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20th May 2018, 10:10 PM #31australian metalworking hobbyist
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- Jan 2009
- Location
- Holbrook, NSW
- Age
- 73
- Posts
- 490
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20th May 2018, 10:49 PM #32Member
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- Apr 2018
- Location
- Sydney
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- 64
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20th May 2018, 10:50 PM #33Intermediate Member
- Join Date
- Apr 2016
- Location
- New South Wales
- Posts
- 45
According to the forum algorithm I am an intermediate member, which is not an indication of expertise. I am sure I do not know everything, other than the location of serial numbers. It so happens that I read posts several times then I jump to confusion, mixed with conclusions.
In my opinion, the sentence reading "what process would you recommend for measuring the minimal error in alignment of the tail stock other than getting a new one ?" while not exactly making sense, is answered by the earlier post #14 refering to the use of a "waisted cylindrical test bar". I could be wrong, as I do not know everything, but I think people in general don't know what they don't know.
"There is only very minimal offset when I bored a small hole using the tail stock, about less than 0.1mm on the small test piece." That's very good, incredibly good, considering what it sounds like you are doing. But I am not clear on what you did there, as I can only read your description not see it.
An 0.1mm error is about 4 thousandths of an inch, which I suspect will double in error to 8 thousandths of an inch on the workpiece near the tailstock when you turn something, if you are using the tailstock in the turning process.
It is also not clear to me what you will do to work around the "set over screw" adjustment, as the tailstock alignment occurs in two dimensions, one dimension the height corrected via your 3D printed spacer, and the second dimension corrected via the set over screw(s). If you put a spacer plate between the top and bottom halves of the tailstock I have the sneaking suspicion the set over screw(s) will not mate (screw together through the side, for lateral adjustment) from the top through to the bottom halves of the tailstock. I could be wrong about this, I do not have an Hercus tailstock anywhere near me to look at inside. Intuition, which could be wrong, suggests to me that if you have two chunks of metal with a set over screw running through both, after you raise the upper chunk of metal by 13.6mm or by ½" the screw may or may not be going to go in very far before it bottoms out. I do not remember what is the geometry / mechanism inside the tailstock for the sliding lateral adjustment of the top versus the bottom halves.
DT
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20th May 2018, 10:57 PM #34australian metalworking hobbyist
- Join Date
- Jan 2009
- Location
- Holbrook, NSW
- Age
- 73
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- 490
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20th May 2018, 11:07 PM #35Member
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- Apr 2018
- Location
- Sydney
- Posts
- 64
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20th May 2018, 11:14 PM #36australian metalworking hobbyist
- Join Date
- Jan 2009
- Location
- Holbrook, NSW
- Age
- 73
- Posts
- 490
To anyone who hasn't seen this bush method of Tubal Cain, the link I supplied was TAILSTOCK ALIGNMENT on LOGAN HARDINGE South Bend Lathes Part 2 - YouTube It works quite well. Not just the setover screws but gives the height difference as well.
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21st May 2018, 09:17 AM #37Senior Member
- Join Date
- Aug 2015
- Location
- Adelaide
- Posts
- 240
Hi ml018
Was this the DGM that was on Gumtree with the broken headstock casting?
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