Armed Polite Society

Please login or register.

Login with username, password and session length
Advanced search  

News:

R.I.P. Scout26

Author Topic: Softening steel  (Read 182 times)

zahc

  • friend
  • Senior Member
  • ***
  • Posts: 5,235
Softening steel
« on: May 04, 2021, 07:20:56 PM »

I want to turn the teeth of of a small (13tooth) bike track sprocket with a lathe.

I'm pretty sure they are hardened chrome moly. So they won't turn. Can I heat it up to a certain color and let it air-cool to anneal it? I don't have an oven, just a torch.
Maybe a rare occurence, but then you only have to get murdered once to ruin your whole day.
--Tallpine

Boomhauer

  • Former Moderator, fired for embezzlement and abuse of power
  • friends
  • Senior Member
  • ***
  • Posts: 12,996
Re: Softening steel
« Reply #1 on: May 04, 2021, 07:23:26 PM »

Get a tempil stick for the temp you need to heat it to so you donít overdo it
Quote from: Ben
Holy hell. It's like giving a loaded gun to a chimpanzee...

Quote from: bluestarlizzard
the last thing you need is rabies. You're already angry enough as it is.

OTOH, there wouldn't be a tweeker left in Georgia...

Quote from: Balog
BLOOD FOR THE BLOOD GOD! SKULLS FOR THE SKULL THRONE! AND THROW SOME STEAK ON THE GRILL!

Jim147

  • friends
  • Senior Member
  • ***
  • Posts: 5,830
Re: Softening steel
« Reply #2 on: May 04, 2021, 07:31:22 PM »

Get a tempil stick for the temp you need to heat it to so you donít overdo it

Thats the right way but I just heat it up to just red and let it cool off.
Sometimes we carry more weight then we owe.
And sometimes goes on and on and on.

BAH-WEEP-GRAAAGHNAH WHEEP NI-NI BONG

BobR

  • Just a pup compared to a few old dogs here!
  • friend
  • Senior Member
  • ***
  • Posts: 5,894
Re: Softening steel
« Reply #3 on: May 04, 2021, 07:36:44 PM »

If you do it just right the teeth will melt off and you won't need to turn them, follow me for more tips.

bob

bedlamite

  • Hold my beer and watch this!
  • friend
  • Senior Member
  • ***
  • Posts: 8,527
  • Ack! PLBTTPHBT!
Re: Softening steel
« Reply #4 on: May 04, 2021, 07:45:47 PM »

Depending on the alloy, critical temp is going to be somewhere around 1200-1400F, heat it to that and let it cool slowly, preferably insulated and overnight.
Is defenestration possible through the overton window?

griz

  • friend
  • Senior Member
  • ***
  • Posts: 2,546
Re: Softening steel
« Reply #5 on: May 04, 2021, 07:48:39 PM »

Just out pf curiosity, why do you want a toothless sprocket?
Sent from a stone age computer via an ordinary keyboard.

zahc

  • friend
  • Senior Member
  • ***
  • Posts: 5,235
Re: Softening steel
« Reply #6 on: May 04, 2021, 07:58:23 PM »

I just want the inside part that screws onto the hub. The teeth are 1/8 wide and I need them to be skinny to fit a skinny chain. So I plan to turn a regular sprocket down into a hub then silver braze a narrow 8 speed cog back on. Alternately I could turn the teeth down narrower instead. Or I could have one laser cut.
Maybe a rare occurence, but then you only have to get murdered once to ruin your whole day.
--Tallpine

zxcvbob

  • friend
  • Senior Member
  • ***
  • Posts: 10,293
Re: Softening steel
« Reply #7 on: May 04, 2021, 08:21:25 PM »

What about using a grinder instead of a turning tool?  Just go slow.  You could still use the lathe to keep it concentric, although it might be easier to grind most of it off freehand.
"It's good, though..."

griz

  • friend
  • Senior Member
  • ***
  • Posts: 2,546
Re: Softening steel
« Reply #8 on: May 04, 2021, 09:05:29 PM »

I just want the inside part that screws onto the hub. The teeth are 1/8 wide and I need them to be skinny to fit a skinny chain. So I plan to turn a regular sprocket down into a hub then silver braze a narrow 8 speed cog back on. Alternately I could turn the teeth down narrower instead. Or I could have one laser cut.

I kind of thought that would be the goal.  My only advice would be the same as Bob's, chuck it in the lathe and use a grinder to evenly take the teeth off.  That has the advantage of not having to take the temper out, but doesn't give you as much dimensional control.  Good luck.
Sent from a stone age computer via an ordinary keyboard.

HankB

  • friend
  • Senior Member
  • ***
  • Posts: 13,004
Re: Softening steel
« Reply #9 on: May 04, 2021, 11:15:26 PM »

Is the quench temperature the same as the annealing temperature? If so, can't you judge the temp is "about" right once the steel loses its magnetic properties?
Trump won in 2016. Democrats haven't been so offended since Republicans came along and freed their slaves.
Those who work for a living are being BURIED by those who vote for a living.
Government is a broker in pillage, and every election is a sort of advance auction in stolen goods. - H.L. Mencken
Patriotism is supporting your country all the time, and your government when it deserves it. - Mark Twain

Bogie

  • friend
  • Senior Member
  • ***
  • Posts: 5,537
  • Hunkered in South St. Louis, right by Route 66
    • Third Rate Pundit
Re: Softening steel
« Reply #10 on: May 04, 2021, 11:20:43 PM »

Lathe, put something over the ways to catch the debris, and grind with something held in your toolpost. Or, do you know anyone with a milling machine and a rotary table?
 
And... Look at the Bridgeport Mill User Group on Facebook. When you join it, answer the questions, and tell 'em I said hi from Facebook Maximum Security.
Blog under construction