Loose mandrel V pulley assembly on an ML10

[Andrew TinsleyParticipant @andrewtinsley63637]

Just getting started on the simple spark erosion tool that Rob kindly found the diagrams for. Suddenly I lost drive to the chuck. Investigating further, the 3 cone V pulley was loose on the mandrel shaft. For what it was worth, I engaged back gear and the same problem. Started to look for a locking grubscrew on the pulley assembly. Could not see one, so took a look at the diagrams in the ML10 manual. There appeared to be no fixing device to couple the pulley to the mandrel.

Not doing very well today! Can any ML10 owner tell me how on earth the 3 pulley assembly is fixed to the mandrel?

More than likely I am missing something obvious, but goodness knows what!

Thanks,

Andrew.

[Martin of WickParticipant @martinofwick]

The cone pulley is designed to spin on the mandrel when the little wedge shaped key 51 on the bull gear is lifted out of engagement with the ring gear on the pulley.

Check that the the teeth of the key are pushed down fully engaged and locked into position with set screw 53 (which if not tight can allow the key to disengage due to centrifugal force.

Once you are sure the key is fully engaged  in the lower position with the teeth well meshed, check you have disengaged the back gear cluster and moved it out of position and locked it out with nut 69, pull on the belt to turn the pulley. All should be well, you should see the bull gear turn with the pulley, and the spindle should turn also.

I believe that the bull gear is keyed to the spindle with a woodruff key, but check the bull gear does turn with the pulley. If key 51 is fully engaged and the  bull gear and spindle does not rotate with the pulley, then there might be issues with the woodruff key. you can check setscrew 54, but I think this is really only to set fore and aft position, not lock the bull gear to the spindle.

 

 

[Andrew TinsleyParticipant @andrewtinsley63637]

Thanks Martin,

After much thought I came to the conclusion that the pullies were integral with the gear on the RHS. Then I realised that the backgear cap head screw must have something on the other side of the bull wheel which fitted the integral gear on the pullies.

Checking the manual diagram, this looked like item 51 which is called the backgear key. I suspect that this item has come loose and fallen into the murky depths, which explains my problem.

I decided to write down my thoughts in the small hours, as I am suffering from a bout of insomnia. Lo and behold, there was your post, confirming my vague suspicions. I shall hunt for the “missing” item 51 in the morning.

Thanks for taking the time to spell out in detail, my problem, much appreciated.

Andrew.

[HopperParticipant @hopper]

The acid test is the bull gear should rotate with the headstock spindle. If it does not, the bull gear key is sheared. Very unlikely but not impossible.

If the bull gear spins with the spindle but the stepped pulley and belts do not, then you are on the right track looking for the drive dog that locks the bull gear to the smaller gear on the stepped pulley.

The bull gear is the large 63-tooth iron gear at the large end of the stepped pulley on the headstock spindle. The smaller bronze gear next to it is the gear attached to the stepped pulley and should rotate with the stepped pulley. The drive dog locks these two gears together for direct drive when not using back gear.

[Andrew TinsleyParticipant @andrewtinsley63637]

Problem solved, there was a piece of swarf preventing the back gear key from engaging with the pulley gear. Because of the tight installation of the lathe, this was very difficult to see until I removed the belt guard cover.

Thanks everyone for increasing my understanding of the ML10! now to get on with making the simple spark eroder.

Andrew.

[HopperParticipant @hopper]

Good stuff! Carry on lathing.

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