Engineer bods, how can I repair my speedo drive?

**Ixion** · 10th February 2009, 10:28

Originally Posted by Max Preload

Get a new one laser cut. You'd be suprised how cheap it is. And on such light gauge, fettling would be very minimal if needed at all.

You measure it, I'll draw it & DXF it.

Hm. That sounds interesting. But remember, I am from the open hearth and flat belt generation. This laser cutting - who would do such a thing ? Presumably it is not the sort of technology that Joe's Engineering and Tractor Clobbering Services would have ? And how cheap is cheap , approximately ?

I can measure it, the tolerances are nothing fancy .

EDIT: Gee , who'd think of looking in the Yellow Pages. North Shore Laser Cutting Ltd and Arran Lasercutting. Wonder what they do. The latter mention one offs. I'll measur e the thing tonight. And find out what DXF means

**The Pastor** · 10th February 2009, 10:30

I think if its cadded up they just plug the cad file in and hit go.

**Ixion** · 10th February 2009, 10:31

The cads. And where does the BLOODY HEAVY HAMMER come in?

**Skunk** · 10th February 2009, 10:45

Originally Posted by Ixion

I can weld it, but I'm not keen to weld onto the wheel, cos of it being hardened and tempered. Welding the plate and reforming is possible, just take a while.

I was thinking of welding the plate back to size and die grinding it to shape.

**Max Preload** · 10th February 2009, 16:22

Originally Posted by Ixion

I'll measure the thing tonight. And find out what DXF means

Drawing eXchange Format. I'm not doing much in sheetmetal development these days (read none since mid last year) but I could possibly contact a couple of friends who still are that could put it in with another job going through and it'll cost nothing. Nadda. Zip. Zero. Zilch. Might have to wait a bit though until they put some through. NSLC were always good to deal with - lead times were longer but the price was always right.

Either way I'm happy to CAD it for you - scribble a sketch out - it'll take me all of 2 minutes.

**Max Preload** · 10th February 2009, 19:34

Fill this in if you like, taking the inside dimensions from the machined boss.

There appears to be a slight taper on the 3 lugs but I expect they're only edge contact so it wouldn't matter a great deal. If you want to bother measuring it that's fine - easy to add. Also I expect the proximity of the flats relative to the lugs wouldn't make a difference either - after all, the driven piece spins.

**Ixion** · 10th February 2009, 20:59

Thank you very much indeed. Attached image I have added the measurements. The only one that is even vaguely critical is the inside diameter where it fits on the boss. But I can fettle that to fit if needed. All the rest could be +/- 1mm even.

The taper I think is for ease of stamping the part out in the factory. The lugs are edge contact , and the drive lugs are only about the same size so the taper is irrelevant.

**Max Preload** · 10th February 2009, 21:25

I only get 9.71 along the flats (chord) but what's more important is the A/F on the boss anyway. Just verify the lug height from the ID (7.37) to make sure it doesn't interfere with the hub.

I've left a 0.5mm radius on the lug tips for cosmetic and laser cutting reasons (sometime you get a burr in sharp corners) and on the root for the same reason but also to remove the stress raising that comes about from sharp corners.

2mm thick wouldn't make any tangible difference would it? The seal is in the worm drive right, not the hub?

**Ixion** · 10th February 2009, 21:47

Originally Posted by Max Preload

I only get 9.71 along the flats (chord) but what's more important is the A/F on the boss anyway. Just verify the lug height from the ID (7.37) to make sure it doesn't interfere with the hub.

I've left a 0.5mm radius on the lug tips for cosmetic and laser cutting reasons (sometime you get a burr in sharp corners) and on the root for the same reason but also to remove the stress raising that comes about from sharp corners.

2mm thick wouldn't make any tangible difference would it? The seal is in the worm drive right, not the hub?

Yep. Width (OD to ID) is 2.92, so 2.92 + 4.45 = 7.37. The length of the chord was hard to measure , there's not a clear start and finish.

2mm thick would be fine. Theres a washer and circlip but theres also about half a millimetre of end float anyway. 0.08 mm isn't going to make any difference at all. And the plate doesn't seal anything it just sits in there .

**gatch** · 10th February 2009, 21:52

my 2c..

loctite 680, I'v used it to glue a lightly loaded pinion gear to a 1" shaft, hasn't come apart yet, mind you the loctite is really only good for about 0.2mm clearance, much more than that its not so effective..

welding the hard steel.. preheat, preheat, preheat then cool slowly.

failing all these laser cutting a new one would be mint..

i love techmology