Crankshaft Keys

On a certain single cylinder 2 stroke the armature winding is attached to
crankshaft on a taper. It also has a small round peg to align it,
because it carries the points cam and obviously the alignment is critical.

The little peg fits into a hole in the crankshaft taper and a keyway in
the armature. It is approx 5mm x 2.5mm dia [1] and appears to be
hardened steel.

I assume they are a fairly standard engineering size [2]. Where would
be able to source these little pegs/keys, by which I mean what type of
supplier would I be looking for in the Yellow pages?

The Frankfurt wreck is missing its and my little tin of pegs is now empty
[3].


[1] Obviously I'd actually measure it properly before blundering into a
shop that sells them.
[2] Most fasteners, seals, bearings and the like seem to be readily
available off the shelf and not manufacturer specific.
[3] Probably because I'm forever losing the little fuckers

 

They are called Woodruff keys, and are available from quality
engineering suppliers.Where you'll find a good engineering supplier will
be more difficult, as even here in the Midlands, they are very rare, as
most of the engineering factories have shut down.A quick google search has
shown a few possibilities, so start there.
You will need to know the width of yours.The height is not really a
problem as you can file/grind it down to the right height.
HTH
Alan.

 

No, they are a half moon shaped peg that slides in a slot between the
shaft and the pulley.

This is a dowel.

 

ITYM "nail + angle grinder".

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, sweller

Give J&L a whirl. http://www.jlindustrial.co.uk/

Failing that, if you can accurately measure the bugger (or have a
prototype) let me know and a supply will be with you shortly.

 

Tap in a piece of drill rod (the round bit of a twist drill), (then grind
off the extra length).
2mins work, <£0.50, and a piece of piss to do.
JB

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, JB

Most twist drills don't have hardened shanks.

 

Cheers, when I finish work and can get one of dowels accurately measured
I'll email you.

 

Cheers, when I finish work and get the dowel accurately measured I'll
email you.

 

Or
it may well be known as a ROLL PIN if it looks like a letter C from the end.
In which case they are hardened to spring steel temper and a **** to get out
usually if worn down too far for mole grips to grab.
Most engineering suppliers have selections as do many car spares shops.
Measure and select.

 

Yeah, or one of those too.

 

Still hard enough for the task in hand, I reckon and probably much tougher
too.

JB

 

Cheers, I measured one up on the way back from work.

The dowel is 4mm x 4mm dia. So all I need to do is get some 4mm dia
silver steel then cut and file to length?

It also transpires the 125/150 crankshaft uses a woodruff key (the half
moon thing). It's a long time since I worked on the little engines and
as they use the same dynamo and points mount as the 250's I thought they
would be keyed the same. Obviously not.

Where to get 12mm long x 4mm wide woodruff keys? Although I recall some
in a tin somewhere in amongst the MZ NOS...

 

sweller wrote:

You've got an MZ with nitrous?

--
Oldbloke

2000 Honda CB500, 1991 Suzuki TS50 (m'boy's)
BOTAFOT #140
"He's like Robbo's chubby kid brother"

 

<VVBG>

 

Stupidly obvious I know but the last time I needed a woodruff key I
popped into my local dealer who charged me 50p for one.

 

Firstly there is no local dealer for this make and secondly I didn't want
a woodruff key (I can get those from www.namrick.co.uk which is just
round the corner).

The problem I had was getting a small hardened peg, which I now know is
called a dowel. Anyway the problem is now sorted thanks to the
suggestion of making my own from silver steel.

Thanks anyway.