Question about saw making

[mark weathersbee]

I'm making a panel saw out of 1095 shim stock and wanted to ask how are saw makers straightening the shim stock out flat? Since mine was coiled it has a slight curve due to this memory.

[Kees Heiden]

Have a look at this:

[Brent Cutshall]

When I'm straightening a blade, I heat the tension points(the spots on the outside of the peak of the curve) with boiling water and see if I can't bend it back. The hot water doesn't seem to take the temper out of the metal. If that doesn't work, I turn to hammering. I haven't watched Kees's video but it will probably tell you what you need to know. By the way, what do you use to tooth the blade?

[george wilson]

I think I was the originator of pouring boiling water on the blade and straightening it while it is still hot. Which means INSTANTLY. As thin as a saw blade is,it will very quickly lose the heat. Tons of surface area,hardly any metal mass.

The video above that I just watched is also a way to straighten a saw. But,just because David Weaver can do it,doesn't mean YOU can do it! David is a very thoughtful craftsman. AND,he has a proper anvil. Most of you don't. I urge you MOST EMPHATICALLY,DO NOT try to hammer your saw over a block of wood,no matter how hard the wood is. You can buy a small 3"x3" or 4" square hardened,polished jeweler's hammering block from Rio Grande for a LOT LESS than an anvil would cost. And,it will work just as well,as long as you hammer OVER the block,and don't slip up and hammer over THIN AIR!! I have made a few of these hardened blocks for my wife's jewelry business,but have a pristine 200# anvil downstairs in my own shop. It was never really used,came out of a school shop. It had been whacked as hard as the boys could with a ball pein hammer.(WHY are boys so STUPID and SO DESTRUCTIVE!!) I spent hours grinding out those little dents with my portable belt grinder with zirconia belts. Got steel dust all over me!! But,that anvil is polished so well that silver can be hammered on it without leaving any marks from the anvil.

The gentle,constant curve that David's saw had is EXACTLY the type of curve that you can use the boiling water method on. And,what I like best is,you don't leave any little hammer marks on your saw(which would irritate me every time I looked at them.) Yoiu can SAND the saw to make the hammer marks less obvious,but they will still be there,and I'd still see them!! You will have to be careful to not burn your hands while pouring boiling water on the WHOLE BLADE. DO NOT let your gloves get wet!! You will get burned worse by the time you manage to get them OFF!! Been there,done that!! Keep your gloves dry. Let the water run off and instantly flex the saw so as to eliminate the bow.

We made our first batch of saws from spring steel that had been coiled. Every one of the crosscut and rip saws had this same bend. So,we had plenty of straightening to do!! Then,I noticed that we could buy STRAIGHTENED blue steel 1095 shim stock. Used that there after. They usually straighten metal sheet by stretching it in very powerful machines that can stretch with millions of pounds of force. At least,that is the way they straighten thick,wide plates of aluminum.

Boiling water is 212 degrees F.. Saw blade steel is heated to 750 degrees to turn it blue. So,don't worry at all about ruining the temper.