Gallery, Projects and General > How do I??

What went wrong with my chuck taper?

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John Hill:
John, if I recall correctly the arbor came from a Jacobs box but the chuck  was 'chucked' in a plastic bin with a lot of others newly arrived from China. They were shop man "gifts" given because I gave the shop man a box of beers for helping me move the lathe home and get it set up in my garage.

I could almost swear there is a subtle difference in the taper as there is a distinct impression that the small end of the arbor is smaller than the hole in the chuck and there were clear bright marks on the arbor indicating the most pressure had been at the other end. So I dont think it is a case of the arbor being too long as that would surely give the wobble at the other end.

It is stuck on right now, I will be checking for centreing this afternoon (it is Saturday and of course it is pouring with rain in sunny Wellington).  If it is out I will be pondering the next step.

I am wondering at this process:


1: put a bar in the main chuck, 1/2", 12mm or whu.
2: skim bar to be accurately concentric with spindle;
3: place the small chuck on the bar with jaws towards main chuch, tighten firmly.
4: put arbor in tailstock
5: put 'something' on arbor
6: bring up tailstock and clamp down
7: use tailstock ram to advance arbor gently into the chuck just until contact is made while turning the lathe by hand
8: withdraw arbor and look for marks.


Question is, what stuff should be used in 5?  I dont have engineer's blue though I guess I could get some, maybe I will try with a felt pen marker.

If the tapers are subtly different can I lap the two pieces together in this rig up?

[Thinks, why dont lathes have a hand grip on the spindle?  Using the chuck key as a tommy bar seems so uncouth and I am sure is not good practice]

Darren:

--- Quote from: John Hill on February 27, 2009, 05:46:05 PM ---John, if I recall correctly the arbor came from a Jacobs box but the chuck  was 'chucked' in a plastic bin with a lot of others newly arrived from China.




--- End quote ---

Oh, one of those.
I too have a brand new Chinese chuck with a new arbor and have exactly the same problems. It spins on the arbor... :bang:

I have just bought a Bison keyless chuck to replace it, but yet to get hold of a 6J arbor for it.

John Hill:
Well Darren my chuck seems to be well fixed to the arbor now.  I have just trimmed both ends of a bit of scrap and centre drilled each end without problem.

sbwhart:
Hi John

It looks like you've got your problem licked. Just to try and answer your ?:-  felt tip marker is fine or just ordinary pencil just rub it up and down on the stub will give you a witness mark. For the stub taper to work the male and female have got to be a dead match, as the length of engaugement is short, and the torque they have to withstand when drilling is high, I've had the same problem, best way to fix it is lap to best fit and use heigh strength loctite or supper glue,:-  that'll stop it breaking wind in Church.
 :ddb:

On the subject of chucks from China the one I got supplied with my 3 in 1 some 5 years ago was next to useless I chucked (pun intended) it in the scrap bin, and replaced it with a UK manufactured Jacobs that are no longer available. The Chines chuck supplied with my Seig mill is a different kettle of fish its very good more like the UK Jacobs  :thumbup: up to yet I've had no problems with it.

Cheers
 :wave:
Stew

John Hill:
Thanks Stew, I will buy some Locktite next week.  The trick though as it has enough clearance to wobble will be to get it stuck while it is in line,  hopefully doing it in the lathe will get it aligned.

Regarding breaking wind in church, there was a funny incident which almost made me laugh at my father's funeral.  It was a long service and right near the end just then the pall bearers were being called to carry him out a side door of the church blew open, I heard one of his brothers behind me say "He's had enough of this already!"

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