Slotted brass for dovetail saw back?

[Mike Allen1010]

Quick disclaimer; I don't know anything about metalworking so I apologize in advance if this is a stupid question. That said, I very much appreciate any advice or suggestions!

I am attempting to build a couple brass backed back/dovetail saws. My understanding is I should use 260 brass alloy. The brass backs will be 1/4" thick x 3/4" wide. My problem is I need to be able to cut a slot .020" wide x 3/8" deep in the 1/4" dimension of the back to accommodate the saw plate.

I have nowhere near the skills, experience or tools to do this myself. Does anyone know where I might be able to get these slots cut? Is this something I could likely find a local machine shop to do? Would a supplier of brass bar stock (McMaster Carr?) offer this kind of milling service?

Wenzloff and Sons saw makers used to sell slotted saw backs but that's not currently an option and I'm kind of stuck.

I attempted to laminate the saw plate between 1/8" thick brass sheet stock, drilling/punching holes and peening 1/4" diameter brass rod to hold it solidly, but I ended up with exactly what I was hoping to avoid -- bent/wavy saw plates.

I very much appreciate any advice and suggestions.

Thanks in advance,
Mike Allen

[Stephen Pereira]

Hi,

Sounds like a job for a slitting saw on a horizontal mill. How long are the brass backs?

[Mike Allen1010]

Hi Stephen,

The brass back for the saw I'm currently working on (kind of already wrecked!) is 14" long and the slot could be either .020" or .025" wide.


In general the backsaws I'm trying to make have brass backs that range in length from 10" to 18". However, if it makes milling the slot easier (?), it would be no problem from a saw building perspective, to use a longer piece of brass and just cut it to length after the slot has already been cut. I think the bar stock typically comes in 36" and 72" lengths.

Should I be looking for places that offer "metal machining services" and ask if they have a "slitting saw on a horizontal mill"? Thanks very much Stephen for the insight!

Any and all advice and recommendations are welcome and much appreciated!

Mike Allen

[Bruce Page]

Agree that the slitting saw is the way to go. This can be done on either a horizontal or vertical mill. Most machine shops will have slitting capability. I would make a sketch/drawing of the finished saw back including tolerances and send it out to a few shops. I would not force the slitting saw option, it is better to let the shop decide the process.

[Stephen Pereira]

Agree that the slitting saw is the way to go. This can be done on either a horizontal or vertical mill. Most machine shops will have slitting capability. I would make a sketch/drawing of the finished saw back including tolerances and send it out to a few shops. I would not force the slitting saw option, it is better to let the shop decide the process.

I agree with Bruce to not force the slitting saw option..let the machine shop
do their thing. The reason I suggested the slitting saw and horizontal mill is because that is they way I would do it AND because I just acquired a nice little Burke #4 horizontal mill.

Mike..to help you visualize a horizontal mill with slitting saw..it would be like a tablesaw upside down..blade above the table. Horizontal mills have become almost obsolete these days ..big mills can be had for a song.

[Mike Allen1010]

Thanks Stephen and Bruce, I really appreciate the advice.

I'm working on a sketch and canvassing San Diego area machine shops for someone willing/able to do the work.

The good news is this has to work better than my first attempt at laminating saw backs which was kind of a smoking hole in the ground!

It doesn't really show well in the pictures below but a couple of the saw came out straight, but one of them is crooked as 10 miles of bad road.

Thanks again, Mike

back saws1.JPGback saw 2.JPGback saw 4.JPGback saw 5.JPG

[Stephen Pereira]

How is the brass back fastened to the saw?

[Steve Ryan]

You may be able to do this on a router table with a slitting saw. Need to lower the RPMs and take light cuts so as not to clog the gullets in the blade. I would make a slotted carrier from a big chunk of hard maple and clamping screws to hold the brass strip. Spray a bit of WD40 on the blade after eack pass to help prevent the chips from welding themselves to the saw blade.

[McKay Sleight]

A number of years ago two of us that were shop teachers were in charge of a summer workshop for Utah's woodworking teachers. As I remember, we had 2" flat stock and a machine shop in salt Lake folded the brass. It worked great. We made at least 50 saws. The blue plate was simply press fit. This allowed us to tap the saw upside down on the front or back of the brass to align the blade. We ended up with flat blades that were easy to cut. With the left over blue steel we made scrapers.

[Mike Allen1010]

How is the brass back fastened to the saw?

Stephen,

I laminated the saw plate 1095 spring steel played between two pieces of 1/8" thick 260 brass alloy, glued it together with epoxy and then drilled quarter inch diameter holes through everything. I then inserted 1/4" diameter 260 alloy brass rod and peended that into the holes.

The saws seem to be holding together solidly, problem is I think peening the brass rod introduced stress into the Saw plate that caused a bends/waves in the blade.

Mike

[Mike Allen1010]

A number of years ago two of us that were shop teachers were in charge of a summer workshop for Utah's woodworking teachers. As I remember, we had 2" flat stock and a machine shop in salt Lake folded the brass. It worked great. We made at least 50 saws. The blue plate was simply press fit. This allowed us to tap the saw upside down on the front or back of the brass to align the blade. We ended up with flat blades that were easy to cut. With the left over blue steel we made scrapers.

McKay,

It sounds like you guys have it figured out. Bending the brass sheet stocked over 180° so that there was a pressure fit with the saw plate would be great. I've only seen tutorials on the web where people do this in their home shop with a homemade bending break and to a novice like me it seems really problematic, given the whole goal is to get everything straight, parallel etc.

Maybe I should be looking for machine shop that can do the folding operation.

I found a local machine shop that thinks they can mill the slots into brass bar stock; when I get some back I'll let you know how it turns out.

Thanks again for the suggestions!
Mike

[Stephen Pereira]

Stephen,

I laminated the saw plate 1095 spring steel played between two pieces of 1/8" thick 260 brass alloy, glued it together with epoxy and then drilled quarter inch diameter holes through everything. I then inserted 1/4" diameter 260 alloy brass rod and peended that into the holes.

The saws seem to be holding together solidly, problem is I think peening the brass rod introduced stress into the Saw plate that caused a bends/waves in the blade.

Mike

Apparently 1095 spring steel is not so hard it cannot be drilled.

Perhaps the peening process did introduce stress or bent the saw plate..pretty thin material. If the brass wasn't so thin (1/8') I might consider drilling/tapping. If you used brass countersunk screws you could file flush to make them disappear

If you can't find a machine shop locally..or they charge an arm and a leg.. I would try milling the slot for you. I'm just now getting my little horizontal mill up and running and it would be an interesting first project.

I'd have to make a practice run, insure that there was little or no run out in the arbor/saw blade but I think it is doable.

[Johnny Kleso]

You can slot it on a drill press..
Mike Wenzof tried my method and said it worked well but choose to use folded backs..
I have not tried it but will tell you how..

You whant to make sure your DP table is super dquare to spindle..
Use a dial indicator

Lower blade and cheap 1/2 shank arbor as close to table as you can

Make space to raise table and allow arbor not to rub table top

You also need a adjustable fence so you can multiple passes to slot brass back

You need to use oil while slotting and use a speed some where around 700 RPMs

Use Push sticks or build a fixture to carry brass backs

[george wilson]

By now,I think Mike W. is now selling brass backs again.

[John T Barker]

It sounds like you have a lot of good info and suggestions here. I love that I am seeing tool making threads on this forum. Doing a search to find backsaw info I found an old drooling favorite, norsewoodsmith.com and also found a site called backsaw.net. How cool. Shopnotes also did an issue a year or so ago on making a backsaw. Just in case you didn't do the simple...which I'm sure you did.

John