Any metallurgists out there? Non Laverda

1200ts

1200ts

Hero member
Location
USA - Riverside CA
Having been shamed by Julian and other members for lack of progress on motorcycle projects, I have returned to my current project, a 1929 AJS. I have made a new crank pin and bearing and am now on to the valve gear. The attached pictures are the cam lifters which as you can see are shit. The cams have been welded and reground with very hard metal. The question is what steel should I make new cam lifters out of? I have been told 4140 is the way to go but have also been told 8620 would be better. I made the crank pin out of 8620 and connecting rod sleeve out or 52100. What they were using in 1929, who he fuck knows?

I know how to machine parts, but am definitely no mechanical engineer. The Laverda group has some very smart members, I hope some can help.

Bruce
 

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Personally I would make them in something like as you say 4140 and get the faces built up in Stellite then ground,  works very well indeed as a cam follower surface.  and this combo would give you close to the ultimate cam follower within sensible limits.

Regards,
julian
 
I can see why you'd want to make new ones.. I found Newman Cams in the UK very useful (if you're in the UK) they built up some Vincent followers and  hardened some bushings for me. Probably also offer good advice..or service...

Rob
 
Nrewman cams are very close to me (and I used to shag the governers daughter) David Newman is no longer around and sadly neither is his daughter, but the firm survives and goes from strength to strength.

I thought those followers were military pins for inserting into square morticed holes with circular countersinks

CLEM
 
What effect will the welded stellite have on heat treating the part? I would think it must be welded before,  as welding after will temper the steel too much?
 
Pity the shanks appear too long to substitute Triumph or BSA cam followers. Any latitude in the shank length ?

Scrumpy, there's a few firms here whose owners i wish had daughters as they've shagged things of mine......
 
1200ts said:
What effect will the welded stellite have on heat treating the part? I would think it must be welded before,  as welding after will temper the steel too much?
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Depends on how they do it but Yes, they probably need re heat treating afterward,  We have had it done on many occasion, just send them away and they come back done. And last forever.  The shaft to be honest does not need to be incredibly hard as I've seen followers made in all sorts of materials and all have seemed to work fine in the shaft area. Titanium for instance is a shit follower material in theory but has worked on many a machine!
I actually tried "tipping" some followes myself once with Eutectic plasma spray system but used a too hard material and my grinding wheels couldn't touch it!  :-[ :-[ :-[ :D    "fucking Amateurs"  :LOL:

Julian
 
1000/3C_Stefan said:
Bruce, how about some homemade case hardening, could be done relatively easy. 8620 it is then plus some of this: https://en.wikipedia.org/wiki/Potassium_ferrocyanide, should be available at your next pharmacy or the like.

Would recommend first to do all the following outside and not inside the shed.
Put a good bit of the  Potassium Ferrocyanide into an old ashtray or similar, then heat the respective surface of the cam lifter to bright cherry red and dip it into the cyanide salt, wiggle a bit around, redo the same procedure a few times, around 10 times, maybe a bit more for increased case depth. If some salt particles stick to the surface dont remove them before reheating. Finally heat again to bright cherry read and quench in oil followed by very slight annealing (grey). Should be good enough for the old AJS poffer.

Regards,
Stefan
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.. and if that little recipe doesn't get the CIA after you I guess nothing will. :o
 
Talking on the internet about getting blacklisted by the CIA should do it!  8)
 
1000/3C_Stefan said:
Probably I should dust off the Stingers in case they send them drones in... 8)
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Was nice meeting you Stefan.... :D

Shit, now they've got me in their sights too!

piet
 
Jees we used to case harded bits in 1st form high school metalwork class,cannot be that dangours if they let 13 year olds do it athough that was well before occ health and safety went nuts ,brings back memorys of queing to get on one of the 4 laths used by 40 kids.
 
I reckon there's a whole bunch of stuff we used to do in high school that they wouldn't let kids within 100 miles of nowadays!  Not just in the metalwork and woodwork shops either.

When I was at high school in the 60's, we had a kid brew up an explosive mixture in the chemistry lab. I think he gathered up all the most reactive chemicals he could find, put them in a gas jar and shook it up. Not surprisingly it went kaboom, took his hand off, injured a bunch of other kids and blew all the windows out of the chem lab. The school didn't take any responsibility - they said it was his own stupid fault for playing with chemicals.

Cheers,
Cam
 
I have a had a knofe in my pocket since I was ten years old (that was the age of knifery in my familly),I carried one or another throughout all my school days, I would sharpen my pencil with it, over the teachers waste bin at the front of the class, I would whittle sticks in the playgorund, and uise it to open cardboard boxes or a film canisters (the real to real type were always sellotaped up) carrying this knife was always acceptable,50% of boys and a few girls did this, but whenever there was any kind of playground fight, no one ever got a knife out of their pocket.Ads a scout and an army cadet a bigger knife was usual, now I risk "detection" by walking around with my knife in my pocket, but I still do
CLEM
 
send them off to the same place where the cams were welded.

get them welded with the same material so that there is no conflict in hardness, ie, one will wear more being softer.

to make new followers you will need to know the hardness range of the cam lobes to determine the material qualities required.

KISS.
jacko.
 
CLEMTOG said:
I have a had a knofe in my pocket since I was ten years old (that was the age of knifery in my familly),I carried one or another throughout all my school days, I would sharpen my pencil with it, over the teachers waste bin at the front of the class, I would whittle sticks in the playgorund, and uise it to open cardboard boxes or a film canisters (the real to real type were always sellotaped up) carrying this knife was always acceptable,50% of boys and a few girls did this, but whenever there was any kind of playground fight, no one ever got a knife out of their pocket.Ads a scout and an army cadet a bigger knife was usual, now I risk "detection" by walking around with my knife in my pocket, but I still do
CLEM
Click to expand...

Pfft, it's a knife!

I just thought you were happy to see us!
 
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