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

[Don B]

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

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.

 

[COMachinist]

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

 

[COMachinist]

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

 

[hvontres]

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.

 

[COMachinist]

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

 

[Don B]

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?

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

 

[COMachinist]

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

 

[Don B]

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)

 

[COMachinist]

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)

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

 

[Don B]

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.