Re: Asian Import mills, EMCO, PRAZI, Myford, MOTORS

Hi Jeff,

Thanks for the ENCO descriptions! I'll be following your conversion
closely. It is interesting to hear your comments on rotational
alignment, I suppose it won't matter, just a chore to measure out. I
would want to use a pair of bearings, secured to the casting, and
preload them to take thrust. And then use a slotted flex coupler
(similar to the way Sherline did it). Are you going to use NEMA #23
motor mounts? What motors do you have? I just bought 3 180 oz/in
motors, intended for the Sherline. humm, might work on the "big mill"?

How long, and what dia ball screws are needed? I got my "scrap" ones
out last night. I had been given some round ways w/ ball screws some 10
years ago. I had mounted a pair of 15 deg steppers that had 9:1 timing
belt drives on them. Two assemblies bolted together with a "saddle" I
machined from aluminum were SUPPOSED to give me a x-y platform. Before
I knew about CNC. I ran the steppers (with a 555 timer and drivers),
but I think that was before we moved into the new house, so I didn't do
any more with it. Not much travel. The ball screws are probably only
12" long. The ways are only about 3" apart! I think if I rebuild the
end plates, space the ways out to about 10-12", and build NEMA #23
mounts, I can run them with 60-70 oz/in motors (I have an extra motion
control kit from MaxNC). Yeah! Another project!

Good to hear that motor is not a problem. But at $200 or so more for a
US motor, I think it could be replaced later if needed. Is it a
standard mount/motor?

I don't know much about the gibbs. Aren't the gibbs tapered, so that
the ways get a little tighter as the gibbs are pushed in?

cadman@... wrote:

>
> Hi Alan,
>
> Well you know what my project is. I have taken appart the ENCO X and
> Y tables to measure everything. I'm just about finished designing the
> ball screw conversion for X and Y. I have not looked at Z yet.
>
> Some notes about "Quality" on ENCO. The iron looks like good quality
> cast iron. Can't find any pits or bubbles in the machined places.
> The stock machine uses "Thrust bearing" for the X and Y screws. They
> are a press fit on the shafts. This is the only thing that keeps the
> screw from sliding back an forth. (Other than the pinned collar at the
> end of the screws) The assembly procedure for these machines must have
> fixtures to hold things. While measuring the threaded holes and
> locating pins for the lead screw bearing blocks, I could see that
> every hole was placed at a random location. The only thing that is
> important is the location of the bearing hole. It must be on center
> to the lead screw. They don't care about rotational alignment, this
> is why the mounting holes and locating pins could be anywhere.
> The 2HP import motor runs great! Lots of power. 110 or 220 your
> choice. I liked the belt pulleys, they look like they were machined
> out of solid aluminum. (Thats a 10" dia bar stock!)
>
> The nuts are machined from one casting of copper or brass. The way
> they try to handle nut wear is by bandsawing a slit through the
> threads and placing a screw to "pinch" the thread if slop devlops.
>
> I'm not too concerned with the stock bearing and nuts since I will be
> replacing them with ball screws. What bothers me is the "Jib
> adjustment" They only give one screw to tighten the ways. It is
> located at the end of the jib (If you can believe that). I am not
> sure if it does anything at all. The only real jib tightning is done
> by the way clamps. You know the ones that you tighten to lock the way
> from moving.
>
> CADMAN