Is there a fix for centers not lining up?

[Jim Underwood]

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?

[Mike Golka]

You could shim it up but I would complain to the manufacturer first.

[Joshua Dinerstein]

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

[Hank Walczak]

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

[Dan Forman]

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

[Bernie Weishapl]

Try a different center and make sure your lathe is level front to back and side to side. Make sure your headstock is tight.

[Jim Underwood]

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...:confused:

[Steve Schlumpf]

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.

[Larry Marley]

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.

[Steve Mellott]

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

[Jim Underwood]

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.

[Jim Underwood]

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.

[Chris Haas]

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

[Wally Dickerman]

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

[Jim Underwood]

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

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.

At least that's my two cents... :D

[Jim Underwood]

Thanks Wally, I'll give that a try. You probably noted that I said the leg mating surfaces didn't appear to be flat earlier in the thread....:cool:

[Bob Borzelleri]

Jim...

My Nova 1624-44 alignment was slightly off (tailstock was dead on horizontally, but probably about 1/64" or more vertically). I took everything apart and cleaned every surface mating part I could find. Then I adjusted all four legs to a point where I felt they were both level and supporting the bed equally.

I used a double ended MT2 taper to check alignment and then reset the tailstock. It was dead on.

[larry cronkite]

Jim
I had the same problem with the same lathe and the factory told me tweaking the leg levelers would solve the problem. It didn't. I built a ballast box to hold 300 lbs of sand and now move my lathe (on casters) all over the shop and no more line up problems.

[Paul Atkins]

1/64" off is a lot when you are supporting a piece in a chuck or faceplate with the tailstock. It makes a 32nd inch circle around the true enter. This will induce wobble or vibration and will not work. If you are turning center to center, this will not make any difference. I have moved my tailstock up to 3/8" off center to get a taper using my carriage on my 'large' lathe. I think a new machine should have centers that line up from the get go. Jet should make it right.

[Philip Morris]

Well, my warranty runs out in May, so I figured I better get this resolved.

Jim,
Thought all the new Jet's had a 5-Year warranty?

[Jim Underwood]

I'm not sure about the warranty period. I thought it was a year warranty. I'll have remember to look at the paper work tonight...

I received the lead screw and quill yesterday, so early this AM I went out to the shop and did some fiddling with it all. I put the lead screw and quill in the new and the old tailstock and it doesn't seem to make much difference to their respective misalignments. However, I did notice that the vertical offset was less on the new tailstock, and I was able to adjust the feet to remove the front/back misalignment.

So for the new tailstock/quill/leadscrew, the vertical misalignment is about .009" and with the quill extended, it's about .015". I must place a .003" shim under the tailstock center end to get it to align, and with quill extended it must be .006". So it's much improved, but not quite there yet... I suppose I would have noticed this last year had I not been so discouraged by it all- and had I hit upon a way to measure the slope of the quill.... I'm still only able to "eyeball" the vertical misalignment with a pair of calipers held up to the two points. So the measurements I give are only approximations. I wish I knew a way to really measure the misalignment accurately.

I'll call Jet today and see what they make of the newest development.

[Rob Holcomb]

I used to think this way too. Not just in the turning forum, but in the general forum too. I remember thinking "man these people are really petty about some things" Then, my skill level improved and so did my expectations. I began to realize why a 64th makes a difference. Now, I want dead on or I'm not happy with my project. I guess the better you get at something, the more you demand perfection out of a tool and your own abilities!


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

[Jim Underwood]

I was just talking to a friend of mine last night as we did a demo together at a local Art Gallery...

He reminded me that if you're off the slightest bit when turning a tenon, then when you reverse the piece, it's always off, and wobbles when you rechuck it.

Once I get this problem solved, I've got to take a hard look at my chucks too. I've got some small jaws on one that won't center the work even if it's a piece of cold rolled steel....:rolleyes:

[Jake Helmboldt]

Jim, didn't you say you had previously received a replacement tailstock (and the problem persisted)? If so it would seem the problem may lie elsewhere? I'm wondering if your observation of the leg issue is inducing some misalignment?

[Jim Underwood]

Well yes, I did, but if you'll re-read my post just a couple replies up, you'll notice that I state that after fiddling around with the new tailstock/quill/leadscrew this AM, the results were noticeably better when I did some comparitive measuring with the old tailstock.

So, I'm convinced that most of the problem is the tailstock quill bore not being parallel with the shoulders that ride on the bed ways... the tailstock center/quill bore is pointing down toward the base of the headstock.

Today, the Jet tech instructed me to check the vertical alignment with the headstock moved to the head and tail ends of the bed, just to make sure it wasn't an issue with the bed... Of course I couldn't do that while I was at work, so it will be Monday before I can report back to him....:rolleyes:

[Jim Underwood]

This weekend I had a chance to mess with this problem again.

(I spent most of the weekend cleaning up the shop, throwing away stuff - three trash runs to the dumpster, and I ain't done yet!:eek: I also rebuilt my lumber rack so it's shorter and twice as many arms. It feels like I just moved crap from one place to another- but I know I got rid of a ton of junk, so it's got to be better, right?:confused:)

The results are pretty much the same at the head or tail of the bed. Quill extended it's about .015" vertical misalignment, quill retracted it's about .009" vertical misalignment.

So the tech is going to send me a whole tailstock... after checking it on a machine there at the warehouse....:cool:

I'll let you know how that turns out.

[Jim Underwood]

I got the whole tailstock assembly this morning via FedEx... I'll get to it this afternoon, and let you know what happens.

I first gotta mow the weeds for a couple hours...:(

I'll say one thing now though, whether I'm too picky or not, Jet is certainly accomodating!

I also found out that the warranty is five years. It depended on the date you bought your Jet machine. Apparently my 1642 is under this warranty, but the 1014 is not. If I had to make a choice, I'd certainly rather have the 1642 warranted....