Hardness testing of saw plates

[Ray Gardiner]

Hi Rob,

Stick with it, and keep an open mind, listen carefully to the advice being offered, eventually the data will make sense.
I have a few old Disstons and an Avery 6402 hardness tester, I'll see if I can get some sensible results. in the next few days.. I can't actually test any 1095, since all the 1095 I've got is too thin 20thou and 15thou for the 150kg Rc test. And I don't have a RN Superficial tester.

Ray

[george wilson]

Rob and all saw makers: You can save yourself trouble by buying STRAIGHTENED 1095 sheet,instead of buying it rolled up. It is difficult to get the curve out of 1095 that has been rolled. We did it by pouring boiling water over the blade and bending it backwards. It will not straighten by just bending it backwards cold. This is particularly aggravating when making crosscut and rip saws that have no back to hold them straight.

Rob,I will not dispute your readings if you have done them correctly. I already have applauded your admission of mistakes. I did disagree with your previously wrong numbers. Post reasonable numbers and I will not disagree. You seem to have done that by now,and I'd let the matter lay. With all due respect,it would have avoided this long discussion had you checked your work more carefully before posting.

It is not necessary to lecture me about the scientific method. I am well educated,and in high school scored in the 98th. percentile on a nation wide physics test about 1958. My experience in serious woodwork dates from 1954.

I wish now that this whole discussion just be left alone. I'm not going to keep this up for 10 more pages.

I have seen your saws,and,again,with all due respect, would rather not get into a discussion about them.

Below are pictures of ONE batch of planes,ONE batch of saws,and a couple of back saws I made for my own use. This might give you some perspective of what I did as toolmaker.

[Rob Streeper]

Rob and all saw makers: You can save yourself trouble by buying STRAIGHTENED 1095 sheet,instead of buying it rolled up. It is difficult to get the curve out of 1095 that has been rolled. We did it by pouring boiling water over the blade and bending it backwards. It will not straighten by just bending it backwards cold. This is particularly aggravating when making crosscut and rip saws that have no back to hold them straight.

Rob,I will not dispute your readings if you have done them correctly. I already have applauded your admission of mistakes. I did disagree with your previously wrong numbers. Post reasonable numbers and I will not disagree. You seem to have done that by now,and I'd let the matter lay. With all due respect,it would have avoided this long discussion had you checked your work more carefully before posting.

It is not necessary to lecture me about the scientific method. I am well educated,and in high school scored in the 98th. percentile on a nation wide physics test about 1958. My experience in serious woodwork dates from 1954.

I wish now that this whole discussion just be left alone. I'm not going to keep this up for 10 more pages.

I have seen your saws,and would rather not get into a discussion about them.

George,

This is off the topic of saw plate hardness but it is still important generally here. I have received several PM's that are supportive of my efforts and none that are critical. As we all know the majority of comments posted openly on this thread have been critical with the least insulting of them asserting my incompetence.
I think it a matter of concern to the community that uses this forum that there is at least a portion of the population that does not feel free to share their thoughts openly. I propose that everybody think a little while about why some here don't want to comment openly and what factors have impelled them to feel that way.

[David Weaver]

George,

This is off the topic of saw plate hardness but it is still important generally here. I have received several PM's that are supportive of my efforts and none that are critical. As we all know the majority of comments posted openly on this thread have been critical with the least insulting of them asserting my incompetence.
I think it a matter of concern to the community that uses this forum that there is at least a portion of the population that does not feel free to share their thoughts openly. I propose that everybody think a little while about why some here don't want to comment openly and what factors have impelled them to feel that way.

When you're done, perhaps you could do a review of what caused you to come up with numbers that are not credible, at least not in the context they are being used, and then describe what it is that caused it.

[Rob Streeper]

When you're done, perhaps you could do a review of what caused you to come up with numbers that are not credible, at least not in the context they are being used, and then describe what it is that caused it. When you assert a saw is hardness 61 and is still sprung and as you have finally admitted, can be filed, you have to expect people will suspect that you are a bit green on what you're trying to assert.

If I am new at something and you torpedo my conclusions and assert that I have a problem that I should figure out, I'm not offended by that. I'd be much more bothered if I gave out bad information due to inexperience or lack of analysis to control quality of the results or how they are implied. For several years, I derided warren mickley because I thought he was wrong about plane double irons. I turned out to be 100% wrong. I'm embarrassed by that, and I should be, and the result of being critical of what I discuss is that the accuracy has improved. Warren told me and others that we didn't know enough about what we were talking about to draw the conclusions, and he could tell that by the conclusions we drew. As a beginner, I was probably offended, I don't recall, but in the end for warren to insist that I and others need more experience was correct.

There's really no other way for people who know the answer to the question of whether or not your data was bad to go about it other than try to figure out why you were so quick to dismiss what is already known in favor of your data. We have to assume you either have a motive for it, you're avoiding analysis (why didn't you admit right away that the saws could be filed as any others?) too prevent their conflict with your numbers, or that there is something that you don't know about the testing methods you don't use. There's no way around it other than to sit back and allow false assertions to be drawn on errant data. Is that a good conclusion?

David,

We're over 100 posts now on this thread and nobody has posted any data that contradicts mine. George speaks from his experience but again there is no data - just words.
Ask yourself why is there no data? Handsaws have been produced for centuries. You might think that somebody somewhere would have done a study, even a limited one like mine, but I have never seen one.
I have identified all of the technical errors in my results, the commenters here have simply said 'you're wrong' without giving any data to support their positions.
George maintains that the Rockwell C scale is the only scale to use. However all of the cited references, most of them mine, point out that for materials of this hardness range C scale only gives valid results with materials of 0.032" or thicker. For thinner materials the N and T scales are specified as appropriate.
Let me lead you through my reasoning.

First open this chart: http://qs-hardnesstester.com/hardnes...thickness.html

Now look under the heading of the C scale on the left side of the table and you will see that, for materials of the hardness range were talking about here, the minimum thickness is 0.034" for Rc45 and 0.032" for Rc 52. Thus the practical lower limit of C scale testing of saw plate materials is 0.032" to 0.034". For thinner materials the C scale is not appropriate.

Now look at the 30N scale of the chart. You will see that for materials of at least Rc hardness of 47 the minimum thickness is 0.22". The minimum thickness for materials of Rc57 is 0.020". Materials of these thicknesses are below the application range of the C scale.

All of the saws I tested are 0.020" thick or thicker, meaning that the N30 scale is the scale to use and that is what I did. For thicker plates I cross checked on the N45 materials and in the past I have used the C scale for saws that are thicker than 0.032", including the soft one made by Maker 3.

So, if you're asserting I'm wrong because I've used the wrong hardness scale you're indicting not only my competence but the competence of the entire industry of professionals in this area.