Cam Update

I was doing some research on material for the camshaft. I first emailed Andrews cams to ask them what they used, but expected no reply. In the meantime I searched the internet and got varied results. Various types of hard cast iron were mentioned, as well as a few tool steels. Then the other day I heard back from Andrews, and they said they use “8620”. That was cool of them to reply. So now I am looking into whatever that is (I assume a tool steel). If that is unattainable, I will go for 01 tool steel, my favorite for knife making. I have also made progress on the heat treatment front. About a year ago I acquired a used pottery kiln. It was always my intention to use it for heat treatment and casting, but I had not wired it until now (it is electric, like a giant toaster). I figured this is a good excuse to get it going, so I wired it and turned it on. It gets hot, but there is no way to tell how hot! I guess pottery is really forgiving in the heat department, as there are no gauges or even accommodations for one. I went back online and began to research thermometers for these things. I found a company that supplies equipment like this through a knife making forum. The company sold me a “probe” that goes through a tiny hole into the kiln, and a digital thermometer that is supposed to be very accurate. The probe is made of a special metal, tungsten i believe, that won’t melt along with everything else inside the kiln. When this arrives, I can (hopefully) get a max temp for this kiln. That temp needs to be in the 1600 degree F range in order to heat treat the majority of tool steels, including o1. I have used a oxy acetylene torch for years but there is a problem with that method uneven heat soak. In other words, the metal isnt evenly hot, because the torch has to be waved back and forth over the metal object to heat it. That can lead to an uneven hardness, or a warped part, when finished. The kiln should do a perfectly even heat soak if it gets hot enough…. I’ll report back. Oh, and if anyone out there is a cam or heat treatment expert, comment with your contact info so I can pick your brain.

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9 responses to “Cam Update

  • Josh Kurpius

    My brother’s father in law makes specialty gears for company’s like ford for their concept cars. I took a tour of his shop one day… it’s pretty impressive. I’m not sure what kind of steel he uses but I can probably get an answer. I believe he heat treats the gears on site as well. I’ll get the skinny.

  • Unkl Ian

    8620 is intended to be case hardened.
    In the soft state it machines real easy.
    Good choice for cams that don’t have real
    crazy spring pressures, but that is something
    I would send out for heat treat. The part is
    then ground to final size.

    • lockbaker

      do you think there is any harm in hardening the whole cam, all the way through? That way i could do 01 tool steel here. I figure a harley cam is so short and fat there is no way it would be to brittle, which I figure is why other cams are only surface hardened (to maintain a more resiliant core, like a samurai sword). I have a rockwell hardness tester so I can verify. what do you think?

  • Unkl Ian

    Usually, the camshaft is rough machined, then Copper plated. Then the lobes and bearing journals are rough ground to shape. The Copper plate prevents the shaft from absorbing any extra Carbon, so it is only toughened during heat treat. Where the Copper was ground off, you end up with a hard surface, with a tough core.

    The lobes are typically case hardened .060 to .100″ deep.

  • Unkl Ian

    I remember seeing a guy online, with old Indian flathead race parts. The rocker arms had been reworked to change the ratio, but it was the cam that was interesting. and The lobes were separate pieces, and assembled onto the shaft. Detroit is now doing this on some cars. That way the lobes can be HARD, with a tough shaft.

    Something tells me O1 isn’t the ideal choice for a camshaft. I’ll see if i can find something better.

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