Cam-lock D4 chuck issues

[Newton]

Things whent terribly wrong for me during turning some brass.
I had chucked up on a sollid 40mm rod of brass-held by the chucks jaws.
The plan was to do some light cuts to trim it down to go through the headstock.

Long story - short; I did not use my tailstock (with center drilled hole) and using a ultra sharp incert - the brass rod got pulled in to my tool holder and jamed the whole thing, smacking my 650kg lathe in to the air, belt on motor spin, broke a part of the backing plate for the incert and scared the living $hit out of me.

Scared me so much that I was not to happy to go near it again and had me wondering if some of this "cats lifes" had been ticked off.

Anyway-lesson learned - idiotic error so don't turn the knife :embarrassed2:

Here is the problem;

I immediately meassured TIR and at first it looked ok (1month ago). I did a shaft this evening and thought I should recheck again and I'm out by a lot.
Now, I hope this is chuck related- where the jaws is now fairly loose in the chuck- well not loose but there is some fair play in them.
So reboring these is a no go.

Now the machine use the Cam lock D4 setup and I have never played with this setup.
Is there anything which might be damaged in the back plates studs or should I only
try to re-tighten the D4 locking screws?
Or should I try to take everything appart and follow up with my dial indicator
to see where the damage is done?
Hope the bearings made it :embarrassed2:
I guess it might be time now for that 6jaw Bison I dreamed about when I bought the machine :sorry:

I have never taken these things appart but I'm sure I'll figure it out but any feedback from you who have done would be highly appreciated.

Thanks
K

 

[pescadoman]

How are you measuring runout? How bad is bad?

Did you use master jaw each time for tightening when testing??

Standard 3 jaw chinese? Notorious for bad runout....

Have you removed the chuck and put a known good morse taper dead center in the tail stock after thoroughly cleaning inside?

You said you already bored the jaws? If there is slight play when not tensioned, I don't see why that is a reason you can't bore again. Maybe I am missing something.....

I am also guessing you fed the cutter into the rod or the feed rate/depth was off OR you used a rod.....say longer than 200mm without a tailstock? It could have been alot worse...

 

[Newton]

How are you measuring runout? How bad is bad?

Did you use master jaw each time for tightening when testing??

Standard 3 jaw chinese? Notorious for bad runout....

Have you removed the chuck and put a known good morse taper dead center in the tail stock after thoroughly cleaning inside?

Randy;

I use both a sanding mandrel from atlas and I have a precision grinded and hardened rod (used to dial in the tailstock between centers). Chuck up on both and measured I guess 15mm ish from jaws.
How bad-I did not bother to read it of - it was normally 0,00075 if I remember correct before the accident... I'll double check tomorrow-I posted the numbers some time up here....

Standard chineses 3jaw- but as long as it was in the mentioned range I was happy...

Not used master jaw but have considered a "real" collet chuck. Installed that on my tip changing lathe.

As mentioned - headstock has not been touched - i.e chuck has not been taken off. Would have a look at it tomorrow (local time is 02:23 at night-reading up on Cam-Lock through Mr.google).
Not sure what you mean by cleaning and using a dead center in the tail stock? I chuck up on the mentioned parts and meassure on these-not between centers.

K

 

[Newton]

Randy
I checked a pic I had done when the machine was OK and TIR was 0,0007".
By bad I mean it might be in the 0,003" range now....


K

 

[rhncue]

Randy
I checked a pic I had done when the machine was OK and TIR was 0,0007".
By bad I mean it might be in the 0,003" range now....


K

Brass is a very sticky metal. When cutting in a lathe it is best to use slow speeds with a large radius tool and a negative rake is best.

Dick

 

[conetip]

Things whent terribly wrong for me during turning some brass.
I had chucked up on a sollid 40mm rod of brass-held by the chucks jaws.
The plan was to do some light cuts to trim it down to go through the headstock.

Long story - short; I did not use my tailstock (with center drilled hole) and using a ultra sharp incert - the brass rod got pulled in to my tool holder and jamed the whole thing, smacking my 650kg lathe in to the air, belt on motor spin, broke a part of the backing plate for the incert and scared the living $hit out of me.

Scared me so much that I was not to happy to go near it again and had me wondering if some of this "cats lifes" had been ticked off.

Anyway-lesson learned - idiotic error so don't turn the knife :embarrassed2:

Here is the problem;

I immediately meassured TIR and at first it looked ok (1month ago). I did a shaft this evening and thought I should recheck again and I'm out by a lot.
Now, I hope this is chuck related- where the jaws is now fairly loose in the chuck- well not loose but there is some fair play in them.
So reboring these is a no go.

Now the machine use the Cam lock D4 setup and I have never played with this setup.
Is there anything which might be damaged in the back plates studs or should I only
try to re-tighten the D4 locking screws?
Or should I try to take everything appart and follow up with my dial indicator
to see where the damage is done?
Hope the bearings made it :embarrassed2:
I guess it might be time now for that 6jaw Bison I dreamed about when I bought the machine :sorry:

I have never taken these things appart but I'm sure I'll figure it out but any feedback from you who have done would be highly appreciated.

Thanks
K

No need to dig at you Kent. Being scared is a good thing.The lesson will be well engrained into your brain forever because of the adrenaline. Anyway to the info you really need.
After a serious crash like this, it pays to check every thing out. In extreme cases there can be damage to the cross slide and the main bed itself.
Take the chuck off and check the reference face for running true. If it is not ,it will show that the spindle is slightly bent. Do not try to straighten the spindle in place, usually ends in the front bearing being damaged and the bearing housing getting damaged.Just face it off to true.
The chuck itself may have damage to the jaws or the chuck body itself.

Anyway you get the idea, go through everything. Then you will know for sure the condition your machine is in.
Neil

 

[pescadoman]

Randy;

I use both a sanding mandrel from atlas and I have a precision grinded and hardened rod (used to dial in the tailstock between centers). Chuck up on both and measured I guess 15mm ish from jaws.
How bad-I did not bother to read it of - it was normally 0,00075 if I remember correct before the accident... I'll double check tomorrow-I posted the numbers some time up here....

Standard chineses 3jaw- but as long as it was in the mentioned range I was happy...

Not used master jaw but have considered a "real" collet chuck. Installed that on my tip changing lathe.

As mentioned - headstock has not been touched - i.e chuck has not been taken off. Would have a look at it tomorrow (local time is 02:23 at night-reading up on Cam-Lock through Mr.google).
Not sure what you mean by cleaning and using a dead center in the tail stock? I chuck up on the mentioned parts and meassure on these-not between centers.

K

Srry... I meant HEAD stock..

 

[pescadoman]

"Master" meaning the socket that is marked with an "0" to tighten. Ideally, you should always tighten using that socket.

 

[Newton]

"Master" meaning the socket that is marked with an "0" to tighten. Ideally, you should always tighten using that socket.

Ah, I learn I learn :wink: Heading down to the shop now and would shoot some pics of radial and axial TIR.

Thanks all for the help so far.

Kent

 

[DaveK]

Brass is a very sticky metal. When cutting in a lathe it is best to use slow speeds with a large radius tool and a negative rake is best.

Dick

Exactly what I was thinking, brass (and many other copper-based alloys) will self-feed big time with the wrong tool geometry.

Also, when chucking material there is a general rule that one should have no more than 3x the diameter sticking out of the chuck. In other words if you are turning down a 1" rod you should have at MOST 3" sticking out of the chuck. This rule does not apply if you support the material with a rest or the tailstock.

Newton, I am very pleased that you were not injured from the crash ... a hand or finger in the wrong spot and it might be gone.

Dave

 

[Newton]

Currently in my shop trying to loosen the chuck;
What I have read-the camlock bolts should only be turned 90 degrees but my chuck has no indication to when it's locked or open.
Should I remove them all together or just count on the 90 degree rule and use the rubber hamer?

Currently on my phone in the shop scratching my head.
The manual is useless..
Kent

 

[Newton]

Sorry friends-I figured my last Q out. A gental tap and the chuck comes off

 

[Newton]

Results

Well, it was a OK experience to get this done. Removing the chuck was easy when
the locking screws was figured out.

 

[Newton]

Chuck removed and headstock mounting

Some dust and crap was expected behind the chuck - and as shown - it was not clean..
The headstock axle has a small tapper in it's center which the chuck is attached to.
The studs secure the chuck on the tapered register.
Now the chuck is not resting on the back plate as far as I can see. I might be wrong here but I would try to measure this tomorrow.

 

[Newton]

TIR measured

Face has very low TIR and the axle has some but I think this is acceptable.
If I manage to get a new chuck on this level I would be happy as a kid on Christmas...
My dial indicator is not reliable at these values as the two measurements performed inside the axle show.
I could not feel any play so I think the bearings survived..

 

[Newton]

Stud and final TIR after reinstall

One of the studs was not flush with the chuck. I opened the locking and turned
it one revolution so it lined up with the other 3.
On the picture it looked slightly bent, but I did not take the whole thing out to check.

Total TIR @ 20mm from chuck is now up at 0,0024 if I understand this correct which is a tad higher than what it was... Closer to the jaws TIR goes naturally down..

 

[Newton]

Conclusion

Lesson learned - no doubt about that.

Now for the technical part - I'm not sure how to correct this with the setup.
I guess one option is to face the driving side to get rid of the small TIR, but I think the trouble is in the chuck. There is nothing to carefully tap the chuck on, in case it must be on the chucks face - where the jaws are. I can then only try to tap between the jaws to see if there is something to correct on the tapper - but I think this causes more trouble than good.

Facing the drive side must in case be done at the same angle on the tapered center - which I'm not overly keen on.

Now have any one changed / upgraded to quality chucks on these type of lathes ?
What do you then do ? Is a new Bison chuck for instance produced to fit the Camlock setup or should there be a new "drive side" setup which matches the chuck by carefully facing and fixating the chuck ?
Never done this but considering to upgrade to a better chuck now so I can work with the machines initial spec - not the one I have forced it to now by my mistake...

Any experts out there which has their expensive 6 jaws in place which could comment on the procedure ?

Thanks
K

 

[Newton]

You said you already bored the jaws? If there is slight play when not tensioned, I don't see why that is a reason you can't bore again. Maybe I am missing something.....

I am also guessing you fed the cutter into the rod or the feed rate/depth was off OR you used a rod.....say longer than 200mm without a tailstock? It could have been alot worse...

I have a beefy boring bare which I in case would use to clean up the jaws. That was my idea (never done this). If the jaws has a fair amount of play-would this be eliminated by the force due to the rotation so they would always stay at it's "widest" position? In this case I agree that boring these should be OK.
But as mentioned- never done it before.

I did not measure the length on the rod-it was for sure to long to be held by the chuck. However-it all was fine when I used a slightly worn incert. However my brain figured it was wiser to change and use a brand new high radius -pollished Alu incert. This was so sharp that it digged in to the bolt and jamed. Feeds and speeds was something I just dialed in for some light cuts...
At the end I did dear to go back and my brass live center for the woodlathe (used for sanding,cleaning) did work out ok :wink: