Well I'm finally done with my Micro Mark mini mill cnc conversion. I converted it it all ball screw and servo motor. I'm using Gecko 320 drives and camtronics power supply at 80 volt and 20amps. The system is geared 20:1 the ways were lapped and I replaced the gibs with brass.

The z axles was machine from Ron steels plans, and modified for servos.

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Here are some pics of my z axis assembly.

The belt pulley for the z axis is too big in dia and the motor for the spindle hit's it so I'm in the process of changing it.

I assume you wont be running any coolant? Also, it looks like the X axis motor will be mighty close to the column? will it fit?

Have you considered converting your spindle to belt drive? Its much quieter and you can calculate the speed of your liking to an extent. 3000rpm is great for that motor, I have taken .25" deep cuts with a 3/8" rougher on mine at about 2500rpm and the machine started chattering before the motor crapped out.

Jon

No problem with clearance everything fit perfect just the one belt pulley I have to change.
I have looked every where for info on converting to belt drive, please share how to do it.

Why the brass gibs?

Eric

Lower coefficient than the iron on iron. When I lapped the stock set-up what i found was I was just wearing away the metal and had to keep tighten the set-screws, with the brass that did not happen and because of that I ended up with no play in the x and y.

I took my spindle and all that other stuff apart so long ago that I dont even remember how it all went together and all, but basicly when you take off the motor mounting plate, theres a spacer ontop of the top bearing and on top of that is the spanner nut, I think thats how it goes, What I did is cut the spacer down, made a pully that goes over it and use the spanner nut and tighten it down on top of it, I made a pully that I press fit onto the motor shaft and a motor mounting plate. I am making a new motor mount for my new motor along with new pullies.

-edit- I too have brass gibs on my machine:)

Jon

Paul,

On your first post in this thread you said you have the camtronics box running the servos at 80VDC!!! Thoes Clifton servos are rated at 12-60 with a nominal at 36VDC. Are they getting very hot when you run at that voltage?

Yes I'm running 80vdc and no their not getting hot at all so far.

They will only see the 80 volts when near stalled. Otherwise they see much less voltage.

Eric

Did you use the Mcmastercarr ballscrews? One nut or two per screw? Any backlash?

Eric

I used ball screws and nuts from roton. Their is no backlash since I used brass gibs, I could really tighten up the gibs.

How much did they cost, if you don't mind my asking?

Eric

How much did they cost, if you don't mind my asking?

Eric


http://www.cnczone.com/forums/showpost.php?p=48904&postcount=7

Paul do you have a link where you found a power supply for the Clifton servos ?

Thanks
Ken

I got the power supply and box from camtronics http://www.seanet.com/~dmauch/ . I will post some pic later this week.

Finally got my machine all together, looks great and so far is working very well. I will post some video and more pics when I get a chance, now I can start my laser project. :)

you tease!
sure, tell us all about it but make sure not to show any pictures!

Paul, What encoders did you use on your set-up?
The Clifton motors I have came with renco encoders which I want to change....

thanks
kevin

I have us 250 digitals on them.

Here is what 20 hours looks like, this is my Camtronics power and enclose.

I assume you have checked your gibs and everything, when you tighten down the ballnuts, make sure you have the gibs already tightened and set where you want them, then tighten the ballnut screws slowly and carefully while moving the axis a little bit. This is what I found to work the best.
I have one good ballnut and one not so good ballnut, one where I have .0016 about and another where I have .008
What kind of flanges do you have your ballnuts mounted to? I know the flange in my Y axis is only about 5/16" thick and it flexes a little bit,

Do you have preloaded nuts with larger balls or did you manage to fit more than one nut in there?


some pictures would help;)

Jon

If your gibs are too tight that will definetly cause backlash

Do you have a current meter ? If so set the meter to
measure the current of the drive, loosen the gibs a bunch,
then set the axis moving back and forth full stroke,
at some slow but reasonable speed say about 5~10 sec
each direction.
start tightening the gib until you start to see a rise in current
and make sure that the current is more or less
the same in each direction.
Repeat with the saddle and head.
This is one of several methods used on real CNC

Another method as used on BP ez-tracks, is to center the
table, place a mag base on the saddle, and then the indicator
against the end of the table. loosen the gib and then start to tighten,
while first pushing and then
pulling
on the table to deflect the indicator. again do this at
both ends of the table and try to balance the deflections.
again repeat with saddle and head.

The Bridgeport builders used a torquewrench to apply
the push and pull evenly.

No numbers here because only you can know what is reasonable on your machine.

It's been several years but I think that BP set the tables
and saddles to .0003~.0005

How did you like your roton ballscrews? Were you ever able to get rid of all the backlash in your system?

Do you have any pictures of the final assembled product? I'd love to see what you did with your z-axis.

What preload did you order on your ballscrew? i'm wondering how it would be possible to get rid of the backlash.

Why did you lap your ways? what does this do?


The roton ball screws are worth the money and work very well. I did get rid of the backlash, and got it down to .002. I have many pics in my photo gallery, with a machine like this IMO their is no way unless you take GREAT lengths to eliminate all backlash. I ordered over sized balls to pre-load the nuts. All machines need their ways lapped, that is what will make them glide smooth.

Wheres the pics of the semi-finished mill man? your keeping us all waiting:)


Jon

My photo gallery- http://www.cnczone.com/gallery/showgallery.php/cat/500/ppuser/1

Yes.... I thought it was up and running?

Here is my laser side plate- it suppose to be 5.699 and come out-

This was suppose to measure 3.020 and -