Fitting Metric Chuck and Fitting to Flexispeed

[Michael GilliganParticipant @michaelgilligan61133]

Posted by James Alford on 06/10/2015 07:40:29:

Thank you for all of the suggestions. The one which I originally favoured was turning off the existing thread, fixing on a sleeve and threading it to fit the new chuck. However, having looked carefully at the spindle, the wall between the inside taper hole and the outside, once the thread has been removed, will be very thin, especially near the end. This rather puts me off the idea.

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… Which takes me back to my original suggestion of truncating the threads and tapping the adapter to match.

Happy to discuss this further, if you wish.

MichaelG.

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P.S. … The viability of the 'overhang' version would depend largely upon what work you expect the lathe to do.

Edited By Michael Gilligan on 06/10/2015 10:02:40

[Robert DoddsParticipant @robertdodds43397]

James, Michael,

Don't underestimate the problems with truncated threads at the sizes involved and with limited or no screwcutting capability.
To be effective the 1/2" tapped hole in the adaptor needs truncating as well as the O/D of the spindle nose. Without a single point screwcutting capability it would require a reduction on O/D of a 1/2" tap by careful grinding to produce the truncated thread in the adaptor. Its very likely that if free hand ground the tap would run off and ultimately affect the concentricity of the chuck.
After our esteemed editors work on the Mega Adept I was persuaded to fit 14mm metric chucks to a Super Adept but there the nose thread is 3/8" so I had plenty of metal to work with an adaptor.
My cautionary tale here is with regard to the register diameters of different chucks. One new off Flee bay and another from RDG and I got one of each of !5 and 16mm register diameters with different spigot depths as well.
Needless to say I made the adaptor to suit the first, longer one so the later one butted against thread rather than the register face of the adaptor.
So, Check out the detail of the threads and register diameters in your proposed chucks before you buy.

Bob D

[Michael GilliganParticipant @michaelgilligan61133]

Robert,

A quick 'thought experiment' for you …

1. What does the leading portion of taper tap look like ?
2. How difficult would it be to grind away the following [full-depth] section, so that it's below the diameter of the lead ?

MichaelG.

[Robert DoddsParticipant @robertdodds43397]

Michael,

Your point is well made It's a technique i've never needed to use before. With the extra wall thickness on my nose adaptor I chose to complete both threads in a single chucking leaving only a truing skim to size on the Adept after parting off and truncated threads were not a consideration for 3/8 BSF.

I'll go away and reconsider my position in the local Bodgers Society.

Bob D

[Neil WyattModerator @neilwyatt]

For the record, my little lever scroll is the backplate type, so I've made an 1/2" threaded backplate for the adept.

Perhaps a chuck swap with someone who needs a 14mm threaded chuck would be the simplest solution for the OP?

Neil

[James AParticipant @jamesalford67616]

I ordered a new 65mm od, 14mm threaded chuck which arrived today. Over the next week or so, I shall have a good look at it and see which suggestion I feel most capable of doing successfully and which suits the particular chuck. I shall update on my progress.

Regards,

James.

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