Member
I started the test pulling the plane with a string on the knob, but then I reread your post and ended by pushing the plane at the base of the rear. I did not really complete the tests; both planes were still cutting with their own weight at 200 strokes, but I got tired of it. I don't care to go beyond where my instincts suggest sharpening.
Member
Our results are quite different... The differences between you and me could be:
- blade type (I know that I can get a lot more shaving with a better blade. Maybe your old stanley blade is much better than mine)
- I'm planing a 26" long timber. What's your length?
- Timber 1" wide. What's your width?
- Pine (if it's white pine) is 380 Janka, Fir is 660.
- Stropping.
- The plane itself. Yours are smaller than my no.5... I should be getting more shavings here!
- The higher angle (48 degree approx) that I'm using.
From earlier post I got that you're using planes for a very long time. With your experience, if you had to figure out why we are getting very different results, which one of the items listed (or maybe something else) would you suggest to look at?
Contributor
One of the points I recall from the booklet that came with my sharpening system is angles at 25º or less tend to be more prone to chatter.I can see the merits of using the more acute bevel angles. I wonder now if perhaps going to an angle even less than 25 degrees might not be a bad idea. Thoughts?
It may be worth giving it a try and then reporting back.
I do know my chisels with bevels of less then 25º are great for paring but are more prone to wear at the edge.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
[OP]
Member
Warren is probably putting a better edge on his blades than any of us, and that would go a long way to explain the difference.Originally Posted by Normand Leblanc
Wood compressibility (~Janka) is another strong candidate IMO, as is abrasiveness.
Last edited by Patrick Chase; 05-27-2016 at 12:55 PM.
In Memoriam
Did anyone come up with an answer to optimal clearance angle??
David
Member
And the grain of the wood. It is the shaving that pulls the edge down. So the strength, the elasticity, the shaving thickness and the grain direction all play a large role. You can only compare results in a scientific way when you keep things constant.
Contributor
Yes, though the one that seems to work best for me may not be the one that works best for you.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
Member
This thread was a good resource for me. It helped me to refine my procedure quite a bit.
At this stage, all I can say is, a clearance angle of 14-20 degrees has given more shavings than 8-11 degrees by a significant margin. This is true for every single test performed to date. 14 degrees seems to be the lowest clearance without major loss of edge life but 20 is as good or better.
This is with BC Fir and Cherry and with blades from Stanley and Record.
Other species (harder) will be tested as well as modern steel blades (O-1, A-2, PM-V11, Hock). All results will be for everyone to see and discuss/argue. It's quite a bit of work, more than I was thinking, so it will require a couple of weeks.
[OP]
Member
One question I keep coming back to is: What's the value of not having to apply downward pressure?
Put another way, if a plane won't self-initiate at some clearance angle but works with very modest pressure, is that a bad thing? Should we even care? Those totes are angled for a reason, after all.
Member
I'm making an assumption!
When a test is completed it gives a picture of the cutting edge. At that particular moment the edge is shaped with a given wear "flat" on the bevel and a given rounding at the tip. The assumption is to pretend that all tests are giving a similar picture (same edge wear). I know that it's not perfectly true but it should not be far from the reality. One thing is sure...the vertical force required that keeps the blade from cutting is very close test after test and that imply a similar "flat".
A completed test doesn't mean that the blade needs to be resharpen. It only means that the edge has been worn-out as much as the previous test (or all the other tests). You can add whatever downward pressure you wish, each one of us have its own technique, but it has been demonstrated that the force required grow linearly with the number of shavings if I remember correctly.
Taking this into account, the idea is to reduce the rate of growth of that "flat" while keeping a strong edge. I think that we have agree on that earlier. What I'm saying right now (all tests are far from completed) is the flat seems to be growing faster with a 10 degree clearance angle compared to 20 degree. The 10 degree blade will feel dull before the 20 degree one.
Have a good day
Member
4. Real users who do apply pressure (me, Warren, Derek) report MUCH longer blade lives than Normand's data suggest at fairly low clearance angles (~10 deg).
Normand; ignore comments such as that made above; it adds little to no value to the discussion; you have my support and no doubt many others who look forward to following your progress with great interest.
regards Stewie;
[OP]
Member
Yeah, grain direction is a huge variable here. Planes start cutting very easily indeed right before they tear the living sh*t out of your workpiece (yes, I know about cap irons. Yes, that was an exaggeration for dramatic effect :-).
Contributor
+1 on the above
While using my #6 today I notice that there may be some downward pressure. However the majority of effort is toward the direction of travel.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
Contributor
I suspect now that old steel was probably softer. New steels are much tougher and therefore can keep an edge longer. I can't wait for the tests on PMV11.
Member
You don't even have to wait, comparing old steel with newer ones like A-2 or PM-V11 is something that I have done already. The link is somewhere in this thread but in case you missed it.
http://oldchips.blogspot.ca/2016/05/...iron-with.html
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