Re: Mill/Drill CNC Conversion

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

> Hi Jeff,
>
> Thanks very much for posting the pix! I've been wanting to get

a better

> view of what needs to be done to convert the mill. I assume

you've got

> access to another mill, so that you can make parts without

having to put

> the mill back together! That's what I was dreading! Have you

made CAD

Basically what I did was to measure EVERYTHING on the mill
first and make drawings (no CAD yet, but I'll create and post
them in the future.) I had to take the table apart and put it together
3 or 4 times, but I must say I got pretty good at it by the end. Not a
big deal, really.

> drawings of the parts? I'd also like to get a rough idea of the

prices

> for the ballscrews and angular bearings.

Bearings were about $12 each (and I may have a few left over, if
you're interested), ballscrews were $?? from Reid Tool
(McMaster-Carr is about $1.00/inch, Reid was cheaper) Ball nuts
were about $23 each, but they are not pre-loaded
(non-backlash). The pre-loaded ones are about $160 (!) each.
For my initial test of the Y-axis, there was no discernable
backlash, but I'll have to wait to put an indicator on the table
before I know the exact backlash number.

>
> You had to bore the ends of the ballscrews? What does this

involve?

Actually a piece of cake. I cut the screws to length (it comes as
one piece) on a cut-off saw, then used my 7x12 mini-lathe to drill
and bore a hole in the end. For the longer (X-Axis) screw I had
my friend bore the holes on his large lathe.

> Something that one who's first full sized machine is the RF-31

could

> accomplish? I don't yet have a 9x20 lathe. Perhaps the

ballscrews can

> be ordered that way? Can you explain the "stub shafts" that are
> "pinned" in the end of the ballscrews?

You can order the screws pre-cut and machined, but it's fairly
expensive, and being the frugal (and now broke) home
machinist I decided to do everything myself. The stub shafts take
the place of the machined ballscrew ends and have features for
keyways, bearing diameters, and threads. Though you could
attach the two together with a shaft-lock compound from Locktite,
I chose to pin mine together with a roll pin. I had to use a solid
carbide center drill to get the hole started in the ball screw, but it
did a pretty good job.

>
> This is all "big stuff" to my little shop. SO, my RF-31 will have to
> "upgrade" itself!
>
> I suspect that a "RF-31 retrofit kit" such as you've done would

be a

> good product for this list (and the mill-drill list)!
>
> Alan KM6VV
> P.S. What area of the country are located in?

I'm in Cincinnati, OH.

Good luck!

-Jeff

>
>
> jeffswayze wrote:
> >
> > Hi Folks,
> >
> > It's been a while since I've been active on the list but now that

my

> > son is 13 mos. old I've got a little more time to work on my

CNC

> > conversion.
> >
> > For starters, you can check out some pictures I took last night

in a

> > folder I created in the "Photos" section. Look for "Jeff's

Mill-Drill

> > CNC Conversion"
> >
> > Although I've had all the materials for quite some time, I've

now

> > done the majority of the machining and can start putting

things

> > together. Last night I was able to assemble the Y-Axis parts

and lo

> > and behold - it worked! As you can see in the pictures, the

system is

> > comprised of a bearing housing for the angular contact

bearings, a

> > 5/8" ballscrew with a stub shaft pinned into the end, a mount

for the

> > ballnut (to replace the existing Acme nut), the ballnut and a

pulley.

> > As you can see in the picture of the assembled axis, the

stepper

> > motor is mounted to the left of the base. I still need to get the
> > correct-sized belt, but next to that I'm pretty much done with

that

> > axis.
> >
> > For the X-Axis I've made the mount and bored the holes in the

ends of

> > the ballscrew. I've yet to turn the stub shafts and create a

motor

> > mount. However, the X-Axis should be pretty easy since I'm

planning

> > on using the existing thrust bearing mounting holes (my

angular

> > contact bearings are the same size - woo hoo!) and

tightening the

> > ballscrew up with nuts at both ends.
> >
> > If anyone has questions or sees errors, please let me know.

I'm

> > hoping to have both axes operational by next week, and the

stepper

> > drivers and software ready by the week after.
> >
> > I'm definitely going to do a Z-Axis, but not right away. I want to
> > get the X-Y working first. If anyone has suggestions on how

to drive

> > the quill with a stepper, please let me know as well. I've seen

Dan

> > Mauch's method, and currently my goal is to do something

similar.

> >
> > Enjoy the pictures. I'll update them as I make more progress.
> >
> > -Jeff Swayze