If my New Jet 1642 centers aren't lined up exactly (the tailstock center is 1/64 lower than the headstock), is there a fix for it?
[OP]
Contributor
If my New Jet 1642 centers aren't lined up exactly (the tailstock center is 1/64 lower than the headstock), is there a fix for it?
Member
You could shim it up but I would complain to the manufacturer first.
Always drink upstream of the herd.
Member
Jim,
Contact Sean at Tool nut and have him get in touch with Jet for you. I did with a small problem I have had. Between the 2 of these groups it has been the best customer service I have ever had.
Joshua
Member
I have 2 questions for you. Since this "misalignment" is this small, any chance that the centers you're using to make this test are responsible? If the alignment is really off by a 64th, will this make any real difference for practical purposes? I have no idea what is acceptable if it's not exact.
Hank
Member
It may indicate that there is some twist in your lathe due to it not being properly leveled, or some rocking in the head or tailstock.
Dan
Eternity is an awfully long time, especially toward the end.
-Woody Allen-
Critiques on works posted are always welcome
Contributor
Try a different center and make sure your lathe is level front to back and side to side. Make sure your headstock is tight.
Bernie
Never put off until tomorrow what you can do the day after tomorrow.
To succeed in life, you need three things: a wishbone, a backbone and a funnybone.
[OP]
Contributor
There is absolutely NO runout in the headstock. I've measured.
The centers are the stock centers for the machine. Rotating them makes no difference in the mis-alignment (since there's no runout).
The machine has been leveled front to back and left to right. My custom levelers made that extremely easy...
The only thing I can find that might possibly cause it (except for the TS or HS being machined at different heights) is the machining on the legs being off. The bottom of the bed itself was very straight when looking at it with winding sticks. And a flat board didn't rock on the bottom of the bed, but it did on the top of the legs.
Bolting the legs on to the bed might have twisted things a bit...
Moderator
Jim - are things off no matter where you move the headstock/tailstock? My first thought would be that the lathe is not level. Simple way to prove this - raise or lower the back adjustment of just one leg and see what happens to your alignment. You will be surprised!
Get back to us with what you find.
Steve
“You never know what you got til it's gone!”
Please don’t let that happen!
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Member
Jim,
if the live center is always lower, the tail stock is low.
you can check to see that there is nothing on the bottom of the head stock, or at the rear of the tail stock. Sounds like it is how it was machined. Using a straight edge, across the bed, measure the spindle height to center using the live center in both stocks. You need to determine which one is off.
Just cut off the parts that don't look like a bowl...
Member
Jim:
I bought a Jet 1642 last year and had the same problem. I tried all the possible solutions proposed on this website and could not solve the problem. I then contacted Jet and they replaced the tailstock at no cost to me. This new tailstock aligned to the headstock and solved my problem. I think that contacting Jet is your best solution.
Steve
[OP]
Contributor
Contacted Jet this morning. I will have to check a few things and then get back to them on Monday since I'm not going to be able to get to the lathe until the weekend.
I'll let you all know what happens.
[OP]
Contributor
Well I never posted back last year, but here's what happened.
After I tried several suggestions by Jet technicians, the vertical alignment was still out. So the Jet technician sent me a replacement tailstock. That still didn't fix the problem. In fact the front to back alignment was worse. I had to pull the center towards me when tightening the tailstock to get it centered, and leveling the bed made no difference.
I was discouraged that the new lathe had this kind of problem, and was daunted by the prospect of replacing the headstock. It's one thing to swap the quill, leadscrew, and banjo on a tailstock (I can do it blindfolded now I've done it so many times), but it's quite another to swap out everything on a headstock and get it right... In addition, I felt maybe I was just being too picky... And I got real busy at work due to layoffs, and other things. So... I let the matter drop. I shouldn't have I suppose.
Well, my warranty runs out in May, so I figured I better get this resolved. So I called Jet yesterday (and let Sean know what was going on). The techician suggested putting tailstock and headstock in the center of the bed, running the quill all the way out, and back in, then re-check the alignment. That didn't change anything, so lead screw and quill are on their way here, as per a conversation with the technician this morning.
Meanwhile, this evening I began looking it over to see if I could determine the source of the misalignment. After trying several things with varying results, I finally hit on putting shims under the center end of the tailstock and checking the alignment.
With the quill all the way in it takes a .009" feeler gauge (one on each bed way) under the center end of the tailstock to line up the headstock and tailstock centers. With no feeler gauges under the tailstock, the vertical alignment is out approximately .012-.017". (All measurements are taken with banjo and quill ltightened down.) With the quill all the way out, it takes .013-.014" feeler gauges under the center end of the tailstock to line things up. With no feeler gauges under the tailstock the vertical alignment is out approximately .030-.035".
What this tells me is the the tailstock machining is off. The shoulders where the tailstock meets the bed are not parallel with the quill bore. In addition, since it takes an additional amount of feeler gauge thickness when the quill is out, the height is not quite right to begin with. It also seems to me that the new tailstock shares the same problems, since it's quill seemed to be doing the same thing when extended. I haven't measured, but it is also visibly lower when extended.
This is my initial assessment. Perhaps some of you machinist types could help me with additional tests, ideas, clarifications, or corrections.
Last edited by Jim Underwood; 03-23-2010 at 10:25 PM.
Member
let me ask the stupid question.....
whats the big deal.
we are turning wood here, and sanding after its turned. we arent turning rocket parts for the space shuttle.
i personally wouldnt get wrapped around a 64th, or maybe even a 32nd, but i dont know if i'm extremely wrong in my thinking.
just my 2cents
In Memoriam
Jim. I once aquired a used lathe that had the same problem that yours does. The previous owner said that it had always been lined up okay. A machinist friend advised me to position the lathe and level it. Then loosen all of the bolts on the legs, then retighten them. It worked. The lathe lined up perfectly. Might be worth a try.
Wally
[OP]
Contributor
When you are turning pen parts and want them concentric with the barrels, bands and nibs, you want things to line up as closely as possible to start out with. If your centers aren't lined up, then I'm not sure it's possible to get concentric pen parts. In this kind of work, you need precision.Originally Posted by Chris Haas
At least that's my two cents...
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