chuck problems ? maybe others

[Steven FrancisParticipant @stevenfrancis]

Had my Amadeal 210 lathe about 10 weeks, turned a couple of small pieces of stainless (30mm x 14o/d) and an airgun barrel last week, besides those .. its been mostly used for turning plastics and facing up repairs.

Accuracy has been pretty good for a 3 jaw self-centreing? 0.02-0.03 mm runout at the spindle plate and chuck body, similar on the ER16 straight shank holder. And reversing the workpeice wasn't far off either..

Until the weekend when I did the barrel and entered chatter city. I used the offcut as a test piece , tried speeds, feed rates, tool overhang, Wasn't pretty in the early stages but I got the job done.

Chatter is work in progress. However I'm getting a tap when parting off 30mm delrin that disappears as the tool gets further in.

But for some reason the chuck jaws are out, #3 jaw is loose and about 0.3mm further out when loosely wound together, test rod run-out can be anywhere between 0.04 and 0.25mm by loosening and re-tightening the chuck.

I've stripped the chuck, washed and blown it out, bit crud, no lumps of swarf just grimy. And 'factory spec rust' on the back of the scroll gears.

Reassembled, 0.02-0.03 run-out on the spind;le /chuck body again but the #3 jaw is still slow and workpeice run-out still suffers random centering.

Was waiting for a new tool to arrive in order to finish off a couple of bits and I had to dial them in but repeatability has gone right out of the window

[Steven FrancisParticipant @stevenfrancis]

[BazParticipant @baz89810]

If you have only had the machine a few months you should be telling this story to the bloke who sold it to you and asking for a replacement chuck.

[Steven FrancisParticipant @stevenfrancis]

Posted by Baz on 06/07/2022 17:07:37:

If you have only had the machine a few months you should be telling this story to the bloke who sold it to you and asking for a replacement chuck.

Cheers Baz, was feeling a tad frustrated and was hoping for advice- agreement on possible reason for failure before I got on the phone and tried to be politely miffed.

[Tony Pratt 1Participant @tonypratt1]

I would have thought the 3 jaw chuck would repeat every time if using the same chuck key hole & the same bar even if it's not concentric. As per Baz you need to speak to the retailer.

Tony

[John HaineParticipant @johnhaine32865]

Have you had the jaws out?

[SillyOldDufferModerator @sillyoldduffer]

Posted by John Haine on 06/07/2022 18:20:06:

Have you had the jaws out?

Are the jaws in the right slots? They should be marked 1,2,3 possibly as part of a mysterious code, and one of slots will be stamped 1, or perhaps have a dot or other indicator. If the chuck body isn't marked, try the jaws in other slots – it matters!

Otherwise I can't think of a reason for a chuck to suddenly misbehave short of physical damage. The bad chatter may be a clue: check everything – does the spindle move when the chuck is heaved on by hand, or when spun by the motor? Any sign of damage to the scroll, jaws or slot. Was the chuck overtightened, especially with an extender (don't) in hope of reducing chatter?

There are always three suspects when a machining operation goes wrong:

• the machine or an accessories has developed a mechanical fault (rare but possible)
• operator error – the list is endless. (Most of the trouble in my workshop is caused by me)
• difficult material. Possibly the airgun barrel is made from a steel that doesn't machine well. Gun barrels, which might be hardened for longevity, are sometimes rifled by drop forging them onto a mandrel which toughens the steel even more. Gun barrels may not be easy to machine. Should be OK if it filed and sawed without major bother.

Dave

[Steven FrancisParticipant @stevenfrancis]

Posted by John Haine on 06/07/2022 18:20:06:

Have you had the jaws out?

Yes, chuck off stripped and rinsed out. Only noteable thing besides the corrosion on the scroll plate gears- the key/pinion retainers were loose and one was scratched.

No improvement.

[Steven FrancisParticipant @stevenfrancis]

Posted by SillyOldDuffer on 06/07/2022 19:01:24:

Are the jaws in the right slots? They should be marked 1,2,3 possibly as part of a mysterious code, and one of slots will be stamped 1, or perhaps have a dot or other indicator. If the chuck body isn't marked, try the jaws in other slots – it matters!

Otherwise I can't think of a reason for a chuck to suddenly misbehave short of physical damage. The bad chatter may be a clue: check everything – does the spindle move when the chuck is heaved on by hand, or when spun by the motor? Any sign of damage to the scroll, jaws or slot. Was the chuck overtightened, especially with an extender (don't) in hope of reducing chatter?

There are always three suspects when a machining operation goes wrong:

• the machine or an accessories has developed a mechanical fault (rare but possible)
• operator error – the list is endless. (Most of the trouble in my workshop is caused by me)
• difficult material. Possibly the airgun barrel is made from a steel that doesn't machine well. Gun barrels, which might be hardened for longevity, are sometimes rifled by drop forging them onto a mandrel which toughens the steel even more. Gun barrels may not be easy to machine. Should be OK if it filed and sawed without major bother.

Dave

don't believe that I've overtightened the chuck and certainly wouldn't use an extension to crank it round. Didn't hand-crank it until my knckle popped either.

Chatter if I'm correct is vibttation- run-out, endfloat, tooling & set-up.

The scroll looked ok, did I measure the whole spiral? No- but there didn't appear to be any stress or binding marks. The key gear retaining pins were loose, one scratched. pretty sure that was #2- might have been when it got sticky winding the jaws out.

The jaws are marked and went back in their respective keyways.

• the machine or an accessories has developed a mechanical fault (rare but possible)

buggered if I know, Murphy's law

• operator error – the list is endless. (Most of the trouble in my workshop is caused by me)

not impossible by any means although I am at a loss to how

• difficult material. Possibly the airgun barrel is made from a steel that doesn't machine well. Gun barrels, which might be hardened for longevity, are sometimes rifled by drop forging them onto a mandrel which toughens the steel even more. Gun barrels may not be easy to machine. Should be OK if it filed and sawed without major bother.

hmm… no idea of the maker but it wasn't Lothar Walther ( which is harder to cut and file) nor was it cold hammer forged BSA. Roughing was rough and so was finishing., don't believe I got it hot enough to work-harden.

[Robert ButlerParticipant @robertbutler92161]

Steve

Did you start the jaws correctly and in sequence when replacing after your clean up?

Robert Butler

Edited By Robert Butler on 06/07/2022 22:02:54

[Steven FrancisParticipant @stevenfrancis]

Posted by Robert Butler on 06/07/2022 22:01:45:

Steve

Did you start the jaws correctly and in sequence when replacing after your clean up?

Robert Butler

Edited By Robert Butler on 06/07/2022 22:02:54

no and yes… wrong sequence is one land out, but yes re-assembled correctly.

jaw #3 was out of alignment before the stripdown and clean-up, expected to find swarf, delrin…just grey oil.

[Howard LewisParticipant @howardlewis46836]

Looks like you have a Friday afternoon chuck. Maybe two jaws for your serial number, #3 from another?

0.25 mm run out is far too much. 0.125 mm AT MOST for a new 3 jaw, I would have thought

Talk to your supplier about a replacement under warranty

Howard

[Steven FrancisParticipant @stevenfrancis]

Thanks for the replies, at the very least kept me from stewing on my own.

Called the supplier and a replacement is on its way.

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