How was this chuck damaged? A forensic investigation.

I inherited a Goodway 16x60 engine lathe from my father. My sibling used the lathe just before my father died. My father said that he thought that my sibling had damaged something badly when he used it. My sibling will not confess to any such sin, but...
This are pictures of a Bison 3245 scroll chuck. The chuck was a complete rust ball so I disassembled it to clean it. Then I discovered the evidence of bad things. My question is really two-part: what could have happened to cause this damage and, more importantly, what damage should I be looking for on the lathe itself?
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Is that a tiny crack coming from the corner?

that would be a HUGE crash. That is the worst damage I have ever seen on a chuck. I don't know how you could crash a Goodway hard enough to do that to the chuck and not damage the lathe.

It is as if something was pulled from the chuck to the tailstock. One of the jaws is cracked but to answer your question, the crack is wider on the outside and less so toward the center of the chuck.

So would that mean that the lathe is most likely junk? What could be measured? Sorry for the newbie questions but I am a newbie.

My guess is something significant diameter and length was held in the chuck. The miscreant then did heavy work without the support of the tailstock. Or even more likely, tried to part a workpiece and the chips bound and the workpiece tried to climb the parting tool.

As far as the lathe being junk? No idea. It could well be undamaged. A survey is in order.

OP, are you saying that those cracks go the full length of the jaw slides?

It is difficult to imagine how that damage could be done. I would expect cracks from the inside corner(s) in the event of a MAJOR crash. Are all three slots damaged, or just one? Are there no visible indications of damage on the carriage or ways of the lathe? From the cracks, I would guess that the force was inward, towards the headstock. It's almost like the chuck was dropped on its face. If it is only one slot that is cracked, and the jaws don't show comparable damage, I'm guessing the chuck wasn't on the lathe when this happened, or at least it wasn't spinning.

Check the lathe spindle for runout and, by prying upward on the spindle, check it for bearing play. Do this several times, rotating the spindle a little each time, to see if there is localized bearing damage.

I think GBENT has the right idea as a parting crash could cause that kind of damage. Look for other damage around the compound -cross slide -saddle. If you got any tooling with the lathe look for a dead parting tool/holder.

#2 for what gbent says. Large, long workpiece held in the chuck with insufficient jaw engagement on both scroll and jaw guides. Typically the jaws on reasonably modern chucks of OK or better quality are marked to show maximum permitted extension beyond the chuck body. Usually mark is approaching half way along the jaw indicating that at least half the jaw must be supported by the guides to safely hold the workpiece.

If the jaw isn't properly supported the classic parting off jam up could easily wrench the workpiece sideways over the jaw with sufficient leverage to break things. Especially if the material is long and being cut far too far away from the chuck. Look for a snapped parting blade.

Large lathes, even at the lower end of the market are remarkably durable. Verify that the spindle is still straight by turning by hand with a lever type dial indicator on the taper inside to indicate any run out. Need to clean the taper first. If that seems OK run it up with faceplate fitted and listen for 'orrible noises. If all sounds quiet report back and folk here will guide you through the enxt stage of checking.

16 x 60 means you could theoretically handle a workpiece 5 ft long! I'm betting that your sibling was trying to work on the far end of a 3 or 4 ft long piece of material. Lots of leverage back at the chuck if a jam up happened with a workpiece that long but the chuck will have taken the brunt of the force. Especially as it is cracked because the action of forming a crack would have taken a lot of energey out of the force before it got to the spindle.

Clive

Thanks for reposting the pics here. Is there impact damage anywhere on the jaws or anywhere else? There may not be if damage was on a workpiece that is gone now.

Demoman357 said:

I inherited a Goodway 16x60 engine lathe from my father. My sibling used the lathe just before my father died. My father said that he thought that my sibling had damaged something badly when he used it. My sibling will not confess to any such sin, but...
This are pictures of a Bison 3245 scroll chuck. The chuck was a complete rust ball so I disassembled it to clean it. Then I discovered the evidence of bad things. My question is really two-part: what could have happened to cause this damage and, more importantly, what damage should I be looking for on the lathe itself?
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I had an employee do this very same type of damage to a new Buck chuck. He had the jaws over extended and was taking heavy cuts. I didn't see what happened exactly to cause the failure but I heard the crash from the other end of the building and immediately saw the carnage.
My chuck was ruined as yours is.
The damage to the lathe was in the apron assembly. the bevel gear set. The keys where sheared as well as broken teeth. And a broken crossfeed handle casting. the machine is a LeBlond 17" .

I'm wondering if the lathe was started with nothing in the chuck? Bison is a fairly good chuck but they are a little loose especially after use. I haven't seen it but have heard of jaws coming out when lathe started and nothing in the chuck. What jaw number 3? I'd check the lathe or carriage where if the jaw would hit. Especially if was possibly off the scroll. Every time Joe Pieczynski on YouTube does anything on a lathe with the chuck either he mentions or there is text on the screen warning not to run lathe with empty chuck.

A hard slam whack of the running chuck wreck to the tool post or to a vise. Lathe may be OK but not much hope for that chuck..It could get worse and fail.

Bent spindle tube and a broken gear the next thing to look for......with not , then the lathe may be OK /fine.

A crack somewhere in the saddle ..you might look it over also.

Can't tell by pics and not familiar with that lathe. If threaded spindle maybe he hit reverse and spun it off? I'd expect to see some damage to ways in that case, but maybe it launched over his head.

With the jaws hanging outside the chuck body in order to hold a part much larger than the chuck was designed to hold, the chuck wrench could have had a cheater pipe applied. The lathe would not even need to be turned on to break the chuck. Is the chuck wrench bent?

I have been unlucky a few times buying used Buck 6" 3-jaw chucks on eBay and have seen exactly the same cracks. One chuck had even been "repaired" by brazing. This type of failure is more likely with cast iron body chucks than with steel bodies.

Larry

Looks like whatever happened, the jaws most likely were extended too far from the body, a short part could have come loose, and got between the jaw and the bed.
There was a Goodway at a local school, not a bad machine, it took a beating for more then 10yrs.
Some years ago. a large 50hp lathe was crashed at Lampson Crane, The chuck came apart as well as the cross slide and compound, that machine was scrap. The Goodway has no where near that kind of power, hopefully there will be no damage.

For obvious damage, I would remove any gear cover in the head and look at all of the teeth in the gear box. If all are present, that's a good thing.

Also I would remove the chuck and check with an indicator to see if there is runout on the spindle in the hope that there is no damage.

Others mentioned possible damage to the carriage and that should be checked as well. As mentioned above, I suspect that heavy work was attempted with no support from the tail-stock.

For more details, I suggest a dose of sodium pentathol to be used on the sibling. Do it in a dark room with a piece of rubber hose handy. It's amazing the things you can find out that way.........just kidding, of course, but I'm just sayin'.

Newman109 said:

For more details, I suggest a dose of sodium pentathol to be used on the sibling. Do it in a dark room with a piece of rubber hose handy. It's amazing the things you can find out that way.........just kidding, of course, but I'm just sayin'.

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Pentothal might be overkill here. My Jewish wife said "a little wine goes in, a little truth comes out."

L Vanice said:

With the jaws hanging outside the chuck body in order to hold a part much larger than the chuck was designed to hold, the chuck wrench could have had a cheater pipe applied. The lathe would not even need to be turned on to break the chuck.

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I like this theory! I'd like to see a video of someone field testing it. Any volunteers?