Thanks Stan. Thats alot of info. Bottom line is I just want to be able to part mild steal,brass,aluiminum one inch in dia. and smaller. I would think that if the speed is around a hundred RPM one could part above listed materials of said dia. Ofcourse, I am speculating. The only thing I know for sure is at 500RPM one inch leaded steel does not part without a great deal of vibration. I am still a little unsure as to weather I will only utilize the sherline motor or go for the entire headstock assymbly. I have two taig lathes. One has the new power feed and one (my first) without. When I got the new taig lathe with power feed I utilized the motor (stock taig motor) from the old lathe. It is the old lathe that I intend to set up with the sherline motor. For general work I find the stock taig drive with power feed great. So, I figure I can utilize it as is and switch chucks with work intalled over to the older lathe with varible speed when low speed, high torque is needed. Seems like a good plan,but, I guess only time or those with other experiance will tell.
--- In firstname.lastname@example.org, Stan Stocker <skstocker@...> wrote:
> Hi Johnny,
> The Sherline has a slightly larger pulley on the spindle. Sherline
> specifies the usable lathe RPM range to be 70 - 2800 RPM. The low speed
> actually is usable, so I'll ballpark a Taig set up with Taig pulleys on
> a Sherline motor will get down to around 100 to 125 RPM.
> Sherline pulley ratios are approximately 4:1 for the low speed torque
> belt position and 2:1 for the high speed belt position. IIRC, the Taig
> low RPM spec is 500 for a 1725 motor, so the existing pulley set will
> get you close but not quite down to 70.
> On small lathes if you really need very low speeds you may have to bite
> the bullet and go with a jack shaft setup as is common with watchmakers
> lathes. I don't think there's enough meat in the small lathe spindles
> to pull off a traditional back gear setup, more importantly to me is
> that it wouldn't give you anything a jackshaft doesn't, and would be a
> large amount of work! An alternative drive would be to go with a servo
> motor and controller, although this is an expensive or careful shopping
> option. Never done this one myself, but some have done this.
> If you have to do lots of slow speed work, and don't mind giving up
> higher speeds you can always make up a single groove pulley set to
> accommodate your needs. A four inch diameter pulley would fit without
> having to remove the carriage stop rod, with the stop rod off a stock
> Taig has enough room to have a 9 inch diameter pulley. With a 3/4 inch
> driving pulley you would have a 12:1 ratio. Probably be able to turn
> with good torque down to around 20 RPM.
> With a continuously variable motor, probably a three step pulley could
> cover the entire range for not too much extra work. This would allow
> both the lowest Sherline speeds or lower, and well as allowing the 5K
> speed Taig supports. Not used all the time, but occasionally nice for
> polishing. Not sure I'd try this with a 9 inch pulley, but with a four
> inch largest pulley it would be workable. A nine inch pulley running a
> 5K would be just a bit too spooky for me :-)
> If you rarely need a really low speed you can always just add a
> handwheel to the outboard end of the headstock. To do persnickety stuff
> cozy to a shoulder sometimes I use the WW closer handwheel or hand pull
> the belt to turn the spindle very slowly while looking through a loupe.
> Only suitable for very fine cuts, but it you're hogging waste you're not
> likely to be viewing the cut under higher magnification.
> Take care,
> On 02/18/2011 11:26 PM, Johnny wrote:
> > Thanks for all the input on the sherline motor conversion. I am leaning toward using the stock taig pully's. I have a spare and It will be less expensive than the entire sherline headstock assymbly. Can someone tell me what the low end speeds will be with taig pullys on both motor and headstock? What is the lowest speed I can expect? Will this low speed give good torque for parting?
> > Thanks again.
> > Johnny