ML7 spindle overhaul

[Peter BondParticipant @peterbond14804]

After a considerable period of time in storage, I've been able to sort out enough space to retrieve my ML7. Had only just bought it when it had to be mothballed, so it has acquired a coat of brown in the meantime, annoyingly; most of it cleans off with WD40 & Scotchbrite at least.

One thing I hadn't understood when I bought it was that the backgear is trashed – both the bullgear and the smaller gear of the cluster. I've taken the spindle out, but other than undoing grub screws (and in the case of the screw retaining the 25T gear at the rear of the spindle, destroyed it) I can't get much to move.

I've seen that the 25T gear is press fit – but so far nothing I've tried has moved it. The pin beside the threaded collar should theoretically come out with pliers, but I haven't tried yet. Additionally, the screw retaining the backgear cluster appears to be blocked and I can't get a key into it. Can't quite see what's going on there, unfortunately.

Any suggestions on removing the gear as well as extracting the backgear cluster, please?

TIA

[Peter BondParticipant @peterbond14804]

How do you take it apart?

[RobboParticipant @robbo]

Have a look at the exploded diagram here **LINK** it will help you see how it goes together – and comes apart.

It's a long time since I had an ML7 headstock apart, so will have to dig in the memory grey cells and see what I find!

Edited By Robbo on 17/12/2014 10:07:01

[Peter BondParticipant @peterbond14804]

Thanks – but at the moment I'm stumped on just removing the tail end gear (#7). No room to get a puller on, doubt that I could use a small wedge (thinking bearing splitter) without risking damage to the threaded collar and I suspect that clamping the gear and trying to drift out the spindle would knacker the gear, even with some copper wrapped around it.

[Martin KyteParticipant @martinkyte99762]

Just looking at the exploded diagram and it occurs to me that if you unscrew the threaded collar it should push the gear off the spindle. You say that you have removed the grub screw. As the gear is keyed onto the spindle it should just be a push fit rather than a press fit.

regards Martin

[Gordon AParticipant @gordona]

Insert a suitably sized open ended spanner between the threaded collar and the 25T gear. Gently heat the gear and carefully lever it off in stages whilst rotating the spindle by hand, loosen the collar as you go to take up the gap; it worked for me.

Sorry but I have not had any experience with removing the backgear cluster.

Gordon.

[Gordon AParticipant @gordona]

Forgot to say, but I found that the 2BA thread that is cut half in the gear and half in the spindle was burred at the edges causing the gear to jam on the spindle. A little more effort was required in this area.

Gordon.

[RobboParticipant @robbo]

To remove the backgear cluster, you must first remove the 21/56T gear cluster (50 on diagram) by removing the csk socket screw (48) in its centre, there is just enough room in the headstock to push the gear off its spindle

Then remove the backgear lever (53), there are 2 grubscrews one at rear and one underneath, usually covered in paint and gunge. Take these out and prise/push/ wiggle/swear the lever off the eccentric assembly (51) where it protrudes through the headstock.

The eccentric assembly can then be pushed into the headstock and removed.

As has been said, the gear on the end of the spindle (7) should push off once the locking grubscrew (6) is removed.. It may be very tight so try the methods suggested.

Phil

[Peter BondParticipant @peterbond14804]

I may have some odd ideas about "gently heat" – is this well below black heat? I was concerned that getting too carried away would destroy any HT on the gear. A suitable size spanner might be a bike spanner (or I'll just cut a slot in some mild if needs be).

The csk screw on the backgear cluster is definitely blocked; worst case I'll carve a slot in with a carbide burr I suppose. Don't like destroying fastenings as it's always a pain trying to get the replacements – virtually everything I have is metric rather than Imperial.

[Gordon AParticipant @gordona]

Hi Peter,

You could use a bike spanner or maybe a couple of large screwdrivers diametrically opposite each other . I used a cook's blowtorch with a very fine flame on the gear whilst rotating the spindle. The whole assembly had been stored in the refrigerator overnight (coated in oil and clingfilm). I don't think the temperature of the gear reached much more than that of boiling water, too hot to touch but nowhere near changing the colour. It just seemed to make the job easier.

Good luck

Gordon.

[Peter BondParticipant @peterbond14804]

Success, thank you! Some gentle warming with a Sievert, coupled with driving a slim wedge between the threaded collar and the gear started things enough to get a bike spanner in. The collar was a bit of a pig too, I suspect there may be damaged threads (no copper plug in the hole) which will need to be deburred.

Pulley next.

When it comes to aligning the gear for reassembly, is the sensible way to line up the half holes with a bit of rod prior to drifting it on?

[Peter BondParticipant @peterbond14804]

Can't seem to edit, but to add – backgear cluster is off too. Careful use of a small chisel on the edge of the screw after heating got it turning; not excessive damage to the head, thankfully. Under the scope it was clear there was the broken ball end of an Allen key blocking the socket; that's removed so I can reuse the screw.

[Ian S CParticipant @iansc]

Peter, you'v got to be fairly quick if you want to edit your post, the edit post sign above your posting goes away after a short time.

Ian S C

[Gordon AParticipant @gordona]

Peter,

You could try the reverse of the removal proceedure, ie cool the spindle and heat the gear. If you mounted a chuck on the spindle, passed a length of threaded rod down the centre of the spindle and held one end in the chuck, with a large washer and a nut on the other end you could draw the gear back on. Aligning the half threads on the gear and spindle by eye may be accurate enough. There is little or no axial load on the gear, the grub screw is probably just there as a backup if the gear tries to slip under radial load. Of course there's always Loctite.

Gordon.

[Matt C BeechParticipant @mattcbeech]

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From:	Matt C Beech
Subject:	Re: ML7 spindle
Date Sent:	23/12/2014 23:58:17
To:	Peter Bond
Hi Peter, IIRC the 25T gear is a screw fit, and has a small grub screw in the end to stop it turning. This was missing on my ML7 when I got it. You can see this clearly on the photo here. Mine was damn stiff, and I had a job getting it off. What I ended up doing was soaking it in a bit of WD40 for a while, and then putting the end of the spindle in some cloth and gripping it in my bench vice (wooden plates) and gripping the bull gear with both hands and turning the spindle. Photo here of the setup. Heating up to 70-80 dec C in the oven also helps loosen the parts as the metal expands if the above doesn't work. I had to heat it up to get the push fit ring off that holds on the pulley wheel and bull-gear. Matt

[Peter BondParticipant @peterbond14804]

Fantastic, thanks all (and thanks Matt – forum sw had logged me out, I hadn't realised so hadn't seen the msg…)

The spindle is back together;heated the gear to 100C for 10 mins before tapping it on and rotating it using the blocks of wood. Punched a new bit of copper for the threaded collar (Which is a swine to turn). At some point I'll photograph the sorry remains of the backgear cluster & bullwheel – at least 75% of the teeth on the bullwheel are gone, all of the backgear small gear are stripped. How does anyone do that to a piece of machinery???

Whilst I was at it, I decided to replace the drive belt too. Removing the shaft took far more persuasion than I feel it should – a 4lb hammer and a drift to ge the shaft to move at all. Oh well, it went back in with less faff. Nothing seems to want to move easily on this, even taking the Woodruff keys out was a pig.

Discovered that the forward spindle bearings have only one shim pack; the rear have both of theirs. Given I probably only need 4 shims, I think I'll just cut some from tool wrap, which is 0.002".  Sharp stuff, too.

Next up – sort a stand for it, then wire in the motor and see how the spindle runs before starting on the rest of it.

Edited By Peter Bond on 30/12/2014 17:35:21

[Peter BondParticipant @peterbond14804]

Finally got around to sorting the photo out –

If that doesn't count as vandalism, I need a new definition.

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