Twisting a lathe bed

[cbatzi01]

Hi everyone,

Like many people, I am having a OOR or concentricity (more likley) issue with a jet mini 1014. I turn between centers using 60deg cones with no luck. If I try to line up the two points, the tailstock sits just behind the headstock point (in essence, they don't line up).

I have used a dial indicator and get about .01-.02 runout by checking it with a mandrel. What is really odd, is the hand wheel is all over the place. Visably spinning "funny" like it isn't seated correctly.

I have called JET support twice. Call #1 resulted in the hypothesis of a bent spindle or bad bearing (this led to the dial-indicator).

Today's follow-up call resulted in a different solution....twisting the lathe bed. The support guy suggested mounting the lathe to the bench and putting a shim under the opposing leg, and tightening it down in ord to twist the bed, and bring it in line. He also said the twisting it would be much easier than just shimming the tailstock with a piece of tape/metal.

I am looking for a second (and third, and fourth..) opinion before I go to down on my lathe. For the record the JET support people have been great. Very knowledgeable and eager to help. I was prompted to call after the comments from another member.

Has anyone ever heard/tried this?

Thanks in advance!

 

[jthompson1995]

I don't see owtwistingthe bed will fix the problem as it will not twist evenly throughout the bed. You would line up the points with the headstock and tailstock close together, but as soon as you back the tailstock up, they would probably be out of alignment again. As long as the ways are straight, you should take the time to add the shims and get a permanent solution.

 

[johnnycnc]

Chris,
Since you have an indicator, try this; with the spindle socket empty,
as in no mandrel or dead center, put the indicator tip INSIDE the spindle
morse taper socket and check runout there.This is the starting point for your
drive accesories and if not right there,it needs fixed=bad bearings or defective
spindle.
If this checks ok, then put your dead center in,(you said you were turning
between centers) and check the runout on the center tip, right where the bushing
sits.Is it good? if not there's part of the problem.Also is the dead center worn,
or grooved? again, this can be a problem.
On the tailstock, check your live center for runout, you'll have to turn it gently by hand
with the indicator on the tip.
any problem there? also, same as dead center; worn, grooved?turn freely?
As for headstock to tailstock alignment, most lathes are not perfect, on of my
Jet 1014's is off with the tailstock side to side as viewed from looking straight down on them.
there was also side to side play in the whole tailstock, so my solution was to
pull or twist it to where it was best alignment every time before locking down.
Made enough difference to remember to do it every time.
A helpful tip for the tailstock.Don't extend the quill any farther than needed,as they
wear, they can develop slop, and droop or float (my older one does), causing
small misalignment issues.
My thoughts on Jet wanting you to "twist" or pull the lathe bed to align the centers is
that this is a band-aid for an underlying problem.
The pitfalls to this, that I can see are (IF it possibly worked) what happens when the
wood work bench you pulled it to changes with temperature/humidity/season changes?
also, if you move, or want to move the lathe outdoors to enjoy the weather?
Another issue,let's say you have a solid steel workbench and can really muscle it as you
attempt to straighten things out.Guess what..that lathe bed is cast iron and it is by
nature BRITTLE.Cast iron will not tolerate shock or stress like steel will, and you could
possibly wind up cracking it if not initially, then down the road as it sits with stress pulled on it.I wonder if Jet would replace it with a cracked bed?
The mandrel runout could be caused by a dirty spindle taper, the morse taper
fittings on male and female should really be "white glove" clean, and burr free.
Your OOR has many causes, but let's get your lathe aligned first.
hope this is some help.

 

[Rifleman1776]

I agree with John. It is a dishonest suggestion by Jet. Push the issue.

 

[mick]

Chris I had similar problems with my JET after I replaced a set of bad bearings. I experienced OOR issues at the headstock end and perfectly round pens at the tailstock. This happened turning on a mandrel or turning mandreless. I tore everything down on two different occassions and reinstalled the bearings(after determining that they were ok).I still had the headstock OOR. Finally one day I was installing a dead center in my headstock and noticed instead of seating it wanted to "rock" up and down but not side to side.cleaned it out. Checked for burrs and even hit it with a fine emery clothe. Long story short I called Jet ordered a spindle, lil over 30 bucks shipped and now no problems whatsoever.
The wobble of your handwheel leads me to believe that either the handwheel is not installed right.....or your spindle is bad.

 

[DurocShark]

Yeah, "adjusting" the ways feels like a cust serv rep at the end of the day wanting to hurry up and get off the phone.

 

[marcruby]

Is this lathe still under warranty? I would consider a kink in the lathe bed a manufacturing problem. Certainly, you trying to remedy it by 'unbending' would probably create more problems than it would solve.

Marc

 

[Randy_]

Is this a problem that has just developed or has it been going on for a while??

I'm working with a guy right trying to diagnose his OOR problem. Just for fun, I sat down and made a list of all of the common things that could cause such a situation. I came up with 15 possible causes and I'm sure that I missed a few so you can see that figuring out what is wrong can be a challenge.

Hi everyone,

Like many people, I am having a OOR or concentricity (more likley) issue with a jet mini 1014. I turn between centers using 60deg cones with no luck. If I try to line up the two points, the tailstock sits just behind the headstock point (in essence, they don't line up).
Give us your best estimate of how far off the points are from perfect alignment. I think you will find that most lathes are off a little. I think anything less than 1/2mm is probably not worth worrying about and should not be a problem.


I have used a dial indicator and get about .01-.02 runout by checking it with a mandrel. What is really odd, is the hand wheel is all over the place. Visably spinning "funny" like it isn't seated correctly.
That much runout is too much to accept. Is that measurement right at the arbor, in the middle of the mandrel or near the live center? The handwheel should not visibly wobble if it is screwed on tight to the spindle......even if the set screws aren't tight.


I have called JET support twice. Call #1 resulted in the hypothesis of a bent spindle or bad bearing (this led to the dial-indicator).

Today's follow-up call resulted in a different solution....twisting the lathe bed. The support guy suggested mounting the lathe to the bench and putting a shim under the opposing leg, and tightening it down in ord to twist the bed, and bring it in line. He also said the twisting it would be much easier than just shimming the tailstock with a piece of tape/metal.
Every JET guy I have ever talked to is nice; but twisting the bed of the lathe to fix a misalignment is crap. If the body of the lathe or the component parts are misaligned, they need to replace your lathe!!

Johnny's suggestion to check out the runout of the inside surface of the spindle taper is good; but you need to do a little more.

1. Measure the runout of the small flat on the spindle behind the nose threads and just in front of the shoulder.

2. Put the mandtrel arbor in the HS spindle and measure the runout around the circumferece of the arbor.

3. With the mandre; in the HS, run the TS with a LC installed up to the and note if the tip of the LC matches up with the center hole in the end of the mandrel. If it doesn't, how much is it off and in which direction?

With the above information, we can get a little better handle on exactly what is wrong.

 

[cbatzi01]

Wow! You guys never fail with the solutions. I agree with you all that attempting to twist the bed is a bad idea. It's nice to have it confirmed by someone else. I spent a little time tonight cleaning, tightening, re-seating. I'll try to include everything into this post:

We'll start with the runout measurements:
Handwheel now=>.008"
Behind the headstock threads:=.001"
deadcenter:=.001"
Inside HS taper=.001"
Taper endof mandrel:=.005"
Middle of mandrel:=.007"
Endof mandrel:=>.008"
*I rolled the mandrel on a glass sheet before measuring to ensure it wasn't bent. It was OK.

This measurements are consistent with quick and dirty checking by laying a flat tool (skew) in various places while the lathe is running. I get considerable "bounce" on the handwheel, smooth running at the HS end, and bounce towards the tailstock.

I swapped several centers in and out of both tapers and the front to back misalignment was consistenly 2/64"-3/64". After my fooling around, a little they seemed closer than previously.

I wiped out the insides of both tapers and they were clean (just a hint of oil in there).

JohnnyCNC mentioned something specific with groves in the two cones (live/dead). I recently noticed some very slight grooves being worn into them. However my OOR problem existed before going mandreless. The quill on the tail stock is solid, and as mentioned I always keep a minimal amount of extension when turning.

The lathe is about 15mos old, so I am not sure about the warranty.

The test of truth is putting a blank and turning it to size...which I did. Unfortunately the problem still exists. I have one side wall a little fatter on one end, and the opposing side fatter on the other end. resulting in a poor fit with the kit hardware.

So, what next?

Thanks in advance for all of your help!

 

[johnnycnc]

Wow! You guys never fail with the solutions. I agree with you all that attempting to twist the bed is a bad idea. It's nice to have it confirmed by someone else. I spent a little time tonight cleaning, tightening, re-seating. I'll try to include everything into this post:

We'll start with the runout measurements:
Handwheel now=>.008"
Behind the headstock threads:=.001"
deadcenter:=.001"
Inside HS taper=.001"
Taper endof mandrel:=.005"
Middle of mandrel:=.007"
Endof mandrel:=>.008"
*I rolled the mandrel on a glass sheet before measuring to ensure it wasn't bent. It was OK.

This measurements are consistent with quick and dirty checking by laying a flat tool (skew) in various places while the lathe is running. I get considerable "bounce" on the handwheel, smooth running at the HS end, and bounce towards the tailstock.

I swapped several centers in and out of both tapers and the front to back misalignment was consistenly 2/64"-3/64". After my fooling around, a little they seemed closer than previously.

I wiped out the insides of both tapers and they were clean (just a hint of oil in there).

JohnnyCNC mentioned something specific with groves in the two cones (live/dead). I recently noticed some very slight grooves being worn into them. However my OOR problem existed before going mandreless. The quill on the tail stock is solid, and as mentioned I always keep a minimal amount of extension when turning.

The lathe is about 15mos old, so I am not sure about the warranty.

The test of truth is putting a blank and turning it to size...which I did. Unfortunately the problem still exists. I have one side wall a little fatter on one end, and the opposing side fatter on the other end. resulting in a poor fit with the kit hardware.

So, what next?
Thanks in advance for all of your help!

what kit are you turning? it could be your bushings.they can fit so loose as to cause this.they can also be off center one diameter to another, and
hole off center to the diameters.This can and will prouce your condition!

 

[Randy_]

Wow! You guys never fail with the solutions. I agree with you all that attempting to twist the bed is a bad idea. It's nice to have it confirmed by someone else. I spent a little time tonight cleaning, tightening, re-seating. I'll try to include everything into this post:

We'll start with the runout measurements:
Handwheel now=>.008"
Chris: Is this better or worse than it was before? Just asking out of curiosity as given the measurements you made on the other end of the spindle, I don't think the handwheel thing is a major issue. Is that handwheel runout something you can see by eye as wobble or just something you are detecting with the dial gauge?
Behind the headstock threads:=.001"
deadcenter:=.001"
Inside HS taper=.001"
It seems you missed an important one here. Need a measurement of the runout of the circumference at the end of the arbor (the piece that has the male MT) where it is attached to the mandrel.
Taper end of mandrel:=.005"
Middle of mandrel:=.007"
End of mandrel:=>.008"
Just to be sure we are all on the same page, you are measuring the runout of the mandrel while the TS end is unsupported by a live center are you not??

One other question we asked that didn't get an answer: When the mandrel is in the HS and you advance the TS with a live center installed, how much does the LC point miss being in alignment with the center hole in the end of the mandrel??

*I rolled the mandrel on a glass sheet before measuring to ensure it wasn't bent. It was OK. But there could be a problem with the arbor, itself, or the hole in it that the mandrel screws into!!

This measurements are consistent with quick and dirty checking by laying a flat tool (skew) in various places while the lathe is running. I get considerable "bounce" on the handwheel, smooth running at the HS end, and bounce toward the tailstock.

I swapped several centers in and out of both tapers and the front to back misalignment was consistently 2/64"-3/64". After my fooling around, a little they seemed closer than previously.
That is too much of a misalignment!! We need to get that corrected one way or another after we figure out what is going on!!

I wiped out the insides of both tapers and they were clean (just a hint of oil in there).

JohnnyCNC mentioned something specific with groves in the two cones (live/dead). I recently noticed some very slight grooves being worn into them. However my OOR problem existed before going mandreless. The quill on the tail stock is solid, and as mentioned I always keep a minimal amount of extension when turning.

The lathe is about 15mos old, so I am not sure about the warranty.
Jet used to have a 2 year warranty; but changed it to a 5 year warranty recently.....don'r recall exactly when. If I were to guess, I would say your lathe is old enough that it is on the 2 year warranty; but, obviously, you still have coverage either way so no sweat there.

The test of truth is putting a blank and turning it to size...which I did. Unfortunately the problem still exists. I have one side wall a little fatter on one end, and the opposing side fatter on the other end. resulting in a poor fit with the kit hardware.

So, what next?
Make a few more measurements. We are almost to the point where we have enough information to make some reasonable judgments as to the problem. Preliminarily, it looks like you may have two separate problems. One with your mandrel/arbor (although that could be a problem with the HS spindle, too) and one with the alignment of the HS and the TS. We still need to work on that a bit to figure out exactly where that lies.
Thanks in advance for all of your help!

Hang in there, buddy. We will get you fixed up pretty soon!!

 

[cbatzi01]

what kit are you turning? it could be your bushings.they can fit so loose as to cause this.they can also be off center one diameter to another, and
hole off center to the diameters.This can and will prouce your condition!

Hi,

I have looked into the poor quality bushings option. I turn Jr. Gents, patriots, and sierras mostly. I checked the wall thickness of each set of bushings with a pair of digital calipers. Everything was OK there. I even have replaced the bushings thinking that turning/sanding into them was changing their size.

The problem still exists.

 

[marcruby]

I just had a thought - probably erroneous, since every time people start talking about .001 measurements I start to get a headache. It's easy enough to tell if the ways are twisted, all you need is two stiff straightedges. Lay one across the ways at the tailstock and another across the ways at the tailstock end of the ways. Then go look to see if they line up. This is the same method I use to true a blank, although it's a little harder to plane the ways of a lathe >

I don't know if that helps or not, but I thought it might be worth mentioning.

Marc

 

[Chris Bar]

When you mention handwheel not spinning correctly, are you speaking of the headstock or the tailstock? If tailstock, the center might have been extended too far and disengaged from the handwheel gearing (only speak from perspective of the PM though). Or if an alignment problem, you might need to remove the head and tailstock, and clean the bottom surface (and also the lathe bed ways), and remove any crud or metal casting artifacts possibly bent back onto the machined surface, and do the same for the lateral tracking surfaces. Had similar issue with mine lately and that solved a misalignment problem. Other than checking for bad bearings or bent spindle shaft, have no suggestions, if you are sure the bed casting is not twisted (see previous comment on checking this).
PM sent a tech to replace bearing in my new lathe; you might need to contact them again if all else fails.

 

[cbatzi01]

Hi Guys,

Sorry for the delay, but the combination of a head cold and NCAA games have kept me on the couch.

Here are the new results:

The hand wheel wobble is noticeable to the eye.

I measured the circumference run out of the spindle and it was minimal (<.001).

Randy, I did actually have the end of the mandrel supported by the tailstock. When I left it unsupported, the runout doubled to .016. That seems like a significant change to me . Again, as I move the dial indicator closer to the spindle, the runout decreased, but never below about .005.

The live center seemed to match up with the hole in the pen mandrel arbor fine. I have a double ended morse taper for lining up the swiveling head of a Jet 1442. Not sure if that would help at all, though, as the Jet 1014's head doesn't move.

Now I am thoroughly confused.

Thanks!
Chris

 

[Randy_]

.....Randy, I did actually have the end of the mandrel supported by the tailstock. When I left it unsupported, the runout doubled to .016. That seems like a significant change to me
Yeah, that is very interesting. Not sure exactly what it means. I'm going to have to think about that a bit??

OK, Chris, I am starting to build a pretty good mental picture; but I still need to clarify a few things. Last post I asked you to check the runout of the arbor. Not sure whether you have done that or not. We need to be sure we are using the same terminology so let me point out that the item that most folks refer to as the pen mandrel is actually composed of two parts.....the mandrel and the arbor. The mandrel is actually the long thin rod-shaped piece that is threaded at both ends and carries the pen blanks when they are being turned. The arbor is the tapered chunk of steel that actually slips into the MT on the end of the head stock spindle and into which the mandrel screws.

What I need for you to do if you haven't already done so, is to put the arbor/mandrel into the headstock MT and measure the runout of the "arbor" on the section that extends from the spindle. The closer to the end of the arbor the better.....maybe within a 1/4" of the end of the arbor.

And now for the final test, put the mandrel/arbor in the HS and note how closely the point of the TS livecenter matches up with the center of the end of the mandrel. Then switch the mandrel/arbor and the live center so that the live center is in the headstock and the mandel in the tailstock. Again bring them together and not how closely they match. Is the match about the same or is one configuration better than the other?

I'm going to go out to my shop and take some measurements on my JET just to have for the sake of comparison and then we can start to look at where your problem might lie.

 

[cbatzi01]

Hi Guys,

I followed Randy's suggestion and put the the arbor only in the HS and the 60deg cone in the tailstock. I pushed them together and as I looked from the TS, down the axis into the hole in the arbor, the alignment was off to the right. I when I actually extended the quill to push the cone into the the hole in the arbor, once they made contact on the right hand side,the coneshifted/pulled/moved a tiny bit to the left.

As far as the run out on the arbor itself. Towards the HS, up against the edge of the spindle, the there was almost no run out. Towards the other end, the run out was .001-.002.

Any suggestions?

 

[Randy_]

Hi Guys,

I followed Randy's suggestion (No you didn't.:biggrin: Please go back and read what I asked for again. If it is not clear, let me know and I will try to do a better job of desdcribing the experiment. If you can get me this one final piece of information, i think we can start making a god diagnosis about what the problem is.) and put the the arbor only in the HS and the 60deg cone in the tailstock. I pushed them together and as I looked from the TS, down the axis into the hole in the arbor, the alignment was off to the right. I when I actually extended the quill to push the cone into the the hole in the arbor, once they made contact on the right hand side,the coneshifted/pulled/moved a tiny bit to the left.

As far as the run out on the arbor itself. Towards the HS, up against the edge of the spindle, the there was almost no run out. Towards the other end, the run out was .001-.002.
OK, good. That is the figure I wanted to get.

Any suggestions?

Chris: I got side-tracked and did not take the measurements off of my lathe as I promised. Let me run out to the shop real quick and measure it up. Then we can compare with yours and see if we can figure out anything.

 

[Randy_]

OK, here are the measurements off of my lathe. Mind you, I don't know what the JET manufacturing tolerances are supposed to be (asked a tech about some of them one time; but he claimed not to know) so all we can do is note the differences and look for any large differences; but not really know if any of the measurements are out of spec.

Runout Measurements For Randy's JET 1014
(Chris' measurements in red)

HS handwheel = 0.006" (no wobble visible to my eye)
HS handwheel = 0.008"
HS spindle = <0.001"
HS spindle = 0.001"
Spindle taper = <0.001"
Spindle taper = 0.001"
Arbor = <0.001"
Arbor = 0.002"

Mandrel (end unsupported)
at HS = 0.003"
at HS = 0.005"
at mid = 0.008"
at mid = ??
at TS = 0.012" (tiny amount of wobble visible to my eye.)
at TS = 0.016"
Mandrel (with LC engaged)
at HS = 0.003"
at HS = 0.005"
at mid = 0.002"
at mid = 0.007"
at TS = 0.002"
at TS = 0.008"

The alignment of a center in the TS and the headstock is off by about 1/64". The alignment of the end of the mandrel with the live center is off by about 1/64" as well. If I switch the LC to the HS and the mandrel to the TS the misalignment is about the same .....1/64"±; but the direction is different.

It is a little too late for me to think about what these measurements might mean so I will look at them after a good night's rest and see if anything jumps out at me, tomorrow.

Added: I've added the measurements that Chris posted (in red) next to the measurements from my lathe so they are more easily compared. Now to see if anything junps out or points to the problem?

 

[Randy_]

Chris: After looking at all of these measurements and thinking about them for a day or two, it looks to me like the arbor that holds your mandrels may not be accurately drilled and may not be holding the mandrels in the correct configuration.

If it were me, I think I would get another arbor or see if you can get it replaced by the folks who sold it to you originally. Personally, I use Berea mandrels and arbors and they have always served me well though I now use a Beall collet chuck.

 

[cbatzi01]

Hi Randy,

I sincerely appreciate the thought and effort you have put into my problem. I am not disagreeing with you about the arbor. I have a couple from rockler, and a pro pen mandrel from CUSA, and have not measured them for the "centerness" of the hole. Unfortunately, a bad arbor doesn't solve my problem entirely as I typically turn without using the mandrel whenever possible. These days, I turn a lot of sierras, patriot pens, and Jr. Gents.

I am replacing my 60deg live/dead centers with ones from JohnnyCNC. They arrived today, and I hope to use them this weekend. The current ones were becoming "grooved".

I am not 100% of what is going on here, clearly. I took a crack at another pen this past weekend, and could see that the dead center was visibly "wobly". I went back down tonight to take a measurement, it wasn't nearly as severe. I measured right at the fatest part of the deadcenter, right before the slope, and i twas approximately .005 off. I could swear that the wobble was bigger on saturday. I could feel it when applying the finish. Maybe I should turn a barrel down to the bushings and measure the wall thickness at the thinnest/fattest parts. Would that be helpful?

I almost feel like replacing the spindle/arbor because at this point it couldn't hurt anything!

As I said before, I truly appreciate your help with this. I know you must have more interesting things to do besides contemplating my little problems!

 

[Randy_]

.....I took a crack at another pen this past weekend, and could see that the dead center was visibly "wobly". I went back down tonight to take a measurement, it wasn't nearly as severe. I measured right at the fatest part of the deadcenter, right before the slope, and i twas approximately .005 off. I could swear that the wobble was bigger on saturday. I could feel it when applying the finish. Maybe I should turn a barrel down to the bushings and measure the wall thickness at the thinnest/fattest parts. Would that be helpful?

......As I said before, I truly appreciate your help with this. I know you must have more interesting things to do besides contemplating my little problems!

Don't worry about me, Chris. I enjoy working on these little mechanical challenges!!

Now on to another look at your problem. I have been assuming there was nothing wrong with your spindle based on your earlier measurements of the runout of the spindle and a dead center which were essentially zero. And now you are saying that there is a wobble in your dead center and distinctly measurable runout which entirely changes the analysis.

A wobbling dead center means either a defective dead center or a problem with your spindle.....most likely either dirt in the MT, or defective machining of the MT pocket or hole.(not sure what the precise term is)

There is another thread running right now, started by a guy who has a wobbling dead center, and he has discovered a defect in the MT pocket of his lathe. You should take a look at this thread and see if it mirrors your problem. perhaps his situation will point you to a solution of yours.

http://www.penturners.org/forum/showthread.php?t=43728