# Lethe Leveling = Drive you crazy



## Janderso (Apr 14, 2022)

I know this is the Members hangout.
I don't want to begin another thread about lathe leveling.
This all started when I checked to see if I was turning a taper. I turned a 1" piece of cold rolled about 2". I didn't like what I saw so I got serious.
My 15" Colchester manual says to, "Take a light cut with a keen tool over a 6 inch length of 2" diameter steel bar gripped in the chuck but not supported at the free end. Micrometer readings at each end of the turned length should be the same"

I got the twist out with my 12" machinist -super fussy level (yes I made sure it was calibrated and yes I know how to do it)
I took a .003" pass after a clean up pass with a sharp HSS tool.
I measured with a quality micrometer and came up wit a .001" taper over 6".
That's gonna have to be good enough.

Just wondering what you'all feel about this? Should I keep going? Is .001" good enough over 6"??
It takes a lot of up and down on the knees to make super small turns of the adjusting screws. I have 8 of them. I only use the inboard adjusting bolts. Once I have it where I want it, I bring the outside 4 into equal tension.

What are your thoughts?

Edit- It obviously wasn't 2" bar  -close enough.


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## matthewsx (Apr 14, 2022)

It depends on how long of pieces you're turning and how tight of a tolerance you need them to be. I wouldn't worry about it until it becomes a problem, but then again I'm not making parts for NASA.

John


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## benmychree (Apr 14, 2022)

Best to neck down that bar into the likeness of the two collar method, less tool wear for the distance and much less time feeding that distance.


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## MrWhoopee (Apr 15, 2022)

Let is settle for a while. Test again in a couple of years, or when it becomes a problem.


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## mikey (Apr 15, 2022)

Jeff, *the test that your manual is outlining for you (the one showed in your pic) is to align the headstock with the ways*. In my experience, it is the correct way to set up a lathe - headstock alignment first, then careful leveling, then tailstock alignment - in that order. 

They are asking you to take light skim cuts, in the range of 0.001 - 0.002" deep, with a sharp HSS tool over a 6" length of an unsupported work piece large enough not to deviate with those cuts. Aluminum or mild steel works well. You are supposed to measure the OD at the chuck end and free end and determine if there is a difference. If there is a difference then the headstock is not aligned with the ways and you need to fix that. For example, if the OD at the tailstock end is bigger than the chuck end then that means the tool is farther away from center on the tailstock end so that end is bigger. To bring the tool closer to center you need to rotate the headstock in a CW (clockwise) direction, lock it down and test cut again. These rotational changes are typically very small, on the order of thousandths of an inch, but make a very real difference. In any case, find out how your headstock locks down and give this a go.

How accurate do you need to be? I would get it so there is ZERO deviation down that 6" length. Why? Because this affects *everything* else you do with regard to setting up the lathe accurately. If the headstock alignment is off then any adjustments you make when leveling will also be off. The same will be true for tailstock alignment. 

So, if I were you, I would do it in this order: Make sure the lathe is sited where you want it and roughly level the cabinet longitudinally and across the bed. Do this first. Then align the headstock as above and get it to zero. Then you can work on leveling the lathe and when the level is stable for a week or two, align the tailstock last.


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## Janderso (Apr 15, 2022)

Good advice, as always. Thank you.

Mikey, you are right, I showed a pic of the headstock adjustment procedure.
. I don’t imagine it would take much to move to zero. 

John, the two collar method would have made more sense.

To be honest, what prompted me to mess with the leveling was I noticed some movement, vibration when using the lathe yesterday morning.
I checked some of the leveling bolts and found a few were not tight.
I’m using the threaded holes in the casting to support my lathe. I have the bolts sitting on 3” OD steel risers. It is my practice to tighten the bolts to get everything level. I’m sitting at the higher end of the adjustment bolts. Maybe I’ll lower all of them and start over.
It seems like I am fiddling with these a bit too often. Lathes do settle after each adjustment, in my experience.

I would leave it alone but it bugs me. I know the lathe is capable of better accuracy. .001” over six inches is certainly adequate for anything I have done thus far, maybe it’s a quest to find the same reading. I may never achieve it and adjusting the headstock makes me a bit anxious.

Just some thoughts from a retired senior citizen.


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## matthewsx (Apr 15, 2022)

Many years ago I had a British .303 rifle that had metal sights, I could hit a beer can from 150 yards with that thing and it was a joy to shoot. I took it to the range and decided I would "sight it in" Nope....

You can definitely make your lathe better, don't be surprised if the process includes making it much worse for a while. Mikey is right of course, what you measured will affect everything else you do with the machine. Just have to figure how much of a project you want to make out of it....

A while back you were looking at property, if you're still thinking of moving that might be a consideration too.

But then again I'm not retired so there's that.

John


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## Janderso (Apr 15, 2022)

matthewsx said:


> Many years ago I had a British .303 rifle that had metal sights, I could hit a beer can from 150 yards with that thing and it was a joy to shoot. I took it to the range and decided I would "sight it in" Nope....
> 
> You can definitely make your lathe better, don't be surprised if the process includes making it much worse for a while. Mikey is right of course, what you measured will affect everything else you do with the machine. Just have to figure how much of a project you want to make out of it....
> 
> ...


John,
First, property. We have become so discouraged we have decided to make the most of where we are.
Over priced property is for suckers in my book. To bid $100,000 over asking price is just foolish.

I will probably not go any further with the lathe other than making sure it’s level (no twist) and stable.

My dad showed me a rifle he bought at a local hardware store. It was in a garbage can display, there were several to choose from.
After removing all the cosmoline I was looking at a .303 Enfield. Mark IV As I recall.
I took it out to my range to check it out. That has got to be the smoothest bolt I remember.
With the iron sights I couldn’t see if I was on target. After a few rounds I asked the guy in the stall next to me (he had a scope) to see if I was on paper. He looked at the target, then looked at my rifle, he said, dude, you are spot on. Keep it up.
It turned out I was about an inch low left but the group was about the size of a quarter.
Surprised the hell out of me!
Another thing I remember, that thing kicked like a mule. Brass plate and all.


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## mcostello (Apr 15, 2022)

If You think leveling a lathe is frustrating,don't try adjusting the headstock to remove taper. You have to bias one screw against another and try to move the metal bar .001" when it is around 12" out. Gonna use a torque wrench next time. I probably have well over 20 hours in this sofar. The taper could not be removed by leveling, Some one must have moved something as the taper when I got it was .012" in 1 inch. I have it down to .002" in 1 inch now.


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## mikey (Apr 15, 2022)

Janderso said:


> I would leave it alone but it bugs me. I know the lathe is capable of better accuracy. .001” over six inches is certainly adequate for anything I have done thus far, maybe it’s a quest to find the same reading. I may never achieve it and adjusting the headstock makes me a bit anxious.


Jeff, adjusting the headstock is a simple, routine procedure. It is not hard. Loosen the bolts that hold the headstock to the ways, bump the headstock into alignment, then tighten the bolts. Hardly earthshaking and well worth doing. Get that right, then level it. 

And if you're looking for validation, no way would I accept a thou deviation over 6"; I would accept zero.


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## StevSmar (Apr 15, 2022)

I liked this video because he had a nice model for imagining what’s going when levelling:





I’m just about to head to the basement to try levelling. I may be joining you in frustration…


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## Winegrower (Apr 15, 2022)

mikey said:


> no way would I accept a thou deviation over 6"; I would accept zero.


Yep.   Why be retired and have your lathe cutting tapers.  

For amusement, I have the very original sign-off sheet for my lathe, and went through every spec and reading I
could understand.   It was amazing how it still met all the specs I measured.

Edit: Takisawa TSL-800D, 1976

As they say:  Retirement…the days drag on and the years fly by.


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## mikey (Apr 15, 2022)

Winegrower said:


> Yep.   Why be retired and have your lathe cutting tapers.


Thing is, if your headstock alignment is off then you can't really level the lathe. If it is aligned then leveling the lathe follows rather easily in my experience.


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## macardoso (Apr 15, 2022)

I leveled my 12x26 Enco. Will need to again since I just moved it across state lines.

Headstock is most important like Mikey said. I have a 3" diameter, 6" long aluminum cylinder that I skim cut for this. Use the jack screws on the back of the headstock. Everything moves it (including the mounting bolts) so I have to sequentially get it lined up, then tighten the mounting bolts a bit, then adjust the alignment screws a bit more, repeat until the mounting bolts are very tight and it is lined up.

My issue from there is that the lathe is on a flimsy and bent sheet metal cabinet. Really limits what I can accomplish with leveling the bed. Still would trust the lathe for 0.0002" taper over the 6 inches closest to the headstock and not more than 0.0008" over the whole bed. That's pretty darn good to me


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## Janderso (Apr 15, 2022)

mikey said:


> Jeff, adjusting the headstock is a simple, routine procedure. It is not hard. Loosen the bolts that hold the headstock to the ways, bump the headstock into alignment, then tighten the bolts. Hardly earthshaking and well worth doing. Get that right, then level it.
> 
> And if you're looking for validation, no way would I accept a thou deviation over 6"; I would accept zero.


It may not be earthshaking but access is an issue. I can actually get to one of four


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## Dabbler (Apr 15, 2022)

Here's my tke on it:  If you are doing a lot of long work, over 12", we then you are not done yet.  If almost everything you do is in the 2" X 2" X 2" envelope, then you are already close enough.

-- most of my stuff is bigger than 6"


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## addertooth (Apr 15, 2022)

Well, I will say something re-assuring.  You are off to a good start.  You have measured your error.  For a lot of my press-fits, an error of a half a thousandth is good enough.  Usually, my press fit surfaces are only about an inch long.  For bearing surfaces, I am more inclined to machine it slightly large, and hone it down.  Now, if you have your goals set on rifle barrels, more work must be done.  I won the alignment lottery with my lathe, and was fortunate to have it good from the seller (4/10ths of 1/1000th of an inch over ten inches, including tailstock error).  I left it alone, and am careful how loudly I whisper around the headstock


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## mikey (Apr 16, 2022)

Janderso said:


> It may not be earthshaking but access is an issue. I can actually get to one of four


One wonders, then, how they assembled the lathe. However, what I or others will accept means absolutely nothing; what you accept is all that matters. If a thou is good for you then leave it and be happy.


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## ddickey (Apr 16, 2022)

Make sure to take spring passes then check your dimension on test bar. Shut off lathe, retract the tool and take a spring pass.
Slightly larger on the TS end is acceptable but larger on the HS end is unacceptable.


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## ddickey (Apr 16, 2022)

mikey said:


> Jeff, *the test that your manual is outlining for you (the one showed in your pic) is to align the headstock with the ways*. In my experience, it is the correct way to set up a lathe - headstock alignment first, then careful leveling, then tailstock alignment - in that order.


But you need to level the lathe before making any HS adjustments, correct?


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## mikey (Apr 16, 2022)

ddickey said:


> But you need to level the lathe before making any HS adjustments, correct?


For me personally, I consider headstock alignment the first and most important adjustment you can make to a lathe. I think it has to be done first and if it is done well then leveling the lathe, which should be done second, becomes much easier and more accurate. 

It isn't that a headstock that is off alignment will affect how you roughly level the lathe; it is that it will affect how you final tune the level. Normally, we use a 2-collar test to dial the final level in, right? Well, if the headstock is off then you're dialing in the level with your 2-collar test to at least partially accommodate that headstock offset and not just the true levelness of the lathe. The thing is, _you cannot separate the two sources out when doing it this way. _Better to align the headstock first to eliminate that variable.


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## ddickey (Apr 16, 2022)

I guess I should ask how you check for HS alignment. The way I see it if the lathe is not leveled first how would you know if it is the HS or twist caused by not level?
I always thought you leveled first. Take test cut then if there is still a taper then HS alignment.


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## Winegrower (Apr 16, 2022)

A short while ago I took a risk and bought an eBay lathe test bar from India.   When it got here, I measured diameter everywhere with a Mitutoyo digital mic, reads to 50 millionths.   Mostly all the same readings, a few were plus 50 millionths.   I cut a headstock center, put the test bar between center and spun it with a 0.0001 DTI against it.   Again almost no needle movement, definitely less than a tenth runout.   So by running an indicator along the bar, I could see some tailstock offset, and corrected that as much as possible.  It's notable that there is a slight change when either locking the tailstock or the quill, so I aligned for both locked.    Then the headstock alignment I checked by chucking the bar in the three jaw and again running the indicator along...fortunately this was zero error because it looks a bit of a nuisance to adjust.
Then a two collar test, made by pressing a couple aluminum disks onto a center drilled printer carriage rod, and turned to the "same" X axis setting.   There was a fraction of a thousandth over a foot or so, seemed completely acceptable.

Now my lathe is so accurate that I can still make a part that's off by a quarter inch or so.

Did I just get lucky that the chuck held the test bar so straight?   It got jiggled so it settled in, just like any part would.   Anyway,  I'm happy.


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## Janderso (Apr 16, 2022)

macardoso said:


> I leveled my 12x26 Enco. Will need to again since I just moved it across state lines.
> 
> Headstock is most important like Mikey said. I have a 3" diameter, 6" long aluminum cylinder that I skim cut for this. Use the jack screws on the back of the headstock. Everything moves it (including the mounting bolts) so I have to sequentially get it lined up, then tighten the mounting bolts a bit, then adjust the alignment screws a bit more, repeat until the mounting bolts are very tight and it is lined up.
> 
> My issue from there is that the lathe is on a flimsy and bent sheet metal cabinet. Really limits what I can accomplish with leveling the bed. Still would trust the lathe for 0.0002" taper over the 6 inches closest to the headstock and not more than 0.0008" over the whole bed. That's pretty darn good to me





mikey said:


> One wonders, then, how they assembled the lathe. However, what I or others will accept means absolutely nothing; what you accept is all that matters. If a thou is good for you then leave it and be happy.


You got me thinking about assembly. Shoot, I really have no excuse. The headstock bolts are easy to access. I was looking under the headstock looking fir a different mounting system.??? I am a blind senior citizen.
I lowered my leveling bolts to their lowest position and re-leveled it. That’s hard on the knees.
I used the two collar method, took a .002” finish cut.
I have .0008” difference over six inches. The heavy end is toward the tail stock. I don’t think it’s deflection.

I am going to adjust the headstock. Heaven knows where I’ll end up but now I have a mission.

Mikey and others shamed me into it and I just can’t live with it. Well, I probably could


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## Janderso (Apr 16, 2022)

Winegrower said:


> A short while ago I took a risk and bought an eBay lathe test bar from India.   When it got here, I measured diameter everywhere with a Mitutoyo digital mic, reads to 50 millionths.   Mostly all the same readings, a few were plus 50 millionths.   I cut a headstock center, put the test bar between center and spun it with a 0.0001 DTI against it.   Again almost no needle movement, definitely less than a tenth runout.   So by running an indicator along the bar, I could see some tailstock offset, and corrected that as much as possible.  It's notable that there is a slight change when either locking the tailstock or the quill, so I aligned for both locked.    Then the headstock alignment I checked by chucking the bar in the three jaw and again running the indicator along...fortunately this was zero error because it looks a bit of a nuisance to adjust.
> Then a two collar test, made by pressing a couple aluminum disks onto a center drilled printer carriage rod, and turned to the "same" X axis setting.   There was a fraction of a thousandth over a foot or so, seemed completely acceptable.
> 
> Now my lathe is so accurate that I can still make a part that's off by a quarter inch or so.
> ...


I picked up one of those Edge products tail stock gadgets. I used it wrong. Once I figured it out I found the tail stock was out .002” over about 15”. Sure made it easy to dial her in!


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## Janderso (Apr 16, 2022)

mikey said:


> For me personally, I consider headstock alignment the first and most important adjustment you can make to a lathe. I think it has to be done first and if it is done well then leveling the lathe, which should be done second, becomes much easier and more accurate.
> 
> It isn't that a headstock that is off alignment will affect how you roughly level the lathe; it is that it will affect how you final tune the level. Normally, we use a 2-collar test to dial the final level in, right? Well, if the headstock is off then you're dialing in the level with your 2-collar test to at least partially accommodate that headstock offset and not just the true levelness of the lathe. The thing is, _you cannot separate the two sources out when doing it this way. _Better to align the headstock first to eliminate that variable.


Very true! “ if the headstock is off then you’re dialing in the level with your 2 collar test”
It makes perfect sense to dial in the headstock first.
I sure am glad we had this discussion.


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## ddickey (Apr 16, 2022)

I think it just dawned on me what you guys mean by level.
When i think level it means putting a precision level on the cross slide and seeing no movement of the bubble by adjusting the feet.
When you guys say level are you meaning adjusting the feet to not cut a taper?


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## Janderso (Apr 16, 2022)

I spent the last hour or so loosening the headstock bolts. Next time will be easier. They were full of gronge. A little acetone, a wire brush and compressed air allowed me to get a tool inserted. The only tool I can use is a 3/8 allan tool = no access.
I had a tenths indicator on the work piece. I’m trying to move the headstock so the work piece pivots inward towards the operator.
Since I am heavy on the tail stock end by .001”. I assume I tighten the screw shown in the manual, away from the operator to pivot inward.
I need to move .0005”.
I saw .0005” movement on the indicator. I then tightened all the bolts.
Ran another test cut with no change. I must have bumped something.
Back at it tomorrow. I plan on taking my time.


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## Janderso (Apr 16, 2022)

ddickey said:


> I think it just dawned on me what you guys mean by level.
> When i think level it means putting a precision level on the cross slide and seeing no movement of the bubble by adjusting the feet.
> When you guys say level are you meaning adjusting the feet to not cut a taper?


Correct.
Lathes are on ships at sea. Getting the twist out, to return the bed to a state in which it was ground at the factory.


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## mikey (Apr 17, 2022)

Janderso said:


> I spent the last hour or so loosening the headstock bolts. Next time will be easier. They were full of gronge. A little acetone, a wire brush and compressed air allowed me to get a tool inserted. The only tool I can use is a 3/8 allan tool = no access.
> I had a tenths indicator on the work piece. *I’m trying to move the headstock so the work piece pivots inward towards the operator.
> Since I am heavy on the tail stock end by .001”.* I assume I tighten the screw shown in the manual, away from the operator to pivot inward.
> I need to move .0005”.
> ...


So, if the test piece is bigger on the tailstock end then the tool is farther away from the centerline of the lathe on the tailstock end. To correct this, you want to rotate the headstock so as to bring the work piece closer to the cutting tool and even out the OD all the way down the work. Therefore, you must rotate the headstock in a CW/clockwise direction to correct the existing defect.

I'm not sure how that adjuster "C" works but I do know that using an indicator to tell you how far to turn doesn't always jive. That is, moving the headstock so you see 0.0005" on the DI does not translate into a correction of 0.0005" on the work piece OD. You just have to mess with it until you get it right. Be patient, take your time, don't get in a rush.

I've found that once you do this adjustment, it is unlikely that you will need to do it again unless you turn a big, off-balance work piece and maybe not even then. I normally do a test cut during my semi-annual maintenance check where I check alignment and level and major lube. In the last 5 years, I have not had to realign the headstock - test cuts show zero deviation over 6".


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## Jake M (Apr 17, 2022)

Janderso said:


> I spent the last hour or so loosening the headstock bolts. Next time will be easier. They were full of gronge. A little acetone, a wire brush and compressed air allowed me to get a tool inserted. The only tool I can use is a 3/8 allan tool = no access.
> I had a tenths indicator on the work piece. I’m trying to move the headstock so the work piece pivots inward towards the operator.
> Since I am heavy on the tail stock end by .001”. I assume I tighten the screw shown in the manual, away from the operator to pivot inward.
> I need to move .0005”.
> ...




Maybe I'm misunderstanding what you're doing?  I don't think you want to use a distance to set this angle, as at this scale (I think at least), there's enough movement available in the mounting to have a hard time picking an exact center of rotation.    If the test bar 0.001 fat at the tailstock end, instead of measuring the distance of movement at the end (not knowing the pivot point), I'd use the carriage sweep the test bar.  Rotate the headstock until you see the indicator report the known shape of the bar.  I think that I've extrapolated that you have this covered, but depending on how your cross slide has your brain trained, remember the radius vs diameter thing.  The headstock end should be half a thousandths further away from the toolpost than the tailstock end.   Kind of like tramming a vise, where you don't care the distance, only the change as you sweep it.

Free advice from a guy who's never tried this because hes headstock is keyed to the lathe bed and can not be adjusted.


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## StevSmar (Apr 17, 2022)

My “Initial” lathe alignment went pretty well and there wasn’t very much chasing my tail.

I have a 17.5” MT5 test bar (purchased from India via eBay) which I put between centers to check it’s accuracy. As far as I can tell it’s as advertised with a max runout of 0.0002”. I don’t have a surface plate to do a proper test though.

I assumed the headstock was aligned for this “initial” alignment. If I start turning longer pieces I’ll look at this too.

Next I levelled the lathe using a machinists level. Then I tried to making sure that all four feet at the headstock were equally loaded. I backed off the feet that were “heavily loaded”, put them back to their original location and then tried to put the same amount of torque on the adjacent “lightly” loaded feet. This was a bit subjective and there is probably a better way of doing it… Once all the headstock feet were loaded about the same, I then went back and checked the level wasn’t too far off. 

I did also try adjusting the headstock for “nod” using the four headstock feet, but it didn’t seem to make much of difference, so I went back to trying to make the feet were equally loaded as per above.

After getting the spindle and test bar MT5 surfaces as clean as possible, I fitted the test bar. There was maybe 0.002” of runout at the tailstock end of the test bar. I don’t have a way of knowing whether it’s the test bar or the spindle that has the runout, so I marked the max runout location: removed the test bar; rotated it and reinstalled; checked the runout and repeated. Until it was as good as I could get which was just under 0.001”.

Aligning the ways for twist I did using just the tailstock feet. I’d check the maximum runout readings of the test bar, adjust the feet, check again, etc. At this stage I was struggling to determine if the maximum runout really was around 0.0005”. It did seem to be better, though with all the variables I was juggling it could be just wishful thinking and wanting to be done.

It was about 2 hours of playing around. Not too bad I thought. Probably half of that time was spent thinking about how each foot adjustment would effect the alignment.

I think having a test bar is helpful, though I also think the only real proof will be when I turn a bar with two collars.


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## Janderso (Apr 17, 2022)

Jake M said:


> Maybe I'm misunderstanding what you're doing?  I don't think you want to use a distance to set this angle, as at this scale (I think at least), there's enough movement available in the mounting to have a hard time picking an exact center of rotation.    If the test bar 0.001 fat at the tailstock end, instead of measuring the distance of movement at the end (not knowing the pivot point), I'd use the carriage sweep the test bar.  Rotate the headstock until you see the indicator report the known shape of the bar.  I think that I've extrapolated that you have this covered, but depending on how your cross slide has your brain trained, remember the radius vs diameter thing.  The headstock end should be half a thousandths further away from the toolpost than the tailstock end.   Kind of like tramming a vise, where you don't care the distance, only the change as you sweep it.
> 
> Free advice from a guy who's never tried this because hes headstock is keyed to the lathe bed and can not be adjusted.


I’m glad you brought up pivot point. That changes the game entirely as mikey said.


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## Janderso (Apr 17, 2022)

StevSmar said:


> My “Initial” lathe alignment went pretty well and there wasn’t very much chasing my tail.
> 
> I have a 17.5” MT5 test bar (purchased from India via eBay) which I put between centers to check it’s accuracy. As far as I can tell it’s as advertised with a max runout of 0.0002”. I don’t have a surface plate to do a proper test though.
> 
> ...


You mentioned nod of the headstock.
I hadn’t thought of that as I am only using the inboard adjustment feet then I brought the outboard adjusters down to snug.
I now need to verify if I have created a bit if nod. Maybe not. This is a pretty robust lathe at 2,700#.

I watched , This old tony and Joe Pi this morning.
They both did a good job of illustrating or visualizing with props the intended outcome.
I’m not worried about my longitudinal level. It just makes the process that much more challenging and it makes no difference unless I decide to use flood coolant, which I don’t. I occasionally use a mister.


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## John O (Apr 17, 2022)

Isn't the headstock alignment checked by facing a disc then putting a straight edge across the disc to see if it's flat?


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## mikey (Apr 17, 2022)

John O said:


> Isn't the headstock alignment checked by facing a disc then putting a straight edge across the disc to see if it's flat?


There are several ways to align the headstock - test cuts as Jeff is doing, using a MT test bar and facing a disc as you suggest. I've done them all and test cuts are the simplest, most reliable and the most accurate in my opinion. Do what you think is best.


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## Janderso (Apr 17, 2022)

mikey said:


> For me personally, I consider headstock alignment the first and most important adjustment you can make to a lathe. I think it has to be done first and if it is done well then leveling the lathe, which should be done second, becomes much easier and more accurate.
> 
> It isn't that a headstock that is off alignment will affect how you roughly level the lathe; it is that it will affect how you final tune the level. Normally, we use a 2-collar test to dial the final level in, right? Well, if the headstock is off then you're dialing in the level with your 2-collar test to at least partially accommodate that headstock offset and not just the true levelness of the lathe. The thing is, _you cannot separate the two sources out when doing it this way. _Better to align the headstock first to eliminate that variable.


Mikey,
Question for you.
If the taper is caused by wear to the carriage, am I able to mitigate it by adjusting the headstock?
I say carriage because I do not see or feel any wear/lip on the bed ways at all.
I know there has to be wear but since the bed is induction hardened (I don’t know about the carriage) I can only assume it would be in the carriage.
Thanks,
Jeff


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## mikey (Apr 17, 2022)

Janderso said:


> If the taper is caused by wear to the carriage, am I able to mitigate it by adjusting the headstock?


I honestly do not know, Jeff. One of the reasons why test cuts for headstock alignment is done along the entire work piece and not on a 2-collar bar is so you can measure the OD at both ends and the center. If there is a true taper then you will see it in the OD's in these areas. I would imagine that if there is a really serious wear issue then it might show up in your numbers.


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## StevSmar (Apr 17, 2022)

Janderso said:


> You mentioned nod of the headstock.…


My lathe is not that heavy, about 900lbs. I really was starting to chase my tail by the time I started adjusting for nod and I was losing confidence that I could actually measure anything from my adjustments. My lathe is 12x24”, so perhaps it’s too rigid to adjust for this?

I’m still not sure why nod is important, since the lathe tool is always(?) cutting at 90 degrees to the top.  (Maybe this would be important if I was line boring and the cutting tool was at the top?)

I did my test bar, and the cuts were about 0.001” over 6”. Until I learn how to actually use my lathe I think I’m going to call this good enough.


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## Janderso (Apr 17, 2022)

StevSmar said:


> My lathe is not that heavy, about 900lbs. I really was starting to chase my tail by the time I started adjusting for nod and I was losing confidence that I could actually measure anything from my adjustments. My lathe is 12x24”, so perhaps it’s too rigid to adjust for this?
> 
> I’m still not sure why nod is important, since the lathe tool is always(?) cutting at 90 degrees to the top.  (Maybe this would be important if I was line boring and the cutting tool was at the top?)
> 
> I did my test bar, and the cuts were about 0.001” over 6”. Until I learn how to actually use my lathe I think I’m going to call this good enough.


The further away the cutting tool goes from the chuck your part would grow in diameter if there were an upward nod.
The same actually if it was going down. 
Does that make sense?


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## Janderso (Apr 17, 2022)

mikey said:


> I honestly do not know, Jeff. One of the reasons why test cuts for headstock alignment is done along the entire work piece and not on a 2-collar bar is so you can measure the OD at both ends and the center. If there is a true taper then you will see it in the OD's in these areas. I would imagine that if there is a really serious wear issue then it might show up in your numbers.


TOT, used an example of supporting the piece with a live center and showed he was cutting a taper. He shimmed the right front tail stock leg and the taper switched sides.
I thought this method was just for checking tail stock alignment.
Assuming he knew his tail stock was spot on, it would be a good way to check for bed/saddle wear and how it effects the cutting dimensions.

Lots to consider and to follow up on.
Thank you for your help on this.


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## StevSmar (Apr 18, 2022)

Janderso said:


> The further away the cutting tool goes from the chuck your part would grow in diameter if there were an upward nod.
> The same actually if it was going down.
> Does that make sense?


Yes, and no…

The way I’m currently thinking of it “nod” and “ways twist” are like a sine and co-sine error. My thought is that they each effect the other. “Ways twist” will directly impact the part changing in diameter as you move along the ways, whereas ”nod” won’t do much when the “nod” is small, because the lathe tool is 90 degrees away. As the ”nod” gets bigger, then the error increases more rapidly?

I’m just happy my test bar was around 0.001” over about 6 inches, when I know what I’m doing I’ll likely experiment more:


(My first try at knurling was in the middle…, after I’d finished playing with the two collars.)


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## Janderso (Apr 18, 2022)

John O said:


> Isn't the headstock alignment checked by facing a disc then putting a straight edge across the disc to see if it's flat?


Haven't heard of this method. 
The way I see the results of the facing test, it would still be flat even if the headstock was out.
If you could measure to see if the face was 90 degrees to the datum with the straight edge, that is an interesting test.
What am I missing?


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## Aaron_W (Apr 18, 2022)

Janderso said:


> Haven't heard of this method.
> The way I see the results of the facing test, it would still be flat even if the headstock was out.
> If you could measure to see if the face was 90 degrees to the datum with the straight edge, that is an interesting test.
> What am I missing?



I was wondering the same. I could see using a square to determine something was amiss, but not seeing how a straight edge would show that unless it was so grossly out of wack that you could see it by eye.


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## Winegrower (Apr 18, 2022)

Seems that if the headstock was out, facing would produce a cone shape.  I imagine a dial indicator swept across the face would show that.


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## ddickey (Apr 18, 2022)

Some use a parallel and hold it against the headstock with an indicator on the cross slide and sweep. Any error past the center axis is an alignment issue.
Also, remember lathes do not face flat.


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## John O (Apr 18, 2022)

Janderso said:


> Haven't heard of this method.
> The way I see the results of the facing test, it would still be flat even if the headstock was out.
> If you could measure to see if the face was 90 degrees to the datum with the straight edge, that is an interesting test.
> What am I missing?


If the headstock isn't parallel to the cross feed you will have a taper from the edge to the center.


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## Dabbler (Apr 18, 2022)

I think before you get to geometry discussions and the like:

The primary order for any lathe setup is to:

1)   Ensure/adjust headstock to true
2)   Set up tailstock to be centred and run parallel to the headstock orientation
3)   Adjust lathe bed to pass the 2 collar test.

if you try to do it in any other order you are chasing your tail...  I wasn't sure from some of the comments that this was the common understanding.


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## Winegrower (Apr 18, 2022)

ddickey said:


> Also, remember lathes do not face flat.


Please explain your comment?


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## ddickey (Apr 19, 2022)

Unworn lathes should face very slightly concave.


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## Aaron_W (Apr 19, 2022)

Winegrower said:


> Seems that if the headstock was out, facing would produce a cone shape.  I imagine a dial indicator swept across the face would show that.



Yeah that makes sense, I was thinking if there was an angle it would show all the way across, but of course if it is significant it will stop cutting past the center.


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## Winegrower (Apr 19, 2022)

ddickey said:


> Unworn lathes should face very slightly concave.


Why would that be?


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## ddickey (Apr 19, 2022)

I believe two reasons. As the lathe wears it will cut less concave eventually flat.
And a slight concave surface is much better than convex in probably every circumstance.


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## mikey (Apr 19, 2022)

The "facing to align" method didn't inspire confidence when I tried it. You're supposed to face up to center and then indicate the face. The face should indicate true/flat on the front side but should show any misalignment error on the backside of center. 

Tony Wells used to push this method. You guys should try it and see if it works for you. I didn't have a good experience with it.


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## Winegrower (Apr 19, 2022)

ddickey said:


> I believe two reasons. As the lathe wears it will cut less concave eventually flat.
> And a slight concave surface is much better than convex in probably every circumstance.


I have to question what wear could possibly change the perpendicularity of the cross slide to the ways axis.

It seems obvious flat would be better in all circumstances instead of convex or concave.   If you wanted convex or concave, set your compound slightly off perpendicular and go for it.


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## Janderso (Apr 20, 2022)

Dabbler said:


> I think before you get to geometry discussions and the like:
> 
> The primary order for any lathe setup is to:
> 
> ...


Dabler,
This is the first time I hVe seen a sequence of operations to set up a lathe.
I’m sure everyone knows this bit of information but I didn’t.
Chasing my tail is what I do best.


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## Janderso (Apr 20, 2022)

Winegrower said:


> Please explain your comment?


Thank you


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## tq60 (Apr 20, 2022)

We never thought much about headstock until we saw the video.

The DUH...factor.

Smaller lathes may oy have 2 feet on headstock end, our Logan is like this.

The SB 14.5 and the 16 x 54 L&S both have 4 adjustable feet at headstock end and it now makes perfect sense.

The bedway is just a stiff flexible chunk of stuff and it can and will move.

So a long rod (long as level) can be placed in the headstock and chuck adjusted so the end of the rod runs true to a dial indicator in the tool post.

A lever now placed here to check.

Place level same orientation on tail stock flat way and compare to headstock.

These 2 measurements need to be same.

When adjusting the twist one needs to be very carefull with headstock to prevent nodding.

We do not do the high precision work over distance so this is a rainy day function.



Sent from my SM-G781V using Tapatalk


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## Winegrower (Apr 20, 2022)

Somewhere, I forget where, I saw an interesting check that seems to hit most of the issues...get a test bar, with your tailstock taper.   Mine is MT3.   Then chuck up and cut a chunk of material, whatever it is, the exact diameter of the headstock end of the test bar.   Now just bring the headstock piece and the tailstock test bar together...pretty easy to see which hand has the chocolate.   Yep, I'm that old.


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## Dabbler (Apr 21, 2022)

One guy invited me over to trouble shoot a MT3 tailstock alignment tool - and the taper was ground at an angle of about .015 per foot.  totally useless junk.  From an offshore place.  

The irony is that you don't need one, just a long indicator arm , or the kit from Starrett with the back indicator.  They come up often enough here, for about 50 bucks with indicator.


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