The Logan 820s are set up to control the back gear by a knob on the front of the headstock. The knob is attached to a shifter rack which "engages a pinion which rotates the eccentric shaft, thereby swinging the back gears into mesh" (quotes from Logan 820 manual). The weakness of the setup is that this critical piece is held in place by a smallish clamping ring, which is held in place by a small set screw. And, of course, I'm guessing it's all meant to be repaired upside down after one loosens the bolts holding the lathe to the bed. If this isn't an example of something being only as strong as its weakest part, I don't know what is...
This is actually the second time I've had the shifter rack come out in my hand; getting it back in the first time must have been beginner's luck. I guess I lost track of the last time I checked the set screw. I get my hand/wrist underneath and inside, turn the eccentric, think I've gotten the gear in the right place, but when I slide the shifter rack back in it doesn't work the gear as it should.
I'd appreciate any assistance on this, if anyone can talk me through doing it right.
Yes -- to preempt the response, I do know it gets special mention on the Logan Lathe board operated by Scott Logan; there is an instruction page for it. But that's pretty cryptic and just says "this part can be difficult".
Also, if anyone has a better idea for clamping it in place I'd love to learn. The drawing from the 820 catalog is below. There is no drawing I know that shows it in place.
Many thanks!
Tim
This is actually the second time I've had the shifter rack come out in my hand; getting it back in the first time must have been beginner's luck. I guess I lost track of the last time I checked the set screw. I get my hand/wrist underneath and inside, turn the eccentric, think I've gotten the gear in the right place, but when I slide the shifter rack back in it doesn't work the gear as it should.
I'd appreciate any assistance on this, if anyone can talk me through doing it right.
Yes -- to preempt the response, I do know it gets special mention on the Logan Lathe board operated by Scott Logan; there is an instruction page for it. But that's pretty cryptic and just says "this part can be difficult".
Also, if anyone has a better idea for clamping it in place I'd love to learn. The drawing from the 820 catalog is below. There is no drawing I know that shows it in place.
Many thanks!
Tim