Pinion Gear Tooth Profile

[G-ManBart]

Hey all,

***Update*** Shockingly I called Logan Actuator, and they still carry this part, so I won't have to make one. It wasn't on their website, but they said they offer a lot more parts than they show. This is for a Logan 6510H.

Long story short, I purchased a lathe recently and there was an "incident" during loading that caused damage to the apron hand wheel pinion shaft. It wasn't my fault, and luckily there is no other damage...literally almost a miracle. The pinion shaft is slightly bent and needs to be replaced. I pulled the apron, removed the pinion and noticed the tooth profile on the gear is unusual. It's like the teeth weren't cut all the way through and the shape is consistent on all the teeth.

This isn't caused by wear...the teeth fit the rack nicely where they mesh, and there was very little slop in the hand wheel. The teeth also nicely match the profile on a gear tooth gauge. The area with the taper does not fit a tooth gauge...they are far too thick. In the picture with the red line it's clear the area to the right of the line is shiny and is the only part of the gear to engage the rack. The rest of the lathe is quite nice and the shop owner claimed they bought it new, and it was clearly maintained properly.

It appears I'm going to have to make this pinion and figured it's worth asking if I should attempt to duplicate this tooth profile, or just cut the teeth all the way through. Would there be any reason to have the wider section with the tapered profile? I looked at my two other lathes and the corresponding pinion gear has normally shaped teeth.

 

[Provincial]

It looks like the gear cutter was not run all the way through the gear blank. What you see as tapered is the runout of the gear cutter. When it stopped feeding at the end of the flat bottom, the shape of the cutter caused the tapered area you wonder about.

To make a new gear, use a cutter designed for a straight spur gear. Cut full depth to your red line, and don't worry about the runout.

 

[G-ManBart]

It looks like the gear cutter was not run all the way through the gear blank. What you see as tapered is the runout of the gear cutter. When it stopped feeding at the end of the flat bottom, the shape of the cutter caused the tapered area you wonder about.

To make a new gear, use a cutter designed for a straight spur gear. Cut full depth to your red line, and don't worry about the runout.

Okay, that's exactly what I thought happened, but figured it was worth asking....thx!

 

[Dave Smith]

you could try to straighten to bent shaft first.
Dave

 

[G-ManBart]

you could try to straighten to bent shaft first.
Dave

I've thought about that, but it's right at the transition from gear to shaft so it might be tricky. There's a bit of a groove (hidden by the bearing in the pictures) that pretty well lines up with the bend and was probably the weak point. The rest of the shaft looks straight and wasn't binding on the other half of the apron.

I just talked to the folks at Logan Actuator and the part is available so I ordered one....not cheap at $180 but it'll save me a lot of time.


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