Clock repairs....

[Matt_Harrington]

Well after a lot of faffing around, I think I have sussed the clock repair technique but you will need a lathe.

Using the tried and tested method or separating the two main parts of the clock - a large jubilee clip around the stainless steel band and judicial levering of band at the back, the rest of the clock is fairly easy to do (assuming that the units work). Mine were working but paint was peeling and the dials were shot.
New faces from 750faces.com, new screws to affix from china (aliexpress) I used M2.5 and tapped the holes accordingly. Powder coated black bezel, re-plated the back part, a dollop of fluorescent paint on the needle and then a good clean of the other parts before re-assembling and then putting in the lathe with the jigs as per the pictures below:

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Then it was a matter of making sure the tailstock is locked hard against the rear 'cap' and then using a roller tool, the ring was 'spun' back on.
I'm simplifying things slightly but that is the general process. The rear nylon cap doesn't have to be so elaborate - it could be a bat held on by the captive studs but I used it as I was experimenting along the way. The trip arm was made using an M3 Left hand tap on some suitable s/steel.
In my euphoria of getting it to work I managed to affix the rev counter backplate the wrong way round!!!  So I'll be looking for another ring......

Let me know if you want more specific details.

Matt

[Oddjob]

I had a conversation with Peter Kent about powder coating the bowls and he said the paint could be so thick it made getting the ring back on difficult. How was yours?

I might go for ceramic coating as an alternative, I find normal spray paint to easy to scratch and the positioning of the clocks leaves them open to that happening.

Nice work BTW.

[Matt_Harrington]

I must admit that there was no issue with powder coating on the bowls. That said, the powder coat didn't seem that thick.
Matt

[Orcade-Ian]

Many thanks Matt for sharing the process - I'll be doing the ones on the 550 eventually.  I realise that these threads are not for everyone but being 'A Ingineer' myself, I love 'em!   Engineer and ingenuity have the same root tha' knows!

I employed a similar technique on my Ducati Elite speedo but I think yours is better so will probably follow your lead - ta!

http://www.stallard-engineering.co.uk/stories/Bikes/European/Ducati%20Making%20parts.htm

I parted with my bending rolls before we moved to Orkney (there are places here with them) but I'm toying with the idea of making a passable replica silencer as they are definitely made from 'unobtainium'

Ian

 

[Matt_Harrington]

Nice work Ian. Spinning is a seldom used technique these days (especially in the home workshop) however, I don't think my lathe (or skills) could cope with making headlamp shell!!
Matt

[JamesH]

Nice work Ian. Spinning is a seldom used technique these days (especially in the home workshop) however, I don't think my lathe (or skills) could cope with making headlamp shell!!
Matt

Great work matt - do you have any more pictures of the tooling used to hold the clocks? What material did you make these from? Looks like a great setup

[Orcade-Ian]

I agree Matt, things like headlamps and deep bowl shaped stuff are out of my league too - usually produced by pressing or deep drawing, so way out of the scope of a home workshop.  There is a chap up here who used to work in Flotta (where the oil comes in) and he has just made a side piece for a very early sidecar mudguard (1925 BSA outfit once owned by a school Headmistress up here) It is a complicated shape and has a wired edge too.  It is hand made and so good it will only require paint to finish it.  Flotta has produced some unbelievably skilled folk up here - unfortunately some have retired or passed away, never to pass on those skills.

Ian

[Matt_Harrington]

Nice work Ian. Spinning is a seldom used technique these days (especially in the home workshop) however, I don't think my lathe (or skills) could cope with making headlamp shell!!
Matt

Great work matt - do you have any more pictures of the tooling used to hold the clocks? What material did you make these from? Looks like a great setup

James, I'll photo the fixtures in a day of so. The one holding the the black bowl is as bought - will give the details of that as well......
Matt

[JamesH]

Nice work Ian. Spinning is a seldom used technique these days (especially in the home workshop) however, I don't think my lathe (or skills) could cope with making headlamp shell!!
Matt

Great work matt - do you have any more pictures of the tooling used to hold the clocks? What material did you make these from? Looks like a great setup

James, I'll photo the fixtures in a day of so. The one holding the the black bowl is as bought - will give the details of that as well......
Matt

Awesome thank you


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[Matt_Harrington]

James, attached are photos of the jigs I used. The white one was made from a hard nylon that I have a large sheet of and I initially tried to make the other out of the same material.
Then I found the PVC-U end cap that has a 90mm internal diameter and fits perfectly and protects the front 'bowl'. They cost around £7 plus del each.
The other advantage of this cap is that you can put the clock into it whilst fitting the stainless back etc. and you can store it in it to protect it.
The nylon one has an extra hole in it as I got the angle wrong for the drive part that comes out of the clock. The pocket allows the rear part of the clock to sit firmly in the jig.

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Hope that helps but let me know if you need any further info.
Matt

[McCabe-Thiele (Ted)]

I'm impressed Matt.

[haynes66]

nice work. i wish i had room for a lathe.  for my 750 clocks i used 4" soil pipe which is pretty much spot on to sit them in while impaling myself on a regular basis with a screwdriver...