# I am confused



## Bamban (Sep 10, 2014)

Last night I had time to make some noise with 12x36 lathe. I chucked in a 7 inch piece and made 2 passing cuts from left to right for about 4 inches just to check the machine operation. to check the work I used an AXA tool holder mounted indicator, first I checked the run out close to the chuck, was under .001. Did not want to drag the indicator across the piece so I pulled back on the indicator and moved it to the end of the cut. The run out at this locations is the same as the previous reading.

The problem is at the tail stock end diameter, the indicator measured 0.007 fatter. I grabbed the micrometer, sure enough end to end on a 4 inch cut there is a 0.014 difference in diameter. I went ahead and put the indicator back and indicated on the turned piece and ran the carriage down the length of the turned piece. Sure enough I could watch the indicator slowly moved all the way from the tail stock to the chuck end. There is definitely a taper.

What did I do wrong?

What is wrong with the machine? 

Is it material flex? The piece is an 0.829 AR shot out bull barrel donated by a friend for me tp learn from


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## Tony Wells (Sep 10, 2014)

You did not say whether you were using the tailstock or not, but if not:

Depending on how much you had sticking out of the chuck, this could be normal pushoff from material flex. I try to keep the ratio 3:1 on the dia v length of stickout if I can. Depends on a few variables.

Also, usually turning is done Right to Left. But then, the tool must be ground for whichever way you are turning.


If you were using the tailstock, you need to set it. It is too far behind centerline by 0.0070. There are a few threads addressing
lathe alignment that you may need to review.


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## Bamban (Sep 10, 2014)

Tony Wells said:


> You did not say whether you were using the tailstock or not, but if not:
> 
> Depending on how much you had sticking out of the chuck, this could be normal pushoff from material flex. I try to keep the ratio 3:1 on the dia v length of stickout if I can. Depends on a few variables.
> 
> ...




Thank you, did not use the tailstock, I thought with .005 cut both times, the piece will take the cuts without flexing, will search the alignment


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## Bamban (Sep 10, 2014)

Tony Wells said:


> You did not say whether you were using the tailstock or not, but if not:
> 
> Depending on how much you had sticking out of the chuck, this could be normal pushoff from material flex. I try to keep the ratio 3:1 on the dia v length of stickout if I can. Depends on a few variables.
> 
> ...




Tony,


You are absolutely right.

On turning from Left to Right. I am learning how to use the controls on these machines that just got wired last week. I figure it is safer for me to turn this way to avoid the possibility of jamming the cutter into the chuck in case I screw up and turn levers the wrong way or grab the wrong lever as the cutter approaches the end.
In the mail came my new tool bit holder, a bunch of cutters so I just have to stop doing the laundry and play. Maybe I jumped multiple variables all at once, in the short period I have I had to.

Used the new tooling 
Center drilled both ends of the material
Used a live center and cut the material, .005 again and another ,005.

Measurements, not that good, material registered smaller at the tailstock end. Researched adjusting the tail stock to the head, I made the adjustment with those 2 opposing set screws. Next 2 cuts of .005 yielded better, may not be perfect, but I am happy for now. At least I can make the outcome wiggle.

Maybe I was dealing with multiple things last night; 1. Dull bit, 2. Flexing material. 

Did I do this right? Do I need to get the 0.0005 indicator to fine tune the taper? Or should it be good for now, I will just be turning straight cuts on AR barrels in the future and the measurement are not critical.

Here are the pictures.


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## Tony Wells (Sep 10, 2014)

In reality, it's kind of subjective. Some people are not content until their lathe (particularly new ones) cut straight with a very few tenths. Others are satisfied as long as they can meet the needs of their parts. Be aware that when you adjust a tailstock, it may change it's -X- centerline relationship with the chuck if it is used in a different position on the ways. That's where bed twist and the rest of the worm can usually come come in. Bottom line, if it does what you need, there is no real reason to get fussy about it unless you want to, and it can be frustrating to chase it to the tenth.


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## Round in circles (Sep 10, 2014)

Ensuring that the lathe is bolted down onto a solid concrete base  and levelled with a proper engineers spirit level to remove twist and bed bend also helps tremendously when setting up for a better more accurate cut .

I've been advised to always check it once every few months as well for things do change  . This can help damp out any unwanted vibrations ( frequencies ) that arise , which could amplify or harmonise  up in the lathe bed & affect the quality of your work .


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## Bamban (Sep 10, 2014)

Round in circles said:


> Ensuring that the lathe is bolted down onto a solid concrete base  and levelled with a proper engineers spirit level to remove twist and bed bend also helps tremendously when setting up for a better more accurate cut .
> 
> I've been advised to always check it once every few months as well for things do change  . This can help damp out any unwanted vibrations ( frequencies ) that arise , which could amplify or harmonise  up in the lathe bed & affect the quality of your work .



I do not have it bolted down, just leveled with these. 

http://www.avproductsinc.com/machine-leveling/anti-vibration-feet.html


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## chuckorlando (Sep 10, 2014)

Are you checking run out, taper, or Dia?


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## Bamban (Sep 10, 2014)

chuckorlando said:


> Are you checking run out, taper, or Dia?



At first I was just testing machine operation, tried my hand into turning, and was surprised to see that the turned piece had a taper in it, so I posted for solution, so end up adjusting the tail stock.


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## chuckorlando (Sep 10, 2014)

I must have mussed that part. I was wondering what your tail stock had to do with chuck run out ahahahahah

On the up side, you learned how to turn a taper using the tail stock)


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## epanzella (Sep 11, 2014)

I'm having a little trouble following this thread. You said in one of your posts that you weren't using the tailstock but then you show pics of the part supported in a live center. First you have to turn a piece with the far end unsupported so that you check the alignment of the headstock to the bed. If it's off you can't adjust that with the tailstock. Once you determine the headstock is aligned then you can proceed to check the tailstock. Maybe you did all this already and I missed it.


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## Bamban (Sep 11, 2014)

epanzella said:


> I'm having a little trouble following this thread. You said in one of your posts that you weren't using the tailstock but then you show pics of the part supported in a live center. First you have to turn a piece with the far end unsupported so that you check the alignment of the headstock to the bed. If it's off you can't adjust that with the tailstock. Once you determine the headstock is aligned then you can proceed to check the tailstock. Maybe you did all this already and I missed it.



No tailstock at first, Tony mentioned that a piece sticking out needs to be supported, and he suggested the tailstock be used and if there were still a taper, adjust the tailstock. To clear it in my mind what that means I turned using the tailstock and a live center. The first pass results showed a taper in the opposite direction from the unsupported piece. I adjusted the tailstock following some online instructions, got to turn straight, then posted the end results.

Sorry, I may not be all clear in my articulation, I am a total newbie, I confuse myself at times...


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## chuckorlando (Sep 11, 2014)

Well the initial taper you turned and the one with the tail stock are unrelated issues. If you are wanting to know the chuck run out you could turn a short piece, flip it around so the good ends in the chuck, turn the other end, then indicate that surface while turning the chuck by hand.


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## Tony Wells (Sep 11, 2014)

The original issue, as I saw it, was taper......large on the outboard end; typical of unsupported work. He measured it and found it oversize by 0.0140. So my suggestion was to eliminate the material pushoff by using the tailstock. Then the taper changed direction, indicating to me a problem with the tailstock -X- axis positioning. Never was runout a problem. He did mention it, but in actuality, if the part is turned and left in the chuck, I would expect no/little runout anyway. That was a side point. Perhaps that's what is throwing some of you off. We are diagnosing/discussing either a headstock to way alignment, or simply a tailstock adjustment, primarily.


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## Round in circles (Sep 11, 2014)

Bamban said:


> I do not have it bolted down, just leveled with these.
> 
> http://www.avproductsinc.com/machine-leveling/anti-vibration-feet.html




Lovely machinery stands .

They are for vibration through to the floor and resonance in the machine only , if the bed is slightly  twisted and arched it will still be like that when standing on anti vibration feet , that's why you bolt it down solid into concrete and take time with a level and shims to untwist and unbend it . 
High tensile studding and high strength chemical anchor systems are one of the best way of doing it as it is a stress free anchoring  method with little chance of cracking the concrete .
 Until the lathe is solid & levelled up there's not a lot of point in playing about trying to adjust the tail stock etc.


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## John Hasler (Sep 11, 2014)

Bamban said:


> No tailstock at first, Tony mentioned that a piece sticking out needs to be supported, and he suggested the tailstock be used and if there were still a taper, adjust the tailstock. To clear it in my mind what that means I turned using the tailstock and a live center. The first pass results showed a taper in the opposite direction from the unsupported piece. I adjusted the tailstock following some online instructions, got to turn straight, then posted the end results.
> 
> Sorry, I may not be all clear in my articulation, I am a total newbie, I confuse myself at times...



My first step in checking tailstock alignment on my Logan was to put dead centers in both headstock and tailstock and run them together with a steel rule pinched between the tips.  The quill should be retracted as far as possible and locked so it won't droop.   I then adjusted the tailstock until the rule, held horizontal, was perpendicular to the ways.  It should stand vertical as well, but that's less important.  Then I checked by turning some collars between dead centers.  It was dead on to within the limits of my instruments.  Not coincidentally, the witness marks on the back of the tailstock were aligned.

Before I did that, thought, I faced a plate to check headstock alignment (I assumed that the cross-slide was perpendicular to the ways).  The plate was flat so that was ok (in the horizontal plane) .  I then used the two-collar test to decide how to shim the feet to take the twist out of the bed.


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## billdeme (Sep 11, 2014)

The taper can come from 3 things, 1 flex of the part your cutting, with only a .005 cut I wouldn't think so, 2 worn ways, or 3 the machine is twisted. You can fix #3 by, what was previously mentioned earlier, bolt down your legs and jacking up or down the leveling screws till you work out the taper. A lathe that's twisted like that you will be cutting off center at one end of the part or the other = bad finish, tool life, chatter, ect.


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## Bamban (Sep 11, 2014)

Thank y'all for the input and suggestions.  Reading these while waiting for my flight to see the grandkids,  my head is spinning as to what the next steps would be for me. Unfortunately, I won't be back for another 2 weeks. 

In the meantime if y'all kind enough to sort spell out first thing first on my things to do when I get back, at least I can formulate a plan of attack.

A quick one on bolting down, in lieu of bolt down, would constructing a steel plate between the 2 tower like structure of the stand and load it down with 2-300 pounds worth of lifting weights be sufficient to stabilize the machine? Then level it from there. Just a thought outside the norm.


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## Bamban (Sep 11, 2014)

Double tap


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## Bamban (Sep 11, 2014)

Round in circles said:


> Lovely machinery stands .
> 
> They are for vibration through to the floor and resonance in the machine only , if the bed is slightly  twisted and arched it will still be like that when standing on anti vibration feet , that's why you bolt it down solid into concrete and take time with a level and shims to untwist and unbend it .
> High tensile studding and high strength chemical anchor systems are one of the best way of doing it as it is a stress free anchoring  method with little chance of cracking the concrete .
> Until the lathe is solid & levelled up there's not a lot of point in playing about trying to adjust the tail stock etc.



Modern marvels.. Wifi in airplanes and my smart phone keep me connected.

I am trying to visualize how moving leveling feet, even assuming the stand/cabinet is bolted down, would twist/untwist the massive cast iron bed. What's going on in my mind when moving/twisting the cabinet the massive cast iron bed is riding the movement. They are for practical purposes the stand/cabinet/lathe are one unit. Not arguing with you guys, trying to understand. 

Would it be more effective to bolt down/shim and adjust the mounting bolts of the lathe to the stand/cabinet to leve/twii*jel? My lack of experience and knowledge is showing here. I just don't just want to know the how, but the why as well.


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## chuckorlando (Sep 11, 2014)

We are talking very small amounts. You might not even see the variation on a carpenters level. But on a machine level a 1/4 turn to the foot can move the bubble a good bit. We just leveled our 1236 at Nickmickenny. It's not hard just a little time. It does not need level front to back except for draining the coolant but side to side it needs leveled at multiple point on the bed.

Well it dont need it. But if your going that far might as well check it all


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## TOOLMASTER (Sep 11, 2014)

bed twist or head is twisted


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## Vladymere (Sep 11, 2014)

Bamban,

Here is a link to a South Bend pamphlet on installing and leveling a lathe.  http://www.wswells.com/data/howto/H-3.pdf

I think you will find a lot of good information in here.

Vlad


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## Bamban (Sep 11, 2014)

Vladymere said:


> Bamban,
> 
> Here is a link to a South Bend pamphlet on installing and leveling a lathe.  http://www.wswells.com/data/howto/H-3.pdf
> 
> ...



Vlad,

Thank you.

This confirms how I should level my little lathe.

Got lots of learning to do.


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## Vladymere (Sep 12, 2014)

*Thankyou Bamban*

Bamban,

You are welcome to the link.  The pamphlet can be downloaded.  Steve Wells has a lot of good info on his South Bend site.

Here is a link to South Bends 1955 copy of "How to Run a Lathe".  It is split into two parts.  http://campkahler.com/files/How_to_Run_a_Lathe_SB_1of2.pdf
http://campkahler.com/files/How_to_Run_a_Lathe_SB_2of2.pdf

This is an excellent manual on running a manual lathe, and not just South Bend lathes.

I just read your signature line.  Thank you for your service and God bless your father for his service also.

Vlad


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## bfd (Sep 21, 2016)

sharp tool? non aggressive feed rate? too slow speed? all these and more can cause this push away problem. one thing I do is take a return cut by reversing the feed rod not touching the tool bit and watch the chips they should get bigger toward the free end. Then take another cut and see how the chips look. if you really need it to cut straight use the tailstock and center. adjust the tailstock as required to get it straight this will only be on size for this distance longer or shorter will need more adjustment. bill


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