Woodruff keyway repair

Hi guys
Wondered if someone might have some pointers for me on how to repair a woodruff (are they called this in the US? Half-moon shaped disk) keyway on
a steel shaft.
Background: Crankshaft is steel Woodruff key is approx 5mm thick (3/8ths I think)
The alternator pulley bolt (on end of C/shaft) became loose and allowed the pulley to chatter. Unfortunately this has allowed the key to chatter too & has opened out the keyway slightly.
I took the pulley, preheated with a MAPP gas blowtorch, zapped it with the MIG and allowed it to cool. I then spent a fair while with needle files re-dressing the keyway. (Heavy pulley 110A 240V mig, C25 mix)
How might I be able to repair the crank? It will have to be done in situ. Would hitting it with MAPP, MIG and careful use of a Dremmel suffice? (I wondered about making a copper key to give me a non-stick surface to weld up to.)
I really don't want to weld a key in permanently
I've used Quicksteel for the time being.
Thanks :)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Balders wrote:

Mill a woodruff slot on the other side of the shaft?
GWE
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 15 Apr 2008 17:26:44 GMT, Grant Erwin wrote:

Too easy to get wrong, I'd also have to get someone to machine a keyway into the pulley :'(
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Eh, beg pardon. Why? Wasn't it the shaft keyway that was enlarged? The pulley won't care where it lines up with the key or am I missing something?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 16 Apr 2008 08:00:32 -0400, John Husvar wrote:

Ahhh, very sorry John. I didn't say there's the cambelt/ign sensor drive pulley directly behind this one so no going 180 out Both pulleys have a slot in them. There's only one woodruff key which spans (just about) both pulleys. The key is approx 1/2" across its flat - miniscule compaired to the pulleys.
It's the key slot in the crank that I need to be able to repair properly now. Instead of having parallel sides it's more like this (ASCII art time)
\ | \ | |_|
It's also in situ, to strip and get machined wouldn't be worth the grief. A 2nd hand engine would be a better option after the "weld the bugger on" option.
Thanks for the replies so far, much appreciated
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Balders wrote:

I would clean the keyway well, put an isolator on the side of a new key, perhaps thin tape so the key will be removable, install the key and fill the buggered gap with JB Weld (filled epoxy) and let cure. Reinstall the pulleys, apply thread locker to the nut and sock it down tight. I'd expect it to last for years that way.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Pete C." wrote:

Threadlocker on the pulleys themselves wouldn't hurt either. The threadlocker is removable with heat well below that which would be a problem for a heat treated crank.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Pete C." <> wrote in message>

to machine a keyway

was enlarged? The

I missing

cambelt/ign sensor drive

woodruff key which spans

its flat -

repair properly

(ASCII art time)

worth the grief. A

the bugger on"

of a new key,

the key and fill

Reinstall the

tight. I'd

Time's a wasting! Better use JB Kwik! Actually JB is totally worthless in a case like this, you've a much better chance using Devcon plastic steel, it will take a lot more pressure than jbweld. phil kangas
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I have always thought that woodruff keys were generally only intended to index parts and not to drive them. I would certainly look into some form of better security for the pulleys if this is a common failure.
Don Young
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

It is quite common to see the setup the O.P. described - a single woodruff key in the nose of a crankshaft. I've got a couple of Peugeot diesels in a boat built exactly that way and they are at least twenty years old.
Of course they all have a Big Bolt to hold things together that should be as tight as you can get it.
Bruce-in-Bangkok (correct email address for reply)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
">>I have always thought that woodruff keys were generally only intended to

I agree, I have experience with woodruff keyed crankshaft pulleys. As you say, they are commonly used with either a large bolt or tight press fit so it would not seem to me that the key has to stand much or any of the driving torque. If the press fit or the bolt is not tight enough the key fails pretty quickly.
Don Young
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 15 Apr 2008 17:26:44 GMT, Grant Erwin

Thats what I do all the time
Gunner
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
How bout making a new key out of thicker stock, make the bottom part a tight fit in the wallowed out slot in the crank, then narrow the top part to fit the pulley Get a good trial fit, then use Loctite bearing mount to secure the key in the crank and let it set before final fitting the pulley..... Joel in Florida
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
make the bottom part a

^^^^^^^^^^^^^^^^^^^^^ Or, a related idea: Make a key that is tapered, so you can partially insert it in the slot. Heat it red hot and pound it in. Then wrestle it out with pliers and grind on it until you can fit everything together securely.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Leo Lichtman" wrote > Or, a related idea: Make a key that is tapered, so you can partially insert

Done that. Some Toyota 4 cyls seem to have this problem. A single mom, unable to afford a new crankshaft or even the labor, so I took a larger key and ground it to fit the tapered slot, then locktite-ed the whole mess together. Got her back on the road, too bad for the next owner.
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 15 Apr 2008 10:45:48 -0700 (PDT), snipped-for-privacy@aol.com wrote:

That sounds like an idea, cheers :)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

A step key, eh? Old-timers' repair method, but one that works well.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Balders wrote:

Does this pulley mount on a taper? Or a straight shaft?
Pete
--
Pete Snell
Department of Physics
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 15 Apr 2008 15:27:18 -0400, Pete Snell wrote:

Pete, it's a straight shaft. It's actually a Subaru Impreza crank that's fitted to a vehicle. I've heard of a fair few that have done this - not just Subarus. I wonder why they don't machine a longer slot in the crank and insert a square section longer key, say 1" - 1.5"
If it all goes very pear shaped it would probably be easier to get a donor engine. Well there's always the weld the pulley option first ;) All for the sake of a bolt and a 10p (20c) key!.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Balders wrote:

Wow, That seems like a problem waiting to happen (guess it did...) What about putting a pin in the face of the pulley and indexing it to a hole in a thick washer, held by the nut? It would take some of the load off the key.
Pete
--
Pete Snell
Department of Physics
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.