09-01-2013, 12:37 PM
(This post was last modified: 09-01-2013, 12:39 PM by Rickabilly.)
It does sound like you've done everything right, but...
Center height is super critical and any number of factors will change the height of a tailstock centerheight, from base or way wear, quill wear, damaged taper, damaged center through to a mismatched tailstock, that is a tailstock that has been switched accidentally in the factory or shop (it happens). either measure your centre from a reliable datum for eample the tip of a freshly turned cone in the chuck and then make an accurate guage for repeatability, also the tool tip needs to be on centre as much as the indicator and any clearances in the compound slide will muck you up as when testing with an indicator the slide is unloaded but whe turning with a tool the load on the slide is much higher and therefore clearances can open up.
Chalk is less than an ideal testing medium, it's too thick by a long way also the grain sizes are inconsistent, try engineers /prussian blue, and never fully rotate the tapers relative to each other;
1, coat lightly with testing medium,
2, insert test piece into hole firmly,
3, rotate relative to each other by no more than 1/6th of a turn and maintain side pressure in one direction only,
4, remove and inspect,
Many tapers will work if forced together with an arbor press, so this technique should never be used as any kind of test
And most importantly make sure it is all clean, and I mean super clean when testing tapers.
I hope this helps
Regards
Rick
Center height is super critical and any number of factors will change the height of a tailstock centerheight, from base or way wear, quill wear, damaged taper, damaged center through to a mismatched tailstock, that is a tailstock that has been switched accidentally in the factory or shop (it happens). either measure your centre from a reliable datum for eample the tip of a freshly turned cone in the chuck and then make an accurate guage for repeatability, also the tool tip needs to be on centre as much as the indicator and any clearances in the compound slide will muck you up as when testing with an indicator the slide is unloaded but whe turning with a tool the load on the slide is much higher and therefore clearances can open up.
Chalk is less than an ideal testing medium, it's too thick by a long way also the grain sizes are inconsistent, try engineers /prussian blue, and never fully rotate the tapers relative to each other;
1, coat lightly with testing medium,
2, insert test piece into hole firmly,
3, rotate relative to each other by no more than 1/6th of a turn and maintain side pressure in one direction only,
4, remove and inspect,
Many tapers will work if forced together with an arbor press, so this technique should never be used as any kind of test
And most importantly make sure it is all clean, and I mean super clean when testing tapers.
I hope this helps
Regards
Rick
Whatever it is, do it today, Tomorrow may not be an option and regret outlasts fatigue.