# Can't get Clausing 100 mk IIIa to cut a with out a taper????



## COMachinist (Jul 6, 2014)

Hi All
Happy birthday to America. 
:happybirthday2:
I have a new Bison 8" fixed jaw chuck I have just mounted, and I can't get it to cut a test pieces with out the outside ring from being .004 smaller than the ring up next to the chuck. The chuck has about .007 run out 2 out from the jaws. 
I turned the back plate to size and faced the back plate. I checked the back plate for run out and the face for wobble but it did the .0001 Starret DTI hardly moved. I turned the spigot so it is a snug fit with a little pressure and used Transfer screws to get the mount holes  marked and drilled them on my mill. The mount SCHC screws fit with no binding. I have checked every thing I could think of. The spindle only has about .0001 run out and no front to back looseness.The preload on the spindle is set to factory specs. I have checked the level on the lathe with my Starret master level and it is with .0005 from head stock to tail stock end cross wise and .0012 length wise. I debured the Bison jaws cleaned and lubed the scroll. I'm just kind of at a loss now. Any ideas??? I loosened and tied to see if I could tweak the head stock but it is fixed because of the V rail. I would like to get this figured out so my son can help with the work, I can't lift any thing for another two weeks so while he is hear, free labor :lmao:. If I can't figure it out then it will have to wait a few weeks longer. Oh it has the same run out and run out both sets of jaws?
Thanks 
CH


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## Don B (Jul 6, 2014)

Unless I'm misinterpreting your description your dealing with 2 separate problems, even though you used a level it sounds like you have a twist in the bedways, it sounds like you need a shim under the the rear mounting location (tailstock end) , sorry I'm not familiar with this chuck I'll let someone who might be comment on it.


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## JimDawson (Jul 6, 2014)

0.007 run out sounds like quite a bit.  Bison chucks are normally pretty good.  I would put an indicator on the chuck face and see what the run out is there.  It almost sounds like the chuck internally is not parallel with the mounting surface.

I think you did everything correctly, and you have good measuring instruments to work with, so I don't think the problem is there.

Is your test bar supported by a center on the outboard end?  If so it could be a tailstock alignment issue.

I guess the worst case is get out the tool post grinder and re-grind the jaws.


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## COMachinist (Jul 6, 2014)

Hi Don
Here is my level readings cross wise. Head stock, center and tail stock areas. If there was a twist wouldn't the level show that. I meanthe bubble on that thing move because the work light heats it up slightly. .0005/foot???? I went back to the chuck that came with the lathe and it has .004 run out and .003 tapper. I put the bison 5c collet chuck on with 12" piece 3/4 drill rod and it has .005 run out and .007 run out in it???? I checked the spindle and the nose and thread stop are all square with in a .0005. My had to head back to his house to get ready for work Monday so I down for a few weeks until my shoulder heals up completely.
:think1:
Thanks 
CH


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## hvontres (Jul 6, 2014)

While you are waiting for you shoulder to get back in order, you might want to take a look at a video Tom over at Oxtool made about adjusting bed twist:
[video=youtube;GErhXyUb2Go]https://www.youtube.com/watch?v=GErhXyUb2Go[/video]

Also, one other thing to keep in mind is that you are measuring the straightness at the top of the V-s. The surfaces that control the relationship of the tool to the spindle are actually the sides fo the front V and the rear flat way. So while the top may be fairly straight, there may be some wear on the critical surfaces that might be causing some tapering.

And if you are turning with a center and the tail stock isn't aligned, then you might also get some tapering. In fact, purposely offsetting the trail strock is one way to turn a taper on purpose 

Good luck and I hope the shoulder is better soon


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## Andre (Jul 6, 2014)

Before you click the link, I just want to make sure you know I'm not saying your doing something wrong or suggesting you do things in a different way. I'm just posting this as a reference.

[h=1]
Leveling and Setup of the Metalworking lathe Part 1[/h]https://www.youtube.com/watch?v=zIDL77qt1tI

[h=1]Leveling and Setup of the metalworking lathe P2[/h]https://www.youtube.com/watch?v=GErhXyUb2Go


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## Don B (Jul 6, 2014)

COMachinist said:


> Hi Don
> Here is my level readings cross wise. Head stock, center and tail stock areas. If there was a twist wouldn't the level show that. I meanthe bubble on that thing move because the work light heats it up slightly. .0005/foot???? I went back to the chuck that came with the lathe and it has .004 run out and .003 tapper. I put the bison 5c collet chuck on with 12" piece 3/4 drill rod and it has .005 run out and .007 run out in it???? I checked the spindle and the nose and thread stop are all square with in a .0005. My had to head back to his house to get ready for work Monday so I down for a few weeks until my shoulder heals up completely.
> :think1:
> Thanks
> CH



Well I'm not saying that shouldn't work but I'd be curious how level it is off the flats, you'd need 123 blocks or something similar and use them in the same position when moving them up and down the bedways, also put a tick/reference mark on the level with a marker or something for positioning, don't rotate the level, use it in the same direction and relative position when moving it up and down the bedways, give that a try and see what results you get.

Edit: my apologies I forgot to add this, those surfaces you're indicating/leveling from are not critical surfaces and may have been treated as such during the machining proses.)


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## Bradrock (Jul 6, 2014)

If it's bed twist or the tailstock, Why is one chuck better than the other?


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## Don B (Jul 7, 2014)

Bradrock said:


> If it's bed twist or the tailstock, Why is one chuck better than the other?



Sorry I only see a reference to 2 jaws not chucks, the chuck will not produce the taper if it's inaccurate it will cause eccentricity between your original diameter of your chucked stock and the new diameter your turning, I see this as 2 separate problems, runout on the chuck is one and a taper issue which is separate, it sounds though as if the chuck back plate mounting procedure was done properly and I'm not familiar with Bison chucks so I'm sure what to say about the chuck part without more info.

Edit: if the jaws are not parallel to the center of the spindle this could also cause original diameter of your chucked stock to be un-parallel (if that's even a word) with the new diameter you're turning, parallelism and any eccentricity can be corrected by regrinding the jaws.


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## Bradrock (Jul 7, 2014)

"I went back to the chuck that came with the lathe and it has .004 run out and .003 tapper."


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## Don B (Jul 7, 2014)

Bradrock said:


> &quot;I went back to the chuck that came with the lathe and it has .004 run out and .003 tapper.&quot;


 Sorry are will still talking about the "Clausing" here, your user name is different than the original poster, I'm getting confused, LOL.

Edit: OK I see where a second chuck was mentioned, missed that, is it possible to show a picture of your test bar setup, and a picture of the 2 different chucks please just for clarity, also how large are the cuts that are being taken from the test bar and what material is it please.


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## COMachinist (Jul 7, 2014)

Bradrock said:


> If it's bed twist or the tailstock, Why is one chuck better than the other?


Hi 
My guess on that one is scroll and jaw wear. It is about as old as the lathe. The Bison chuck is brand new as in never used.
I'm going to check the jaws to see if they are at fault. I have seen Ox's videos on checking a lathe for level, The Clausing 100 is about the size of his head stock, it's a bench top lathe. It only has 4 legs and has jacking screws on the feet. If you note in the video he says you can use the V rails and in fact the Clausing install directions as well as South Bend install direction both say use the V rails to get twist out, and the rail flats to set longitudinal level. So that is not an issue. The Clausing says to use a test bar like Oxtool dose and that is what I did. The spindle preload says to have no play longitudinally and just a slight drag which is what I have. So I'm thinking bearings is not a problem. I could just skim cut the spindle nose and the shoulder to make sure they are dead on?  I'm going to go out and look at a few other possible causes.
Stay tuned 
CH


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## COMachinist (Jul 7, 2014)

Hi All 
No joy in Mudvill tonight. Some thing is not right with this lathe. I just can't adjust out the taper even if I max out the the adjustments for twist. I don't think I can do any more until my son comes over this weekend. I was thinking, which is always dangerous. This lathe has no way to  get the head stock set to straight. So the only way to adjust for tapper is to put twist in to minimize it. So when the ways are level you are at mercy of the front bolt holes that secure the head stock, the back only has an under the ways clamp.  I would need to dismount the head stock and hand scrape the V ways to get it straight and parallel once that is fixed, I can work on the run out issue. I think that is an issue with the scroll and jaws of the chucks. I do have and 8" Buck 4 jaw independent chuck that I can use if I need to turn something with no run out.
Thanks for every ones input.
CH


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## hvontres (Jul 8, 2014)

Just out of curiosity, how heavy a cut were you taking while checking for taper? On my 6300, which is basicaly your lathe a couple of years younger, i was taking about .001" off of a 1.75" piece of aluminum (just the ends, the center was relieved to save some time  )



After some fiddeling, I was able to get the taper down to less than .0005. But I shold re-check it. I think once a lathe like this has sat for a while, the bed takes a bit of a set and then will take some time to re-adjust.

- - - Updated - - -

One other thing you might be dealing with is wear on the front way. The area near the chuck tends to see more wear than the far end. if the wear is in the V-way, the effect would be to tilt the carriage closer to the center as you move away from the chuck. I can't think of a good way to fix that, other than twisting the ways out of alignment to compensate. Does the 100 mk IIIa have adjusters between the bed and the chip pan like the 6300? if it does, those make leveling and aligning the bed much, much easier... no more up and down on the knees to adjust the feet.


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## COMachinist (Jul 8, 2014)

Hi All
Yeah here is my test bar. I take about .002 cuts on the rings. They should be self explanatory.


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## Don B (Jul 8, 2014)

COMachinist said:


> Hi All
> Yeah here is my test bar. I take about .002 cuts on the rings. They should be self explanatory.



So is it reversed now from your first post?



COMachinist said:


> I can't get it to cut a test pieces with out the outside ring from being .004 smaller than the ring up next to the chuck


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## COMachinist (Jul 8, 2014)

Don B said:


> So is it reversed now from your first post?


Yes I just noticed that. I have max adjust in it last night. I cut .002 this morning at the same adjustment and now it is reversed?????? Is it possible this lathe needs to sit over night to stabilize? I take t2 turn off max tonight and recut tomorrow. Stay tuned. 
CH


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## Don B (Jul 9, 2014)

COMachinist said:


> Yes I just noticed that. I have max adjust in it last night. I cut .002 this morning at the same adjustment and now it is reversed?????? Is it possible this lathe needs to sit over night to stabilize? I take t2 turn off max tonight and recut tomorrow. Stay tuned.
> CH




No I'd say something is moving on you, rather than keep going back and forth here I'm just going to describe how I would do this, no insult intended so please don't take this the wrong way but I think you sailed right past a parallel cut and went to the other extreme. 

Your test bar is more than stout enough, put the new Bison chuck on just to make sure this is not an issue of the test bar rocking on worn jaws (i.e. Only grabing on the rear of the jaws) reduce the width of your collars on your test bar, they only need to be a little wider than the spindle of your micrometer around .375 or so, use the very sharpest tool you have so there is no ripping of the material and or the tool is not pushing the material away, move the carriage/saddle to the tailstock end just use .001 cuts, cut the outer collar don't touch the cross slide just disengage the feed and move the carriage/saddle up to the first collar and cut that one, do this at least twice before you measure, this insures that the cut was even (i.e. Exact same material removal on both collars)
It takes so little of a twist in the bedways to produce a taper and can be very finicky to set, when I do mine I go to far one way then the other before I get what I want, that's not uncomone it's just a trial and error thing.

Good luck)


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## COMachinist (Jul 10, 2014)

Don B said:


> No I'd say something is moving on you, rather than keep going back and forth here I'm just going to describe how I would do this, no insult intended so please don't take this the wrong way but I think you sailed right past a parallel cut and went to the other extreme.
> 
> Your test bar is more than stout enough, put the new Bison chuck on just to make sure this is not an issue of the test bar rocking on worn jaws (i.e. Only grabing on the rear of the jaws) reduce the width of your collars on your test bar, they only need to be a little wider than the spindle of your micrometer around .375 or so, use the very sharpest tool you have so there is no ripping of the material and or the tool is not pushing the material away, move the carriage/saddle to the tailstock end just use .001 cuts, cut the outer collar don't touch the cross slide just disengage the feed and move the carriage/saddle up to the first collar and cut that one, do this at least twice before you measure, this insures that the cut was even (i.e. Exact same material removal on both collars)
> It takes so little of a twist in the bedways to produce a taper and can be very finicky to set, when I do mine I go to far one way then the other before I get what I want, that's not uncomone it's just a trial and error thing.
> ...


Took your advise and redid the test bar to your suggestion. I don't really under stand why to only the .001 passes.  I always take take 25-30 thou ruff cuts and 2-5 finish cuts if needed. Any way I kept working on the lathe went back and checked ever thing twice to make sure it was tight and level reran a test cut and I'm down to 0006"/ft taper and that is more than good. Let the lathe set over night and went back out and remounted the test bar, and did another cut for repeatability and measure .0007 so that is good for me. Now I am working on the round out problem. Which is now down to .002 but still I think I should do better with a Bison chuck.
Thanks for all your  help guys. I may be back about the run out.
CH


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## Don B (Jul 10, 2014)

COMachinist said:


> Took your advise and redid the test bar to your suggestion. I don't really under stand why to only the .001 passes.  I always take take 25-30 thou ruff cuts and 2-5 finish cuts if needed. Any way I kept working on the lathe went back and checked ever thing twice to make sure it was tight and level reran a test cut and I'm down to 0006"/ft taper and that is more than good. Let the lathe set over night and went back out and remounted the test bar, and did another cut for repeatability and measure .0007 so that is good for me. Now I am working on the round out problem. Which is now down to .002 but still I think I should do better with a Bison chuck.
> Thanks for all your  help guys. I may be back about the run out.
> CH



That's good I'm glad you where able to get the taper to an acceptable limit, I only meant the .001 cuts for the actual testing/measuring cuts and not for the roughing/shaping/turning of the test bar, my apologies if I miss worded the instructions.


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## hvontres (Jul 11, 2014)

COMachinist said:


> Took your advise and redid the test bar to your suggestion. I don't really under stand why to only the .001 passes.  I always take take 25-30 thou ruff cuts and 2-5 finish cuts if needed. Any way I kept working on the lathe went back and checked ever thing twice to make sure it was tight and level reran a test cut and I'm down to 0006"/ft taper and that is more than good. Let the lathe set over night and went back out and remounted the test bar, and did another cut for repeatability and measure .0007 so that is good for me. Now I am working on the round out problem. Which is now down to .002 but still I think I should do better with a Bison chuck.
> Thanks for all your  help guys. I may be back about the run out.
> CH



The .001 for the test bar cuts is to keep the bar from flexing when you take the cuts far from the chuck without a center in there. The idea of the test it to only measure taper caused by bed twist, not tool forces. If you have a large, unsupported part far from the chuck and take heavy cuts, the tool pressure will cause the part to bend away from the tool and the cut will be shallower, resulting in a larger OD than near the chuck where the part can't flex as much. This will then show up as "Taper" in your measurements and cause you to chase your tail while trying to get rid of it.

When you are making a real part of this size you would use either the tail stock or a steady rest to support the far end and give the whole setup more rigidity. But even then, if you need a really straight part you might want to take a really light final pass to make sure the whole length of the part is a straight as can be. I have also noticed the opposite effect when using a long boring bar to make a deep hole. The bar will deflect away from the work and won't take the full depth of cut you dialed in the first time. Once you get close to size, it's a good idea to take a second "spring" pass without changing the cross feed. this will usually take another .002-.003 off of the part on my lathe.

Hope this helps, and happy swarfing


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## Don B (Jul 11, 2014)

hvontres said:


> The .001 for the test bar cuts is to keep the bar from flexing when you take the cuts far from the chuck without a center in there. The idea of the test it to only measure taper caused by bed twist, not tool forces. If you have a large, unsupported part far from the chuck and take heavy cuts, the tool pressure will cause the part to bend away from the tool and the cut will be shallower, resulting in a larger OD than near the chuck where the part can't flex as much. This will then show up as "Taper" in your measurements and cause you to chase your tail while trying to get rid of it.
> 
> When you are making a real part of this size you would use either the tail stock or a steady rest to support the far end and give the whole setup more rigidity. But even then, if you need a really straight part you might want to take a really light final pass to make sure the whole length of the part is a straight as can be. I have also noticed the opposite effect when using a long boring bar to make a deep hole. The bar will deflect away from the work and won't take the full depth of cut you dialed in the first time. Once you get close to size, it's a good idea to take a second "spring" pass without changing the cross feed. this will usually take another .002-.003 off of the part on my lathe.
> 
> Hope this helps, and happy swarfing



A very good description...!)


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## COMachinist (Jul 11, 2014)

Hi All 
I'm still not sure what I did to get it to cut with min tapper. I did end up with the lathe out of level cross ways to get the taper out. Other than that I have no clue but it is repeating with good numbers. I'm working to get the TIR down to a manageable level now .001 should be doable. Stat tuned for that.
Again thanks to all
CH


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## Vince (Jul 17, 2014)

Just my .02, When I level a machine I do not go across the v ways. I  stay on the flats.
I made the mistake of leveling across the v's on my Clausing and could not figure out why I was getting a taper cut.
Upon closer examination I found that the v's are not the same. They looked the same but were actually not.
I have run across this quite a few times since, some machines you can actually see the difference but others are really hard to tell.
Vince


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