Thread: Hardening of sawplates
12th March 2014, 08:26 PM #31
Well I had a go at using my hardness guages today and my conclusion is that they are very hard to use .
I I started with the 60RC file which seemed to easily file the saw back. I progressively worked to down through 55RC, 50RC and 45RC. I could eliminate the 45RC quite easily. I felt the 55 file away, but I just wasn't sure about the 50 file.
I think BobL said that for a file to work comfortably the has to be a differential of at least 10RC. That probably puts the plate somewhere around the 50RC mark, which is pretty much what we were anticipating all along.
In other words the test is inconclusive, but amusing in a trivial way.
Oh, for those who aren't familiar with the guages:
RC65 down to RC40
"Power tends to corrupt. Absolute power corrupts, absolutely!"
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18th March 2014, 12:10 AM #32
This won't be news to most people, but I forget some of the things I read ... or more where the info was ...
The manufacturing process at Disston is talked about a good deal in the 1912 catalogue from Rose Tools ...
18th March 2014, 04:51 AM #33
18th March 2014, 06:46 AM #34
I was looking at the 1912 again ... I was referring to the pretty pictures section before ... but now I took in ...
- Automatic progressive toother
- Harden saws under dies
- Temper saws under dies
18th March 2014, 09:14 AM #35
10th January 2015, 08:39 AM #36
The next level
It's been almost a year since I touched on this subject but recently I happened across a hardness tester for thin materials, otherwise known as a superficial hardness tester. This is an Ames model 2-S (http://www.amesportablehardnessteste...uct/model-2-s/).
This is a pretty simple to operate tester that, within it's limitations, gives results that are more than good enough for testing saw plate hardness.
Ames 2-S hardness tester 1.jpg
The kit consists of the tester, a diamond indenter, a 1/16" carbide ball indenter for softer materials, two test blocks one with a hardness of Rc49 +/- 0.5 and one that is Rc62 +/- 0.5, two anvil extensions, three anvils, and full documentation indicating that this tester was produced in 1969.
After reading through the directions and performing a couple of tests on each block I find that the instrument is perfectly calibrated and really pretty simple to use compared to the more conventional hardness testers although it has a somewhat larger measurement tolerance.
I cut samples of each thickness of saw plate material and tested each five times on the appropriate 15 kg loading scale, here are the results. I also did measurements on the 30 and 45 kg loading scales and came up with results that were substantially the same excepting the 0.015" material.
So it turns out that commercially available 1095 sheet stock is actually pretty hard, measuring about 2-4% above the manufacturer specified hardness range of Rc 48-51.
Now to disassemble some saws and test them - should be very interesting.
10th January 2015, 10:00 AM #37
Okay, here's the data for the saws. I picked these out from my collection. I have saws from three custom or boutique saw makers. Each saw plate was tested five times.
Here's my interpretation: Somebody is using soft steel for making saws sold at premium prices.
10th January 2015, 10:37 AM #38
One point that hasn't been considered is back in the day we had real files made of quality to file in the teeth, and sharpen the saws. If you make you saw more advanced and potentially harder…What are we to file with as most file today are made out of butter???
An advancement is saws would require an advancement in other tools that relate to it's manufacture & maintenance and we know files are going backwards not forwards. What are the other options?
I also wonder on saws with poor use that causes to buckle and flex the blade how much that introduces work hardening over time?…..Live a Quiet Life & Work with your Hands
10th January 2015, 11:13 AM #39
I got started on this direction firstly because of my other observations about poor performance of the oddball saw I describe above from Maker 3. Second, given the diversity of materials we use, ranging from sheets and rolls of steel of known or at least nominal characteristics to scraper blades ,I thought it a good idea to look into the properties of these materials. I like to test and measure things as I find doing so frequently helps me work better.
The other thing that struck me was the statements around the web that Disston had decided a century or more ago that Rc 52 was the best hardness for saw blades. I don't mindlessly challenge received wisdom but I thought that surely the state of the art had moved on some.
As to hardening, well there is an upper limit. In my heat treating experiments I found I could get 1095 steel so hard that it shattered under the testing diamond and then I could draw it back to any final hardness I wanted, unfortunately I was getting too much distortion. My next step in the hardening experiments is to go cryogenic because it has been found to both increase the hardness and the toughness of steels. Cryogenic hardening has been all the rage in gunsmithing circles for a number of years and the benefits there are apparently considerable.
As to sharpening, fortunately things like this exist http://www.ebay.com/itm/10Pcs-5-1-2-...item27e744e7b2. Cheap enough to give them a shot.
10th January 2015, 11:27 AM #40GOLD MEMBER
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- May 2008
Hi Rob. With the softer saw plate you tested was there any visual difference. I say this because I received a very small batch of saw plates a while ago that had a distinct color variation to that I am normally use to. It had more of a slight dull gal steel appearance to it. I ended up putting those saw plates aside and have never used them over concerns they could actually be a softer saw plate. I ran a file across the edge of one of those saw plates and it seemed to validate my concerns.
10th January 2015, 11:29 AM #41SENIOR MEMBER
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10th January 2015, 11:56 AM #42
There was a major long running and long winded thread on saw file on this forum and I think diamond file were a part of that test also.
I'm all for testing and playing and research even if just for personal curiosity. I only made the comment that while some strive for excellence (the craftsman) industry strives for profit and the public in general for easy solutions. None of these work in favour of the craftsman and as some advancements are made in technology as you say, better materials or processes available. Others are degrading for greater profit.
An example is poorly made and uncomfortable injection moulded saw handles. There was a international petition made to manufacturers to improve the quality of saw files to be fit for purpose, which I recollect made no impression on the suppliers. Nearly all were made in China, India, Brazil despite branded country. This leads to limitations on what is practical for us to use in our saw making as these current files barely pass on the current materials. So other than for academic purpose and curiosity improved saw plate leads to the necessity of advancements in toothing and sharpening. Ok if you have a saw toother to punch the teeth but still need to file them sharp.
I'm just being philosophical in the state of industry I guess.…..Live a Quiet Life & Work with your Hands
10th January 2015, 11:56 AM #43
The weird plate does have a different hue to it. It appears to be slightly colored, maybe a little yellowish or gold toned. The effect is very slight but it looks very different from all of the pieces of 1095 I have and from the plates of all of my other saws.
10th January 2015, 12:02 PM #44
I agree. Part of the reason I'm able to get cheap high end tools like this tester is because of the ongoing de-industrialization of America. Industrial equipment brings 10 cents on the dollar these days here if you're lucky. The tester for instance has an old Ampex property tag on it. Ampex still exists but when was the last time you saw an Ampex branded electronic device? Makes me feel like a vulture feeding off of the remains of what America was.
10th January 2015, 12:04 PM #45
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