# Saddle causing .150 taper 3” off chuck no tailstock need help.



## Uguessedit

Have a BT1337g it’s been a great lathe. Recently it’s been gaining an appreciable amount of taper to an astounding .150 thouthandths when I chuck a 5” 6061 1.5” round bar and dial it in to zero concentric. To add further clarification this isn’t a tailstock issue or a bed level issue. Bed is perfectly level front to back and lathe is fastened to the floor. Yes I reverified leveleling and it hasn’t changed in 6 months. The tailstock when used is aligned perfect and I can center a perfect hole in a part however whether I use the tailstock “or not” the part tapers. Majority of the time I don’t use a tailstock it gets in the way for the little parts I make. I’ve been talking to the manufacturer and they believe it’s the lead screw nut and cross slide gibs. I tightened the gibs to the point I could barely crank by hand to attempt ruling out issues and  checked the bed for wear though were talking a 1 year old lathe with a hardened bed. Using a straight edge it is straight across showing now wear. So then I thought perhaps an issue with the gap bed and though I’ve never removed it I did have a fastener come lose recently and saw the manufacturer had short screws where the threads barely caught and the casting let loose so I removed the gap bed and cleaned it all up, paint removed, grease, etc.., cleaned to near new and reassembled with longer screws and the problem still exists. The saddle/carriage feels solid and tight physically when I grasp it but it’s obviously pulling away the closer it gets to the chuck. Spindle bearings are solid and no runout the machine is overall healthy. There is approx .015 play in the lead screw with the saddle locked down. I don’t see how that is going to give me .150 taper. The taper is back to back no matter which lathe chuck I use or how I set up the machine It duplicates itself precisely every time. When I used just the cross slide to cut instead of whole carriage I still got taper but it wasn’t as much. Does this sound like I’ve just worn out the gibs and lead nuts? I’m going to have the parts shipped 2 day air in the morning and see if they help but I’m a little Leary if it is going to fix the issue. If anyone else has ever had this occur that would be great to hear your experience. I do use the cross slide and carriage a lot and the lathe is used every day for the past year since new. It gets a good 2-3 hours a day use. Hopefully I’ve covered all questions you may have. Photos of taper attached. Thanks.


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## pdentrem

If it is not the gib on the back of the saddle, then I have to think more. Have you put a long straight bar in the 4 jaw and used a DI to zero it and then run the DI from end to end? Not spinning the shaft. What is the runout? Run it on the top and then the side where the tool would hit it.


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## jwmay

What’s your intended depth of cut?


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## stupoty

If you try turning something between centers you can check that the head hasn't moved out of line, a part between centers "should" turn with no taper even if your head is out of line.

only mention as you say you get the same using the compond set to zero degrees (sorry if i miss understood that)

Stu


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## Uguessedit

I did some further testing and took the saddle down and saw the lead screw nut has the locking screws on it to remove backlash so I tightened it up and put it back together and locked my turret in place (no swing/etc), and it still tapers. I cut 4 different parts back to back all down to the exact same specs using the power feed for consistency. The 4 parts are all exactly the same identical taper. This is weird. I’m starting to conclude something happened and this lathe is junk. I did have a parr crash a few months back but I’ve used this lathe hundreds of times since. It’s the past couple weeks that it really aggressively changed where parts have become unusable. If the manufacture can’t help figure it out I’m going to ask if they will trade it in at a discount of course. Even if half it’s better to let them rebuild it and deal with it and start new. My only other thought is convert it to Cnc but I don’t really have the time and it’s nice to have a manual lathe around the shop. I do have all the components here, ballscrews and servos and a few PCs I could go ahead and do it. I feel like it’s defeating me.


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## Uguessedit

stupoty said:


> If you try turning something between centers you can check that the head hasn't moved out of line, a part between centers "should" turn with no taper even if your head is out of line.
> 
> only mention as you say you get the same using the compond set to zero degrees (sorry if i miss understood that)
> 
> Stu


It tapers no matter what. If I push all my body weight into the carriage while it’s power feeding I can almost eliminate the taper. If I push on the saddle or turret it does nothing. It’s a carriage issue and the bed is straight and not worn. The next thing is probably pull the carriage maybe where it rides on the bed has worn. That’s gotta be the issue I’ve tried everything else.


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## francist

Looking at your first two pictures where you are measuring the bar, I see a difference of 0.0145", not 0.145". Or am I reading your calipers wrong?
Agreed still a taper, but an order of magnitude less.

-frank


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## Uguessedit

Here is a link to a YT video I made that best explains the issue. 






It is a private video and requires use of the link out of respect for the manufacturer until the issue is resolved. Any issues let me know.


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## Uguessedit

francist said:


> Looking at your first two pictures where you are measuring the bar, I see a difference of 0.0145", not 0.145". Or am I reading your calipers wrong?
> Agreed still a taper, but an order of magnitude less.
> 
> -frank



I’m sorry you’re correct I’ve been running on a couple hours sleep. Frankly I’m a bit burnt out at the moment between work and trying to alleviate this issue. I did upload a video here that clearly shows the issue occurring. It also doesn’t help I’m a metric guy and I know everyone here is probably standard units. I would normally resort to .41mm ;-)


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## JimDawson

That almost looks like the head is out of line with the bed, rotated a bit clockwise looking down on it.  Not sure how that could happen, if it was going to move I would expect it to go in the other direction.

You need to put a bar in the chuck and run a dial indicator down it as @pdentrem said above.


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## pdentrem

Now that you mentioned a crash I believe the headstock has shifted. The test I mentioned earlier will prove it.
Pierre


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## NortonDommi

Back to basics with Rollie's Dad's method


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## stupoty

pdentrem said:


> Now that you mentioned a crash I believe the headstock has shifted. The test I mentioned earlier will prove it.
> Pierre


Thats why i sujested turn between centes as a  test as i dident know if OP had a test bar for mesuring it.

Stu


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## jwmay

It’s an interesting problem. I’d suggest getting some sleep, and coming back with fresh eyes.


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## markba633csi

Does it cut taper when hand feeding also? Seems like it must be a shifted headstock, I would check for that
Mark


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## pacifica

I've had a shifted headstock and it cut a .005" taper over 10 ". It takes about an hour or two  of adjusting(by very small amounts) and then taper goes away.
After adjusting I'm at .0001" taper per 10".


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## Latinrascalrg1

stupoty said:


> a part between centers "should" turn with no taper even if your head is out of line.



That is Not correct.....If either the headstock or tail stock or both are "Out of Line" with each other it will turn a taper, Unless (and this is a HUGE "UNLESS")  Both the head AND tail stock somehow happen to be "off center" the exact same distance making the barstock parallel to the carriage travel which is Not Likely to happen.


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## stupoty

Latinrascalrg1 said:


> That is Not correct.....If either the headstock or tail stock or both are "Out of Line" with each other it will turn a taper, Unless (and this is a HUGE "UNLESS")  Both the head AND tail stock somehow happen to be "off center" the exact same distance making the barstock parallel to the carriage travel which is Not Likely to happen.



Yeah I see what your saying but a center in the head stock and slightly tweaked, lined up with a tail stock center aligned to the head stock center (OP said tail stock was dead nuts to center) will exhibit much less taper than an out of line head with a chuck holding a part in a fixed axis. 

I don't see how you would have the tail stock not lined up with the head stock if you set it up to match your head end?  You would generally dial in the tail stock to align to the head I would have thought.

Might be just the way I align my tail stock, I check their point to point when turning between centers and adjust the tail stock to remove taper. If you could do that it would show the saddle was tracking repeatably parallel and not some sort of gib issue.

But yeah caveats apply mileage may vary.

And I probably worded it badly.

Stu


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## Latinrascalrg1

stupoty said:


> I don't see how you would have the tail stock not lined up with the head stock if you set it up to match your head end?  You would generally dial in the tail stock to align to the head I would have thought.



Yes I agree and would think unless the person was new to the trade and uninformed that they would dial in their machines if possible.  However, from what ive learned thus far,  depending on how one goes about this Alignment process the tail stock may or may not align perfectly with the headstock over then entire bed length based on the conditions of the mating surfaces and how true they are on each machine.  Normally most of the wear is close to the headstock so if you placed the tailstock in the well worn area of the bed to dial it in with the headstock then there would be a very very good possibility for it to be off in areas that are not as worn or vise-versa.

Now i may be WAY OFF here but right or wrong this is what ive learned on the subject but that don't mean I'm not willing to learn something  new about it so please correct me if I'm wrong.


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## stupoty

Latinrascalrg1 said:


> Yes I agree and would think unless the person was new to the trade and uninformed that they would dial in their machines if possible.  However, from what ive learned thus far,  depending on how one goes about this Alignment process the tail stock may or may not align perfectly with the headstock over then entire bed length based on the conditions of the mating surfaces and how true they are on each machine.  Normally most of the wear is close to the headstock so if you placed the tailstock in the well worn area of the bed to dial it in with the headstock then there would be a very very good possibility for it to be off in areas that are not as worn or vise-versa.
> 
> Now i may be WAY OFF here but right or wrong this is what ive learned on the subject but that don't mean I'm not willing to learn something  new about it so please correct me if I'm wrong.



Yeah I see that bed will cause some issues with this, I do "point to point" my centers for alignment but my sadle and tail stock travel on two different sets of ways so I guess thats another source of inaccuracy. The sadle ways are somewhat warn near my head stock and the tail stock ways are fairly immaculate all over (apart from where a previous owner ground an extra bit of swing for something that didn't fit).

You could use this factor to find the most worn area of your ways like this I guess.

I'm getting the thread off topic , sorry about that. 


Either way It to me looks like a head miss alignment issue rather than a saddle issue especialy as the same result happens with the compond slide set to zero degree's, definitely worth a check. 

As others have said i'f you have some known strait stock or test bar you could mount it in the chuck, maybe use the tail stock to move an indicator , this would rule out a saddle issue.   OP has prism ways so it should be stable enough to slide the tail stock with it lose and still be quite stable with regard to position.

Running a test indicator up and down a test bar using the saddle, wont be very helpful if the saddle is suspected as the root of the issue perhaps ?

Stu


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## jwmay

Any progress here?  

Not sure if this is helpful at all, but my machine sits on crappy basement concrete, and it moves all the time, according to the weather and precipitation.  Could that be a contributing factor in your case?  

I don't know much, but this shifted head stock thing seems like the most remote of possibilities in my uneducated and inexperienced mind.  But something is definitely very solidly misplaced...otherwise where would the repeatability come from?  Imagine a chip embedded in the rear way.  As the saddle moved across it, if the chip stayed put, the saddle would cant less and less as more of the saddle had moved past it.  Or imagine the path of a flat plate with one dowel underneath it.  The leading edge would climb for a certain distance, and then fall for a certain distance.  Each time you rolled the plate, it would travel along the same line...Like a teeter totter with a moving hinge point.  Anyways, I obviously don't know the answer, but maybe this little imagination exercise would be useful. HA!


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## stupoty

jwmay said:


> Any progress here?
> 
> Not sure if this is helpful at all, but my machine sits on crappy basement concrete, and it moves all the time, according to the weather and precipitation.  Could that be a contributing factor in your case?
> 
> I don't know much, but this shifted head stock thing seems like the most remote of possibilities in my uneducated and inexperienced mind.  But something is definitely very solidly misplaced...otherwise where would the repeatability come from?  Imagine a chip embedded in the rear way.  As the saddle moved across it, if the chip stayed put, the saddle would cant less and less as more of the saddle had moved past it.  Or imagine the path of a flat plate with one dowel underneath it.  The leading edge would climb for a certain distance, and then fall for a certain distance.  Each time you rolled the plate, it would travel along the same line...Like a teeter totter with a moving hinge point.  Anyways, I obviously don't know the answer, but maybe this little imagination exercise would be useful. HA!



Is your lathe sitting on leveling feet , free standing or bolted down?

If its bolted down this could cause a twist in the bed which may be causing the taper, if it is free standing it may have twisted a little to allow all feet to make contact with floor. If leveling feet then check level with a reasonably acurate level.

Stu


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## stupoty

jwmay said:


> Any progress here?



I was on my phone when I replyed , sorry I thought you were the OP. my bad  





Uguessedit said:


> Bed is perfectly level front to back and lathe is fastened to the floor. Yes I reverified leveleling and it hasn’t changed in 6 months.



I just re read the thread to see if I missed something, you say the lath is bolted down to the floor and level, you could try loosening the hold down bolts and giving it a try.

Also perhaps the pre load on the spindle bearings has changed due to wear etc. this might be making the whole spindle cock a bit when you start cutting, although it does look rock solid on your video from what I see.  

I did the angle math and I came up with about 2 degree taper.  Thats quite a lot.


Stu


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## stupoty

Also I had a look at the manual and the head sits on a flat surface not the ways so their is nothing to lock it in line and could perhaps shift with a heavy force.





__





						Bolton Tools BT1337G Operator's Manual (Page 24 of 49) | ManualsLib
					






					www.manualslib.com
				




Stu


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## Uguessedit

Follow up: Well I’m still contending with the issue. The manufacturer has been very slow to return calls and today I finally was able to put a parts request in although I have to wait to get a quote back in a few days it’s a painstakingly sloooowww process. In the interim I removed the compound slide and installed a machined piece of 4140 that has removed .22mm or .0085 so it has lessened the taper by 50%. Rather than two sheets of paper thick of taper it’s now one. It’s still too much for some parts I need to make that slide together. The next thing to do is to replace the y axis lead screw and nut. If that doesn’t fix it then a new carriage top. If that doesn’t work then I will call a local repair shop to come out and see what they can do. I suppose the lead nut could be moving that much under load it’s really hard to tell I cannot get anything to indicate that tells me I’m having an issue. I did cut a piece of tool steel and a piece of 6061 and both tapered identically so that was a good sign I suppose that it’s not affected by material and it’s a mechanical issue. After all this I think it’s time to upgrade to a 16” lathe if after a year of use we are wearing these parts out this fast. I would hope to get 3-5 years before replacing mechanical components.


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## Cadillac

Reading through all this the one thing I haven’t heard mentioned is the saddle adjustment on the flat way of the bed. What could be happening is the saddle is lifting at the start of the cut and settling in getting closer to the chuck. One test you can do is put a mag base on the ways or casting and have it read the saddle then the topslide. Pushing down and pulling to see and verify if any play from saddle to ways. You can do the same with the compound. Have you checked for play in the spindle bearings? Pry bar, blocks of wood and a gauge try moving chuck up/down and side play.
I wouldn’t think your leadscrew have anything to do with it unless it’s slipping in the nut which you would see the handle moving. Finding the slop with a gauge will lead you in the direction.


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## Bob Korves

The obvious likely problem is that the head is not aligned with the bed.  I did not see in the posts above any reference to testing properly for spindle not in line with bed.  Start there.  It is even possible that the bolts that hold the head stock to the bed were never finish tightened after alignment at the factory, or perhaps that alignment was never done.


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## Technical Ted

This is out of your owner's manual. Check B below. Sounds like the issue to me.

===================================================================
*10.5 Making small taper when external turning*
A) It is not on the same line between the spindle center and tailstock center. Please adjust
the tailstock according to operation manual instructions.
B) The moving line of carriage does not parallel to the spindle center. Please loosen the
lock screw of headstock and adjust the spindle center to required position and lock.
======================================================================

Good luck,
Ted


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## Cadillac

I’d make sure the lathe is dead level so your not compounding the error. Step 1 is level bed then you can check spindle alignment.


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## stupoty

Uguessedit said:


> if after a year of use we are wearing these parts out this fast. I would hope to get 3-5 years before replacing mechanical components.



Has the lathe had very hevy use ?  As cadillac pointed out vertical movement can also cause a taper to occur, this might be caused by ware on the ways, but from the amount of taper you are describing the ware would need to me massive.




Uguessedit said:


> The next thing to do is to replace the y axis lead screw and nut.


This is so unlikely to be the reason you are having taper issues as is any backlash.  You already said it happens when using the compound slide set at 0 degrees.

You could turn the part using manual feed on the hand wheel and see if the same thing happens if you wish to prove it to yourself.

The one thing we do know is that your taper seems to be repeatable.  A lose/wobbly item is unlikely to give such repeatable errors.

You have vertical element to your ways on the back side of the lath, you could put a dial indicator on the saddle and run up and down the back side of the ways to see if the caridge is moving relative to it.


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## Cadillac

Put a indicator on the flat way of the saddle. Have to point riding the flat way while taking a cut and see if there’s movement in the cut. You shouldn’t get more than acouple TENTHS of movement on any sliding surface if not NO movement. Good luck


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## RJSakowski

Uguessedit said:


> Follow up: Well I’m still contending with the issue. The manufacturer has been very slow to return calls and today I finally was able to put a parts request in although I have to wait to get a quote back in a few days it’s a painstakingly sloooowww process. In the interim I removed the compound slide and installed a machined piece of 4140 that has removed .22mm or .0085 so it has lessened the taper by 50%. Rather than two sheets of paper thick of taper it’s now one. It’s still too much for some parts I need to make that slide together. The next thing to do is to replace the y axis lead screw and nut. If that doesn’t fix it then a new carriage top. If that doesn’t work then I will call a local repair shop to come out and see what they can do. I suppose the lead nut could be moving that much under load it’s really hard to tell I cannot get anything to indicate that tells me I’m having an issue. I did cut a piece of tool steel and a piece of 6061 and both tapered identically so that was a good sign I suppose that it’s not affected by material and it’s a mechanical issue. After all this I think it’s time to upgrade to a 16” lathe if after a year of use we are wearing these parts out this fast. I would hope to get 3-5 years before replacing mechanical components.



Turning a taper should not be affected by the cross feed lead screw or nut.  Nor should  the tailstock be the cause if not using the tailstock center.

Turned parts will tend to have a slightly larger diameter at the tailstock end, the amount dependent upon tooling geometry, condition of the cutting edge, the depth of cut, the material, and the diameter of the stock.  Since the tailstock end is smaller in diameter, this isn't the cause of your prob;lem

Aside from that, there are only two conditions which will cause a turned taper.  The headstock is misaligned or the lathe bed is twisted.  The effect of headstock misalignment is fairly obvious. Rotating the headstock in a horizontal plane will bring the part closer or further from the cutting tool as the carriage moves away from the headstock, depending which way it is rotated.  Some lathes like the Sherline actually rotate the headstock to purposely cut tapers.

 The carriage rides on the vee way at the front, being prevented from lifting by small plates at the front and back of the carriage that ride on the under side of the ways.  The vee way determines the distance of the cutting tool to the spindle centerline.  If the bed is twisted, if corkscrews which will raise the front edge of the carriage and drop the back edge or vice versa.  Since the cutting edge is several inches above the pivot point, the effect is to move the cutting edge closer to the spindle axis.  The effect increases as you move away from the headstock causing a taper to be cut.

There is also a slight shift in vertical position of the cutting tool which moves the cutting edge up or down  depending upon the direction of twist.  This effect is usually minor compared to the lateral movement although it will increase if the cutting edge is significantly lower or higher than the horizontal plane though the spindle axis.

By the same token, if the headstock were rotated in a vertical plane it would have a similar effect, raising or lowering the toll relative to the spindle axis as you moved away from the headstock.This would be extremely unlikely unless the headstock was removed from the ;lathe or there had been a severe crash.

Considering that the lathe had been performing satisfactorily in the past and  that you have not seen any serious change in level and the amount of taper that you are experiencing, I would suspect the headstock has shifted.  It is possible that the mounting bolts were not tightened sufficiently and a crash could have caused a shift.  In any event, I would check that first.  I would position the carriage close to the headstock and lock it in place.  I would mount a faceplate with a small boss about half the cross feed travel distance from the centerline.  Mount an indicator on the crossfeed and rotate the faceplate so the boss is at the front and more or less horizontal with the spindle axis.  Zero the indicator on the boss and mark the contact point with a Sharpie.  Rotate the boss to the rear and move the indicator with the cross feed to intersect the mark on the boss.  A difference on readings would mean that the headstock is not perpendicular to the cross feed travel and, by inference not parallel with the ways.

There are some caveats.  The assumption is that the carriage cross feed travel is perpendicular to the carriage ways  The second is that any degree of twist is not affecting the measurement.  This is probably a safe assumption since the effect of the twist is least with the carriage near the head stock. 

Here is my faceplate modified for this measurement.  The boss is a bolt with the head slightly domed and polished.


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## bretthl

Just a suggestion ... mic the work piece at 1/2" intervals and plot the diameter vs distance.  If it is a straight line trend then it may be, as others have suggested, a head stock alignment problem.  If there is a shift in the trend (not a straight line) then perhaps the problem is in the carriage or ways.


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## stupoty

Hay , hows it all working out for you at the moment?  Have you managed to nail down your issue yet?

Stu


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## pacifica

I think I would do this first: 



. Along with the face plate test by rjsakowski, check runout in spindle bore, level lathe,turn a test piece of 1.5 to 2" steel that is 10" long(no tailstock) and go from there(align headstock?).


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## petertha

Misaligned headstock & related taper cutting problem has been discussed quite a bit. I know I have posted & included these same pics just cant find the link(s) right now. There is a very fast & accurate way to verify.
First - do your lathe levelling due diligence
Second - buy a MT3/cylindrical test bar like this inexpensive ($50) import I bought on Ebay. They are cylindrical ground & plenty accurate. If you have an MT socket like MT5/MT3, plug that in the spindle, then the test bar so it is extending cantilever. No chuck is involved. No tailstock is involved. No material cutting is involved. Mount DTI to saddle, run down the test bar along the horizontal plane. What do you read? If its pointing in or out (anything but zero) you will be cutting a taper longitudinally and a cone in cross feed. Its as simple as that. You need to correct this by loosening your HS bolts & carefully adjust the shimming/jacking bolts so the HS rotates in so the bar is parallel to bed axis. The screws are uber sensitive so just crack them & re-measure.

While you are at it, repeat test with DTI along the top of the bar. Is it pointing up or down? Trickier to solve but same basic problem.

Only when this is remedied can you introduce the tailstock into the picture.


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## petertha

ps - I notice several of the same vendors also offer MT5 ended cylindrical test bars if you want to go that route if your spindle is MT5. This eliminates the MT5-MT3 intermediate sleeve, but I would assume they are pretty ground accurate too. My tailstock is MT3 so it can serve double duty there. Basically its acting as a big long lever exaggerating any angular deviation.

For example (no affiliation)
https://www.ebay.ca/str/atoztoolstore/Lathe-Test-Bars/_i.html?_storecat=18372947012


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## stupoty

petertha said:


> ps - I notice several of the same vendors also offer MT5 ended cylindrical test bars if you want to go that route if your spindle is MT5. This eliminates the MT5-MT3 intermediate sleeve, but I would assume they are pretty ground accurate too. My tailstock is MT3 so it can serve double duty there. Basically its acting as a big long lever exaggerating any angular deviation.
> 
> For example (no affiliation)
> https://www.ebay.ca/str/atoztoolstore/Lathe-Test-Bars/_i.html?_storecat=18372947012



I'm really tempted by a test bar, I was thinking of getting it in MT3 and have a sleeve so I can put it in the MT4 head stock and my tail stock.

I wonder how much difference their is between sleeve brands for run out ?

Stu


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## Rex Walters

stupoty said:


> I'm really tempted by a test bar, I was thinking of getting it in MT3 and have a sleeve so I can put it in the MT4 head stock and my tail stock.



If I could only afford one, I'd buy the larger test bar for the headstock. A sleeve is probably accurate enough but will more than double potential errors (two mating surfaces for grit/burrs/whatever to cause you to pull out your hair).

The tailstock is far less critical IMHO. Drills and reamers will tend to follow their own path anyway (you'll need to use a boring bar regardless for accurate holes) and the tailstock is adjustable for cutting/not-cutting tapers when turning between centers. The spindle taper you want dead nuts aligned to the bed ways in both dimensions (horizontal and vertical, maybe ever so slightly pointing higher toward the tailstock — a few tenths over 12" at most).

A taper test bar isn't a mandatory tool unless you have reason to distrust the accuracy of your lathe (or are planning to rebuild it). It's kind of a one time use tool. (But I own both!).


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## petertha

Rex Walters said:


> The tailstock is far less critical IMHO. Drills and reamers will tend to follow their own path anyway



That's the beauty of being able to plug same MT# test bar into either head or tail stock. You can similarly check TS alignment by mounting a DTI in the lathe chuck & turn it around the OD. Yes, you can also do this with a regular dead center, but what the longer bar is providing is extended cantilever length so its going to exaggerate the angular discrepancy: up/down/left/right. Yes big drills & reamers might find their own drilling holes & such but its still better to have the TS aligned. Turning between centers depends on this. No sense having a 0.0002" live center when teh TS is in or out 0.002". Another example, after breaking 2 teeny carbide center drills in tool steel it finally dawned on me to check the TS, sure enough it had migrated off a couple thou. Actually that's not quite true. What I learned is that just tightening the TS down against the displacement grub screws while adjusting can drift it (on my particular lathe). So now I leave an indicator ball on the bar as I'm setting it up & just tweak it down while the needle is giving me constant reference.

Yes it probably goes without saying you have to clean any mating surfaces, particularly between rotating parts. Setting up the machine is the one time you should be extra diligent unless you want to repeat this whole process. HS alignment is a PITA. Maybe I got lucky but before committing to the MT3 test bar I put a tenths indicator on the MT5 ID taper of the spindle, measured nil runout. Inserted the MT5-MT3 socket adapter, exact same thing. Pulled & clocked it a few different ways, same thing. So I trust it.


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## stupoty

Rex Walters said:


> If I could only afford one, I'd buy the larger test bar for the headstock. A sleeve is probably accurate enough but will more than double potential errors (two mating surfaces for grit/burrs/whatever to cause you to pull out your hair).
> 
> The tailstock is far less critical IMHO. Drills and reamers will tend to follow their own path anyway (you'll need to use a boring bar regardless for accurate holes) and the tailstock is adjustable for cutting/not-cutting tapers when turning between centers. The spindle taper you want dead nuts aligned to the bed ways in both dimensions (horizontal and vertical, maybe ever so slightly pointing higher toward the tailstock — a few tenths over 12" at most).
> 
> A taper test bar isn't a mandatory tool unless you have reason to distrust the accuracy of your lathe (or are planning to rebuild it). It's kind of a one time use tool. (But I own both!).



Yeah , I think you are right about the sleeves, I have had my head stock off before but it does sit on the ways for alignment so I might just use the button on  the face plate method fof double checking it and call it good.

Although a shiny test bar ? who could resist that ? I will just keep my eyes peeled on ebay unless I find plenty of spare cash in my pockets for some reason 

(although the power hack saw motor rewind is priority for cash injection currently)

Stu


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## Rex Walters

petertha said:


> You can similarly check TS alignment by mounting a DTI in the lathe chuck & turn it around the OD.



I might be misreading, but whatever you do, do not rotate a test indicator around the horizontal axis such that you perform some readings with that dial facing up and some with it down. Gravity absolutely will affect your indicator reading significantly.

It’s a common mistake but easily proven to be terribly imprecise - Richard King demonstrates this effect at the beginning of all of his classes:






I also still prefer dedicated test bars for headstock/tailstock rather than a single bar and an adapter sleeve. But your process sounds great if you only have one for the tailstock.


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## petertha

Good point, I should have clarified I'm measuring tailstock in/out relative to operator which is the typical jackscrew offset adjustment relative to bed axis. So I assume the DTI would be seeing the same gravity forces in those 2 orientations where the face is vertical but pointing either towards or away from operator on either side of test bar centerline. But maybe that cant be trusted either? I'm going to repeat that Richard King test at home. I've read about it but never seen it demo'd live like that. Very interesting.

Actually, full disclosure, I have one of those Edge test bars that I use for TS adjustment. I bought it subsequent to the MT test bar. What can I say, I'm a tool junky LOL. The DTI stays in same position from heatstock ring to tailstock ring so the DTI sag issue isn't there. You can also DTI off the top of the HS ring & then compare to TS ring. My TS is about 0.001" high which I'm told is normal.


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## darkzero

stupoty said:


> Although a shiny test bar ? who could resist that ? I will just keep my eyes peeled on ebay unless I find plenty of spare cash in my pockets for some reason



Those things are pretty cheap on ebay. MT3 bar is like $33 shipped all the way from India. I paid like $60 shipped for my MT5 bar. Been sitting in the tool box for years though but at least it's there.


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## john.k

I d be checking that the saddle wasnt fouling some part of the bed ,or gap,and forcing the ways apart as it moves forward..................I checked a similar happening  once,and the problem was the small piece of rack attached to the gap was oversize.


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## petertha

Rex Walters said:


> ... whatever you do, do not rotate a test indicator around the horizontal axis such that you perform some readings with that dial facing up and some with it down. Gravity absolutely will affect your indicator reading significantly. It’s a common mistake but easily proven to be terribly imprecise - Richard King demonstrates this effect at the beginning of all of his classes:



Well I finally had to try this for myself. I have 2 new-ish Mitutoyo DTI's. One is 0.0005" the other 0.0001". When I hold them by the body or by the dovetail mounted boss adapter & rotate in by hand, the dial goes nowhere in any rotation. It sits in the exact zero position. Do you think this is a fair comparison to Richards demo or should the needle be loaded? 

Seems to me I tested this once upon a time too clocking around an accurate dead center with DTI in chuck & needle on OD. Pulled out the dead center rotate 1/4 turn, rinse & repeat. Same setting looking at the underside measurement with a mirror. I just don't recall the needle moving under gravity but I wasn't really looking for the effect either.

I haven't yet mounted it to a mag holder & plate yet like video, that will be next. But now isn't that introducing potential drift of the indicator holder arms & assembly into the equation vs the DTI in isolation? Sorry if this is off topic. I know this has come up before, just cant find the link.


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## Rex Walters

petertha said:


> Do you think this is a fair comparison to Richards demo or should the needle be loaded?



I’m don’t know what percentage of the gravity effects are with the indicator itself vs the holder arm assembly. I even asked this very question during the class this week. 

I wouldn’t be at all surprised if it isn’t almost entirely with the holding assembly. But since you always need some sort of holder assembly regardless, and there are many better ways to indicate the tailstock in, I’d still avoid rotating an indicator.

Richard said Stefan G. did some testing of this sort with various indicator holders to see which were most rigid with this type of testing, and that (quality) old-school rod and flexture clamp type holders were way more rigid than flexible mounts of any type.


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## stupoty

Rex Walters said:


> I’m don’t know what percentage of the gravity effects are with the indicator itself vs the holder arm assembly. I even asked this very question during the class this week.
> 
> I wouldn’t be at all surprised if it isn’t almost entirely with the holding assembly. But since you always need some sort of holder assembly regardless, and there are many better ways to indicate the tailstock in, I’d still avoid rotating an indicator.
> 
> Richard said Stefan G. did some testing of this sort with various indicator holders to see which were most rigid with this type of testing, and that (quality) old-school rod and flexture clamp type holders were way more rigid than flexible mounts of any type.



I was surprised the Noga flexed that much over the relatively short distance, next time I am at a loss I will try this with my rod and clamp type holders and see how flexy they are.

Stu


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## john.k

I have found that a lever type gauge solidly mounted on a square bar ,held in a 4 jaw ,has negligable gravity effect,and can be ignored,.........however a dial gauge mounted on two angled rods to a magnetic  base attached to the chuck face will have several thou gravity effect............and in one case ,an owner decided his tailstock was 005 high!.......,and had the base surface ground,on the evidence of a dial gauge.


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## jwmay

It’s been one month since Uguessedit has replied to this thread. We’ve since gone down quite the rabbit hole with him absent. I wonder what’s happening with the machine in question.


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## petertha

I’ll upload some pics from my camera, but here are my findings. New & tight Noga mini DTI mag base. I chose it for test#1 because its the smallest one I have. Mitutoya 0.0001” DTI. Installed on a 3x5 chunk of steel.  About 2 thou preload & needle zeroed sitting upright. Rotate the steel base 90-deg I get about 0.0002” deflection. Rotate it 180-deg so completely inverted, get about 0.0010-0.0012” needle deflection. So it’s real. My guess is a longer arm mag stand and/or a heavier Dial Indicator vs DTI may well exaggerate these findings. My gut feel is 99% of this is ‘gravity effect’ is attributable to the indicator holder assembly itself because when I grip the DTI by the short stub arbor that comes with the kit in a lathe collet & spin around a dowel pin I get no measurable difference. So that has eliminated pre-load & inversion on exact same DTI. The only remaining variable is the holder assembly. Maybe if you absolutely have to go inverted then consider a bolt-together holder vs the hydraulic or tension lock style. I'll try my longer Noga next.


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## petertha

I know this is detracting from the thread, but I'll post my pics & re-post elsewhere under something like Gravity vs indicator holder.
Noga Mini + Mitutoyo 0.0001: Level = 0.0000, 90-deg = 0.0005 - 0.0008", 180-deg (inverted) = .0011
Noga 14"? + Mitutoyo 0.001: Level = 0.000", 90-deg = .0042", 180-deg = .0055" (suspect a smidge more because it didn't return to zero & there might be some flex in my bar).

Conclusions
- I think the DTI by itself might not see much gravity effect, but the contribution of the DTI holder assembly sure can.  
- if you have to use a holder, best to find something significantly more rigid. Or else find some independent way to DTI reference in an angled/inverted position. Reading DTI values at different rotation clock positions is a no-no.
- assembly weight is the enemy here. I suspect a dial indicator would be worse because it weighs more than DTI


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## bretthl

petertha said:


> I know this is detracting from the thread, but I'll post my pics & re-post elsewhere under something like Gravity vs indicator holder.
> Noga Mini + Mitutoyo 0.0001: Level = 0.0000, 90-deg = 0.0005 - 0.0008", 180-deg (inverted) = .0011
> Noga 14"? + Mitutoyo 0.001: Level = 0.000", 90-deg = .0042", 180-deg = .0055" (suspect a smidge more because it didn't return to zero & there might be some flex in my bar).
> 
> Conclusions
> - I think the DTI by itself might not see much gravity effect, but the contribution of the DTI holder assembly sure can.
> - if you have to use a holder, best to find something significantly more rigid. Or else find some independent way to DTI reference in an angled/inverted position. Reading DTI values at different rotation clock positions is a no-no.
> - assembly weight is the enemy here. I suspect a dial indicator would be worse because it weighs more than DTI



I’m confused.  I thought a dial test indicator is used to take a relative measurement. So unless there is flex in the arm caused by the spring tension from the indicator itself then things should be okay.


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## petertha

Yes, that's the whole issue. Flex in the apparatus that is holding the indicator, not so much an issue with the indicator itself. Think of it this way - if you press your finger on the articulated arm, the indicator registers displacement. Well gravity is like your finger, its a force acting on the mass of the arm assembly. Its moving under its own weight vs. the assumption that it stays locked in position. So the indicator cannot distinguish this displacement from something that is out of round.


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## plunger

Ive bought a lathe like this. It also had a bad taper that I could not get rid of .I had it reground by a very dubios character.He said it would take six weeks but I had to physically remove it six months later.He took a six meter lathe and because his grinder wasnt long enough he ground it from both sides and blended it in. But thats another story.
The remark about the gap should be looked at. I would try a three jaw chuck in a 4 jaw to push it away as far as possible from the headstock and try taking two cuts from the tailstock and headstock side and then compare.
Just out of interest when I removed the headstock I was shocked to find there are no vees under the headstock. But what shocked me about it is that instead of being scraped in you could clearly see that they had used an angle grinder . There were actually big gouges taken out.


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## Illinoyance

Many lathes have jack screws that are used to align the headstock to the bed.  See if your lathe has them.
Before checking for, and correcting taper issues be certain the bed is not twisted.  Check it with a precision level.

Use a test bar as shown in the video.  Relieve the middle of the bar leaving a collar about 1/2" wide at the outboard end and next to the chuck.  Take a light test cut across both collars (without disturbing the cross slide) .  Measure them.  If there is a difference, use the jack screws to bring the headstock in line with the bed.  It will take several attempts.  Adjust, make a trial cut, measure, repeat until both collars are the same diameter after a test cut.

After you have the headstock true to the bed it is time to address the tailstock alignment.  Make a test bar with a center in each end and a raised collar at each end.  At the headstock end leave room beyond the collar for a lathe dog.  Set up the test bar between centers and drive it with a dog.  Make a test cut across both collars (without disturbing the cross slide).  Measure the collars.  Adjust the tailstock until a test cut produces equal diameters on the collars.  Save the test bar.  In the future you can set the test bar between centers then set an indicator to zero on the collar nearest the headstock, them move the carriage and see if the indicator reads zero at the tailstock end.  If it does your tailstock is dead on.  If not adjust the tailstock to get the indicator to zero.  You might have to repeat that check a couple time to get both collars to read zero.

The sequence of tests and adjustments is critical.
1. correct twist in the bed, commonly refereed to as leveling the bed.
2. adjust the headstock so the spindle is parallel with the bed.  A bar held in the chuck should show no taper when turned.
3. Adjust the tailstock using the two collar method.

The tool used to make test cuts should be HSS and very sharp.  Test cuts should only be a few thou depth of cut.  Heavy cuts or carbide inserts will deflect the test bar making it difficult to achieve good results.

I am now in the process of aligning the headstock on my Nardini.  I had about .020" taper in 6".  It is a time consuming job.


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## bretthl

plunger said:


> Just out of interest when I removed the headstock I was shocked to find there are no vees under the headstock. But what shocked me about it is that instead of being scraped in you could clearly see that they had used an angle grinder . There were actually big gouges taken out.



I don't think any Asian made lathes have head stocks that rest on way vees.


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## Illinoyance

The quality of Asian tools can vary all over the map.  A lot of it has to do with the quality control the importer has in place.  I suspect many importers care very little about the quality of machines they sell.


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## bretthl

petertha said:


> Yes, that's the whole issue. Flex in the apparatus that is holding the indicator, not so much an issue with the indicator itself. Think of it this way - if you press your finger on the articulated arm, the indicator registers displacement. Well gravity is like your finger, its a force acting on the mass of the arm assembly. Its moving under its own weight vs. the assumption that it stays locked in position. So the indicator cannot distinguish this displacement from something that is out of round.



If you don't move the indicator base/arm the gravity acting on the arm should not change.


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## Al 1

Check to see if head stock bolts are loose.  Al.


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## Illinoyance

Put a magnetic backed indicator against the QCTP and quit worrying about deflection.

BTW, after several hours of adjusting and testing I have my Nardini cutting zero taper over 6" length.
Next, I make a test bar to run between centers and get my tailstock centered.


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## john.k

Using an angle grinder to fit lathe heads ,and mill parts is quite standard practice on the budget &hobby chinese machines.......but you would expect after a million machine fits ,the assemblers would develop a certain skill set.


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## stupoty

Hi soooo I was checking out my headstock the other day and realised I have a bit of a taper issue also, I have to dismantle part of the power feed to get at the left hand attachment clamp for my head stock and was amazed to find it lose when I did get to it.

I have this new shinny thing direct from India that I am hopeing will help to adjust it all 







Nice , (I havnt checked its acuracy yet but from first impressions  )

Stu


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## Illinoyance

I a m not a fan of test bars.  If the headstock taper doesn't run perfectly true and the test bar isn't perfectly true the results of the test setup are meaningless.   I prefer to chuck up a piece of bar or pipe and do the two-collar test.


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## stupoty

Illinoyance said:


> I a m not a fan of test bars.  If the headstock taper doesn't run perfectly true and the test bar isn't perfectly true the results of the test setup are meaningless.   I prefer to chuck up a piece of bar or pipe and do the two-collar test.



Yeah I was doing test cuts to align but the need to re assemble the power drive between adjustments was making it very very slow going 

it's old american iron, the tapers fairly good 

Stu


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## Cadillac

stupoty said:


> Hi soooo I was checking out my headstock the other day and realised I have a bit of a taper issue also, I have to dismantle part of the power feed to get at the left hand attachment clamp for my head stock and was amazed to find it lose when I did get to it.
> 
> I have this new shinny thing direct from India that I am hopeing will help to adjust it all
> 
> View attachment 294721
> 
> 
> Nice , (I havnt checked its acuracy yet but from first impressions  )
> 
> Stu




I have that same box must be the same distributor. Mine was accurate. I find useful on many machines worth the 50 bucks in my book. Always good to have multiple ways to verify readings too.


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## john.k

At least its easy enough to see if the test bar is running true,and maybe even correct any runout.....Even if it doesnt run true,you can still split the difference to get a baseline ,before the trouble of a test cut.This assumes its straight and of constant diameter.


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## stupoty

Cadillac said:


> I have that same box must be the same distributor. Mine was accurate. I find useful on many machines worth the 50 bucks in my book. Always good to have multiple ways to verify readings too.



It seems fairly good, I have done some examination of it in vee blocks and their was perhaps some lack of conectricity with the taper and the strait part but it could also be a small wabble on my test set up , the strait part seems very strait, I used it on the centers to set up my tail stock to make a aluminium MT4 lap, because it turns out when you have a foot of metal projecting out of the spindle that tiny burr makes a bit of a difference 

Do you think the OP will ever come back ? 
Can we turn this into a test of how far of topic a thread can go 

I think theirs a real opportunity to now turn the thread into a thread on lapping 

Stu


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## jwmay

I saw he’s posted a few days back on a couple different threads. But he never did update this one.


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## qualitymachinetools

Hey check this out, some have already mentioned this, but in case anyone needs a visual, look starting on page 31:  http://www.precisionmatthews.com/wp-content/uploads/2017/02/PM-1340GT-PM-1236T-11-10-17-V5.pdf
If this machine mentioned is like one of ours, these headstocks are bolted down to the bed on a flat plate, not fit to the ways. They will have some sort of adjustment screws, usually up behind the motor.  And if the machine was crashed, it can definitely move this, causing that problem. Sure they are not quite as rigid as the older type like the big american lathes that had the headstock fit to the V Ways, but they are also better because they can be dialed in. I am certain thats your problem, this should get you back up and cutting straight in a few hours.

Edit: I see this thread is older, didnt look at the first dates, but hopefully you are up and running, if not, or if anyone else comes across this, that should help out.


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## john.k

This is a common problem,and hundreds will look at these posts in the future as reference material........so the OP is immaterial ,many others will benefit.


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