The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: Sunbeam on 03.10. 2011 21:05

Title: Plating on dynamo.
Post by: Sunbeam on 03.10. 2011 21:05

Has any member crossed this bridge before? I am rebuilding a Lucas dynamo for my other bike (ajs) and wish to get a close match to the original plated finish on the dynamo's body. I think that the finish was cadmium or zinc and Frost Restoration do a range of metal sprays. Aln aternative is to send to a 'specialist' for rebuild who would then plate the dynamo body. Any info appreciated.

Howard.

Title: Re: Plating on dynamo.
Post by: trevinoz on 03.10. 2011 22:36

Howard,
               Up until the early 50s the body was nickel plated.
I suspect that after this the plating is cadmium.
I get them zinc plated and this gives a satisfactory finish.

  Trev.

Title: Re: Plating on dynamo.
Post by: Goldy on 04.10. 2011 17:38

Dave Lindsley does it but he,s not cheap.       http://www.davelindsley.co.uk/

Title: Re: Plating on dynamo.
Post by: MG on 05.10. 2011 10:24

Hi Howard!

I got good results with sandblasting and chroming over the rough surface, giving a nice dull finish that matches the alloy cases and mounting strap pretty well. The strap is home-plated with the Caswell CopyCad kit btw. (as are all the nuts, bolts, studs, etc.)

(https://www.a7a10.net/forum/proxy.php?request=http%3A%2F%2Fimg20.imageshack.us%2Fimg20%2F3198%2Fp1010584d.th.jpg&hash=9816c90e01433240476425b59e601c8bd8cc98a6) (http://img20.imageshack.us/i/p1010584d.jpg/)

Cheers, Markus

Title: Re: Plating on dynamo.
Post by: Sunbeam on 05.10. 2011 10:25

Hi Goldy, Trev & MG. Thanks for the replies on the finish on the Lucas dynamo. As the bike is a 1957, I will now go the zinc plating route and ring Dave Lindsley for a price.

Howard.

Title: Re: Plating on dynamo.
Post by: trevinoz on 05.10. 2011 22:17

Howard,
                   You may find that you will get the job done a lot cheaper by going directly to a plater. Why pay a middle man?

I clean the bodies with a wire wheel and polish in the lathe with emery cloth. Inevitably there is some rust pitting but to remove all of it would remove some or all of the lettering not to mention reducing the diameter.

  Trev.

Title: Re: Plating on dynamo.
Post by: Sunbeam on 09.10. 2011 22:38

Hi Trev. As the dynamo is ok apart from the plating, I think I'll strip the dynamo then try and find a decent zinc plater in the West Midlands. Nightmare getting a decent plating job done these days!

Howard.

Title: Re: Plating on dynamo.
Post by: wilko on 09.10. 2011 23:53

So you're going to remove the field coils? Egad! Got the tool to replace them?

Title: Re: Plating on dynamo.
Post by: trevinoz on 10.10. 2011 03:17

You don't need any special tool, Wilko.

An impact driver does a good job, as long as you have the correct bit.
I have machined 5/16" BSF allen head c.s screws to the right taper and can get the field pole nice and tight with a decent allen key.

    Trev.

Title: Re: Plating on dynamo.
Post by: Sunbeam on 10.10. 2011 12:59

I removed the original 'butchered' field coil countersunk screw using an impact driver. Magneto / Dynamo repair specialists probably clamp the dynamo body in some sort of jig to remove the screw. I got a new plated screw from FTW Motorcycles some time ago and the job has as been on the back burner till now. Not broken the dynamo down yet but been thinking about once the field is removed / zinc plating done and refitted, ensuring the field air gap is correct.....suppose I could use a feeler gauge between amature and field pole......I'm probably looking too deep ito this!

Howard.

Title: Re: Plating on dynamo.
Post by: iansoady on 10.10. 2011 14:47

The Lucas manual suggests that you need the correct tool to force the field coils into close contact with the body (sorry about the quality)...


(https://www.a7a10.net/forum/proxy.php?request=http%3A%2F%2Fi43.photobucket.com%2Falbums%2Fe398%2Fiansoady%2Fa10%2Fth_dynamos.gif&hash=414a3e65d32a9071291ed88c5245394e6f04c9ff) (http://s43.photobucket.com/albums/e398/iansoady/a10/?action=view&current=dynamos.gif)

You might be able to achieve something similar with a scissor jack or whatever.

Title: Re: Plating on dynamo.
Post by: trevinoz on 11.10. 2011 00:11

What is required is that the pole shoe be contacting the body completely and tight.
This can be checked with a feeler to ensure it's right. The thinnest available, naturall 
    Trev.

Title: Re: Plating on dynamo.
Post by: Sunbeam on 11.10. 2011 22:33

Thanks to all for the very helpful dynamo rebuild advice.

Howard.

Title: Re: Plating on dynamo.
Post by: Stephen Foster on 19.10. 2011 07:39

"Sunbeam" , did You have any success stripping the fiels coil & replacing after plating ?
Im at the same stage & have never done this before , seeking advice .

Regards,

Steve...

Title: Re: Plating on dynamo.
Post by: LJ. on 19.10. 2011 10:36

Why not buy your own zinc plating kit? I've had a lot of success with mine and has come in handy many occasions. The secret of success is using 'stainless' steel wool when cleaning parts and not ordinary mild steel as this leaves a metalic coating that will spoil the plating, the job MUST be spotlessly clean even natural oil from your fingers wont do.

I believe the 'special' Lucas tool when fitting a new field coil is so that the shape is formed correctly to the body of the dynamo when tightening up, as at an early stage of tightening, the body screws are not long enough. Obviously the special tool is not needed when re fitting a previously fitted coil.

Title: Re: Plating on dynamo.
Post by: Stephen Foster on 19.10. 2011 10:47

Thanks for the tip regarding stainless wire wool !
I have purchased a copy-cad plating kit .


Steve...

Title: Re: Plating on dynamo.
Post by: Sunbeam on 19.10. 2011 14:50

Hi Steve & LJ. Before stripping field coil out I'm going to get a price from Dave Lindsley. Have rang FTW, you have to send dynamo in before they will give a price.

Just rang Dave Lindsley......£25 + vat nickel plated, been told Iv'e just missed the batch that have been sent out for plating....3 months wait. Think I will strip dynamo and source local zinc plater.

Howard.