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Advice/Help needed to disassemble ML7 headstock spindle

Replacing Backgears

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Roger Riley10/01/2017 09:58:29
6 forum posts

Hi everyone

I have just joined so please excuse me jumping in with a request for help straightaway!

I need to replace the x2 main backgears on my ML7 as both the bull-wheel (one with the small tooth selector) and the gear wheel below that on the eccentric have lost teeth. I have got the replacement gears from Myford and have installed/replaced the lower gear with no problem.

It is with the dismantling of the spindle where I am stuck - I have taken the small gear off the rear end of the spindle followed by the travel adjuster and ball race no problem.

It is the friction/interferance fit spacer/collar behind the pulleys that I can see no way of removing. Can anyone help me or advise? Many thanks in advance.

Roger

Andrew Tinsley10/01/2017 19:23:25
1630 forum posts

Hello Roger,

I too would be interested to know how to do this. I have my ML7 mandrel out of its bearings and looking at it, maybe one needs to press off the gears? I can't see any other easy answer.

Andrew.

John Olsen11/01/2017 23:36:48
1250 forum posts
94 photos
1 articles

Hi Roger,

There is a video on Youtube that might help **LINK**

The alloy pulley is I think a press fit on the bronze sleeve and small gear. Mine was going loose when the pulley heated up, which it will do with the friction of the belt. That was one reason why I converted it to the poly V belt. I think you will find that gentle warmth will expand the pulley enough to get it off the sleeve.

regards

John

Gordon A12/01/2017 01:06:34
157 forum posts
4 photos

Hi Roger,

The spacer collar is indeed an inteference fit on the mandrel. Leaving the spindle assembly in the fridge or freezer overnight and then some gentle heat on the collar may help. You will need to apply some "persuasion" to the face of the large gear to push the collar off. After this is removed the pulley and gear should just slide off.

Gordon.

mgnbuk12/01/2017 07:47:19
1188 forum posts
71 photos

when the pulley heated up, which it will do with the friction of the belt.

Only if the belt is slipping - vee belts drive by a wedging action & the belt should not be slipping to cause heat if sound & properly adjusted.

Never had much sucess with poly-vees in industrial applications. They don't need much wear to bottom out in the pulleys & then become inefficient flat belt drives. This may well be due to the way we were trying to use them, with maximum reduction ratios (small drive pulleys) on close centres - but designed & installed according to the belt manufacturer guidelines.

Nigel B

Michael Gilligan12/01/2017 09:02:13
avatar
20185 forum posts
1053 photos
Posted by Nigel B on 12/01/2017 07:47:19:

... Never had much sucess with poly-vees in industrial applications. They don't need much wear to bottom out in the pulleys & then become inefficient flat belt drives. ...

.

That's very interesting, Nigel ... Possibly the first negative experience I have ever seen mentioned.

... A few numbers might be useful for future reference [if it's not taking this thread too far off-topic].

MichaelG.

Roger Riley13/01/2017 21:41:23
6 forum posts

We have lift off!


A very big thank you to all of you guys you made me think about the problem and earlier today I managed to dismantle and change the bullwheel! I'm so relieved! The collar finally came off the spindle - I used a rubber mallet to knock the end of the spindle while holding the pulley cone against the bench vice jaws. The putting together again with the new bullwheel was a lesson in patience everything was 'tight as' - the collar did not want to go back on again and although I gave it a good thump there appears to be a little play in the pulley cone - like it has not gone back on far enough. The ball race and adjuster went back ok and the end cog. I remounted the whole assembly onto the shell bearings after coating everything in oil and married up the upper bearing halves and shims. After everything was tightened down I ran the lathe with a mike placed on the front of the mandrel - it flickers a fraction of a thou but looks good - no noise or vibration - no movement apparent from the pulley cone even with that slight play I mentioned earlier. So I'm hoping that might be problem solved - thanks once more to you all.

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