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

--- In CAD_CAM_EDM_DRO@y..., Alan Marconett KM6VV <KM6VV@a...> wrote:

> 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.

Yes! I took the bearing blocks (three of them) to work and used the
"Reneshaw" probe scanner. It made it easy to get the relation between
the bearing hole and the mounting pins and bolt holes.


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

I also am planning to use angular contact bearing (two per end) and
hold them to the new bearing block. I will use a nut on the ball
screw to hold tension to the bearings.

> (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"?


I'm using servo motors. I got them from Camtronics. They don't come
stock with a NEMA mount. I think I will use the standard bolt circle
that is on the motor. I'm adding timming belts with a 2/1 ratio. I
don't know for sure the size of them, I think 420 oz/in peak.

>
> How long, and what dia ball screws are needed? I got my "scrap"

ones

The group has said to use 5/8" dia .2 pitch ball screws. This is what
I plan to use as well.

>
> 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'm not sure, what is standard? It looks like the motor bolts to a
plate and the plate has a pivot point and a locking end to keep it
tight.

>
> 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?

Ah... yes "gibbs" that is what they are called, not "jibs". :)
Yes that is normally how to adjust gibbs. You tighten screw that are
pushing against the gibb and use a nut to lock the screw from moving.
This system was not designed that way. There is ONE screw with a
large head and is located at the end of the gibb. Not perpendicular
to the gibb, but with it's axis, part of the large head catches the
gibb and pushes it against another screw at the other end. I can't
see that it does any good at all.

>
> cadman@p... 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