Thread adapter for mini chuck queries.

[Sachakins]

Hi,
Looking to get one of the 50mm 4 jaw chucks with M14 thread (K02-50 chinese) for ring turning (internal polishing)

Will need it to fit my coronet herald M33 spindle and SIP mini lathe 3/4 16tpi spindle, that belongs to SWMBO

First option would be for two thread adapters, one needs to be M33x3.5 female to M14 male and second a 3/4 16tpi female to M14 male
(I seem to recall a Sherline(?) adapter for the second, but poor review(?))
Second option would be an MT2 threaded 14mm arbor and an MT1 threaded 14mm arbor.
Third option would be an MT1 threaded 14mm arbor and a MT2 to MT1 sleeve adapter.

My questions are:
A) is threaded adaptor better than MT arbor or vice versa in respect of concentricity/runout, and which is the more secure holding?
B) is using a MT sleeve adapter a good idea, again in respect to concentricity/runout, and which secure holding?

Lastly, has anyone even come across a M33x3.5 female to M14 male adapter?

 

[Tris]

Can't help with much here except that a Morse taper is likely to come loose unless you are able to secure it right through the headstock

 

[minilathe22]

I would imagine the morse taper route to be easier to get and more likely to run true, threaded adapters need to have the correct sized register to locate them properly. But as Tris says, you need to make sure it cannot fall out, with a drawbar, or tailstock support (although for making rings this would not be very convenient)

 

[Rorschach]

If you are only putting a light load on it then a MT arbour will be fine, just give a good whack with a soft hammer to seat it. If you are going to actually do any turning etc then get an arbour with a thread in the back and fit a draw bar for safety.

 

[paul-c]

hi sachakins
would something like this not be a suitable solution that could just fit into any chuck

Stainless steel expanding ring mandrel S-Z+3 (USA 9-14) & Ring Cores PLEASE READ | eBay

cheers paul

 

[Dalboy]

What chucks do you have for both machines if axminster then a small set of O'Donnell jaws would be a better option. If not the MT route would be the better option but make sure you can put a draw bar in.

hi sachakins
would something like this not be a suitable solution that could just fit into any chuck

Stainless steel expanding ring mandrel S-Z+3 (USA 9-14) & Ring Cores PLEASE READ | eBay

cheers paul

That would be of no use as the OP wants to work on the internal surface

 

[Sachakins]

hi sachakins
would something like this not be a suitable solution that could just fit into any chuck

Stainless steel expanding ring mandrel S-Z+3 (USA 9-14) & Ring Cores PLEASE READ | eBay

cheers paul

Hi,
Made one of them in wood.
I need to grip the ring on outside so I can polish inside the ring.
Thanks for your input.

 

[Sachakins]

What chucks do you have for both machines if axminster then a small set of O'Donnell jaws would be a better option. If not the MT route would be the better option but make sure you can put a draw bar in.

Record power SC4 & SC2, could use pin jaws. But advantage of these mini jaws you can grip internal and external with out having to change chuck, ideal when polishing, rather than changing from mandrel to chuck all the time..
Thanks for your suggestions.

 

[Richard_C]

If you go the MT route I think a drawbar is essential. Look on this forum for a discussion on drawbar chucks a few weeks back. Not all MT tapers are internally threaded but typically you just need a length of 6mm or 1/4 inch threaded rod screwed into the arbor and secured with a big washer and nut at the handwheel end.

If you put side pressure on an unsecured MT fitting in the powered end it can move and precess out very quickly.

 

[Sachakins]

T

If you go the MT route I think a drawbar is essential. Look on this forum for a discussion on drawbar chucks a few weeks back. Not all MT tapers are internally threaded but typically you just need a length of 6mm or 1/4 inch threaded rod screwed into the arbor and secured with a big washer and nut at the handwheel end.

If you put side pressure on an unsecured MT fitting in the powered end it can move and precess out very quickly.

Thanks, good advice.

 

[paul-c]

Hi,
Made one of them in wood.
I need to grip the ring on outside so I can polish inside the ring.
Thanks for your input.

hi i miss read that. sorry.

on my axminster chucks i have a set of wood jaws which i can just turn an opening to whatever size i need ( when standard jaws are not suitable.)
essentially a bit like a jam chuck.
would this possibly be an option - i realise the downside is that would mean changing chucks which is what i assume you are trying to avoid.
also just thinking along the same lines - if you were to drill and put a small dowel in each wood jaw (so that they ran true)
that would be able to hold the ring externally - im just not sure about the internal diameters of your rings - if the dowels would fit to hold on the inside.
cheers paul

 

[Sachakins]

Hi, cheers for that idea on dowel pins, might try that out before spending out on chuck. Thanks for your input.

 

[Sachakins]

Hi all, thanks for your inputs.
Had another solution offered to me from a friend, which gave me massive dose of a "DOH" moment, followed immediately by me experiencing that, why was I so dumb, or as it was put to me "...for a clever guy, you can be a dumbshit at times..."

Answer is, resize my diy mandrel to fit my pin jaws instead of my 50mm jaws, then I have an instant way to hold ring, as pin jaws in compression fit all my ring sizes when I have to do a quick polish on the inside.....!

To protect the finished ring outer, I just slip a small rubber sleeve on it (slices off a bike inner tube ).

So that teaches me to stop over thinking and over complicating solutions.

So nett result is a total zero cost solution, that is fast to do. Plus already have a m33 to 3/4 16 tpi adapter, so can use the sc4 and sc2 on either lathe.