Lathe Dead-Centre Collet Taper

[rodabod]

Hi,

Does anyone know if it was a standard taper that was typically used for 6mm and 8mm dead-centre collets on watchmakers lathes? Morse Taper maybe?

I wish to mount a Jacob’s chuck on mine by turning an arbor for the drill chuck. So far I have turned a small section of brass to get an idea of the dimensions. I ended up with a 10mm arbor with a large end of 4.4mm tapering to 4.2mm at the smaller end. I adjusted the taper by using ink to highlight the high points when fitting, but I’d rather use a cross-slide to cut an exact known taper.

 

[khunter]

From what I have read each maker used their own "standard", I measured mine when I got it (a Boley clone), it measured 4mm to 3mm over a 17mm length. Doing the math on a cad program it gave me something like 1.7 degrees included angle. The way you are doing it is about the only way to get it to fit your particular lathe. There's a video somewhere on YouTube where the guy is doing exactly how you are for the same purpose. 

[rodabod]

Thanks. I've tried doing that methodically, and the Jacobs chuck fits solidly, but is not completely true depending on what angle it enters the collet.

I think I may turn a straight arbor for the chuck and then mount in the largest collet I can find, eg. a 6mm collet, as I reckon this would turn truer.