You crash the cross-slide into the work. Now what?

HMF

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Most cross-slides have pieces missing. "Badges of Honour" they call them, but, in reality, someone crashed the cross-slide into the workpiece in a momentary lapse of attention. The important thing is what to do if that happens. If you retract the cross-slide and your chuck moves back, it is probably bent, or even worse, the spindle could be.

So my question is, when/if this happens to you, how should you proceed to make things right?


Thanks,



Nelson
 
I don't think any of my machines have enough power to bend a spindle or chuck, but if something happened to cause concern, test the chuck runnout. Failing that, test the spindle. Find the cause. It might be as simple as the chuck shifting on the backplate, maybe damaging the mounting bolts.

When you look at a lathe to buy, and see some crash marks on the cross-slide, which most have, I would wonder what damage or alignment issues that incident caused.

Yet most cross-slides you look at have this type of damage, or it has been ground away, which you can see. Almost every South Bend Heavy 10 I saw, including my own, has battle-scars on the cross-slide, and I wonder what needs to be done to deal with this, if anything.

Nelson
 
I'd say that most of the non industrial (light weight belt driven) lathes are more likely to damage the drive train for the feed/thread and tweak the head alignment (most are bolted to the ways) than bend spindle/chuck. Not saying it can't happen but as mentioned most all of the machines that have been around a while have some crash rash and if grievous damage often resulted from a crash we'd be warning each other when ever a topic of buying used came up. My 12x36 jet looks like it was run by a narcoleptic who just let it feed until the crash woke him up. It's crashed more times than Lindsay Lohan, but runs fine. Quick check is to take a large diameter (bigger better) piece of anything chuck it and face it. Zero an indicator mounted on the tool post on the near side of the face. crank it towards the middle and of course it stays on zero. Now continue past the center (lift plunger if needed to clear hole etc) If the indicater continues to stay on 0 then your head/spindle is still parallel to the ways. You can use any free machining material on hand as long as it doesn't warp which will show when crossing the near side of the piece by not staying on 0. keeping close to the spindle helps isolate alignment from twist etc. This method is not definitive unless the results are perfect, if there is a problem further testing needs to be done to determine the exact cause.

Steve
 
Most likely the main damage would be to the holding accuracy of the chuck jaws.They are pretty easy to very slightly spring and result in not holding work as concentric as before.
 
You've seen this picture before. The speculation is that this was a school lathe.
P6190005.JPG

Everything works well enough. In fact, the spindle bore is the only piece of equipment I own that shows zero runout.

C'mon, guys. Lets see your worst impact damage. (Sorry. No vehicles allowed.)

P6190005.JPG
 
That's pretty horrid! Mine was crashed often with a lantern post and the small round base tended to break out the T slot. Many hours of running and tightening and re-tightening with a QCTP has finally ironed it all flat.
crashed.JPG
You can see the cracks in the T slot.

Steve

crashed.JPG
 
Yeah. The cracks would bother me a lot more than the dings.
 
Yes,cracks!! I had a used Sharp 14" lathe at work. One day when a maintenance guy I had let use the machines for years was running the Sharp,the WHOLE front end of the compound FELL OFF. I know he didn't crash the lathe because I had trained him,he was always very careful to not lose his privileges,and I was in the room. No crash was heard. Must have been a crack we didn't see. Fortunately,I had a compound from a Jet lathe which was mine,but I adapted it to the Sharp lathe. And,that was a good brand,and made in Taiwan,too.
 
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