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Old 05-31-2018, 12:31 AM
Bad Bob Bad Bob is offline
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Default Finger Brake Nose Bars

I just bought a Chicago 4' X 12 Ga. finger brake that is missing half the fingers. I have most of the material on hand to make replacements. The fingers are made of mild steel plate and aluminum blocks, but the nose bars seem to be hardened. A file will cut them, but it's harder than mild steel. Anyone have any insight the material or hardness?
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Old 05-31-2018, 12:35 AM
Marc Bourget Marc Bourget is offline
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I believe the hardness comes from Carburizing the steel.

Easy process, just requires a very hot oven
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Old 05-31-2018, 12:57 AM
metal manny metal manny is offline
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Hi Bob
I'm not sure of the steel grade originally used by Chicago. You say you have the material to remake the fingers, and I assume you have ordinary mild steel bar which you'll mill to fit the brake? Bearing in mind that your machine was originally built to work in production shops, producing hundreds of bends per day, and as you will probably only be producing a few bends at most in mild steel and ali sheet in a given month, you're probably be going to be OK.
Alternatively, if you work stainless and some heavier mild steel gauges, then the work pressure at the tip of an ordinary mild steel finger might start to deform, and you'd need hardened fingers.
If no-one has a definitive answer to your question, and you'll only sleep easy if you have tool-grade fingers, go to a company that specialises in hardening and they should be able to gauge the hardness of your sample and guide you from there on forwards.
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Old 05-31-2018, 06:24 AM
Gareth Davies Gareth Davies is offline
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I'd go for a steel such as EN24T for replacements as it's mildly hard but easily machinable. It's not like they have to be super hard and wear resistant such as the tools on a press brake would have to be.
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Old 05-31-2018, 10:17 AM
bobadame bobadame is offline
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Another good steel for that application would be 4140 HT.
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Old 05-31-2018, 10:32 AM
Bad Bob Bad Bob is offline
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Thanks for the advice,guys. I sent an inquiry to Chicago about replacement parts. I’ll post the info later.
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Old 05-31-2018, 12:28 PM
Bad Bob Bad Bob is offline
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The nose bars run from $66 for 3" to $110 for the 5". Time to fire up the mill.
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