Hammering saw blades on cast iron, will the surface have dents?

[Bencuri]

I want to straighten some hand saw blades by hammering, and the only hard large surface I have is a large block of cast iron. I tried hammering metal on it, and it did not break, but it is definately a soft material and marks remained on it. However, I expect that due to the saw blade being also wide and flat, when I hammer it, there will be no dents formed on the opposite side on the surface of the cast iron. Or am I wrong, and even this way the cast iron surface will deform, and also the saw blade with it?

[iclark]

I want to straighten some hand saw blades by hammering, and the only hard large surface I have is a large block of cast iron. I tried hammering metal on it, and it did not break, but it is definately a soft material and marks remained on it. However, I expect that due to the saw blade being also wide and flat, when I hammer it, there will be no dents formed on the opposite side on the surface of the cast iron. Or am I wrong, and even this way the cast iron surface will deform, and also the saw blade with it?

If you are lucky, the cast iron surface will only deform. If you miss-hit and hammer the saw teeth into the cast iron, they will mark and they may start forming micro-cracks.

The heat treatment of the cast iron makes a huge difference. After all, many anvils are large chunks of cast iron.

Aren't you trying to deform the saw blade?

[Bencuri]

If you are lucky, the cast iron surface will only deform. If you miss-hit and hammer the saw teeth into the cast iron, they will mark and they may start forming micro-cracks.

The heat treatment of the cast iron makes a huge difference. After all, many anvils are large chunks of cast iron.

Aren't you trying to deform the saw blade?

I want to straighten it by hammering. I have read that is the method it can be achieved with, also saw some sawmakers doing this when tuning saws. I won't hit the teeth, I will keep them off the cast iron surface.

[Bencuri]

Actually I have just found a video that says cast iron is better for this purpose than the kind of tempered stuff that the professional anvil is made of:


https://www.youtube.com/watch?v=N_KikzIarLg

[AHill]

Cast iron is almost always harder than saw blades, which are typically very soft as far as steel goes. Is the surface of the cast iron as-cast or is it machined and/or polished? If rough cast, I would not use it to straighten a saw. the rough surface will restrict the saw plate from deforming compared to a smooth surface like an anvil. If you have a table saw or jointer, you can use those surfaces.

[Bencuri]

Cast iron is almost always harder than saw blades, which are typically very soft as far as steel goes.  Is the surface of the cast iron as-cast or is it machined and/or polished?  If rough cast, I would not use it to straighten a saw.  the rough surface will restrict the saw plate from deforming compared to a smooth surface like an anvil.  If you have a table saw or jointer, you can use those surfaces.

It is mostly smooth but has some shallow rough spots. I want to take it to be milled and smoothed before I use it.

[Tony Z]

You might want to do a web search for sawsmith articles by Bob Smalser. I believe he had at least one on hammering a saw plate. In any case the hammer and your technique is as important as the surface you’re working on. As you’re not really pounding, use your cast iron tablesaw or jointer.

[Pedder]

No machinist vise? Close the Cheeks and you can use that as an anvil.

Told me a black smith.

Cheers
Pedder

[AHill]

Bob Smalser's article on straightening bent saw plates:

https://woodcentral.com/articles/handtoo..._866.shtml