Colchester Lathe Help

[punkinracer]

Many moons ago when I bought my MK1 Colchester Dominion, I watched the old codger selling it do his sales pitch. He through a shanked drill chuck in the head stock and said something like "for turnin' small stock you can do this" then he went on and on about other stuff. Well at that time all I'm thinking is that it's purdy green colour and I have to own this thing! Should have paid attention I suppose! The other day I remembered what this old guy did and took my MT3 tailstock chuck and tried it, well it damn near fell through the spindle hole! So mees a thinkin' the internal spindle taper aint MT3! So any body know what it is? And what do you do with the captured nut on the spindle nose, I doubt that it is free to spin on its own in a situation like that? I don't really need to hold stock this way but it just got me thinkin'!

[SGW]

http://www.lathes.co.uk/colchester/ may have useful information.

[punkinracer]

Thanks SGW, that link is getting bookmarked!

This is taken from that link:

The 1.5" bore No. 3 Morse-taper (bushed down from a No. 5 Morse) headstock spindle carried an American L (long-taper) nose - this consisted of a large screwed ring, captive on the headstock spindle, with a matching thread and keyed taper in the chuck backplate.

So what does that mean??? Is that suggesting that the taper is the same as MT3, just bigger diameter? Pardon my ignorance!!!

Thanks,
Pat

[bikepete]

It means the spindle internal taper is Morse 5, can't remember dimensions but considerably bigger than Morse 3, but that the lathe originally came with an adaptor sleeve which was 5 morse external and 3 morse internal so that you coudl use the more common MT3 tooling in the spindle.

Hope that helps,

Pete


[This message has been edited by bikepete (edited 10-26-2005).]

[punkinracer]

Thanks Pete, something just clicked - I think I have that adapter sleeve kicking around - that is what it was for!!!

So say I use this adapter and my tailstock chuck in the headstock - probably need a drawbar too huh? What happens to the captured nut then, it don't come off so is it left to spin around on the spindle?? Not sure I like that idea.

Pat

[bikepete]

Drawbar - yup, good plan. You'd probably get away without if you're just drilling with no side loads (though I like a drawbar even for that - hate to have things spinning in the spindle), but for any milling or boring heads etc or of course collets you'd need one. Should be do-able to make.

Captive ring - no experience with that lathe myself, so just guessing - if it bothers you to have it loose maybe you could just leave a faceplate or chuck backplate fixed on it, and with a bit of luck the centre hole will be big enough not to interefere with tooling/stock held the spindle bore.

Cheers, Pete

[Timleech]

<font face="Verdana, Arial" size="2">Originally posted by punkinracer:
What happens to the captured nut then, it don't come off so is it left to spin around on the spindle?? Not sure I like that idea.
Pat</font>

I used 5C collets quite a bit with my Student (similar to Dominion), just left the ring loose, no problem at all.

Tim

[punkinracer]

Thanks guys you've been a geat help. I'll try the nut loose and if it scares me I'll try a spare back plate route. Tim - has your loose nut chewed up your spindle nose at all? I hope that wasn't too personal of a question!!!

Thanks again,
Pat

[Timleech]

<font face="Verdana, Arial" size="2">Originally posted by punkinracer:
Tim - has your loose nut chewed up your spindle nose at all? I hope that wasn't too personal of a question!!!

Thanks again,
Pat</font>

My nuts and my nose were still fine when last I checked &lt;BG&gt;

Tim

[JCHannum]

A good project is to turn up a spindle protector with the LO-- internal taper and the male thread to both retain the nut from doing the spindle and itself damage and to prevent the odd mishap from damaging the spindle taper.

I made one from plastic for my threaded spindle.

[punkinracer]

Good idea JC, any idea on what thread my nut would be? It's strange looking, seems like every other pitch is missing. Hard to explain - the valleys are like twice as wide as the mountains! Man my old profs would kill me for talking like that but I can't remember the terminology at the moment.

Pat

[lynnl]

Maybe 'crests' and 'roots'?

I know the feeling. I can never think of terms when I need them either.

[Timleech]

<font face="Verdana, Arial" size="2">Originally posted by punkinracer:
Good idea JC, any idea on what thread my nut would be? It's strange looking, seems like every other pitch is missing. Hard to explain - the valleys are like twice as wide as the mountains! Man my old profs would kill me for talking like that but I can't remember the terminology at the moment.

Pat </font>


It should be 4 1/2" x 6, I imagine as it's an American system it'll be ordinary UN thread form.

Tim

[speedy]

You can use your 6" drive plate to hold the ring nut captive. or you could wedge in a short length of rope between the nut thread and spindle OD, easy .

Ken

[scottie]

i got a spindle nose adapter for my dominion on ebay a few years ago, but i dont have the spindle bush.
the spindle is a #5 morse taper
scottie.
p.s. it is 41/2x6 thread

[This message has been edited by scottie (edited 10-26-2005).]

[This message has been edited by scottie (edited 10-26-2005).]