Thread: Saw Making Folded Backs

Originally Posted by DSEL74

Hi Peter,

How did you get from the wide arch to the closed version? It looks like the ends are crimped more than the rest. Corneel used a hammer, others have suggested a machine vice, what was your method as it looks to have worked really well.

Dale,
I used a hammer, a hard mallet and a soft rawhide mallet, a couple 1/2 inch steel plates, and the vice, and I did run it through my jeweller's rolling mills, but that was not a help, I had to hammer it back to shape after that.
There isn't a crimp at the ends.
It is just where I stopped sanding and left the brass oxidation. When bending, the ends tend to cup and deform a little. I can leave it in the waste, or just sand a bit more and polish down to an even colour all along the brass.

Peter

Originally Posted by lightwood

Dale,
I used a hammer, a hard mallet and a soft rawhide mallet, a couple 1/2 inch steel plates, and the vice, and I did run it through my jeweller's rolling mills, but that was not a help, I had to hammer it back to shape after that.
There isn't a crimp at the ends.
It is just where I stopped sanding and left the brass oxidation. When bending, the ends tend to cup and deform a little. I can leave it in the waste, or just sand a bit more and polish down to an even colour all along the brass.

Peter

Hi Peter. Having been and done that with folding your own spine, (kudos for doing so) could you see yourself repeating the same process again given the need for a saw spine, or would you preference to using a slit spine next time.

Stewie;

Cheers peter thanks for explaining your process.

Peter thanks for your explanation. In my case, I have so many dents that I need to sand quite deep. So I am afraid I would erase the namestamp again during the smoothing process. Engraving looks like a better solution in my case. I use the vice

A few years back I made a saw using a 30 ton press to flaten the spine. That was very helpfull, but I don't have access to that press anymore. I tried to flatten the spine with a big vice, but I only managed to bend the tommy bar, before I got anywhere near flat

The hammering process looks rough, but it isn't too bad. The dents are no problem to remove with a bit of patience, a file and a 60 grit belt on the sander. I wouldn't hesitate to do it again. Hopefully my hammering technique improved enough to reduce the problems. It is remarkable how easy it is to get the spine near totally straight. Any remaining problems at the toothline can be remidied by twisting the spine. Of course, a dovetail saw is easier then an 18" tenon saw.

Corneel, as a suggestion you could turn the hammering marks into a feature. I can see it in my mind's eye, and it looks good. Perhaps reality is uglier (as is too often the case)

Seriously though, there has been quite some discussion about decorating the brass backs in this thread, from posts #491 onwards (in particular #494).

Here's my namestamp pressed into one of my sawbacks. Doesn't look too impressive, does it? It quite looks like it allready has 200 years of daily wear and tear. And I made for a lot of extra work to get the saw straight again. The stamp sais C

IMG_1068.jpg

Originally Posted by Corneel

Peter thanks for your explanation. In my case, I have so many dents that I need to sand quite deep. So I am afraid I would erase the namestamp again during the smoothing process. Engraving looks like a better solution in my case. I use the vice

A few years back I made a saw using a 30 ton press to flaten the spine. That was very helpfull, but I don't have access to that press anymore. I tried to flatten the spine with a big vice, but I only managed to bend the tommy bar, before I got anywhere near flat

The hammering process looks rough, but it isn't too bad. The dents are no problem to remove with a bit of patience, a file and a 60 grit belt on the sander. I wouldn't hesitate to do it again. Hopefully my hammering technique improved enough to reduce the problems. It is remarkable how easy it is to get the spine near totally straight. Any remaining problems at the toothline can be remidied by twisting the spine. Of course, a dovetail saw is easier then an 18" tenon saw.

I agree the hammering is not too bad, and getting it straight is one of the easier parts...a selection of the silversmith's hammers is also a bit of an advantage.
As for destroying the punch mark, it will be protected of you were to use a heavy, hard plastic hammer when you are near the punch mark. It will also move the brass without leaving deep dents.
I also use a very hard round face timber mallet. Some local timbers we can get are ideal for that kind of thing.
I use a heavy cast iron hammer with copper on one side and a hard plastic on the other. I don't use the copper side for this job, I only use the plastic side.
One of these

There is a lot of enthusiasm around this forum from those who have been recently inspired with the forging and filing of metal.
Often, with those who are new to this kind of thing, there is a reluctance to let the metal get right out of shape on the way to where it needs to be, all straight and square. So they try and get the shape without really letting the metal have it. Understanding how the metal can be manipulated, then having the experience to get it back into shape without too many grunge marks will come in time. It is an advantage to actually stand and watch someone do it, but it sounds like you are getting there.

Do you like to leave the brass a little springy, or would you do an annealing after it is pushed all the way down? If it is softened, even partially, it will planish more easily, but I think it won't be as springy as the older backs are.
I prefer a bit of spring myself, and even give it work over with a planishing hammer to harden it up somewhat.

Do you have a planishing type hammer?

Regards,
Peter

Hi Peter,

What brass alloy would you recommend for folded backs?

I was buying some brass from George White, and noticed he has 3/4 x 3/4 x 1/16 brass angle, he also has 1/8" but I'd think bending that might be a bit ambitious... I'd consider the 1/16 first.

Like this...


The alloy is C38000, and it crossed my mind that it's already half way to becoming a folded back... maybe anneal it first and then drive over it a few times with a truck...

Regards
Ray

PS .. That alloy is probably not suitable for bending...

Typical Uses for C38000 Architectural Bronze "Low Leaded" Brass:
ARCHITECTURE: Thresholds, Architectural Sections, Door Frames, Window Frames
BUILDERS HARDWARE: Hinges, Builders Hardware, Butts
OTHER: Extruded Shapes

Originally Posted by RayG

....PS .. That alloy is probably not suitable for bending...

You are dead right, Ray. That's the most common alloy you get in Aus, it seems. Machines well enough (comes off the lathe tools in chips rather than continuous curlies), but it does not like to be bent too far, and hates being peined.

I buy 1mm plate from the same place, not sure what alloy it is, & it takes 90 degree bends quite happily when I make 'shoes' for my marking gauges, so maybe 1/16th will take bending ok, with just one or two annealings. If you find a local source for soft plate suitable for peining, please let me know, I want to build a couple more dovetailed planes before I expire, & though I've learnt to live with the hard alloy, an easy-peining one would be much nicer to work with, I'm sure.....

Cheers,

Originally Posted by IanW

If you find a local source for soft plate suitable for peining, please let me know,

Cheers,

Hi Ian,

I have some 1/4" Brass Alloy 260 ( CS26000 ) tucked away for that exact same reason...

George White have it, but the sheet size is 1800 x 900, and you don't want to know what a 1/4" sheet costs...

George White | Australia's leading stockist & distributor of non-ferrous metals - Product List

Principal Design Features
Brasses (Copper-Zinc Alloy), Cartridge Brass, 70%. C26000 has the highest ductility in the yellow brass series. Easily machined but is more often cold formed.

Regards
Ray

PS... Back on topic, for folded brass backs, this stuff would be ideal for folding, but I note that it comes in 1.5 tonne coils...
George White | Australia's leading stockist & distributor of non-ferrous metals - Product List

Thumbsucker just had the left over of a plate of the proper brass from making planes in the market place for $100. It was quite thick so good for larger planes. If it had been a bit thinner & cheaper I would have grabbed it. If still available it might suit someone else's needs.

Yes, 1/4" is way too thick for what I have in mind, unfortunately, or I might have tried gazumping Doug.

I used 1/8" for the sides of my 9" coffin smoother and that seemed adequate - I would have liked 5/32" or 4mm, but there was nothing available in those thicknesses that I could find. I think Lightwood used 3/16" for the sides of a slightly larger plane, & he was (is) happy with that. I've forgotten what my plane weighs, but it is heavier than my post WW2 Norris A5, and quite heavy enough for me in a long session. I was using it this morning, in fact, on some rather recalcitrant wood, & noticed once again what a difference the high angle blade makes - on the one hand, it handles cranky grain so much better than anything else I have, but on the other, it is decidedly harder to push around! So when I get that round tuit, I'm going to make a small smoother with a slightly lower angle, just to see if I can hit the perfect compromise. I probably won't, of course. but I'll have a lot of fun trying....

Cheers,

Originally Posted by RayG

Hi Peter,

What brass alloy would you recommend for folded backs?

I was buying some brass from George White, and noticed he has 3/4 x 3/4 x 1/16 brass angle, he also has 1/8" but I'd think bending that might be a bit ambitious... I'd consider the 1/16 first.

Like this...


The alloy is C38000, and it crossed my mind that it's already half way to becoming a folded back... maybe anneal it first and then drive over it a few times with a truck...

Regards
Ray

PS .. That alloy is probably not suitable for bending...

Typical Uses for C38000 Architectural Bronze "Low Leaded" Brass:
ARCHITECTURE: Thresholds, Architectural Sections, Door Frames, Window Frames
BUILDERS HARDWARE: Hinges, Builders Hardware, Butts
OTHER: Extruded Shapes

Ray,
The extruded brass alloys, the machining alloys with lead have very poor cold forging properties. They will fracture and crack as you bring a hammer into the same room.
On the other hand, cartridge brass, #260 is better than good, it is excellent. It can have it's cross-section reduced by about 75% before it needs annealing.

Regards,
Peter

I'm lucky, probably. There is a metal supplier with a huge selection in the town where I work (Rotterdam). They are not particularly cheap, but better then unavailable. Spring steel I get from ebay in Germany, it's difficult to find that stuff in small quantities.

A picture of the hammers I use, and my new saw smithing anvil. The hammers are simple sledge hammers, but I eased the corners a bit on the bandsander. The "anvil" is a piece of scrap. In a harbour town, one mans offcut is another mans sawsmithing anvil. That Thor hammer looks like a very usefull tool, I'll check if I can find something similar with enough heft.

IMG_1020.JPG