Scavenging instant karma

  1. Screwdriver

    Screwdriver Member

    Messages:
    4,729
    UK London
    There's a bike shop near me I frequent and I'm always popping in, helping out, doing stuff. I'm fixing a couple of old air compressors for example. They're next door to a car repair garage type setup and they're always throwing stuff away: springs, disks, odd bits of metalwork and a couple of days ago, two stubby drive shafts off a BMW.

    "What the **** do you want those for?", chap in the bike shop scoffs. "Well it will be a decent high carbon steel, tough as old boots" I recite. "I might make some tools out of it or blades whatever, I could even turn it down to make a pin like this one"

    [​IMG]

    That's a taller pin for a headstock stand I made recently but we digress.

    "Oh, now you mention it, could you make one of these?" He says.

    [​IMG]

    "Well, duh, yeah, I'll probably make them out of these" I scoff back at him.

    [​IMG]

    Now if the conversation hadn't gone that way to start off with, there's no way I'd use presumably induction hardened 4140 (?) to make a headstock out of (that's what it is. Plus I sort of have to bore it out). But for the craic I almost have to, just so that I can turn old junk into real money. His money.

    Here's where I got to.

    [​IMG]

    Man, those things are TOUGH. There was a crispy shell on the outside which cost me two cutting edges off my carbide bit. The core is relatively soft but might turn out to be tough and possibly gummy. I wan't to avoid drilling it out if I can. It's for a Harley so weight isn't an issue. :D

    Little bit worried about handing it over to someone else to o the installation/welding though. I hear this stuff can be tricky to weld. Anyone have experience of welding old drive shafts? Is it 4140, 1050, EN8??

    Incidentally, if I ever do this again (he says looking at the other piece) I will be annealing it first...
     
  2. Arclikeharrypotter Member

    Messages:
    979
    Location:
    Northampton
    If its 4140/en19 then it should be preheat to around 250, then requires cooling and tempering. Think if you use a stainless or nickel based filler you can reduce the amount of preheat.
    @Brad93 will probably know
     
  3. Screwdriver

    Screwdriver Member

    Messages:
    4,729
    UK London
    Hmm. Thought so. My worry is the chap who will be welding it will use whatever he happens to have on hand or if we're lucky, whatever rods they have in Machine Mart. For the record, I wouldn't be so casual if I was making a structural part for someone elses motorcycle but I was asked if I could make this threaded tube and I said yes:dontknow: I will voice my concerns.

    Out of interest, if you were making a motorcycle ssteering stem, what would be the material of choice? I am assuming mild steel is out of the question and also of course that whatever these shafts are will be better.
     
    ronan likes this.
  4. Brad93

    Brad93 M J B Engineering

    Messages:
    5,393
    Location:
    Essex
    Without knowing the material you’re shooting in the dark.

    EN19 slightly easier to weld than EN24.

    Still need high preheat and slow cooling.

    For a bang up job you’d heat treat it.

    You can use a 312 stainless consumable. What that allows you to do is reduce your preheat to about 75° Celsius and then cool slowly.

    If you type welding EN24 in on google the TWI have quite an in-depth guide.
     
    Screwdriver likes this.
  5. Screwdriver

    Screwdriver Member

    Messages:
    4,729
    UK London
    I am extremely wary of performing any "mission critical" welding on other people's machinery, I got to "hydrogen induced cracking" and decided producing this part from mystery metal is probably not a good idea. I can't dodge that responsibility by proxy just because I'm not doing the welding. So having said that, what do you suppose manufacturers make steering stems from? It's the pin that welds to the bottom yoke, goes through the headstock and bolts to the top yoke.

    Like I said, I am assuming it's not going to be mild steel but it doesn't really need to be super strong or durable because the stem carries bearings and is firmly bolted. My seat of the pants engineering view is that there are sheer forces involved but no bending moments or wear resistance requirements. Maybe a mild steel would be ok, possibly even preferable?:dontknow:
     
  6. Seadog

    Seadog Forum Supporter

    Messages:
    4,085
    Location:
    NE London - UK
    I'm sure you looked on line, Steve. EN8, EN16, EN24T. Then again I've seen MS or CRS mentioned :dontknow:
     
Advertisements