Hardening metal

[kibble]

Does anyone have any experience in the hardening of steel? I was looking up some information online and found some stuff on it. But I was curious to hear feedback from those of you who may have done it before.

The only reason why I'm interested in this is because I discovered just yesterday that some of the brake parts I'm gonna make are too soft to hold up to constant use. They bend quite easily but I don't want to use heavier metal or have to remake the same parts out of something else. I would rather figure out how to harden what I already have. If any one of you has any experience, I'd be grateful to hear what you've done.

[jr dragster Tyler]

heat up red hot then dip in cold water.

[kibble]

I read about that too, but I figured I'd ask. I guess I'll bust out the torch and try it. This is what's happening; when I press on the brake pedal, it puts force against the bar and it makes it bend down a bit instead of moving completely forward so that the other end presses into the master cylinder. It takes a lot of force to move the master cylinder. As you can see in the pictures, the flat bar looks a little bent.

[jr dragster Tyler]

Nice kart where doing the same with the diamond plate idea. We found that a MPS gas torch didnt quite get it red hot though maybe you have something different.

[bigbuddy29]

is the m/c for power brks or manual brks. i see in your pics the push rod going into the m/c is not centered that also could part fo your problem. could be that the m/c is for power brks. would take pressure to engage brks.:cheers2:

[kibble]

Well the m/c came out of a car so I'm pretty sure it was for power brakes. It works just fine the way I have it set up and I know that the bars aren't exactly lined up yet, but where the hole is that the bar pivots on is where it's the weakest. It's really easy to bend by hand and much easier with your feet. I just bought some locknuts today and I will try to harden the bar. I'm gonna try a brazing torch to heat it up.

[jr dragster Tyler]

Why not just replace it with thicker steel?

[bigbuddy29]

hey kib, after looking at it closer. looks to me that when you push on the pedal, you are putting more pressure at center of the bar where it pivots, than at the end of the bar. if you point of pressure at the end should be easy to push, and bar won't bend.

[kibble]

Why not just replace it with thicker steel?

That's what I'm trying to avoid.

Bigbuddy, I'm not sure I understand what you're saying. I have the rod that attaches the pedal to the bar at one end and the pivot is in the middle. The other end is the one that pushes on the m/c. I'm not pushing in the middle of the bar.

[jr dragster Tyler]

Big buddy has a point what he's saying is use lerverage more to your advantage. Putting the pivot point closer to the cylinder rod.

[kibble]

Yeah, I had thought about that too, but the problem is that the pedal can only move so far and putting the pivot closer to the cylinder will give me less range of motion on that side. I had to make it so that pusing the pedal from where it is to the very end, gives me a decent range of motion on the other side. I appreciate the input guys. I think I understand what big buddy was saying now. I suppose I could try modiying the lengths and the pivot a little bit. The calipers are adjustable and I could use that to make up for differences in the other parts.

[dpaxson]

i've tried doing this before but i believe that normal mild steel can't be hardened because it has a lower carbon content than is necessary for hardened steel. you can temper and un-temper metal that's already hardened (like a file or something) but i don't think mild steel will work. plus hardened steel can end up really brittle which would be a lot worse than something that bends

[Kenny_McCormic]

build it beefier

[newrider3]

He probably solved the problem in the seven months since he posted this thread guys.

[kibble]

He probably solved the problem in the seven months since he posted this thread guys.

:roflol: Yeah, I actually got this taken care of like a few days after I last posted in this thread.

But thanks anyway for trying to help, guys! :thumbsup:

[fluxcored]

Newrider may just have a point there! :2guns: :2guns:

:roflol: :roflol: :roflol: :roflol:

Oh yeah - dpaxson, I think you're right btw.

[Sdannenberg3]

Well I would say sorry for being off topic, but this thread is dead and I dont know if its quite "new thread" material but.... How much did you pay for the diamond plating Kibble?? I was looking to do that to my kart but it was like $50 for a little 2'x2' piece!!!

[kibble]

Yeah, I paid just a bit less than that, I believe. I picked it up from the wrong spot thinking that it was only like $10 and when I got to the register and they rang it up .... I think you can imagine the rest. :ack2: This was for a 12x24 piece.

I hesitated, but I got it anyway because it was the only thing that would look the way I wanted it to and it's light weight.

[2or3wheels]

How did u fix it?

[kibble]

Well, actually I did two things:

I heated it up til it was glowing red and then dropped it in a bucket of cold water and two, I made a little bracket on the opposite end like so:

http://www.diygokarts.com/vb/showthread.php?t=862

Look at post 56.

This prevents any down force on the lever that pushed on the m.c. so it doesn't bend down.

[I like karts]

I think if you heat metal red hot, then dunk it in used motor oil that is dino and not synthetic it hardens it. It bonds more carbon to it, therefore making it harder. Be careful though, cause it makes a lil fire. (Saw them do it on mythbusters)

[ryf]

the used dino oil is the most correct way, the thing you need to do is put it into the liquid and swirl it around, you can't do that as safely with oil, water works, used dino oil works better as it does allow carbon to bond as well, the other reason people prefer oil is you can reheat repeat and add more carbon, I have made knives this way. another thing to think about, is keep your old lawn mower blades, and if you need something already tempered, its thick, strong and tempered.

remember you must swirl it to temper properly, the boiling of the liquid along the surface slows the temper, and you want this to be cooled as quickly as possible (I've gone so far as to swirl in ice water with good results. if you just drop it in the oil or water, it will temper, but not nearly as well. have fun with it.

[MDMike]

first Id heat cherry red, quench in oil, Then heat cherry red and quench in water. There's several ways to harden steel. Casolite (case hardening) which is a powder used after heating red hot.
But the oil and water works well. (I come from a Machinist family)

ps. Yes be careful of fire when using the oil.