Record 9 1/2 - angles and edge retention ?

[No skills]

Yeah I know, more sharpening..

Literally playing around with said plane and various bits of wood today and noticed how quickly the edge was being lost - some fracture - some rounding. Now I don't think I've noticed this before as I'm usually abusing pine or similar, today was hardwood end grain (mostly beech but a mixture) which is a fair bit harder.
I could determine a drop off after the first half dozen shavings and another half dozen and the edge was visually damaged.

So the question is am I expecting too much from an iron sharpened at too low an angle or is this blade made of chineseium?

First edge was circa 25 degrees (basic jig) sharpened with diamond stone to 1200 and then stropped with green compound on leather, after seeing what was happening with the cutting edge I did a few cycles of shavings then resharpen (freehand for speed) and ended up with a bevel of around 30 degrees - the edge had no improvement in life over 25 degree.
I've used this plane for a while now and it's probably had a couple of mm of steel removed from the iron over the years from sharpening so it's not exactly on a factory fresh crumbly edge.
It dates from the late 90's so not an old iron but not a new one either - have they been crappy for this long? My other couple of bench planes (60's - 70's record #4's) are sharpened in the same way and seem to hold an edge way better than this even on the odd piece of hardwood.

What's the opinion of the forum?

 

[Vann]

If 30 degrees made no apparent improvement over 25 degrees, I'd begin to wonder about the cheese content of the iron, but I'd probably try 35 degrees next, just to see what happens. Of course, at 35 degrees, you no longer have a low angle.

1990s? Yup, chances are a high cheese content in the iron.

Cheers, Vann.

 

[Derek Cohen (Perth Oz)]

Of course, at 35 degrees, you no longer have a low angle.

The 9 1/2 was never "low angle" with its 20 degree bed. Even a 25 degree bevel angle creates a common angle plane (same as a #4). A 35 degree bevel angle would be useful, turning the block plane into a small 55 degree smoother, which should do well on moderately interlocked grain.

Edit to add: A 55-degree block plane is a great plane for chamfering (with-the-grain) edges. It will deal with most reversing grain in this vulnerable area.

Regards from Perth

Derek

 

[Vann]

The 9 1/2 was never "low angle" with its 20 degree bed. Even a 25 degree bevel angle creates a common angle plane (same as a #4). A 35 degree bevel angle would be useful, turning the block plane into a small 55 degree smoother, which should do well on moderately interlocked grain.

I couldn't remember off the top of my head if the 9 1/2 was low angle or not.

So what he says.

Cheers, Vann.

 

[Downwindtracker2]

Thanks for the idea, Derek. I'll have to try that on of one of my #9 1/2s. They are fairly common here, <$20 Canadian. ( divide 20 by 1.60) The low angle #60 1/2 are not as common, I've only found one, a war time one.

 

[JohnPW]

You can sort of test for blade hardness by trying to scratch it with a another blade you know that's hard enough.

 

[ED65]

Honing at a steeper angle is definitely an option here as long as you don't mind the increased planing resistance. You can go very steep; I gave my Stanley 9 1/2 of indeterminate but recent vintage a very very steep bevel to turn it into a performer on tricky grain. I think my angle of incidence is now a little higher than 65° and it's great at combating tearout, and edge retention is super as you'd expect, but by God it can be hard to push.

Another option: as this is a bevel-up plane you have the opportunity to add a back bevel to thicken the edge, without affecting the planing performance as it does on a standard bench plane. A 15° back bevel can substantially increase edge retention since it produces an edge with an included angle of 45°, a big step up from the standard 25 or 30°. Unfortunately you can't go much steeper than this as you can on a bench plane because you have to leave clearance on the flat side.

It dates from the late 90's so not an old iron but not a new one either - have they been crappy for this long?

I think the average blade from then to now is okay if not spectacular.

There's always a chance with modern mass-produced tools that the heat treat didn't go as expected. Sometimes they're a little harder than the norm, but unfortunately they usually end up softer. Even highly-regarded kit like Pfeil chisels can be affected by this so we shouldn't be too critical of 90s Record.

But a soft edge is fixable. Redoing the heat treat can be done without too much bother if you have a blowtorch and you can easily get the business end to the kind of hardness you'd expect from a Hock iron or similar, if that's what you want.

 

[Derek Cohen (Perth Oz)]

A 15° back bevel can substantially increase edge retention since it produces an edge with an included angle of 45°, a big step up from the standard 25 or 30°. Unfortunately you can't go much steeper than this as you can on a bench plane because you have to leave clearance on the flat side.

This will leave a clearance angle of 5° - much too low for planning (the plane will stop planing).

I would not recommend, nor see any purpose, in a backbevel (this is not a ruler trick) on a BU plane. Especially where the bevel angle is above 30 degrees.

Regards from Perth

Derek

 

[Ttrees]

I've heard before people talk about the tip of their irons to be inferior steel than whats further down .
I can't remember if its too brittle or to soft though !
I think it could have been the brittle issue .
I bought a 90's Record/Irwin 60 1/2 low angle and it was such a lemon that I would not be surprised if the
iron was garbage too .
I held onto the iron for wide marking knife use, and used the plane shoe for another Stanley 60 1/2 lemon .
Indecently I bought some reaaally cheap chisels for beaters and tried briefly tried to sharpen them,
with less than stellar results .
Its on my list of unimportant things to do / experiment with , but I keep beating them even further so,
I used them for concrete yesterday :shock:
Will try soon enough though

 

[No skills]

I'll have to try running a known ok bit of steel over the planes blade and see what happens, reheating the blade is certainly an option I can try.

I think a grind back a few mm and then sharpen at 35 degrees will be the first major thing to happen, if anybody's interested I'll update when I do it.

 

[ED65]

This will leave a clearance angle of 5° - much too low for planning (the plane will stop planing).

With respect Derek I don't think that's right. I believe the conventional wisdom is that clearance needs to be 10° or greater yes? But some real-world experiments have shown this isn't so.

Paul Sellers posted something on this a few years ago when he was making a broader point about not having to be obsessive about honing angles on bench planes. As part of exploring it he did bench testing with a clearance angle of only 3° and in his words, "This plane has relief of only 3-degrees less than the bedded angle of the pane and it cuts very nicely; as well as one honed to 30-degrees. Wow!"

Additionally I know someone who has tested a micro back bevel of roughly 5° in a 60 1/2 (presumably giving a clearance angle of 7° or so) and the plane cut perfectly well even on softwoods. But he did say that you really need to stay on top of your honing to keep the plane working.

In reality there's no one relief angle that works best in all cases and mostly the way planes are set up it's designed to be ample, which in effect means often more than needed. And planing hardwood end grain would certainly seem to be one of those cases where you can get away with less clearance.

I would not recommend, nor see any purpose, in a backbevel (this is not a ruler trick) on a BU plane. Especially where the bevel angle is above 30 degrees.

The purpose is to thicken the edge and make it more robust, without increasing resistance. On a BU plane it's not the solution I'd pick personally either (I don't even like back bevels on BD planes) but it is a viable option. The best solution as I see it is to re-harden the iron, since it then allows you to hone exactly as you would normally.

 

[ED65]

...reheating the blade is certainly an option I can try.

If you're worried about distortion you can clamp it to another iron, or a random piece of mild steel if that's all that's handy, during the heating and quenching (clamp flat side out).

...if anybody's interested I'll update when I do it.

Please do, if nothing else I'd be interested to hear if the scratch testing gives you a useful read on whether it's noticeably softer than other blades.

 

[Derek Cohen (Perth Oz)]

A plane with a minimal relief angle will cut, but not for long. With a BU plane, such as a block plane, the absence of sufficiency relief angle causes greater wear behind the bevel - the "wear bevel" - which is hastened. The rule of thumb was set by Leonard Lee many years ago. He has mentioned 7 degrees as the lowermost figure for the relief angle. However, a low angle block plane or typical BU smoother has a bed of 12 degrees, and one is advised not to lower this further. The reported suggestion of 3 degrees flies in the face of this.

The reason I do not see a point for a backbevel (greater than the 2/3 degree of the Ruler Trick) on a 30 degree bevel is that it has strength enough already. I fully appreciate the reason for a backbevel, but emphasise that it will cause more problems than it will solve.

Regards from Perth

Derek