merit - or not - of sway back sawplate ?

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Gavin Longrain
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merit - or not - of sway back sawplate ?

Post by Gavin Longrain » February 23rd, 2014, 11:03 pm

Here's a pic of Atkins 389 and 390 from PATCSawyer...
Atkins 389 and 390 .jpeg
  • When would you want a sway back?
    When would you want a straight back?
I guess swayback may be better to put in a wedge in the kerf.

PATCSawyer advised me by e mail:
  • Both are 4 foot saws, 54" overall with the handles. The 389 (at bottom) is 7-1/4" at the widest and the 390 is 6-1/2" at the widest. The 390 has been filed, the 389 is still in the condition in which I received it. There is a term for the sway-back design of the 389, but I am not a saw historian. Both saws work very well in any type of wood.
I am interested in any other comment or info folks may have.

goodfeller
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Re: merit - or not - of sway back sawplate ?

Post by goodfeller » February 24th, 2014, 9:05 am

The sway back does enable you to use a wedge more easily--and sooner--but there may be another explanation. Legend has it that one morning in 1873, Henry Disston approached his plant superintendent and said he was not entirely satisfied with the company's line of handsaws. He had been studying pictures of Egyptian and Roman era saws and found the shape of the saw had not really changed much since then. He then asked his superintendent to take a piece of chalk and draw a saw blade on the factory floor, which the man did. Disston then took the chalk and said, "See? There's more blade than required. It's too wide. Just cut off and section of the back and curve it." A new product was born that required less steel to make and was thus cheaper as well as lighter. These, admittedly, were handsaws and the sway in a crosscut probably has a good deal to due with actual ease of use, i.e., wedges but that doesn't rule out Disston trying to save a buck at the same time.

Disston, btw, was the first US company to develop a process of melting and re-using steel cuttings, another major savings. The Brits had done this for years at Sheffield. Disston's brother William never came to the US but remained in Sheffield and passed along the latest techniques to Henry. Industrial espionage apparently was a tradition in the Disston clan. Henry's father was sent over to America by a group of English investors to set up a lace making factory in New York. He had invented a lace making machine but British law forbade the export of machines and plans so they sent the inventor instead. Young Henry came with his father who died before the lace factory could be built. Henry moved to Philadelphia and apprenticed as a saw maker. The rest is history.

Not to bore you further but you may recall the question of "crucible" forged steel came up a while back and we generally thought it was an advertising term or gimmick. Turns out that before the Bessemer process was invented, British saw makers used clay crucibles to forge their steel because they made a purer, higher quality steel. Crucible forged steel was the gold standard of the time. US sawmakers even sent their filings back to Sheffield to be re-melted. Disston in 1855 brought some steel workers from Sheffield to Philadelphia and built a crucible mill of his own but continued to use UK steel on specialty items like circular saws into the 1880s.

I am getting all of this, btw, from a great little book my son-in-law gave me by Harry C. Silcox entitled "A Place to Live and Work: The Henry Disson Saw Works & the Tacony Community of Philadelphia," published by Penn State University Press in 1994. It is available on Amazon and eBay. It is mainly about the social engineering Disston did when he set up his model community in Tacony but also has great details on saw making in the opening chapter.

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PATCsawyer
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Re: merit - or not - of sway back sawplate ?

Post by PATCsawyer » February 24th, 2014, 1:03 pm

I don't see a lot of steel savings. The 389 is wider at the handle and the taper at the end is actually wider then the 390.

BD Rec
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Re: merit - or not - of sway back sawplate ?

Post by BD Rec » February 24th, 2014, 6:11 pm

Great info Goodfeller! Thanks for sharing!

Gavin Longrain
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Re: merit - or not - of sway back sawplate ?

Post by Gavin Longrain » February 25th, 2014, 2:34 am

goodfeller wroteCOLON Not to bore you further but you may recall the question of "crucible" forged steel came up a while back and we generally thought it was an advertising term or gimmick. Turns out that before the Bessemer process was invented, British saw makers used clay crucibles to forge their steel because they made a purer, higher quality steel. Crucible forged steel was the gold standard of the time.
Google Huntsman crucible to see more of the process by which steel was made pre-Bessemer.

Here is a statue in showing the process:
Image

You can see the crucible held in tongs and the casting process - the steel is poured from crucible into cast ingots, and a cast ingot waiting forging. I don't know if snooker is popular in US, but a big snooker venue is the Crucible Theatre in Sheffield - 'crucible' is part of Sheffield identity for without it the phrase 'Sheffield Steel' would not exist - they'd have had very little steel indeed.

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sumnergeo
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Re: merit - or not - of sway back sawplate ?

Post by sumnergeo » February 25th, 2014, 8:17 am

Back to the saw plates on the 289 and 290:

Perhaps someone could measure the thickness differences between the two.

For a No. 289, I have .090 along the teeth and .045 at the back near the heel and midway along the saw. At the toe I have .053

For a No. 290, I have .090 along the teeth and .070 at the back near the heel and .090 at the toe.

The 290 is stiffer and heavier, the 289 is more flexible. Since the 289 is also called the Cedar King, perhaps the greater taper made it easier to go through gummy softwoods.

Gavin Longrain
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Re: merit - or not - of sway back sawplate ?

Post by Gavin Longrain » February 25th, 2014, 12:50 pm

sumnergeo wroteCOLONBack to the saw plates on the 289 and 290:
Sumnergeo - is that a typo ? do you mean 389 and 390 ?

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sumnergeo
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Re: merit - or not - of sway back sawplate ?

Post by sumnergeo » February 25th, 2014, 1:47 pm

Yes, 389 and 390.

goodfeller
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Re: merit - or not - of sway back sawplate ?

Post by goodfeller » February 26th, 2014, 11:56 am

Good points, Sumnergeo. As I said in my earlier posting, I doubt economics were the only or even main reason Disston came out with the sway back crosscut design. Along with your point on gummy wood, I am wondering if there were other egronomic factors. You may recall that when we discussed the "big belly" two-man saws a while back, we wondered if that design made for easier sawing. I am wondering if similar considerations might be a play with these sway backs, especially when they were used as two-man saws with helper handles. I'd be interested in PATCSawyer's comparison of his two Atkins. I don't currently have two as similar to each other as his 389 and 390. But it can wait until the snow is gone.

Thanks, for the info on crucible steel, Gavin. I've played snooker but never in Sheffield. Never won either. Two additional trivia points: early on Disston jobbed out his crosscut saw production to smaller Philadelphia firms. He also maintained a Jobbing Shop which was for custom or specialty orders but evolved into a R&D department and accounted for most of Disston's patents.

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