09-16-2017, 08:06 AM
Thanks Pete. I did think about turning it between centres, but couldn't get my head around how I was going to get a center in the collet end of the arbor.
In hindsight, that would actually be really easy - just turn a short spigot to of diameter to suit a collet, center drill then part off and chuck it..
But there's always another way, and here's how I did it - similar, but not exactly "between centres":
Chucked a piece of stock and turned so it would fit one of the collets.
Left it in the chuck, fitted the collet to the arbor and clamped it up on the spigot. Managed to find a 7/16 UNF bolt in the depths of my scrap bucket, and fitted that in the drawbar end of the arbor with a few washers. Spun it up and center drilled the end to take a fixed center.
Here it is set up and turned to diameter:
Next issue was that I'd set the compound up to cut the taper on the tailstock end of the work, but it was now at the headstock end.
No problem, l'll just cut it on the rear of the job running in reverse. Wrong - not enough travel on the cross slide to get to it with a standard toolholder
Finally managed to get to it with a long boring bar. Definitely not ideal and the tool grind was crap so I battled a bit with chatter but got there in the end:
Next step was to make up a drawbar to suit the 7/16 thread in the new arbor. I've got a long high grade shoulder bolt from a previous life that is almost perfect - just needs cutting to length and threading.
Most of my threading gear is metric apart from a couple of small sizes - no 7/16-20 :(
No problem, I'll just cut the thread on the lathe
Except I haven't yet made the 126T change gear I need for 20tpi....
So the temporary solution was to machine down a length of 1" all-thread I've had lying around for 20 years just for this purpose, drill a hole in the end to take the shank of a 7/16 bolt and I'll glue it together with the MIG.
Here it is in all its nearly finished glory - will cut to length and throw some spatter at it tomorrow.
All going well the mill might even get to make its first chips tomorrow!!
Steve
In hindsight, that would actually be really easy - just turn a short spigot to of diameter to suit a collet, center drill then part off and chuck it..
But there's always another way, and here's how I did it - similar, but not exactly "between centres":
Chucked a piece of stock and turned so it would fit one of the collets.
Left it in the chuck, fitted the collet to the arbor and clamped it up on the spigot. Managed to find a 7/16 UNF bolt in the depths of my scrap bucket, and fitted that in the drawbar end of the arbor with a few washers. Spun it up and center drilled the end to take a fixed center.
Here it is set up and turned to diameter:
Next issue was that I'd set the compound up to cut the taper on the tailstock end of the work, but it was now at the headstock end.
No problem, l'll just cut it on the rear of the job running in reverse. Wrong - not enough travel on the cross slide to get to it with a standard toolholder
Finally managed to get to it with a long boring bar. Definitely not ideal and the tool grind was crap so I battled a bit with chatter but got there in the end:
Next step was to make up a drawbar to suit the 7/16 thread in the new arbor. I've got a long high grade shoulder bolt from a previous life that is almost perfect - just needs cutting to length and threading.
Most of my threading gear is metric apart from a couple of small sizes - no 7/16-20 :(
No problem, I'll just cut the thread on the lathe
Except I haven't yet made the 126T change gear I need for 20tpi....
So the temporary solution was to machine down a length of 1" all-thread I've had lying around for 20 years just for this purpose, drill a hole in the end to take the shank of a 7/16 bolt and I'll glue it together with the MIG.
Here it is in all its nearly finished glory - will cut to length and throw some spatter at it tomorrow.
All going well the mill might even get to make its first chips tomorrow!!
Steve