machining ball screw

[KEYTEEM]

hi everyone, am wondering if anyone has sent out ballscrews to a shop
to be end machined and if they have can you recomend one to contact
for pricing?
i just recieved a set and can have them done but might not be able to get to them for awhile cause of lack of time , is this something that can
be asked on RFQ ?

thanx for any advice and help.

[DJ1978]

You could post a pic of the screws and a pic of what you want put on the ends to help.
What machine?

[r1656]

there ya go

[jingham]

I had my ball screws machined to accept the bearings at a local shop. They felt sorry for me and didn't charge me anything. Who ever you take the screws to, be sure that can support the free end of the ball screw when cutting through the hardended outside. If the free end is allowed to flop around, you could wind up with a bent screw that will be very hard to get straight again. Sorry for the elementary rambling, but I hope this helps.

[DJ1978]

Check out this web site. Tell them RC Product Designs sent you. Great people to work with.

http://www.rbrsi.com/

[KEYTEEM]

thanks for the info , i was able to find someone too help

[phantomcow2]

Any job type shop should be able to do it.
Look in your yellow pages. As long as they have a decent size machine with carbide, ballscrew is managable. I've machined it on my 7x12 alright using carbide. I tried it with HSS, it would barely cut.

[Phase1]

I'm in the same boat.....my precision Ballscrews $10K worth (x-axis being 3 metres long) arrive later this month.
The ends of the ballscrews need to be machined, the supplier of the ballscrews have recommended a machine shop that is experienced. The supplier do not recommend letting any old machine shop do the job as there is no room for failure.
After all the machinist only gets one go at getting it right...they can not throw the metal away & start again can they!
You need to find a machine shop that has done this work before, if that is not possible you need to carry out due dilegence or you will have expensive scrap metal.

[Ron111]

Phantomcow2,
(is there a Phantomcow1?, I wonder)
Your a good machinist compaired to me! I did turn down a ball screw and it turned out good, I grinned like a teenager as I took it around to my love one showing what I had done. But Phantomcow2, I had to aneal the last last 2 inches in order to turn it down on my 9X20 Harbor Freight. I was using carbide tooling and had gone through 4 or 5 when I decided to set up a vertical water bath (using a garden hose and a piece of PVC, being from Mississippi, we tend to do a lot with stuff just laying around) and was able to heat just the last couple of inches, and then just let it air cool.

After that, it turned down nicely and threaded easily.

All that said, I planning to do some more ball screws, and it would be nice to turn it down without having to aneal the ends. So, if you can remember the details about the rpm, cutting depth, ect. that you used and how you prevented the screw from whipping. I would love to hear about it, because I still dont feel right about anealing the end (whether it will ever effect anything I don't know)

Ron

[phantomcow2]

You should be able to do it with your 9x20 alright.
FIrstly, does your screw have a machined end as is? Often screws from a manufacturer have an end machined to 15mm or whatever, something you will probably never use. Use a 4 jaw chuck to get the end going perfectly, try to get it no more than .0005" off center. Even then, you've gone so far you might as well get it better .

The screw I machined was 44" long, whip was definitely a problem. The bore of my headstock will allow 3/4" stock to fit through, the ballscrew was 5/8". So I would set the RPM around 250 or 300, while holding the 30" of ballscrew that is sticking out with my hand. YOu want to balance it, get it spinning and make it spin true using your hand. Once its going at a good 2 or 300 RPM, you can let go and the rotation keeps it going true, no whip. I was doing fine sanding at 500RPM with still no whip.

Like I said, I had the RPM between 200-300. I was using brazed carbide tip tooling, 1/4" shank. For the first .060" or so, the screw is hardened (this is a rolled screw). So I would take off maybe .015-.02" off. I put the powerfeed on the finest setting I could go. You have to take it easy because it is an interrupted cut with the threads. I used plenty of cutting fluid also.
Eventually the hardening of the threads is penetrated, and you can go .04" or even .05" off at a pass. THat was what I was doing, you might be able to with a bigger machine.

Once it was getting closer, I took quite lighter cuts. Eventually the only thing I used was sandpaper.

[itsme]

Hi there,

I'm going to be machining a ballscrew today. I know how I'm going to do this, but have just one question.

Is it necessary to protect the ballscrew from the chuck jaws with a small sleeve or something like that or is it safe to grip the screw directly in the chuck?

Thanks
Warren

[Ron111]

itsme,
Like the name, I'll throw in my 3 cents worth.

Things I learned while machining a ball screw (ball screw 101)
1) the screw would wobble when put in the chuck because the surface teeth of the chuck is some places would penetrate the threads of the screw and the screw was off center.

2) My chuck came with an extra set of fingers, which had no teeth (or grooves cut in)

3) These fingers are numbered as to the location on the chuck that they go in (1,2,3, ect.) but the chuck is not numbered, so if you need to swap out fingers do it one at a time and match up the numbers.

4) For me, I had to soften the ends as previously described in the thread.

5) The chuck did not even scratch the hardened ball screw and depending on where the screw is in the chuck, the ballnut may never travel to that far on the end.

That's my three cents worth, things that you may already know, but someone reading over your shoulder may not.

Be sure to post your outcome and let us know how it went.

Ron