macds
Hot Rolled
- Joined
- Jul 24, 2008
- Location
- Milverton, Ontario, Canada
not worth sharing
Last edited:
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Wanted to put this out, especially after reading paper from various steel companies, and the few forum posts I could find.
Had to make up a splined shaft for a man lift, runs the 4wd.
Decided to go with S7 over run of the mill stuff.
My biggest obstacle was how to make it hard (at least on the outside).
A few things I read talked about decarb, high temp wrap, vacuum furnace....
This was an emergency job, no time for that.
So, being a round part (1.5" dia) I stuck it in the lathe at 80 rpm, and let it chew with the torch.
Initially nice and slow to bring it up, then white flame tip once it started to red up.
Then switched up to a hotter, but not short blue cone until bright orange, almost yellow. This took almost 40-45 minutes on a 1.5" dia x9.5" long part.
Once i saw consistent carbon flaking on the surface (like O1), I went a little further, maybe 5 minutes, then killed the oxygen and did an acetylene carbon soak on the part until the acetylene stopped burning off.
Let the lathe run with the part spinning to cool off in still air for a good hour, then did a surface oil quench at around 400C.
Keep in mind that im primarily after surface hardness on this part, while retaining sponginess at the core.
Couple hours later after a nice spinning air cool, part is nice and straight dimensionally, and a file wont touch the skin.
Did I just make the most shatterable shaft known to man, should i bead blast it and draw it down (i think i SHOULD until a straw colour), or do you think it will be ok?
Curious if anyone else has done similar with S7, just to compare notes.
Chrome plating = hydrogen embrittlement. Part must be cooked to drive out the hydrogen after plating.Hi macds:
I'm not in the least upset about the post; I'm just concerned you may have unknowingly bitten a monster on the ass.
We all know about the infamous lawsuit where the moron cut off his own dick (or whatever) with the lawn mower when he and his buddy tried to use it as a hedge trimmer and the maker of the lawnmower got the blame.
In a legal climate as fucked up as that, the liability you expose yourself to even when you are trying to help someone out of a jam is an ever present threat to everything you've spent years to build up.
I've never knocked up against this directly (Thank God) but I have a buddy who got absolutely raped over a motorcycle part (steering component) that was postured to have been a contributing factor in a fatal accident.
He didn't even make the part...he just ground off the bits that were no longer needed and polished the thing (it was a triple tree for a Harley) to make it pretty so it could be chromed.
I don't know if it was even a legitimate contributor to the wreck, but he just got jumped on, and this was way back in the 70's.
It's a lot worse now.
So be careful out there boys and girls...there be assholes in suits with law degrees about, and they will hurt you if they can, all so they can make a pile.
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
I’m with you, Marcus. I spent my entire career responsible for safety related components. You don’t even have to be responsible for a failure to lose in court. Especially if you are in Bumfuk, Iowa.Hi All:
Am I the only one who's terrified of what is being advocated here?
Here's a snip from the original post with my emphasis added:
"Had to make up a splined shaft for a man lift, runs the 4wd."...
"A few things I read talked about decarb, high temp wrap, vacuum furnace....
This was an emergency job, no time for that."
"Did I just make the most shatterable shaft known to man, should i bead blast it and draw it down (i think i SHOULD until a straw colour), or do you think it will be ok?"
I'd be scared to death of liability exposure, not only for doing the job this way, but also for talking about it on the forum.
If that manlift suffers a failure or even has an accident unrelated to the repair and a smart lawyer ever gets wind of this, the OP is in a world of hurt, even if by some miracle, he ultimately escapes with exoneration.
I'm not a doomsayer by any stretch, nor am I terrified of my own shadow, but I'd walk away from this job, forgo the bit of cash I didn't earn and be grateful I can still sleep at night without fear.
I'm not a lawyer but here's what I see:
The OP knew or should have known that it was for an application in which a failure could conceivably cause harm.
The OP chose to violate the accepted heat treat protocol for this material (that he chose without any engineering justification), even knowing this is a potentially critical component and knowing what the correct HT protocol is.
The OP knew his heat treat of the material made its properties unknown, and even speculated as to the potential failure mode, but chose to sell it to the customer anyway.
I for one am convinced a lawyer would have a field day with a confession like this.
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
Hi All:
Am I the only one who's terrified of what is being advocated here?
Here's a snip from the original post with my emphasis added:
"Had to make up a splined shaft for a man lift, runs the 4wd."...
"A few things I read talked about decarb, high temp wrap, vacuum furnace....
This was an emergency job, no time for that."
"Did I just make the most shatterable shaft known to man, should i bead blast it and draw it down (i think i SHOULD until a straw colour), or do you think it will be ok?"
I'd be scared to death of liability exposure, not only for doing the job this way, but also for talking about it on the forum.
If that manlift suffers a failure or even has an accident unrelated to the repair and a smart lawyer ever gets wind of this, the OP is in a world of hurt, even if by some miracle, he ultimately escapes with exoneration.
I'm not a doomsayer by any stretch, nor am I terrified of my own shadow, but I'd walk away from this job, forgo the bit of cash I didn't earn and be grateful I can still sleep at night without fear.
I'm not a lawyer but here's what I see:
The OP knew or should have known that it was for an application in which a failure could conceivably cause harm.
The OP chose to violate the accepted heat treat protocol for this material (that he chose without any engineering justification), even knowing this is a potentially critical component and knowing what the correct HT protocol is.
The OP knew his heat treat of the material made its properties unknown, and even speculated as to the potential failure mode, but chose to sell it to the customer anyway.
I for one am convinced a lawyer would have a field day with a confession like this.
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
its the 4wd, not the lift part... cool your panties.
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