Today I did a little more work on that bobsled. So, yesterday I drove a bolt through the runner and it cracked straight across the 2 inch wide runner. So, today the other runner is bowed and not straight and I need to straighten it out. I put a magnet to both runners and the magnet attaches to the runner. So, not sure why that first runner cracked the runner in two, and not sure how much shaping this second runner will that.

I'm guess they both are steel because magnet likes but why di that one crack like cast. You think just old fatigued and how much pressure and pounding will the second take to get it back in shape.

Any thoughts and advice besides heating it up.

Can you post a picture of the grain structure of the one that broke, then we might be able to tell if it’s cast or not because cast iron is magnetic.

Darn I really feel stupid now Lol. I thought cast wasn't magnetic! I'm not much of an iron fabricator so that doesn't surprise me. I which I could show that broken on but I installed that one already and has a wash and bolt holding that on in place. I'm tryin to et the iron install so I can keep on building wood parts and drilling holes where they need to be. It does have some spring to it not what I known cast to have any and is very ridged.

Yeah cast is very rigid, maybe a hardened steel and just a bad spot in the tempering, don’t beat it a press or at least steady pressure is your best friend, if it’s hardened or cast it’ll be tough without heat, and FYI most stainless steel isn’t magnetic.

Thanks Bob. A Magnet will attach to cast iron then?

I can't see the reasoning of making a sled runner out of cast iron. Bet what you have is some kind of steel.

Cast iron makes great engine blocks. And heavy castings, like for lathes or milling machines. Cast iron is iron with a high carbon content yet un-tempered. Very brittle. It does not weld well. care must be taken to bend or even weld it by heating it up first so it does not crack when it goes through temperature changes.
Wrought iron is not cast iron. They are both iron as is steel. Steel is of course an iron product also. Wrought iron is what the old time blacksmiths used. It has NO carbon content. Carbon must be induced into wrought iron in order to harden it, (case hardening). Yes, cast iron is magnetic.

Yup.

Thank You for the clarification. It just surprised me when that one broke and I totally agree cast would be a terrible iron to use as a runner where it gets all kinds of twisting and uneven ground to go over. Today I will heat things up and apply even pressure with clamps to see if I can straight and form the one runner.
Thank You very much and to all.

Hit it with a grinder cast will show reddish sparks or very few large yellowish sparks carbon steel throws a shower of small yellow sparks unless its old your part is cast steel possibly cracked before you started hammering on it

Steel IS Iron with a small % of Carbon and maybe some other metals alloyed to it.

Slow process but steady pressure and some heat I am getting shaped back to form. I really believe now it ain't cast but the stuff is old fatigued and worn out from years of use and laying in the dirt. I'm sure it could have been forged late 1800's early 1900's.

I got pressure on the run side ways now and will keep working to shape I hope.

Go slow and things should work out.

Most of the old runners were cast. Faster and cheaper than steel, and they also wear better. Snow is also less likely to stick to cast iron than to steel.

Snowy, the fifth wheel on the front bunk could be either cast or steel. I've seen both. Bunk is held on with one centered pin. Some of the old logging sleds had bunks 8+ feet wide.

A possible source for parts and advice a lot closer to home for you would be Engle's Coach Shop. [video:youtube]https://youtube.com/@engelscoachshop?si=YXCp5p_xKcevTt8a[/video] He has an eight video series on a bobsled.

He also has a website. I think you would really like his chuck wagons and sheep wagons.

I believe you mentioned that in my thread on bobsled rebuild. That got me thinking when you said cast for runners. I'm sure you are right then! It is amazing that I'm making progress in actually straighten and taken a bow of that one runner. I thank You very much for that site and I visit it and look look at their stuff.
Some years back I rebuilt a buggy and all that was left was the iron. I got it to original status down to all square headed nuts. It was a few years to get it done.
Thanks Sir!