drewfio

I'm considering the fabrication of replacement cones for old Maillard hubs. I've had a tough time finding replacements (as discussed in this thread). My father has worked in the auto industry and worked in a shop specializing in restoring old cars. This often involved machining custom or obscure, no-longer-produced parts. He is a car guy, not so much a bicycle guy, but seems confident he could machine a part of the same specification. The only aspect he does not have experience in and is not keen on attempting is case hardening. So my questions are:

1. Is case hardening a hard (get it?) requirement for this part?
2. If not, what material or variety of metal/steel would be best for attempting this?
3. How fast would they wear in comparison, without case hardening?
4. If they do have a shorter life span without hardening, could I just have a bunch made, and replace them out as they wear out?

I realize finding replacements might actually possible if I am patient, and that replacing the wheels altogether might be a good investment anyway. I'm interested also as a learning experience, and I think it would be awesome if it worked out. Plus, it seems like a fun thing to work on with my father, and might be a way to get him more interested in cycling, or making other (less critical) custom parts.

repechage

Look up heat treating locally.
possible to do it yourself.
the better cones were ground after - as heat treating will deform the part slightly.

have him make up a bunch that way when they fail, just replace.

oneclick 

1. No. All that is required is that it be hard. Case-hardening is not even the best method - it's just cheap and easy (at scale) and good enough most times.
2. Essentially, steels need carbon to be hard. Low-carbon steels (0.1%-ish) can be case-hardened. High carbon steels can be hardened by heat-treatment.
3. It depends on whether they need case-hardening to start with, but regardless, if they are soft, you *will* need new ones, and soon.
4. Don't bother - case hardening is not the only way. Use a good air-hardening steel and you can probably ignore the distortion that'll happen when you heat treat it, plus you can anneal the stock to make the part.

randyjawa 

You can buy heat hardening powder, believe it or not. I used it a few times, as a millwright. I found that it worked pretty good, hardening a handmade soft steel to to the point where steel cable would not scratch it. Cannot remember what it was called though. Google case hardening compounds and check it out.

plonz 

Hardening powder, case hardening, heat treating...

Kinda reminds me of the engine builder I once worked for. Built stock car motors and would bury the blocks and heads underground. Pretty much sealed my exodus from engine building!

MB33 

You should do a run of Normandy Competition High Flange cones too. They would sell like hotcakes here and on ebay.

smontanaro 

OTOH, if they were in high demand AND the process was relatively straightforward (and not too expensive), you'd think they would already have been reproduced, no?

3alarmer 

.
...case hardening is not a big deal, but kind of a PIA to do yourself. There are various methods, but the only one I've seen done was packing the pieces in some case hardening compound, and furnace heating for a period of time. It's kind of an ancient process, so not high tech unless you want to make it so. there are people who will do it for you, which if you are gonna machine up a batch of these to sell to other people, might be your best bet.

More on the process and the history, as well as suitable steels is well explained on Wikipedia.

reconnaissance

Ground up bone is a good case-hardener.

clubman 

Apparently horse hoofs are good. Interesting discussion here on a small forge forum. I think these are the guys you might want to find.

Headpost

Any chance of adapting an already existing and easy-to-find cone? I'm thinking of milling one down if it's too wide, then the dustcap could be separate piece.

Just an idea. I have lots of bad ideas.

noglider 

You mean Normandy Sport hubs? I wouldn't invest much in those. I've overhauled more of those hubs than any other, as I was a shop mechanic in the 70s and 80s. I don't have much love for them. This fall, I overhauled the hubs on my trailer, and I noticed they seemed like Normandy Sport hubs. I looked, and yup, they are Atom hubs, same thing with small flanges. Oh well. They're in good shape.

MB33 

I mean the Competition, as is found on a lot of 60's and 70's French race bikes.

MB33 

You'd think so. Has any member ever had a machinist make them a custom machined set of cones? If so, how expensive was the process? Did it cost thousands of dollars? I wonder if this is more a question for the CABE.

balindamood

Perhaps a dumb question, but if you find the need to actually machine a new part because the old one wore out too soon, why would you make the replacement out of the same material that did not last? Why not use better/harder steel so you just have to machine it rather than the extra steps? I get wanting to keep things original, but hub cones?

oneclick 

This is probably the simplest solution, especially if you can avoid case-hardening. To do that you must find cones that are made from hardenable steel. There is a spark-test that'll tell you enough about the carbon content to have a good idea if they'll do (make sure you test below any case layer).

You need a lathe with a cross-slide mounted grinder. Make a template of the cone curve and diameter - surround the cone with that modelling plastic stuff, cure it, remove the cone, and cut the cast in half, so you have a half-collar. That'll get you not only the curve but the diametrical separation.

Anneal the cone. Chuck a known good axle (on the unthreaded centre portion) in the lathe and mount the cone on it. Set up your grinder and get your curve correct and as smooth as you think is worthwhile. Remove the cone, flame-harden the whole thing, temper it, install it, and -

post here, with pics please.

noglider 

Oh the Competition hubs were very good hubs.

delicious

I don't have the skills to offer any advice, but I hope you do try and machine these and share how it went. This sort of knowledge is increasingly valuable as cups & cones get harder to find.

drewfio

I really appreciate the responses and information! There is a real wealth of knowledge at Bike Forums.

I think if we tackle this, we'll try to fabricate them first without hardening to see how they come out. Then at that point try to put a couple hundred miles on them to inspect the wear (is that enough to assess at some level?), or explore hardening methods, or both. This won't all be done very immediately, but I will definitely post developments (with pics) when we get started.

Sluggo

As somebody said previously, case hardening is not the way to go. If you are starting from scratch, use steel with enough carbon (at least 0.4%) that you can harden all the way through. Heat it up to cherry red, drop it in some water (if 1040) or oil if it is a fancier steel alloy (like 4140). After it's cool, put it in the oven, maybe with a roasing chicken, at 400F for a couple of hours and cool slowly to make it less brittle. Polish to finish.

Hardening powder is just carbon or an organic carbon source. The carbon diffuses into the steel only a microscopic distance. Once you wear through that, you are into soft material. The only cones I have seen that were clearly case hardened were on an English 3-speed. They were worn through the hardened layer, after which the balls just pushed the soft steel aside.