Is a Disston D12 really superior?

[Patrick Chase]

I've been collecting saws for a long time, and have probably 75 Disston #12 and D12s. I also have a Rockwell hardness tester that can measure both the Regular and Superficial scales. I'm here to tell you there is a difference! When I have enough measurements on my findings, I intend to publish them, until then, I can just tell you that pre 1928 #12s are much harder. I have one that measures at 56 C! That is harder than some cheap chisels.

What on Earth do you sharpen those things with? The only triangular file I own that could possibly be up to the job is a Vallorbe Valtitan (Rc72, $25 each). Are there other options besides that?

I have some solid WC flat files from my days of ski racing, and I have no doubt that one of those could cut Rc56 steel, but AFAIK they don't make triangular files like that.

[Mike Brady]

Johnny, good to see your post. I learned a ton about planes from you here and on your web page.

[steven c newman]

Been using a 6" Extra slim from Stanley for my saws. No issues. Even on a Nibbed No.7 or two...

[lowell holmes]

One thing not mentioned in this discussion is that if you re-tooth, you can change the tpi and also the rake of the teeth.
If you view Ron Herman's video on sharpening you will realize that is easy to make your saw exactly what you want it to be.

[Dan McKean]

"Properly filed and set, these saws perform like no other. It is not hype, but reality."

I just bought my first D-12. 1950's era, paid 5 bucks. Not knowing how to properly file and set the teeth myself, who/where might you recommend to do this for me? BTW, it cut a 2x4 in half pretty smartly!

[Ray Selinger]

I'm old enough to have used hand saws in construction .I never considered using handsaws as a pleasure until I used a D-12 at school . As apprentices, we were doing our practical.

[lowell holmes]

Obviously, I miss-spoke when I call it a lambs tounge saw plate, I meant lambs tounge handle.

[Patrick Chase]

I'm still curious to know what people are using to file an Rc56 saw plate?

Blue-hard 1095 is only Rc50 and already hard enough to separate the good files from the, well, not-so-good. Rc56 is in a range where only the very hardest chromed files like the Valtitans can go IMO. Most files that woodworkers use for saw sharpening aren't chromed at all AFAIK.

Is Rc56 typical for a D12 or was that a particularly exceptional example?

[Patrick Chase]

Obviously, I miss-spoke when I call it a lambs tounge saw plate, I meant lambs tounge handle.

The 16th Century called and wants its spelling back.

[lowell holmes]

I don't know why I miss-spelled the word. I know that tongue is the proper spelling.

[george wilson]

I agree with Patrick. Except that the 1095 blue spring steel that we (and everyone else making boutique saws) always registered at 52 Rockwell on our Versitron hardness tester,one of the very best ever made. Even at that hardness,the saws would wear out a GOOD USA Nicholson saw file in one sharpening. How you're supposed to file a 56 RC. blade,I have no idea!!!!!!! 52 is about the hardness spring steel can BE without cracking if flexed. Sometimes we would break off a tooth setting teeth. Then,we had to re tooth the saw and start over. Our saws beat the heck out of ANY antique ones. They were the most highly prized tools we made.

[Kees Heiden]

Over on the Australian forum Rob Steeper caught some ridicule when he first published his hardness meassurement from old and new sawplates. He also thought some plates were up to 56 or so in hardness. After a while he learned to use his tester properly (it isn't as easy as it looks, especially not with thin material), and he started to meassure on the whole sawplate, not just some spot under the handle. In the tooth line all the saws then prooved to be of normal hardness, around 50 HRc.

I don't remember if he meassured a No 12 though. Probably not, those saws are a little too precious to cover all over with little divots.

[Pete Taran]

If the insinuation is I don't know how to use my tester, and the reading is wrong, it's not. I test in 3 spots, one near the cutting edge, one near the back and one near the center. The results are averaged. Further, I use the superficial scales for this thin metal which is required as the plate thickness is not sufficient to use the major scales. I also use a calibration block in the range of the resultant reading before testing to ensure the machine is not out of calibration.

56 C is indeed hard, but not nearly as hard as a file. I just tested a new production Nicholson mill file in the tang area close to the cutting teeth and it measured 68C. 68C will definitely cut 56C. I have not tried to file the saw I mention as it is in my collection, but I have filed saws which are very hard like this one. It takes several files to do the job. The first one gets trashed reshaping the teeth, the second gets worn out but is only deepening the gullet and just gets dull. Files get destroyed when a small spot of the file is rubbed over and over as is the case when getting out of whack teeth right.

Finally, people should not be surprised about handsaws with steel this hard. Disston also produced a line of saws called the Disston #340, #342 and the #344. I have all of these in my collection, but the #340 was handy so I just measured it. The Disston #340 was a handsaw for cutting metal. This particular model was made especially for structural iron workers use. The 342 was for cutting metal trim and steel mouldings and the #344 was cutting wood or metal, specifically soft metal placed over wood or iron nails or bolts imbedded in wood.

I calibrated the tester as I always do, using the N30 superficial scale. The result of the measurement was exactly 78 N30, which roughly translates to 61 on the Rockwell C Scale. That is as hard as most chisels, but yet was made to file. In flexing the blade, it doesn't seem any stiffer or prone to fracture than any other of their saws. If you accept the premise that using spring steel to cut iron was a pretty demanding application, then the measurement I took on the #12 of 56C is not at all surprising. Attached is a picture of the saw, major load removed to allow the reading. The superficial scales use the outer green ring.

IMG_1120.jpg

[Kees Heiden]

I wasn't insinuating. Just trying to report what I remembered from that other forum.

Do you get meassurements close to 50 on standard production saws?

[Pete Taran]

Please note that the 56C reported was for a single, outlier saw. Most are in the 48-52 range. The #12s are all on the higher end of the scale, however. I'm waiting for my confidence interval to become statistically small enough to conclude that they are not due to random variation. I'm getting close, but not there yet. Also, the testing spot is hardly noticeable. When using the superficial scales, you are only using 30 Kg of force. You can hardly see it. Getting a hardness tester and learning how to use it has been a very helpful tool in understanding old saw production methods.