Craftsman lathe

[larry phelan 1Participant @larryphelan1]

I have noticed a strange effect with my lathe. When I engage forward running, the start up is quite smooth, but when I engage reverse there is a distinct "jump" as it starts. I thought this might be due to electrical connections, but changing around the leads [it is 3 ph, working from a rotary converter ], it had no effect.

I seems to be more mechanical than electrical, as if the gears dont like engaging in reverse, but run smoothly once they get started. The machine runs OK, it,s just annoying. Anyone got any ideas ???

Has anyone else experienced anything like this ?

PS The lathe is belt driven, could this be a factor ?

[larry phelan 1Participant @larryphelan1]

[BazyleParticipant @bazyle]

Is it just taking up backlash in all the gear trains? Might also be the belt if it is slack.

[larry phelan 1Participant @larryphelan1]

I dont know if it is backlash, but it never happens when running forward, only in reverse.

I will check the belt, which is a link type. The original one died from old age a few years back.

Thanks for your reply

[Coggy CParticipant @coggyclapsaddle]

I have a craftsman and find it pretty smooth starting in either direction, certainly no discernable difference between forward and reverse. It is a relative new machine.

[BazyleParticipant @bazyle]

Pulley or gear loose on due to loose grub screw perhaps. Can you get at the motor pulley to rotate by hand and gradually work through the drive train.

[Clive FosterParticipant @clivefoster55965]

Link belts are asymmetric and all have preferred direction of rotation for maximum power transmission and smoothest running.

Given that they are still wedge belts that sit down into the pulley under load to increase friction and drive capability its possible that a slightly slack belt won't sit down into the pulley groove so smoothly when running "backwards"

Looking at the Fenner Power Twist type it's fairly easy to visualise how such effects might happen. The directional arrows on the link show normal running to be with the tails trailing so it's plausible there is some sort of push effect on the tails increasing tension which isn't present when running the other way. If so its plausible that there is a directional effect as the belt settles into its groove and takes up the drive.

Clive

[larry phelan 1Participant @larryphelan1]

Thanks for the many pointers, will check out everything.

Not easy to get at the motor pulley [are they ever ! ], but needs must .

I did suspect that the link belt might be the cause and was thinking or reversing it to see if the same thing happened, in reverse, as it were. Clive may be quite right.

To Coggy, I suspect you still have the original belts, so may not have come across this effect. The reason I fitted a link type was because I did not fancy the hassle of removing shafts ect, I tend to leave well enough alone, but I might give it a try. As a matter of interest, link belts are about three times the price of standard belts.

I will check out everything, and again, thanks to all.

[Coggy CParticipant @coggyclapsaddle]

Posted by larry phelan 1 on 18/02/2023 08:39:30:

To Coggy, I suspect you still have the original belts, so may not have come across this effect. The reason I fitted a link type was because I did not fancy the hassle of removing shafts ect, I tend to leave well enough alone, but I might give it a try. As a matter of interest, link belts are about three times the price of standard belts.

I will check out everything, and again, thanks to all.

Yes, I'm still running the original belts.

Edited By Coggy Clapsaddle on 18/02/2023 17:19:00

[larry phelan 1Participant @larryphelan1]

Regarding the problem with my Craftsman lathe, I think Clive Foster hit the nail on the head pointing to the link belt.

I replaced it to-day with solid belt and it seems to have cured the problem.

My thanks to all.

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