How to Build a Collet Adapter
Two years ago I sold my WW2 Logan bench lathe and other apparatus when I moved to Arizona. I had taken a shop night class 3 years ago and their 13″ SB with collets really caught my fancy. I had started making Pat Loop’s collet chuck for the Logan (1-1/2 – 8 tpi spindle) but it went with the sale.
Upon arrival in Arizona I revamped, insulated, and paneled a shed on the rear of my new home. Bought an air conditioner and then headed to a machinery dealer. Came home poorer but happy, having purchased a 12X36 gearhead lathe, a mill/drill, etc. Since my interest lays in the direction of small engine (3/4 bore Stuart), the 12″ lathe seemed like an overkill (especially when I degreased the 8″ 4 jaw D1-4, chuck).
Out came “Metalworking 2″ with a 5C collet adapter by Larry Van Duyn. Larry had a fantastic idea (to me) of utilizing a 5MT to 3MT adapter sleeve to make the 5MT to 5C adapter. Frank Mclean had written about setting up an angle using a dial indicator and some simple trigonometery (made simpler with a calculator). I tried setting up 30 degree angles, 45 degree angles, 60 degree angles, until I got tired. But I was then quite sure of my self as to the setting up the proper angle. Then to polish and hone a boring bar. Sort of holding my breath the cut was started. Great luck the marking chalk looked good enough for me.
A 1″ piece of galvanized pipe was my drawbar. I turned one end just enough to true it and remove the galvanizing for about 1-1/2 inches. My first threading on the new lathe was internal on a coupling that was threaded for half it’s length, bored to a slip fit to the drawbar the other half. My friend Lee welded the coupling to the drawbar. Made a collar for the outboard end and then needed a handwheel. I had picked up a 6” cast iron pulley from a junk pile thinking it would really be a classy handwheel. Wrong!!!
Between all that flywheel effect and the instant starting characteristic of the gearhead lathe, at 300 rpm the drawbar would unscrew. So I found a piece of 1/2 aluminum and practiced Mr. Lautard’s method of many narrow cuts. My CAD program really figured out the depth of cuts for me. I think that the width of cut could easily have been much wider. My hat is off to Larry, Frank, Guy, and the others who, through their writings, have contributed so much to my enjoyment of the hobby. These fellows, the pride of Joe Rice, almost make me feel like they are sitting on a chair behind me giving me a kind work of advice occasionally.
I am rather sold on the idea of 5C collets. I have a spindex which will accept 5C. Got that and a few collets some while ago. Picked up a few more collets as the spirit moved me. Nice when I have turned something in the lathe and want to add a flat, hex, slot, or what have you. I also bought a Sherline 3″, 4 Jaw chuck that is 5C mounted. That too will go from lathe to mill very nicely. Sort of shrinks a 12″ lathe when needed.
Author: Paul Pierce
