I am confused

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.
 
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.
Click to expand...

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

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


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.
 
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...
Click to expand...

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.
 
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.
 
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.
 
Last edited:
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.
Click to expand...

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.
 
You must log in or register to reply here.
Back
Top