Back saw for cutting steel and brass?

I have recently taken up repairing antique clocks and like to use hand tools wherever I can as this often reproduces better the style and finish of the original. One task is the cutting of slots in screw heads. Of course this can be done using a circular saw in the the lathe or mill, but I don't doubt that it would have done by hand originally.

My much thumbed copy of Ian Bradley's "Beginners Workshop" illustrates a back saw identical to a woodworker's gents saw and specifically mentions its use for slotting the heads of screws. This feels right to me as hack saws and jewellers saws just don't have the straighteness and rigidity.

The question is where to get such a saw, or how to make one. How many tpi? what should it be made be made of? Hardened or unhardened, and if the former how would one sharpen it?

Interesting question, Nigel

Are you sure that there isn’t some confusion with the traditional file ?

**LINK**

https://www.cousinsuk.com/product/slotting-screw-head-1850-vallorbe-swiss

MichaelG.

How about trying a (junior) hacksaw with the blade reversed, so it cuts on the pull rather than push? Same fashion as a Japanese saw.

That looks an odd section for cutting slots in screwheads although that's what Cousins describe it as.

Ian P

Could he have been using an 'ordinary' backsaw for that purpose?

Check model railway suppliers. I got a replacement blade for a small jewellers saw about 1in x5in when I was a schoolboy and bolted it to some Meccano to save using precious pocket money for the frame. Then I also got a similar mini gents saw from Proops at a show some time ago.
For brass a good woodwork saw is adequate if you can find probably 25tpi plus.

here's one although you already need a saw of some sort to cut off the arm and leg needed in exchange.

Edited By Bazyle on 27/11/2019 12:38:30

Jigsaw blades cut on the pull stroke. It should be an easy task to make a handle for them. If you cant find zero set then rub them on a stone to make them flat and the thickness you want. A cheap option to try if you can't find exactly what you want.

Martin C

Probably a real unicorn hunt these days but maybe look out for a set of Starrett 249 Screw Slotting Blades. Like these **LINK**

As I recall it 4 different widths in the set. They are 8" long and fit a standard adjustable hacksaw frame. Fine tooth blades with no set on the teeth.

Basically a really skinny file with deep safe edges.

Discontinued in the 190's I think. Probably a very slow seller as few folk had need of such and even fewer would know about them.

Clive

I think you would have to be very dedicated to make a saw from scratch!

It does not matter what its made from as long as its harder than the material its going to cut, 99.9% of saw's are made of steel and hardened in some way. Number of teeth, or the specifically the pitch, depends on the diameter of the screwhead as there should always be several teeth in engagement in the length of the cut.

Whilst the earliest makers of timepieces would have cut the slots with a saw or narrow file I bet its wasnt such a long time before they started to use slitting saws.

Do you want to cut the slots by hand to maintain the hand-made look?

Ian P

Ian Bradley writes in an admirably clear way.  This is the extract from the book:

Edited By Nigel Watts on 27/11/2019 13:13:36

A hand shaper would be quite good for making such slots, say and Adept No 1. And a shaper would be able to make fine saw blades before hardening too.

Broadly speaking, yes. Having spent far more time working in wood than metal I also feel more comfortable with hand tools, especially for small one-off jobs. It cuts out all that setting up.

Earlier in the week I was filing the end of some 1/4 inch silver steel rod down to a 7mm square at my clock club to fit into a fly cutter arbor on one of their milling machines. I found it a very satisfying process, particularly when I discovered in a drawer a magnificent vintage 16 inch plus flat bastard file made in Sheffield of best cast steel. It could have been a bit sharper, but it felt just like planing wood. My tutor, who rarely dishes out praise, even complemented me on the flatness of my strokes.

Never come across anything like this before. What an interesting piece of kit!

I wonder if a cheapish modellers' saw like this would work on mild steel. It would be too fiddly to sharpen no doubt but if it had a reasonable life one could just throw it away and get a new one.

Edited By Nigel Watts on 27/11/2019 13:39:44

Fine saws for wood and non ferrous metals Here may be something that may serve your purpose scroll down the page..

Mike.

Edited By MichaelR on 27/11/2019 13:44:38

The illustration just looks like a razor saw too me. Better ones work on mild steel as well as brass.

Neil

Dictum sell a couple of japanese saws for metal like this and less likely this

In the good old days a Eclipse no. 45 Back Saw would be ideal, with 3 interchangeable blades for metal, 32, 44 and 60 tpi, cost in in 1964 5/- (25p). One recently sold on the internet for £22!

.

Thanks for the illustration, Nigel

I have a saw that looks exactly like that in Fig.16 ... but it is only really suitable for balsa, and some plastics.

Perhaps there are [were] better versions available.

MichaelG.

For a VERY narrow slot, perhaps the fine-toothed Zona razor saws might be suitable. Chronos list several . For a wider slot, how about a joint square edge file like these from Arc ?

Brian G