Do me a favor.

dpb

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 8, 2016
Messages
241
1340gt & 1440gt owners: put an indicator on the side of your spindle chuck, apply some pressure, and tell me how much movement you see. By pressure, I just mean to lean on it a bit, no shoving, no levers. Imprecise, I know, but I'm curious about the results. Thank you.
 
On a 1340GT at 4" out from spindle, pushing and pulling on my 5C chuck, I get +/-0.0001" deflection with about 20 lbs of force.
 
I don't like where this is going. No one asks a question like that unless there is a noticable amount of movement.
 
1340gt & 1440gt owners: put an indicator on the side of your spindle chuck, apply some pressure, and tell me how much movement you see. By pressure, I just mean to lean on it a bit, no shoving, no levers. Imprecise, I know, but I'm curious about the results. Thank you.
Indicated from where?

Sent from my SM-G955U using Tapatalk
 
I put a magnetic base on the carriage, with a dial indicator on the right end of the side of my 3 jaw.
 
I don't like where this is going. No one asks a question like that unless there is a noticable amount of movement.
There's not that much, about what MKSJ is experiencing. I'm trying to track down a minor taper issue, and I didn't have anything to compare to.
 
Where/how are you experiencing a taper. Have you done the leveling and headstock alignment. Many chucks have some degree of skew in clamping stock, it can be quite significant and also can vary based on the clamping diameter of the stock. If you provide further information, we may be able to give more specifics.
 
The lathe is level, and Rollie's Dad's method agrees with this assessment. I have not adjusted the headstock.
1.25" 4140, protruding not more than 1.5" from the chuck, will show .0002-.0003" of taper over 1". This seems to occur regardless of depth of cut, feed, etc.
2" aluminum shows no taper, over 1". I don't have a longer piece of aluminum to test.
The difference between the two materials suggests that perhaps I am just dealing with material flex, I don't have enough experience to tell.
I realize this taper is pretty insignificant, for most purposes, I'm just curious about it.
 
The lathe is level, and Rollie's Dad's method agrees with this assessment. I have not adjusted the headstock.
1.25" 4140, protruding not more than 1.5" from the chuck, will show .0002-.0003" of taper over 1". This seems to occur regardless of depth of cut, feed, etc.
2" aluminum shows no taper, over 1". I don't have a longer piece of aluminum to test.
The difference between the two materials suggests that perhaps I am just dealing with material flex, I don't have enough experience to tell.
I realize this taper is pretty insignificant, for most purposes, I'm just curious about it.

A one inch test cut is a little short -especially if you're using carbide cutters. Depending on the cutter and several other factors, it could take about 3/8" of travel just for the cut to stabilize.

Ray
 
I am using carbide, CCMT / CCGT in this instance. The diameter is larger, away from the headstock. I did not know about the need for a cut to stabilize.
 
Back
Top