lathe spindle thread help

[general--lee]

hi i brought a new lathe (another thread below) it has a 3 bolt fixing spindle but it came with a face plate and a 4 jaw which are on a threaded boss which is very similiar to a friends colchester thriumph but the nose before thread is deeper so mine are ....

about 2 1/2 inch at threads by 6tpi ,

internal diameters are 58mm on thread and 66mm on plain shoulder and the shoulder is 22mm deep does this sound like anyones lathe fittings?

basically my mates is same but 29mm plain shoulder

what im after is finding out what they fit then by a spindle off the lathe and cut nose off and make a boss to bolt on to my flange if that makes sense!!!

thanks ken

 

[graffian]

I think it makes sense.
what I think you want to do is buy a billet, turn it to fit the flange, bolt it to the flange and then turn it to be the sort of nose you want. unless your really lucky the spindle from a lathe is going to cost a lot more than a bit of steel.

Could you do a simple sketch, draw it and the photograph it if you don't have any drawing software. 6 TPI sounds very fine, my cincinatti had something like 2.5TPi[it was fractional and the lathe was capable of cutting it] There are standards for spindle noses I will have a look at them, i woudln't be suprised if not a lot of makers followed them;-)

 

[hareng]

What lathe is it?

I can tell you its not an LOO fitting as in older pre 1965 Harrisons before they went camlock.

 

[MrFluffy]

Harrison l5a's had a 2.25 X 6tpi nose before they went to a l00 fitting on the last of the l5a's. I have one on my l5a, along with a L00 faceplate that I can't use with it
So, it sounds very much like a 2.25" l5a nose fitment. I believe there were some other lathes fitted with them too. I cant check the register dimensions for you however as my lathe isnt here yet...

You can verify the information over at lathes.co.uk :-
http://www.lathes.co.uk/harrison/

I wouldnt bother making a adaptor, for the grief your opening yourself up to, you'd be better removing the two backing plates and getting some blanks and turning them to fit what your lathe uses.
If you use a spindle adaptor mounted in the chuck, you will have repeatability issues when you remove and remount the spindle unless you devise some way of re-indexing it back to the original place, and even then if you get any dirt or swarf in there, itll be miles off. Itll be a world of pain long term.
If you turn the new backplates up for the chucks on the lathe itself, you stand the very best chance of making it repeatable and accurately centered. Indeed its supposed to be one of the steps to fitting a new chuck to a lathe properly.

The old backplates have some resale value too, I paid £20 for a 6" one from g&m a while back. You probably will get a decent price on ebay described properly...

 

[general--lee]

hi sorry been away for last few days (fishing in the lake district with horizontal rain!!)

i will take some pics and do a drawing
other then getting a spindle off the correct lahte i will 'try' turning one as graffian said i was going to bolt it lathe spindle then face it turn it round then make nose ???

oh and the internal thread on the chuck and faceplate i want to fit are definatly 6tpi i have a gauge


thanks ken