Saturday, May 8, 2010

Continuation with Smiths SSM and RSM motorcycle instruments and the final blog from me for 2 weeks...

I did an earlier blog on the Smiths 8omm diameter SSM and RSM motorcycle instruments, fitted to British Motorcycles from the start of the 1964 season, replacing the evergreen Smiths chronometric....
I showed some pics of a bezel removal tool, but of course you need to replace the old bezel...always fraught with trouble as the chrome plated brass material of the originals develop stress cracks and are often difficult to satisfactorily remove.
So in this blog I'll show you a tool you can make that can utilise a normal 6" centre lathe to roll on a new or re-roll on a used bezel rim.
The original Smiths factory tool was illustrated in the last picture on that blog....
Go to the right hand side of this blog, find "subject listings on my blog" and scroll down to "speedometers"
Left click on the images to enlarge...

2” diameter ball bearing ( a Velocette Venom front wheel bearing…) attached to a piece of bar as the rolling tool.
Disc with the “V” groove to allow the bezel to “lock in” and resist sideways thrust during the rolling operation.
A circular block with holes for the two rear cases and three holes for the movement case screws with grommets to fit into.
I used a Velocette girder fork front wheel taper roller bearing as the thrust bearing that the live centre in the tailstock of the lathe pushes into.
New bezel rim,shaped glass seal, 87mm x 2mm thick glass, flat rubber seal, slip ring/mask to fit to the re-enameled SSM case. Illustrated are the movement to case screw with grommet and the foam pad the movement sits on. All essential to replace when the instrument is opened to ensure the speedometer sits correctly in its case.
The locking ring in the chuck, the ball race is just visible

This is a speedometer held lightly by the tailstock live centre to show the bezel located in it's locking groove only. The larger aluminium block is then fitted to the back of the speedo and the live centre engaged with it for the rolling operation.
Speedometer sitting in the various holes to allow the block to fit snugly against the speedo back.
The speedometer just apart from the pushing block, showing the holes to engage the back of the speedo.
Several shots of the speedo trapped between the locking ring and the thrust block.
How much thrust? 
A light push by the tailstock to crush the speedo case against the flat rubber seal on the glass and ensure a water-tight seal.

This is the last blog from me for almost two weeks as I will be in the USA from 8th May 2010 returning to Sydney Friday 21st May.
Riding my KSS Velocette special, illustrated above and to the right-hand side of the blog.....

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