Absolutely chuffed to bits!

[websterz]

Today I cut my very first metric single point thread! :big:

I have been working a 3 3/4" diameter lump of mystery steel down into the shape of an ER32 collet chuck for my 7x12 for the past several days. Today I finished turning the collet boss to diameter (40 mm or 1.575 for us Colonial types) and single pointed a lovely 1.5mm thread for the closer nut. Considering my lathe is Imperial I was a bit nervous about cutting metric threads on it. I was worried about nothing as it turns out! By a stroke of good fortune my new control board does not require that the speed be set to zero before reversing the motor. So it was a simple matter of one hand on the F/R switch and one on the compound. Back and forth, pretty as you please, until I had about 2 full threads engaging on the nut. Then I switched over to a double cut 3 corner file and dressed the thread until I had a very snug fit. A quick polish with 200 grit emery to clean up the ragged crown and the nut spins on and off like silk. Here's a video of the final result. (Sorry about the loud radio in the background)

http://vid797.photobucket.com/albums/yy258/websterzdesign/er32chuck.mp4

 

[steamer]

Congrats! Always a right of passage doing a metric thread on an english machine!

Dave

 

[arnoldb]

Well done Websterz Thm:

And YES - you needn't have worried - single pointing metric threads (or close-matching weird imperial ones!) on an imperial lathe isn't difficult at all as long as you keep the leadscrew nuts engaged

;D Enjoy your collet chuck; IMHO it's one of the most useful additions to a lathe there is for model engineering and making small parts.

Kind regards, Arnold

 

[websterz]

I will get some better quality vid of the finished chuck in action tomorrow. It's 98* outside right now and I am staying in the AC!

 

[websterz]

No video but here are a couple of pics of the final product. I added the 4 set screw holes and numbered them for easy reference. I also added 2 tommy bar holes. Ignore the mess behind the lathe...I'll get to it later. Oh, a little trick for indexing the part on the mill for drilling holes. I mounted a 3/8" stud in the collet chuck with a square nut on the end of it, held solidly with a smaller jam nut to keep it tight. It was a simple matter of rotating the chuck in the vise in 90* increments and clamping down on the square nut for equally spaced holes. Why set up the rotab for six quick holes?

The bar is the one that came with my mill for locking the spindle during tool changes. I built a spring loaded one a long time back but kept the little Chinese persuasion bar...knew I'd find a use for it eventually! As luck would have it the spanner that came with the lathe for adjusting preload on the spindle bearings is also a perfect fit on the closer nut. My lucky day!

And yes, the power was OFF when I left the tools in the chuck for the pic.