Proper technique to fold brass backs for saws?

[Tony Joyce]

Provided you have the proper equipment, how tight should the fold be on the brass back.

Tight? will the blade distort the brass when inserted? Can it be too tight?
Loose? press brass together after the blade is inserted? Press just the edges tight? Crease loose?

Inquiring minds wonder? Plus I have friend who has the equipment to do it(Shears, punch presses, brakes, etc). I just need to be able to tell him what I need. I would have bought them from a saw guy, but they are unavailable for the foreseeable future.

[Mike Siemsen]

The older backs are somewhat teardrop shaped with an "eye" at the top of maybe 1/16 to 1/32 of an inch, at least 2 to 3 times the blade thickness. The bottom is about as tight as you can get it, you probably won't be able to get the bottom tight together as there is spring back in the material. If you fold the back over tight together when you insert the blade the back will spread open and the bottom edges will not grip the saw plate. You need the back to pinch the blade.

[george wilson]

We folded many a back making back saws in Wmsbg. I made a press that was made of 2 1/2" square steel jaws,long enough to fold the longest back(and then some). I put 2 bottle jacks underneath the lower jaw. The jaw slid on 1" round cold rolled steel vertical rods. We also made a Vee shaped former to start the bend in the center of the flat piece of brass or steel back material. This was put into the press to squeeze the backs into a "V" shape first. We used 260 alloy brass,and annealed it first. In the case of the thicker backs,we annealed it again after the initial "V" squeeze. I know some said they didn't anneal their backs,but I had them tear at the fold if not annealed. In the final squeeze,I cranked the press shut till the opening left at the blade side of the back was less wide than the blade. If you over squeeze,the back can spring open permanently. The back,as stated previously,should have a little teardrop opening at the top. I also had copper facings on the jaws to minimize any marking of the brass,and minimize the subsequent polishing.

The blades were tapped into the slightly too narrow opening to hold them. I usually zipped their top edge across a belt grinder to get rid of any burr,or sharp corner that would shear off some of the brass when going in.

The Kenyon backs were left round topped. In the case of my Grove style saws(for myself),I ground facets on the bottom edge of the backs before inserting the blades,and ground facets on the top edge after assembly to the blades. Ground the sides,too. This was done on a belt grinder freehand. These saws are in the FAQ section at the top of this Neander column.

You can get the "Vee" folding feature in one of those import 3 in 1 type sheet metal machines. They have a shear,rollers,and the box forming "V" feature at the bottom. I don't know what gauge brass they can manage,but if you anneal it,you should be o.k. for up to carcass saws. Once you get this "V" started,you can proceed to squeeze the backs shut by degrees in a wooden jawed vise. I urge your wooden jaws to be in new condition,so you don't scar the brass,causing a lot of sanding and polishing later.

[Tony Joyce]

Mike,
Thanks, this is exactly the type of information I'm looking for.

George,
I really appreciate your description of the process. There are few, if any, places that can give the type of information you possess gleaned from your years of experience. I, and I'm sure others here appreciate your willingness to share it . Could you give me a short treatise of your method of annealing the 260 brass.


Also what thickness of brass do you recommend?
I assume 3/4" and/or 1" widths(folded width) are appropriate, based on blade depth of cut?

Thanks!

[george wilson]

Just heat it up to red hot. Not necessary to quench it. In fact,it could lead to cracking if plunged into water. Don't heat above red hot,or it might get ruined. I don't have one in hand,but our little dovetail saws had a back that tapered from about 9/16" down to less than 1/2" at the tip,just like the original. 3/4" is fine. 1" too large for anything smaller than a tenon saw. 1/8" brass will be plenty thick for saws up to carcass size.

[David Kuzdrall]

Tony, did you ever find a local source to fold the backs? If so how did they turn out?

[george wilson]

P.S. In my post #5,I meant 3/4 or 1" FOLDED width as Tony Joyce referred to. So,you'd start with a brass strip twice those widths mentioned. I'd like to make it more clear: DON'T quench red hot brass at all. I have had it crack open even in smaller thicknesses,and distort. Just let it lay around and cool. It will be just as soft that way. We quenched before bending the brass into a V shape,and afterwards. If the brass was thick,as in the larger tenon saws,we then bent the backs about half way shut and quenched a third time. The large Kenyon tenon saws used 3/16" brass. Their backs were 3/8" thick when folded. Very heavy backs indeed!

[Tony Joyce]

David,
Actually I haven't per-sued it any more. I had considered trying to do them myself, but it would mean the purchase of some equipment. I have a friend/acquaintance that has the necessary equipment(he owns a job shop) to do this. I just need to see if he has time to do some for me.

Tony

[Charles Murray Ohio]

Does anyone know a reasonable source for 260 Brass?

[george wilson]

Now that I am retired,I buy it from Enco when they have a free shipping deal. They have those just about every month,plus often a 10 or 20% discount WITH free shipping,too. Wait for those deals. Email Enco and request to be on their Email list. I think business might be tight for them these days. They are often offering deals.

[Chris Fournier]

I have done this cold with the aide of a slot milled down the length of the fold. I used clamps and cauls. Not sophisticated but I have three Japanese saws that I have built this way. 0.625" brass, alloy unknown.

[george wilson]

That is pretty thin brass,where you can get away with cold bending. Try it with 1/8" brass and it will likely fracture because the outside surface has to stretch a lot further when the brass is folded.

[Chris Vandiver]

I have done this cold with the aide of a slot milled down the length of the fold. I used clamps and cauls. Not sophisticated but I have three Japanese saws that I have built this way. 0.625" brass, alloy unknown.

Doesn't 0.625" equal 5/8"? Did you mean to say .0625"(1/16")?