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Sherline Gear-Driven Power Feed

mikey

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Great detail, Russ. How does it work?
 

MSD0

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Pretty cool set up in the video.

The Sherline power feed was just a single speed, non-reversible rotisserie motor that was way overpriced. It came with an adapter to fit the motor to the end of the lead screw and it ran really hot. In my opinion, it was a POS.

A much better option is to hook up a reversible DC variable speed gear motor to the lead screw; direct drive via an adapter between the output shaft of the motor to the end of the lead screw works fine. This gives you variable speed and feed to precisely dial in a cut on the fly and it works extremely well. Gearing is fine but why bother tying the feed to the speed for turning? A VS motor is far, far better and is easily disconnected for threading.
I’ve been thinking about doing something like that on my PM1127. The lathe is so much quieter when the change gears are disengaged.
 

mikey

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I’ve been thinking about doing something like that on my PM1127. The lathe is so much quieter when the change gears are disengaged.
It might be worth a try. Your lathe has a saddle drive shaft that can be hooked up if you pull the drive gear off that shaft and hook up a DC gear motor to it. Speeds and feeds greatly affect the cut, both roughing and finishing, and my experience with being able to adjust both on the fly on my Sherline lathe has convinced me that it is a significant advantage.

My favorite materials to do this with are 12L14 and 6061 - mirror finishes on both - but it works for almost anything I turn on that lathe. I especially like turning O-1 at high speed for a finish cut but with a very slow feed; the finish is just fantastic under these conditions and you just cannot get that when the feed is tied to the speed through gearing.

Something to think about ...
 

blu73

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I've had a chance to play around with the power feed I built, and for me at least, it looks like a winner. As I've stated previously, I tend to take cuts of only .010 deep, but to see what the drive could do, I made cuts up to .030 deep in mild steel and the drive didn't seem to hesitate at all. Not very scientific, but with everything cleaned up, lubricated and adjusted, it worked fine. The test cuts were made with the 200 rpm motor installed. I'm thinking about changing that motor out for one that is rated at 100 rpm for better control of feed when turning a diameter. The down side of that would be giving up how fast the feed unit can get the saddle to move out of the way when I want to get a measurement or something. At 100 rpm on the lead screw, that's still about five times faster than the Sherline unit I had. My original reason for building this thing was to get away from having to turn the feed dial by hand when I needed to move long distances. The ability to independently adjust speed and change direction is great. It's all about give and take as far as speed and torque are concerned. I may find that the 100 rpm motor is an even happier compromise. If the 100 rpm motor works out as I hope, I've got a pretty wild idea brewing that I want to work on next.
 

mikey

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My motor is just under 100 rpm and it works great. Lots of torque, speed is adequate, control is very good. I suspect you might be happiest with the 100 rpm motor, Russ.
 

blu73

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You're probably right Mike. I got too caught up worrying about speed. At least I don't have too much money tied up in these things. The average price of a motor so far is around $15, so it's possible to experiment without spending a lot. It seems like I spend more time and effort designing and building things for the Sherline than anything else.

Russ
 
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