Homemade Tip Replacement Lathe

GorstyBoy said:
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Dial Up Modem....
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nataddrho said:
I purchased parts to make a homemade tip changing lathe. There are a couple other threads similar to this but their picture links are broken.

I already made a speed controller out of spare parts that I had, which generates 270 oz-in (1.4 ft-lbs) of torque from 100 to 1000 RPM... I think this is enough for tip shaping work...

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I am planning on directly coupling the motor to a chuck. I'll use cloth or electrical tape on the joint end of the shaft. The tip end of the shaft will fit though a pillow bearing with collets. My amazon order is under $101 including shipping.


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The bearings have set screws in them which I hope will allow me to adjust them using a dial caliper (which I don't own yet). I just plan on using a block of wood with a razor blade screwed into the top as a tool, or maybe just a block of sand paper.

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Is there anything I am missing?
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Im late to this thread but i use those same block bearings for my low rpm finishing lathe, that spins slowly while epoxy hardens.

It looks like your design is good enough, but if you wanted to improve runout you could use a belt and pulley to drive a mandrel that’s fixed in one of your bearings. That would require making a mandrel with a pin that matches your shafts, which would exceed your budget if you don’t have tooling already.
 
kling&allen said:
Im late to this thread but i use those same block bearings for my low rpm finishing lathe, that spins slowly while epoxy hardens.

It looks like your design is good enough, but if you wanted to improve runout you could use a belt and pulley to drive a mandrel that’s fixed in one of your bearings. That would require making a mandrel with a pin that matches your shafts, which would exceed your budget if you don’t have tooling already.
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The runout appears to be because he isn't using a bearing on his drive side. It appears he has his chuck mounted directly to a spider coupling.
 
kling&allen said:
I missed that. Amazon sells these bearings in packs of 2 so I assumed he had one on both ends of his shaft.
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Yeah, I can't figure this one out. The OP seems to have some knowledge, but this would be a perfect project to show what not to do for a lathe spinner. Several people have already commented on how great this looks, so maybe they are taken in by something.

In reality, this is no better, and possibly worse, than one of those spinners that use an electric drill strapped to a board with a bearing on one end. The drill ones at least have a rigid drive that isn't letting the joint end run anywhere it wants.

I'm not trying to be mean, but for anyone who doesn't know, the coupler on the motor is a three-part coupler that is made to be slightly flexible to account for any misalignment between a rigidly mounted motor and the driven end of a rigidly mounted shaft (shaft in the mechanical sense, not cue shaft). These couplers fit together by friction. When they are allowed to run like this, they can walk apart. If that happens while changing a tip, the shaft and chuck (and part of the coupler) will be sent flying.

I encourage people who want to build something like this to see some advice from someone who has worked in machine design.
 
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