinking too simple !

what about using expensive precision ground shaft and realy expensive
linear ball bearings ? what are you trying to do ? make it easy ???

One thing that comes to mind is to use a long table for the X axis
and one of those smaller 4"x4" ones for the spindle. only problem I
see is that if you have a center point and rotate the head, the
cutting bit goes way off center. But then if you rotate the column,
it goes off center the other way, (but not as much) and you lose
rigidity. (like the mini-mill)

For strength, but at the risk of being ugly, you could put a pair of
I beams or Channels from to back, then weld a pair of them as
uprights, and then put in angled bracing from the top to the back.
This would be strong, and simple.

Regarding alignment, you could have it machined or just shim it.
Shimming would be easier and allow you to work out some of the bugs
before sending it out.



/||
/ || table
/ || here
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Dave

--- In CAD_CAM_EDM_DRO@y..., "Guy Sirois" <guys@w...> wrote:
>
> Hey Ballendo,
>
> that's almost exactly what I am doing right now !
> After having searched unsuccessfully for an affordable small mill
for the
> last few years, I decided to make one from two small 5-1/2" x 12"
milling
> tables. I bought them from BusyBee in Canada but are the same as
Enco's
> 201-2826. I will mount them as you describe, with one exception,
the
> vertical one will be retained by its center, so it will be
rotatable (5th
> axis). As the mounting base is round, well it will be anyway, after
I put it
> in the lathe, its edge can be graduated in degrees.
>
> As a spindle, I am using an ER-20 collet extension, which is a
precision
> shaft of 1" dia by 6" long with a collet chuck at the end. It will
be
> installed in a steel block of 4 x 4 x 6" bolted to the vertical
table. I
> will use adjustable taper roller bearings. I have two 90V.DC
variable speed
> motors I will (somehow) attach to the spindle.
>
> The base of the machine is not totally defined yet. As I want
something very
> rigid and massive, I have to be sure the back support member can
not flex at
> all relative to the bottom plate. I was thinking of using large
structural
> steel rectangular tubing of 8" x 10" x 1/2" wall. One length is
laid on its
> side and serves as the base, then another length is put vertically
on it to
> act as the back support member. That should theoretically be very
rigid, and
> can even be filled with cement if necessary. I would obviously have
to have
> the end of the vertical piece precisely squared at a machine shop.
>
> The bottom piece could also be made from a H-beam. The rear piece,
however,
> could not, as I will have a large bolt going through it ( the pivot
for the
> 5th axis) and the web of the H-beam is in the way.
>
> The frame could also be made from two thick steel plates, but then
I might
> have to brace them together to reduce flex.
> Anybody has ideas for a rigid L frame ?
> Anybody else done something similar ?
>
> Regards,
>
> Guy
>
>
> -----Original Message-----
> From: ballendo [mailto:ballendo@y...]
> Sent: Saturday, March 02, 2002 4:42 AM
> To: CAD_CAM_EDM_DRO@y...
> Subject: [CAD_CAM_EDM_DRO] Re: Very small miller/engraver
>
>
> Hello,
>
> MaxNC used to sell plans for a mill made from two import xy vises,
> and a 1/2 thick piece of aluminum. They were sold for $65, and
> included maxnc phase s/w! I don't know the price nowadays, but I'm
> pretty sure they're still offered. (Tell 'em Ballendo sent ya)
>
> The resulting machine is simple to build (using hand tools even),
> slow, but VERY sturdy (I added stiffness to the vertical support).
> Easily capable of machining steel.
>
> One neat part is that the "upper" xy vise, which provides the z axis
> motion, IS a VISE. Making it very easy to mount and adjust/change
> spindles. Another interesting result from using the xy vises, is
that
> there is an "extra" axis. It can move the spindle left/right! This
> can be used to extend the travel of this little mill, OR could be
> used to make a tool changer! I've got the details worked out, but
> have not yet built it.
>
> (I made a second model using larger vises from HF, and better drives
> later, after "proofing" the idea as presented by MaxNC. Which uses
> the 3 and 4 inch xy vises, with radio shack parts for the drives.)
>
> Worth looking into, IMO. Hope this helps.
>
> Ballendo
>
> P.S. Another choice would be the compucutter mill pkg., by R
Bartlett
> in the UK.
>
> P.P.S. I will be offering plans for this bigger small mill w/
> toolchanger, which is derivative, but not a copy of, the maxnc
plans.
> (hint: I've been playing with the IDEAS used in dental handpieces
for
> use in small machine spindles). But my first 2 books are ahead of
> these plans in the pipeline.
>
> --- In CAD_CAM_EDM_DRO@y..., "Graham Stabler" <eexgs@n...> wrote:
> > Has anyone out there built anything in the way of really small
> mills/engravers. I only want to make small parts out of perspex,
> balsa, pcb and ocasionally aluminium. I've seen "The Brute" on the
> web and might buy the plans but just wanted to see if there were
> other alternatives.
> >
> > Cheers,
> >
> > Graham Stabler
> >
> > p.s. First post
>
>
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