My ongoing feud with my new Jet 1642 continues with an interesting turn...

[Joshua Dinerstein]

I took the various advice from those here on the forum, thank you very much BTW, and I got started with great seriousness on trying to diagnose the problem with my lathe.

I got lucky and HF put a Dial Indicator and a magnetic base for it on sale this last Monday. A little more than half off on each. Seemed like a sign so I bought 1 of each. After a bit of experimentation and a discussion with a metalworker at work I got it figured out and started testing out my Lathe to see what could be causing my problems.

I started by measuring the outside of the chuck with it fully seated and ready to use. I am not entirely certain what each "tick mark" on the dial indicates in terms of a measurement but I figure almost no movement would be the key to things are good. I set the base and the indicator up to be rubbing against a smooth portion of the outer edge of the chuck. I rotated the chuck slowly by hand while watching the dial. It was from a -2 full ticks to a +3 full ticks back and forth as I rolled the chuck around. This was pretty bad in my opinion. I could still see the chuck wobble as I rotated and this "proved it" in my mind.

So I removed the chuck and started looking for my drive center. My plan being to full seat it and then use the dial to check it out. My thought was that if the spindle was bent then this would be off as well. I couldn't it in the normal spot, things have been getting stirred as I have been doing this, and instead I located my pen mandrel. This mandrel is a high end hardened shiny steel-rod version and spins so true it is scary. "AH HA!" I thought to myself. Into the headstock it went and I turned the lathe on expecting to see a massive swing of the tip of the mandrel back and forth. No suck luck. The mandrel spins so true it was freaky! This was both good news and bad news. It meant the spindle in the last isn't bent. The bad news... I was back to square one and had no idea what was wrong.

Next I took the dial indicator to the "face" of the spindle right out on the end. It spun pretty true. The indicator did flutter a bit but only a touch and never got 1 full tick away from the starting point. I then moved to the face of the spindle in the headstock. I don't know exactly how to state it but the small "flat" at the base of the threaded area that the chuck seats up against. In measuring this I get about 1 tick swing as I again rotate the spindle by hand. This seemed a bit bad to me but I am not sure how bad.

At this point I noticed that things were a bit damaged, well more damaged than I had seen at first when I bought the lathe. On this flat plane on the spindle there is what looks like a catch would in wood from a bowl gouge. A nice dig in with a raised portion just on the up hill side of it. I then started looking at the rest of that area. The previous owner used a chuck with a grub screw to be able to go in reverse without unscrewing the chuck and must have had some serious catches. The screw has dug into and chewed up a bit of the side of the spindle. (Pics will follow I am just at work at the moment...) And also the bottom threads closest to the face of the headstock are pretty chewed up from what would appear to be the same darn screw. Well I figure those threads are pretty darn important. and between the dings and threads I am wondering if the chuck is really seating right even though it tightens down or if it is canting off to the side somehow as a result.

So I went digging thru the box of goodies that came with it and found the standard Jet faceplate. I screwed it on and got it seated, set the test up and started rotating by hand. Nothing. Spins extremely true. ARGGH! So is it the threads or not?!!? Back to the chuck and the same wobble exists.

So off to Woodcraft I went and bought one of those white easy-off no-lock nylon washers in the 1 1/4" size. My thought was to try and change where it was sitting on the threads and also to try and use the nylon to cover of any of the sharp bumps from dings etc... on the spindle.

I slipped it on and then seated the chuck and wouldn't you know it but almost all of the wobble is gone. I don't get it? Visually I don't see any wobble in the chuck anymore. The dial indicates about a +/- a half a tick on the outside of the chuck now. Again I am not sure how much that really means.

So I am left still frustrated and seeking some advice.
- Is this "close enough"? Is this kind of run-out enough to worry about or have I effectively solved my problem?

- What do those tick marks on the dial indicator (there a 100 of them) really mean?

- Is there a good way to clean up the threads on the spindle? I look for a die and a rethreading die but apparently 1 1/4" x 8 tpi is not a common thread size. Any ideas or is it dangerous to mess with the threads and potentially introduce slop into them?

- Is cleaning up the threads really even needed? What do you think?

- Is there a good way to clean up the dings in the front face of the spindle? Do they really have any effect? Anyone ever had one before? I have never seen anything like this on my old lathe.

Any other thoughts or answers or suggestions I missed? I would love any information anyone might be able to provide!

Thanks,
Joshua

[Joshua Dinerstein]

I spoke with Jet a week or so ago and they sell replacement spindles and bearings. I had thought the bearings bad but apparently that isn't the case for me. Just the end of the spindle itself.

Anyone here ever replaced the spindle in the headstock? Or have the directions to do so? For $75 or so it would be pretty nice to get a clean true spindle from the lathe. But getting the old one out and the new one is could be... a challenge.

The manual for the lathe shows the assembly drawing but isn't all that clear on extrapolating a process from etc...

So if anyone has done it, seen it done, can help or whatever then please by all means do!

Thanks,
Joshua

[David Walser]

Joshua,

Won't Jet provide you with full instructions for replacing the spindle?

[Sean Ackerman NY]

Joshua,

Won't Jet provide you with full instructions for replacing the spindle?

Josh, I'll email / gmail chat you tomorrow.... lemme see if I can get you instructions on this.

[Brian McInturff]

Josh,
You should be able to clean up the threads with a few machinist files. You tried other chucks right? Are you using an adapter? Mark Norman had a slight wobble in his. He said his wasn't seating properly, took a little off the insert(or adapter, can't remember) and presto, all fixed. Check that before you drop some more cash on a new spindle. I think Mark mentions what he did to his in his thread about Walnut Bowl 3.

[Ted Evans]

Hello Joshua, sorry to hear about your difficulties with the spindle. Something you may wish to try before proceeding to more drastic measures is try cleaning up the threads with a triangle file. These have 60 degree angles and will fit into the threads fairly well. Use them to smooth out any rough places or high points. It should not damage anything being that it is the back threads. File the high spots off and test, if still not good file a little more and try to determine if you have all the high spots removed. I have done this procedure numerous times when I did not have a die the right size. Good luck.

Bear

[Jeff Nicol]

Joshua, Does the chuck have an insert that makes it 1", 1 1/8", 1 1/4" or what ever size? If it does, like my stronghold chuck does, the threads on it or the face of that could be the problem. It sounds like the taper is good and the threads are fine if the faceplate is true. So check the chuck before you go to changing the spindle. If you have a very flat level counter or glass top table use the dial indicator and the base to see if the insert is off. I think if you took the jaws off and set the face on the flat surface and touched the dial indicator to the flat on the insert you can slowly turn the chuck and see what is what.

Jeff

[Mike Lipke]

Here is a way to end fretting and start turning:
Use 2 washers.
But don't buy them. Make them out of a milk bottle, or a sour cream container.

[Scott Conners]

That machined face at the base of the threads is what chucks and faceplates index off of to run true. The threads themselves are just to pull the chuck tight to that face. It sounds to me like the ding in that face is causing the chuck to not seat fully and since it protrudes further from the headstock, it shows more runout than the faceplate. It's also possible the faceplate is touching in a different place than the chuck and so isn't affected as much. Personally, I'd try and clean up that face myself with sandpaper/dremel/files before I replaced the spindle...it's already bad, so if you make it worse it won't hurt anything. I'd probably take a small taper grindstone to it in a dremel and try and relieve the high spots only, to make them into low spots and let the chuck seat fully on the remaining true surfaces.

Each graduation on your dial indicator should be one one-thousandth of an inch, or 0.001" if it's built in the standard way. When I finally bought a dial indicator I realised how useful a tool it is for someone with a lathe, it make removing and replacing work with difficult mounts on the lathe much easier, as well as many other useful diagnostic purposes.

[Ken Fitzgerald]

Joshua,

Most of the dial indicators I use have the measurement graduations written in small print on the white face of the dial indicator..



It'll say 0.001"

[Dave Halter]

Joshua,
From everything you describe it sure sounds like it is a chuck problem and not a spindle problem. I would definitely try a different chuck before I bought any replacement parts for the lathe.

Dave

[Scott Hurley]

I had the same kind of issue with my 1642 and a Talon chuck. I took the insert out of the chuck, rotated it to the next set of holes and reseated it. It ran true after that. If you have a Nova chuck with a screw-in adapter, I don't know what to add...

Scott

[Richard Madison]

Joshua,
Sound like you have already pinpointed the problem, which is the chuck insert. Incidently the fact that you get a few thou radial run out in the chuck O.D. is probably not a big deal. It is the jaws that hold the wood, not the O.D.

[Sean Ackerman NY]

Josh, give me a call or check your email.

[Joshua Dinerstein]

Sorry I am late with this. My wife and Daughter had other plans for my time last night.

Yuck. I had hoped these would be better. Some were too washed out with the flash and others to dark with the same flash. Hopefully you can see well enough the damage to the threads and the round base of the splindle behind the threads and of course base plate behind it all on the front of the lathe.

Joshua