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

Hi Guy,

sound like you have this well thought out.

I hope you post your pictures when all is said and done.

Dave

--- In CAD_CAM_EDM_DRO@y..., "Guy Sirois" <guys@w...> wrote:
>
> Thanks Dave for your subdued compliments ;-)
>
> See comments below ***
>
> -----Original Message-----
> From: dave_ace_me [mailto:davemucha@j...]
> Sent: Saturday, March 02, 2002 7:48 AM
> To: CAD_CAM_EDM_DRO@y...
> Subject: [CAD_CAM_EDM_DRO] 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)
>
> *** In this case, the advantage of using a tilting milling table
for the Z
> axis is that you can reposition your cutting bit with the table's
> handwheels. And you don't loose rigidity.
>
> 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.
>
> *** I thought about that but you still have a length of un-
supported beam
> between the vertical frame member and the bottom table.
Rigidity will then
> depend only on the beam's bending strength. And putting the
braces toward
> the front will interfere with the work. It has to be kind of a
cantilever
> arrangement, I"m afraid.
>
> 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
> ==============
>
> Dave
>
> *** I want to be able to machine steel with this machine, so
that's why I'm
> aiming for high rigidity and mass.
> Your comments are appreciated,
>
> Guy
>
>
>
>
>
>
>
>
> --- 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
> >
> >