Help me identify my headstock thread

[PeterSk]

OK, so the Clarke lathe is in my shop in all it's blueness, so today I went down to Toolpost in Didcot to get myself a chuck so I can start turning with a vengance.

I measured the thread before I went, and using my relatively accurate calipers it came out at 18mm, so I figured that 18mm is close enough to 3/4" that the difference was probably in the calipers.

However a 3/4" 16tpi chuck doesn't fit. Careful counting has revealed 6 teeth in 1/2" of measurable thread, so overall 12tpi.

Does this sound like a standard fitting anyone recognises? I've delved into the engineering charts but they aren't really much use, as I can't measure the threads down to thousands of a millimetre

 

[jlawrence]

No idea about you're actual question, but 3/4 inch is 19mm not 18mm.

 

[jasonB]

M18x 2.0 is a standard metric fine thread so that would give you close to your measured pitch. 6 teeth within 1/2" could well be more than 12tpi, you need to measure from crest to crest or root to root.

Machine Mart seem to list all but one lathe with 3/4x16UNC, the other is larger?

Jason

 

[Sportique]

FWIW - I would agree with Jason - to my knowledge the lathes stocked presently by Machine Mart take 3/4" 16 tpi - just a few days ago I happened to have such a nut with me in Machine Mart and it fitted their head thread.

Dave

 

[PeterSk]

This lathe is of unknown provenance, there is an instruction manual with it but it doesn't list important things like thread sizes, merely focuses on a 101 guide to turning.

A lot of head scratching and even more careful measurement with a steel rule and I now reckon its a M18 coarse thread, 2.5mm between threads. Anyone know where I can get an M18 to M33 adapter?

 

[tekno.mage]

You could try Phil Irons who imports Vicmarc kit - Vicmarc make a thread adapter (part number 100M1825) which should be suitable. Take a look here http://www.philironswoodturning.co.uk/i ... &Itemid=78

Kym

 

[Blister]

What is the model number of the lathe ?

 

[PeterSk]

Model number is a very good question. It looks identical to the CWL6B, however it has no identifying markings on it that I can find. The only details on it are the specs of the motor inside.

 

[Jonzjob]

You could have a look at this site http://www.machinemart.co.uk/shop/categ ... ccessories

It may help? Have a look at the 'more info' on the model you think you have, it gives headstock thread size.

 

[PeterSk]

I've already scoured the net looking for answers, and no-one really seems to admit to the existence of my model. All the Clarke documents I've found online say it should be a 3/4 16tpi thread, however this is clearly not true.

Anyway I've made the decision to get rid of this heap of junk and buy a proper lathe...