Thread: Saw Plate Thickness.

In researching for my previous post I came across this from a 1915 Spear & Jackson catalogue. There has been much discussion as to whether some backs are deliberately angled (not parallel to the toothline). This seems to indicate the blade should be parallel to the back and that process of stamping can pinch the back acting as a pivot point.

P1070826 (Medium).JPG

Richardson and Harvey W. Peace also adopted this technique quite a bit earlier (1895 National Saw Co, which was owned by Disston, catalogue).

Regards
Paul

Aha Paul, so it was a deliberate thing with S&J, at least on their larger saws, & not the result of some bored, careless or hungover (maybe all 3!) operator not paying attention to what he was doing.

This raises some interesting questions to me, particularly with respect to using the spine to straighten the blade. It's pretty well established, I think, that you can often get rid of minor bends & buckles by re-fitting the spine to make sure the blade is evenly entered along its length, then tapping it back 'horizontally' to seat in the handle (or simply tapping it up & down at the toe end, in some cases). Doesn't always work, but it has worked for me in a significant number of cases. Rightly or wrongly, I've always put this down to folded backs not being perfectly closed along their length so you are going to have tight & less-tight sections, which can interact with uneven tension in the blade to create or reduce buckling. With slotted backs, you can cut the slot to a perfect fit if you happen to have the right saw blades, and the 'grip' should be the same along its entire length. But given the range of plate thicknesses (which always seem to be Imperial) and my slitting saws being metric, it's rare that I can match slot & plate to that degree of perfection, so I took to cutting slots to as close as my saw selection allows & squeezing them carefully in the vise to get the right firmness of fit. It's a nerve-wracking chore, trying to get the squeeze dead even along an entire 10 or 12 inch spine, not helped by the fact that spring-back varies from batch to batch of the brass stock. It usually takes much trial & error to get the fit I like. Once or twice I've overdone it to the extent I had to resaw the slot & start over...

A question I've always had is when the makers stamped the spine. I wondered if the stamp was applied before folding, but I'm assuming from the catalogue spiel that it was done after fitting to the blade.

Thanks for the information re typical backsaw plate thicknesses. It's not too surprising that different manufacturers gravitated to similar dimensions; my own adventures in juggling with the requirements of weight, stiffness & robustness have led me to the conclusion that the sizes you quouted are the best compromises. I've not come across an old saw with plate as thin as 0.016" yet, the thinnest I've ever measured on a small (Disston) was about 0.018" & I had long assumed that was as thin as the major makers went. I've always felt that using 15 thou plate for small saws was pushing it a bit, but my own 225mm dovetailer (~45mm max depth of cut) has given me no problems in the 10 years plus since I made it. It was probably the 5th or 6th saw I ever made, but by sheer fluke, I got that saw perfect (for me, that is, not everyone who tries it is as enthusiastic, but some are ). It also has a lovely "Rock she-oak" (Allocasuarina huegliana) handle courtesy of BobL, which has very fine rays and a fine fiddleback figure. The wood is so polished from use it positively glows. It's my all-time favouritest saw!

As a final note, on several small saws I've had apart (no S&Js that I can recall), I've noticed the top bolt hole just grazes the spine, or goes partly through the edge of it. Since that would not work to lock the spine & prevent the sequelae mentioned in the S&J blurb, I think I'll stick with my hypothesis that these particular cases were accidental rather than deliberate.

Cheers,
Ian

Originally Posted by IanW

As a final note, on several small saws I've had apart (no S&Js that I can recall), I've noticed the top bolt hole just grazes the spine, or goes partly through the edge of it. Since that would not work to lock the spine & prevent the sequelae mentioned in the S&J blurb, I think I'll stick with my hypothesis that these particular cases were accidental rather than deliberate.

Cheers,
Ian

Having removed the handles on quite a number of saws I can state that the hole placement was not nearly as good as it should have been. I should have mentioned that the " auxiliary" screw only located into the spine and did not go right through.

Some models from Harvey W. Peace and Richardson in the 1895 National Saw Co catalogue:

P1070828 (Medium).JPGP1070829 (Medium).JPGP1070830 (Medium).JPG

Regards
Paul

The catalog blurb,says “ i,e back grips the blade more firmly were the makers marked on” i think they mean stamped.
An of course that makes sense when your building hundred of saws a day, assemble saw then press your makers mark in,as pressing the makers mark in on just the back with no plate would distort the back making it difficult to assemble the plate and back.

But then in my view the plate is possible now pivoting on the makers mark,or pinched in the centre.
We’re as I believe the best approach would be to Pinch the plate at the toe end then tension the plate has it is drifted on towards the heel.
Stretching if you will,tho i have my reservations weather that actually happens,tho like others i have straightened a saw plate by removing it from the back an re inserting it.
I think I’m just rambling on a bit [emoji6].

Cheers Matt.


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Originally Posted by IanW

Aha Paul, so it was a deliberate thing with S&J, at least on their larger saws, & not the result of some bored, careless or hungover (maybe all 3!) operator not paying attention to what he was doing.



Cheers,
Ian

Ian

Perhaps not just their larger saws. If you look carefully at the pic in post #2 you can see the open handle saw used for the 8" and 10" models also features the "auxiliary" (my words) screw.

I find their claim, as if they had just discovered it, amusing. The Americans had used the feature twenty years earlier. Having said that, I don't know when S & J first used it.

Regards
Paul

Originally Posted by Bushmiller

....I find their claim, as if they had just discovered it, amusing. The Americans had used the feature twenty years earlier. Having said that, I don't know when S & J first used it. ...l

Well Paul, hyperbole & stretching of the truth has a very long & (dis?)honourable history in marketing, so we'd hardly be surprised if S&J pinched the idea & claimed it as their own. I think Britain was still dominating the tool market in North America until well into the 1800s (it was during the civil war that their own industrial might began to develop at a break-neck pace). Disston used to advertise his saws were made of "finest London steel (was steel ever made in London?!) even though he'd made it in Philadelphia. So Sheffield makers would hardly be keen to ascribe something they were trying to flog as a novel idea to a bunch of ignorant colonists, would they?

Be that as it may, it's very interesting to me, & I'm glad you brought it to our attention. I'm surprised no-one has mentioned it before, but perhaps nobody else spends as many hours poring over old catalogues as you!? I'm interested because it seems to fly in the face of current wisdom regarding the function of the spine on a backsaw. I guess I've learned from my former life and life experience in general never to become too wedded to ideas that seem logical or 'common sense' 'cos they so often to turn out to be the opposite when someone takes a really good hard look at them.

Ah well, I'll just file it with all the other dubious shiboleths about how tools function & what has to be just-so for them to work properly. Some day, someone (definitely not me!) may find the time to do a proper investigation & sort it out for us......

Cheers,

Originally Posted by IanW

A question I've always had is when the makers stamped the spine. I wondered if the stamp was applied before folding, but I'm assuming from the catalogue spiel that it was done after fitting to the blade.



Cheers,
Ian

Ian

I keep seeing more items in your post on which to comment.

To my mind there are only two points during the process when the back could be stamped. The first would be when the back is still a piece of flat bar before folding. However, the difficulty of placement (in a production line scenario) coupled with the potential for distortion during folding may be why this was not done. From the S & J info it was stamped with the saw plate in place. Stamping before the plate was inserted probably would have resulted all too often in the slit closing up making it difficult to insert the blade.

Regards
Paul