[asifjahmed]

Hello -

I need to machine the end of some 12" and 24" long 5/8" diameter ballscrews. I essentially just want to machine the ends to a smooth 3/8" rod.

Can one of the small 12" lathes handle this job, or does the 12" mean it cannot handle rods longer than 12"?

Please help me understand this.

Here is the lathe I am looking at:
G8688 7" x 12" Mini Metal Lathe

Thanks!

[G0G90]

asifjahmed,

You're correct on the 12" length between centers however, it appears that this spindle has a 20mm (.787") bore to "swallow" some of the 5/8" (.625") shaft.
Use the Steady rest if you attempt this!

My opinion would be to get a larger machine or outsource this task to a competent outfit.

[asifjahmed]

Thanks.

So to do something as seemingly simple as machine a small smooth end on a ballscrew, I need a bigger lathe? Is there any other way to accomplish this? Could a rotary table do such a thing?

I plan to acquire a mini-lathe and a mini-mill in the near future, but if I can't do something as simple as machine the ends of, say - an 18" leadscrew/ballscrew, I might have to rethink this.

[TarHeelTom]

Thanks.

So to do something as seemingly simple as machine a small smooth end on a ballscrew, I need a bigger lathe? Is there any other way to accomplish this? Could a rotary table do such a thing?

I plan to acquire a mini-lathe and a mini-mill in the near future, but if I can't do something as simple as machine the ends of, say - an 18" leadscrew/ballscrew, I might have to rethink this.

You need to grasp that although any machine you buy will have lots of things it can do, no machine can do everything.

There are occasionally gonna be jobs that you just have to farm out.

[asifjahmed]

Ok thanks but you didn't really answer my question. Was hoping for some constructive advice.

Stumbled across this:
http://www.cnczone.com/forums/diy-cn...s_without.html

Seems like that could possibly work if the lathe is insufficient.

[Fastest1]

There are a few concerns. A small lathe can probably do the job, if you are careful or rig a tool post grinder. I didn't look at the lathe, how big is the hole thru the spindle? Personally I would install the screw just past the chuck jaws, support the free end to eliminate whipping and then grind the hardened layer away so I could machine it. You will go thru a few inserts or cutting tools trying to get thru the hardened layer.

[Fixittt]

there have been many threads about this very thing.

There are some things to consider when attempting ballscrews.

You want as little of the screw as passable extending past the chuck. This means having a thru hole large enough to have the screw go thru the center of the chuck and out the back of the machine. You want to turn down as close to the chuck as possible. Another thing to note is that ballscrews in general are case hardened. Which means that some steps are required. Either annelaing the end to be turned and or special inserts need to be used.

here is a great write up on it.

5 Bears - A new ballscrew for the Z-axis

[fizzissist]

...Why not just take the parts to a local machine shop, pay 'em the $35 they'd likely charge, and you're done.

If some guy walked into my shop with a couple of shafts that just needed to be faced off, and he was nice, I might even do it as a favor. From what you're describing, it'd take longer to clean the lathe up when I was done than it would to cut off and face the ends.

If you need precision diameters turned on the ends for bearing supports, or threading, then pay the man, and be happy that you're closer to having the project done, and for far less than the cost of the machines right now.

If you're REALLY nice, the guy might even let you watch (bring your glasses) so you can learn. Then you're getting a very inexpensive lesson. Even crusty old machinists like me are happy to do that.

......Btw....... the rube goldberg turning method using the hand drill and wooden box is exceptionally clever. Hats off to that one! Which brings up a VERY important point for doing this in a lathe!!!!!
Use a support out of the BACK end of the spindle for the shaft. If it wobbles, besides being an extreme safety hazard, the vibration translates directly into the spindle, and into the area you're machining. The smaller the lathe, the more direct the effect.
Think leverage. A little vibration way back may be smaller up front, but more powerful.

[jsheerin]

Here's another video with good information: [ame=http://www.youtube.com/watch?v=B2gH6BywbvA&feature=plcp&context=C21131UDO EgsToPDskIPy-mHEymycSqYDoJ6w14G]Ballscrew Turning Y Axis Part 1 - YouTube[/ame]

[asifjahmed]

Great vid - thanks for sharing.

See how on his lathe, he is able to chuck the ballscrew such that most of it is behind the chuck (and even protruding out of the back of the headstock)? Can I do this on the mini lathe? If so, then machining the end of my ballscrews shouldn't be a problem, right?

[asifjahmed]

So spindle bore means the diameter of shaft that can protrude through the back of the spindle out the back of the headstock?

If this is correct, then I should be able to put the 5/8" ballscrew through the back and only leave enough stickout out for machining. Correct?

[RotarySMP]

Yes you can.