# How To Measure The Diameter Of A Spindle Taper?



## Joe Pitz (Aug 23, 2015)

Hello all,

On my Clausing L-00 spindle and chuck.

I am having some run out issues on my chuck and adapter.  Also some taper when I turn some round stock in just the chuck.

I have put a dial test indicator on my spindle, both when running and when hand turning the spindle and the run out is within .0005.

When I mount the chuck and perform the same run out test I get run out from .005" - .010"

When I turn round stock in just the chuck, I get .004" taper, smaller diameter, at the bar end away from the chuck.

I called Clausing and they sent me a service manual section.

It indicates that either the spindle collar is worn or the spindle nose taper is not true.

I took my adapter and put it on my mill and ran a dial indicator around both bearing surfaces and they are true to .0005".

I placed some plastiguage on the bearing surfaces of the adapter and mounted the adapter to the spindle.
The clearance was .002 on the rear bearing surface and .003 -.005 on the front bearing surface.

Now  I need to determine how to measure the taper on the spindle nose. (again when running the dial test indicator on the spindle, there is very little run out). 

What I now need to determine is if the spindle taper is worn.  

If I can eliminate either the spindle nose or the spindle collar, my cost to repair will be  less.

Can anyone tell me how to accurately measure spindle diameter taper on the spindle nose?

Thanks


Joe


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## Bill Gruby (Aug 23, 2015)

This chart should help Joe.

"Billy G"

http://www.victornet.com/reference/Morse_Jacobs.html


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## RJSakowski (Aug 23, 2015)

Joe,
If I understand correctly, you are experiencing a larger runout when measuring a test bar mounted in the chuck.  This is normal for most chucks.  Unless you have a TruSet or similar chuck, three jaw scrolling chucks are just not that accurate.  That is why machinists use four jaw chucks and dial in their work or turn between centers.  Your spindle runout looks to be close to what I would expect to see.  Your chuck runout is also typical.  Better grade chucks will have less runout but you will pay dearly.  There is a chance that your chuck was poorly fitted to the backing plate and that can be corrected.  There is also possibility that the chuck jaws are worn if it is an older chuck and that can be corrected.  Be aware that in most cases, you will only be accurate at one diameter.  That is the nature of the scrolling mechanism and why machinists mount their work by other means.    It sucks but that is the way it is. 

Taper is another matter and indicates that the lathe ways are not parallel to the spindle axis or they are twisted.  There are lots of discussions concerning tapered turnings and how to correct them.  You should get the same taper whether your work is mounted in a chuck or in the spindle  ( a Morse taper collet, e.g.).  A worn or badly fitted spindle assembly will manifest itself in poor quality turnings, not in tapered turnings.

I would not expect PlastiGage to give you an accurate representation of clearances.  It is meant for measuring bearing journal clearances where you can place thousands of psi of pressure on the PlastiGage material.  I doubt that you can come close to that kind of load in your setup.

Bob


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## RJSakowski (Aug 23, 2015)

Joe,
If you are trying to determine if your Morse tape socket is correct, that is a difficult task to measure accurately enough to mean anything.  Probably the best way would be to blue a known good male Morse taper and insert it into the socket, rotating slightly to seat it.  When you remove the taper, you should see fairly uniform rub marks over the tapered surface.  If you have a ring at one end or the other and the remainder of the taper looks untouched, then it would indicate an inaccurately ground taper.  External tapers can be measured more easily but to do so accurately enough is also difficult.  The common method is to measure the diameter at two positions a known distance apart. The taper is determined by the difference in the diameters which can be fairly small.

There was an energetic discussion of the measurement of tapers in this thread. http://www.hobby-machinist.com/threads/quick-measurement-of-small-taper-angle.34055/#post-288420

Bob


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## Joe Pitz (Aug 23, 2015)

Thanks Bob,  To give you some more info.  I went through a very serious leveling session.  I set up the lathe with a level and then turned a piece of stock.  The taper started out around .010".  I then keep on adding shim material on the low side and was able to get the taper down to .004" but no further.

According To Clausing the headstock is not adjustable.  I am aware of the run out issues of a 3 jaw scroll chuck.  I am more concerned about fixing the taper problem.

I do not have a Tru-Set chuck.  I have a brand new Bison chuck.  I purchased a new adapter plate and turned the plate myself on the lathe.  The only issue I am trying to determine is, is my Spindle collar crooked or is my spindle taper worn, which according to the service manual would cause the taper.

There is one more issue that may be causing the problem, the diameter of the chuck adapter on the smaller bearing surface may be incorrect.

Thanks

Joe


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## Joe Pitz (Aug 23, 2015)

Bob,  Not trying to determine a Morse taper.  My lathe has a L-00 spindle and the spindle nose is tapered.  I am currently trying to calculate what the smaller diameter is so I can mic it.

Outer diameter is 2.750"  Width of taper is 2" and taper is 8° 17' 50".  I am trying to find an online calculator that will allow me to calculate the smaller diameter so I can mic it.

This way I can determine if the spindle nose is worn.  I will more than likely have to replace either the Spindle or the Spindle collar.

Trying to eliminate one or the other.

Thanks for the help

Joe


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## Joe Pitz (Aug 23, 2015)

Thanks Billy for the chart.  

Joe


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## RJSakowski (Aug 23, 2015)

There is always a problem with accurately miking the small end of the taper because determining precisely where you are on the tape is indeterminate.  One method which will work is to turn a short bushing with two different diameters on the ends and of a known length.  You then seat the large end on squarely on your taper and zero an indicator.  Then reverse the bushing and seat the small end and remeasure the the position.  It works best if you have a DRO but it can be accomplished with other measuring tools.  Tom Lipton from OxTools did a YouTube  on the technique a while back.  If I understand you, the taper has a large end diameter of 2.750" and its length is 2" and the taper angle (single side) is 8 deg. 17 min. and 50 sec.  or 8.291146 deg.  The small diameter should then be 2.750 -2*tan(8.291146)*2.  The first "2" is because the distance calculated is for one side and you need to double it.  The second "2" is length of the taper.  That calculates to 2.1671 for the small end diameter. 

If you need to measure an internal taper, you can use the same procedure by turning a shaft with different diameter ends.  

Be aware that the accuracy of the measurement can be no better than your ability to measure the difference in the two diameters.  In this case, it is about .6"  so if you can measure to +/-.001", your relative error could be as large as .002/.6 or .3%.  This would mean a possible error of .03 deg. in your angle determination.

Bob


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## Tony Wells (Aug 23, 2015)

I would be very hesitant to blame the L taper. There is no movement between the taper mating surfaces. No way really do get wear, unless someone is off and on with chucks and fixtures many times a day for years. That spindle taper should be hardened, and take years of use with virtually no evidence of wear. It must be scrupulously smooth and clean, as must the mating taper and registry shoulders if used.

The method mentioned above about using bluing to check the taper condition will work on the L tapers as well. Remove the key and without using the nut, mate up the tapers with a slight twist, and look for even contact. 

On a side point, despite a damaged taper or really much of anything, a turned shaft will represent the true axis of the spindle/bearings. Even if the chuck had 0.030 runout when chucking a piece, when turned, it should be straight, and have negligible runout. I think you are looking at the wrong area for your problem.


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## Joe Pitz (Aug 23, 2015)

Hey Everyone,  My logic may be incorrect.  Here is some more information on the L-00 spindle and collar.

Maybe I am trying to read too much into this.

I guess I am just trying to fix my taper issue.

http://www.tools-n-gizmos.com/specs/Lathe_Spindle_Mount.html

Enclosed is also the section on the service manual on how to test the spindle and collar.

I performed the dykem test.  I did not get much dykem transfer on either bearing surface of the adapter.  But I was able to see a nice pattern on the spindle where the outer bearing surface imprinted on the spindle.  What I did not see was any transfer in the dykem from the inner bearing surface of the adapter.  So that lead me to believe that it could be either the spindle collar, the spindle nose and now I am wondering if the inner bearing surface on the adapter might be off.

So If my thought process is incorrect then this is where I can use the groups help.

Thanks everyone, you are always so helpful to me.

Joe


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## Tony Wells (Aug 23, 2015)

Beware on using that tapered plug method. You will without doubt have some sort of edge break on the ends you measure. The theory is sound, but what you would actually be needed to measure would be a projected dimension. If you have access to an optical comparator, you can get your tapered plug qualified and an actual measurement to target. 

The ideal way to measure inside precision tapers for face dimensions is to verify the angle, then use 2 precision gage balls to arrive at a linear dimension to calculate from.

Or if your pockets are deep........get a nice CMM.


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## Joe Pitz (Aug 23, 2015)

Yes Tony,  I was hoping to hear from you.  I think you are correct.  So when I turn just a section of round stock in my chuck, very light cuts,  .002" and then measure the diameter near the chuck and out at the end,  about 7" away from the chuck.  I am getting .004 taper, thinner at the opposite end from the chuck.

What should I be looking for?

Thanks

Joe


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## Joe Pitz (Aug 23, 2015)

CMM,  I would love to have a CMM,  but unless I make one myself there is little chance I could afford one.

Joe


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## Tony Wells (Aug 23, 2015)

Well, 7" is a long way if the diameter is small. So in any case, if you are reading small at the tailstock end, the true spindle axis has some misalignment issue with respect to the ways. This could be many things. I don't remember what lathe you are working on, or how old it is.  Way wear can cause it. Twist of the bed can cause it. More unlikely, but cutting edge can be a root cause. 

What diameter is your test bar? How much is gripped in the chuck jaws?

On some lathes, the headstock swivels on a largish dowel pin, but I believe you said according to the manual, it is non-adjustable. I would guess then that the bottom of the headstock casting has mating vee and flat surfaces and sits directly on the ways of the bed. If this has been disassembled, and not reassembled properly, like clean, then it will throw alignment out.


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## Joe Pitz (Aug 23, 2015)

Thanks Bob for the diagram,  I went back and looked at the Victor chart (included above)  Their 2.750 measurement is way back on the end of the spindle.  The 2" measurement is further down the taper.  So it may be near impossible to get a measurement and as you indicate it may be really hard to mic such a measurement.

Joe


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## Joe Pitz (Aug 23, 2015)

Tony,

Lathe is 1954 Clausing 6316.  I tried a .750 round stock of aluminum, 2" in the jaws.  I know, how stupid of me ,  I have a piece of 1.750 out in the car.  I will cut a piece of that and try again.  I sometimes get so anxious, to try things. I am going to have to stop that.  I will re-test with the larger stock.

Clausing recommends in their manual not to remove the headstock.  Yes it mounts directly to the bed with clamps.  Image enclosed.

Thanks

Joe


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## Tony Wells (Aug 23, 2015)

I'd prefer that you turn the length of the bar, then undercut the center section before turning a couple of "rings", without changing the cutting position. Use a sharp tool, and a light cut. Use power feed, and patiently wait while it cuts air in the undercut section so as not to disturb anything. If your "rings" are about 6" apart, that will be enough. All of this in a single chucking.


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## Joe Pitz (Aug 23, 2015)

Thanks Tony,  I will perform the undercut method you recommend.

I will post the results.

Thanks a lot

Joe


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## 4GSR (Aug 24, 2015)

I like to add to what has already been said.
I have three lathes that have L-00, L-0, and L-1 spindle tapers.  The spindle noses on all of them are all in good shape and accurate.  Once in a while, when mounting a chuck, I will encounter some problems getting the chuck to mount correctly.  Generally my problem is getting both the spindle taper clean and the chuck back plate taper clean.  They both have to be absolutely clean!  Runout of the chuck body has never been an issue with any of my chucks I use.  But, I do have a heavily worn Buck Adjusta Tru chuck that the jaws are sprung from wear and abuse, not from me, but from previous owners of the lathe.  That chuck if used will cut tapers on any piece of barstock put in it.  I replaced it with a newer set tru chuck that is in much better shape.  When making up the nut onto the chuck adapter, it should make up solid, once hand tight is encountered and the proper wrench is used to tighten up the nut.  If it is "spongy" while making up with the proper wrench, there is trash caught up in the tapers.  Back it off, clean again, and try again.  Wipe the spindle taper and chuck taper clean with your fingers.  Don't rely on compressed air or solvents to remove fines left behind from cleaning.  Only your bare clean fingers will you know if it was good and clean.

I very highly doubt that you are having problems with the taper on the spindle or the nut.  Especially if they were fine with any other chucks mounted to the spindle before buying a new chuck.  You have to remember the spindle and taper are harden and ground.  They were checked to a standard before they left the factory, to guarantee the spindle was correct. The spindle nut went through the same process and it is harden, too!  The spindle and nut hardly ever see any wear.  What I have seen in my past is signs of not properly cleaning the tapers before installing chucks and allowing shavings, crud, etc. get between the tapers and eventually damaging the tapers.  You see this much worse on the taper of the chuck adapters than the spindles.  Got to remember, the chuck adapters are "soft" in hardness compared to the spindle tapers.  This is done for a reason.

I must ask, can you "eye ball" the chuck body and see any wobble?  If so, set up an dial indicator and check how much it is.  The chuck body should be running within about .0015" or less.  IF more than that, pull the chuck from the chuck adapter.  Check the runout of the chuck adapter.  You may need to take a facing cut to get it running true.  But even with a little runout in the chuck or the adapter, this would not show up in the taper that you are indicating is happening when turning the od on a piece of bar stock.  

I think you need to leave the chuck and the spindle alone!

Make the test bar that Tony mentioned.  

I believe what you will find is your lathe has lots of bed wear that is causing it to cut a tapered OD work piece.

Report back and let us know what you find out.


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## Joe Pitz (Aug 24, 2015)

Thanks Ken, After I perform the turning test that Tony  indicated I will run  a dial indicator along the ways and check.
I will report back with findings.

Joe


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## Joe Pitz (Aug 26, 2015)

Hello everyone,  a follow up on my progress.  I followed a procedure that Ken (4gsr) suggested.  I put a dial indicator on my adapter plate and the run out was very small.  I then put the dial indicator on the chuck and the run out was very high .005 - .010"  So I took the chuck off of the lathe and un-bolted the adapter.  The chuck has multiple bolt holes on the rear mount.  When I drilled my adapter I used three of those holes for mounting.

I the ran a series of tests, I rotated the adapter plate one hole at a time, for mounting on the chuck.  Mounted the chuck and ran a run out test.  I then repeated the steps  moving the adapter one hole at a time.  By doing this I was able to reduce the run-out to .0035.  

I have not got to the taper test yet, as I tried some other things first.  I wanted to rough in my tail stock adjustment so that when I turned the relief cuts on the test bar, I could  use the tailstock to hold the bar stock.

I adjusted the tail stock and made some test cuts between centers, both with aluminum and cold rolled steel,  I wanted to see if between centers taper could be adjusted out.

I was able to remove the taper after adjusting the tailstock.  The finish on the turned aluminum had a very nice finish.  The finish on the cold rolled steel was very rough and had areas where the dimension appears to change, like indentations in the cut.

I when through and re-adjusted the cross slide and compound slide gibs.  I also tightened the QCTP holder and tool holder and repeated the tests.

Still the same results with the cold rolled steel.

Note:  My lathe is a 12 x 36" Clausing 6316 lathe.  When I purchased the lathe it came with an AXA QCTP holder.  I have some 3/8" carbide turning tool holders TAR.

I put a dial indicator on the tip of the carbide insert and then with both hands I tried to rock the tool holder.  I was able to move the tool holder easily .0005"

This is with my bear hands,  I can imagine the amount of force that is applied to the tool holder when cutting steel.

So my question at this point is?  Is my tool holder tool small for my lathe?  Should I upgrade to a BXA QCTP holder?  Should I upgrade to 1/2" tool holders?

Or is there something I can do to remove the flex in the tool holder?

Thanks All

Joe


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## 4GSR (Aug 26, 2015)

The Flex you are seeing is from the carriage, cross slide, compound, not the tool post.

I would suggest upgrading to a BXA later as some date in the future.  Upgrading is not going to reduce the .0005" movement you are seeing.

Ken


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## Joe Pitz (Aug 26, 2015)

Ken,  How can I remove the flex in the carriage components.? I am assuming that this is what is causing my poor finish on the steel bar?

Thanks

Joe


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## mikey (Aug 27, 2015)

Joe, what kind of steel are you cutting? If it is 1018 then getting a nice finish is going to be tough.


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## 4GSR (Aug 27, 2015)

Joe Pitz said:


> ....... I am assuming that this is what is causing my poor finish on the steel bar?
> 
> Thanks
> 
> Joe



That has nothing to do with poor finish.  As Mikey said "what is the material that is being cut?".  And you have to look at tool geometry too.
A 1018-1026 grade of material is tough to get a good finish just from a typical insert type cutting tool.  For someone very new at this, you need to get you a piece of HSS and grind a cutting edge that has a higher than normal back rake angle.  In fact a high shear type cutting edge is what you need for finishing to get a nice finish on low carbon steel next to polishing with emery.  In fact, I use emery to finish the surface with at times when I'm having troubles getting a good finish.  And I've been doing this for many years, too!

Going back to flexture in the tool post.  I bet if you measured it on my half worn out lathe, that number would be closer to .005".  And it don't stop me from getting good finishes on the stuff that I do.

Ken


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## Joe Pitz (Aug 27, 2015)

Thanks Mikey and Ken,  Since I am a total newbie, I really have no base line to go against.  So it is good that you guys are providing me some good info in order to establish a 
base line of expected results.  The steel is Home Depot stock, El Cheapo in order to do some testing, more than likely 1018, as it looks real grainy.

I will pick up some more steel and try again.  Yes I have been reading Mikey's HSS tool grinding articles and practicing,  but wanted to get the lathe in order for turning.

Looks like I am almost ready,  I have to make the test bar that Tony indicated and test for run out.  Then I can continue my tool grinding exercises.

So much to do and so little time,  my 8 hour a day job keeps on getting in the way of having fun. 

Joe


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## mikey (Aug 27, 2015)

Joe, you don't need a BXA on that lathe; the AXA is fine on a 12" lathe. If you use the right tools in the right way your tool post is plenty rigid enough.

You mentioned you're using a TAR inserted tip tool. I've not used this geometry but I looked it up and it appears to be a negative rake tool. Negative rake tools work great with a rigid set up but cutting forces are much higher than positive rake tooling. The nose radius of the insert has a big impact on tool performance and this is especially true with negative rake tooling. What is the nose radius on your insert? If it is larger than 1/32" you are going to have some challenges in harder steels, including crappy 1018. The bottom line is that your lathe will work much better with positive rake tooling and even better with HSS tools.

I'm not sure what the steel from Home Depot is but there is a good chance it is 1018. Ken is right - use HSS on this steel. 

When you do the 2-collar test it is more important to have a piece that will have minimal deflection. You do not need steel for this; Aluminum works fine. It does have to be stout so use something in the 1-1/2" OD range. If I were you I would grind a sharp HSS tool for your test; it will cut with minimal deflection. Carbide tools are not meant to take very light cuts like those used for a 2-collar test.


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