Saw Plate Gauge

[Stewie Simpson]

The most commonly used saw plate gauge today for backsaws is 0.020 and 0.025".

Compare that to the min/max recommendations Figure 748 contained within the book Standards And Specifications For Metals And Metal Products; March 1933. (use the + magnifier to enlarge the print).https://books.google.com.au/books?id...20saws&f=false

How times have changed.

Stewie;

[Maurice Ungaro]

It's amazing when I compare my vintage sash saw to my LN tapered DT saw. Different beasts, agreed, but drastically different none the less.

[Jonas Baker]

I have a 10 inch long 1870's era Disston no. 4 backsaw that has a .015" thick plate, so they were made thin back in the 19th century and presumably also in the early 20th century. I prefer the thinner plates myself, but it depends on what I'm doing. I wouldn't want to rip a big board or crosscut a larger piece of lumber with a thin gauge saw, but for dovetails, small tenons, etc. I like he thin plate saws. I feel they are easier to cut on a line for fine work, and they seem to cut through the wood quicker being that they have less wood to remove.

I think saw plates were all over the board back in the 19th and 20th century, and I feel that .020" or .025" isn't out of line for a historical reproduction saw. I will say that many of the back saws I have from the early 20th century are more in line with the thickness that this book recommends.

Best,

Jonas

[Jim Koepke]

Great stuff Stewie, thanks for posting.

It is funny how some people get all preachy about "government procurement specifications." If it wasn't for the specifications they would likely complain about all the useless junk the government purchasing departments get stuck buying because it wasn't spelled out what it was to be.

The more saws that find their way into my shop the easier it is to see why some folks like to have so many different saws for different jobs.

jtk

[Stewie Simpson]

This is the main reason I prefer not to use 0.015 saw plate. stiffness of a piece of metal is proportional to the cube of the thickness. Thus, a 0.020" blade is more than twice as stiff as a 0.015" one.

[Ray Gardiner]

Hi Stewie,

I like the 15 thou plate, but, I'm thinking small joinery (dovetail) saws, I know this has been discussed many times before, but as long as the depth of plate under the back isn't too deep, say around the 2" mark.. 15 thou is fine.

The Government specs linked to, were obviously written to reflect the standards of the day, an era where hand saws were going out of fashion in favour of the electric saw. If the standards had have been written in the early 1800's no doubt the plate specified would be thinner, probably much more in line with today's saw makers.

Also, they might have been thinking that a heavy gauge thicker saw plate would be more durable in the hands of ham fisted government employees..

Ray

[Stewie Simpson]

Thanks for the feedback Ray.

Stewie;

[Kees Heiden]

I think those numbers from the spec sheet are very high. I have a couple of backsaws from that period or a bit earlier and they are all about 0.7 to 0.75 mm thick. Ha and now I let you all do the conversion.

[Jim Koepke]

I think those numbers from the spec sheet are very high. I have a couple of backsaws from that period or a bit earlier and they are all about 0.7 to 0.75 mm thick. Ha and now I let you all do the conversion.

That is less than 0.030". My recollection is my smallest Disston back saw is 0.032".

http://www.metric-conversions.org/le...-to-inches.htm

jtk

[Kees Heiden]

"Very high" might be exagerating it a bit, but I think tenonsaws between 0.032 and 0.042 and dovetailsaws between 0.028 and 0.035 is really quite thick and they would have had trouble to source saws like that.

[Dave Anderson NH]

One important thing to remember about government procurement spec is that they are strictly for selling to the government. Commercial use of the specs is allowed, but often commercial needs are different. Essentially the spec sets standards so that when they are referenced on a purchased order the gov gets exactly what they ordered. In our modern world MILSPECS and Federal Specs are extremely important to ensure critical quality standards. As an example, because of the recent prevalence of counterfeit electronic components, there were instituted very stringent sourcing and testing requirements a few years ago. It got so bad with the fakes that components were having their inked markings removed and new ones silk screened on in their place. The chaos, lost time and money, and potential for mission critical failures has been a nightmare. Weapons systems, electronics, and aircraft can not afford these kinds of problems. The consequences are too severe.