Plane blade expectations

[Alexander Zagubny]

Hey, neanderthals!

I recently started working with some pine boards to make shelves and blade seems to become dull too fast. I want to understand if it's my expectations are too high or blade might be faulty.

I basically used 3 planes: scrub plane with unknown steel (about 30*), 25* and 38* pm-v11. Task performed was removing old finish and flattening with scrub, then flattening with jack (25*) and removing tear-out with smoothing (38*). I tried avoiding putting anything except scrub plane to old finish (which should be yacht varnish) but that was not always possibly.
Later I switched to new pine boards and flattened and prepared for gluing them mostly with jack.
On the next day I noticed that jack plane is not working satisfactory and checked its blade, then other blades. I would say scrub plane blade looks good, 38* smoothing blade looks good as well (in fact I think I only sharpened it once). And 25* blade that concerned meek look really bad: dents, folded steel etc. I tried stropping it (piece of beech with green compound) but it still looked bad after that.

Here is the photo of blade (inserted below), and here is the photo of 1 mm scale for, well, scale.
IMG_20181006_125416.jpg

What do you think? Is it normal wear for half day work or probably the finish damaged the blade? Or pine knots?


I want to notice in advance that I know about Veritas excellent service but I want first to understand if it's my fault or not.

[Laurent Marshall]

I'm curious what other folks will say about their experiences with PMV-11. My experience with regular steels has been that pine knots can mess up an edge quite quickly It also seems to me your jack plane was sharpened with a pretty shallow bevel, I've found 25* to be pretty fragile in a lot of cases, so a 30* micro bevel makes a big difference.

[glenn bradley]

I don't know about placing blame particularly. Knots and so forth can be abusive. I have 25* BU PM-V11 irons but, they are mostly for shooting and other paring-type work. I imagine planing a knot at 25* would be undesirable for any cutter. Also, I touch up irons several times during a planing session. I do not expect to go all day without stopping to tend to my cutting edges. As soon as the resistance starts to climb I pull the iron and touch it up. In just a moment or two I'm back to work.

[chris carter]

My fore (or scrub, whatever you want to call it) is 25* and of some ancient steel (pre-1900), my jack is 01 at 25*, and my smoother is A1 @ 25*. Knots in pine can be pretty abusive and I always skew the blade heavily when passing over a knot. Once I started doing that, I never had any problems with pine knots damaging the blade (and I've done a lot of knotty pine projects recently). Slamming straight into a knot dead on is not only tough on the blade, but jarring to my whole body! I always touch up my plane irons daily. If I'm in the shop for more than a few hours, I'll touch up at some point in the middle of working if a certain plane is doing a lot of work. When I say touch up, I mean hitting the strop for 30 seconds - I don't go to a stone unless there's something serious. If the blade starts getting dull, it seems to be more likely to sustain damage in my opinion. So I sharpen frequently, which is one reason my woodies don't have chip-breakers - it slows the whole process down.

[Steve Elliott]

If the cutting edge is chipping or folding it's a sign that the bevel angle is too acute. Most plane blades need an angle of 30 degrees or a little more to stand up to typical planing forces. Higher cutting angles need somewhat higher bevel angles and lower cutting angles can get away with lower ones, but in general I would expect problems from a blade at 25 degrees.

It's not necessary to precisely measure the angle, just watch what happens to the cutting edge as the angle is increased and find the angle that holds up for the sort of planing you're doing.

[Derek Cohen]

I have several PM-V11 plane blades. BU plane blades are absolutely fine at 25 degrees. I shoot end grain with 25 degrees, and it just lasts. However, 25 degrees is too low for a BD plane, and I found it lasted about as long as A2 at this angle. Take it up to 30 degrees, and it now becomes a very durable edge for a BD plane blade.

Regards from Perth

Derek

[glenn bradley]

I mentioned but, probably should have emphasized that my 25* irons are bedded bevel up at 12* for a presentation angle of 37*. My No 4 ground at 25* is bedded bevel down and presented at about 45*. The impact effect is different although the blade grind is the same.

[Jim Koepke]

What do you think? Is it normal wear for half day work or probably the finish damaged the blade? Or pine knots?

My jack planes with 25º bevels show this kind of an effect often after hitting a knot. Pine knots are exceptionally hard on a blade.

With the chips that look as big as yours, it is time for a trip to the stones, maybe even a light grinding.

jtk

[Jessica de Boer]

BU plane blades are absolutely fine at 25 degrees. I shoot end grain with 25 degrees, and it just lasts.

I don't know if anyone else does this but I make a small bevel on the back of my bevel up blades at 5 degrees. This makes the total angle of the blade 30 degrees and thus the edge stronger but does nothing to alter the shaving angle of 37 degrees since that is determined by the angle of the bed.

[Alexander Zagubny]

I have several PM-V11 plane blades. BU plane blades are absolutely fine at 25 degrees. I shoot end grain with 25 degrees, and it just lasts. However, 25 degrees is too low for a BD plane, and I found it lasted about as long as A2 at this angle. Take it up to 30 degrees, and it now becomes a very durable edge for a BD plane blade.

Regards from Perth

Derek

Mine jack & smoothing plane are bevel ups. Scrub is bevel down.

Actual angle is 1-2* higher due to using Veritas sharpening jig, so I assumed that's a bit higher than nominal and should provide enough added strength.

Yeah, I know that I should re-sharpen that blade but I don't like to sharpen and haven't yet established the procedure with minimal mess. For now I just dropped in spare blade that I planned to use as higher-angle for smoothing. Will try to compare apples to apples as much as possible, that seems to be the only way to figure it out.

And probably having several spare 25* blades makes sense, that will allow batching for sharpening.

I don't know if anyone else does this but I make a small bevel on the back of my bevel up blades at 5 degrees. This makes the total angle of the blade 30 degrees and thus the edge stronger but does nothing to alter the shaving angle of 37 degrees since that is determined by the angle of the bed.

Interesting solution! I read somewhere that as long as you have more than 5* clearance angle, you should be ok (with wood). However bevel up spokeshaves have near zero clearance angle and work.
Does that significantly complicates sharpening?

UPD Ok, actually spokeshave is a different story, it doesn't have flat sole behind behind the blade.

[Jessica de Boer]

Does that significantly complicates sharpening?

Not at all. I have a small strip of metal of the correct thickness which I lay at the long edge of my stones so that when I lay my blade on it with the back facing downward I'm exactly at 5 degrees.

[Jessica de Boer]

Does that significantly complicates sharpening?

Not at all. I have a small strip of metal of the correct thickness which I lay at the long edge of my stones so that when I lay my blade on it with the back facing downward and the edge of the blade at the opposite side of the stone I'm exactly at 5 degrees.

[Derek Cohen]

Hi Jessica

I've not tried a 5 degree backbevel on a BU plane. In theory, this would take the clearance angle close to the 7 degrees recommended as the lower limit. In practice, I have never found that a 25 degree bevel angle needed strengthening on a BU plane. I have used a wide range of steels and typically hard and abrasive woods. The low cutting angle and force vectors in this BU set up appear to reduce the stresses at the bevel edge. This is different from the force vectors of a BD plane with a common angle (45 degree) bed.

This comparison of two shooting planes illustrates the difference: http://www.inthewoodshop.com/ToolRev...tingPlane.html

Regards from Perth

Derek

[Alexander Zagubny]

Hi Jessica

I've not tried a 5 degree backbevel on a BU plane. In theory, this would take the clearance angle close to the 7 degrees recommended as the lower limit. In practice, I have never found that a 25 degree bevel angle needed strengthening on a BU plane. I have used a wide range of steels and typically hard and abrasive woods. The low cutting angle and force vectors in this BU set up appear to reduce the stresses at the bevel edge. This is different from the force vectors of a BD plane with a common angle (45 degree) bed.

This comparison of two shooting planes illustrates the difference: http://www.inthewoodshop.com/ToolRev...tingPlane.html

Regards from Perth

Derek

Derek, could you please share the source of that 7* clearance recommendation?

Not at all. I have a small strip of metal of the correct thickness which I lay at the long edge of my stones so that when I lay my blade on it with the back facing downward and the edge of the blade at the opposite side of the stone I'm exactly at 5 degrees.

I'm probably over-complicating that but that should require precise positioning and precise blade moves to get the same angle, isn't it? However if it provides like 2 times less sharpening it worth trying...


Derek, how often do you usually sharpen? I mean if PM-V11 was capable of 60 shavings cross-grain, why not to raise that number to 100 shavings?
For instance I'm occasional weekend woodworker and need to clean up the sink to sharpen. Preparations and cleaning up the mess after sharpening takes time and I'm certainly trying to sharpen several tools at once. So I usually hesitate to sharpen weekly, more like every other week.



Thank you all for replies! I will try 30* bevel and see what difference it makes. I would appreciate any advises on making the process easier. Like do you have spare blades to sharpen in a bulk or how often do you strop? Freehand stropping on leather or jig on wood? Maybe using dedicated scrub / fore plane or dedicated blade. What works best for you?

I like how freshly sharpened blade slices the wood but I don't find sharpening to be as rewarding as woodworking so I have a problem I'm trying to optimize sharpening process like using stone pond, sometimes hollow grinding for freehand sharpening, reducing hand-water contact (to prevent dry hands), sharpening at the evening when kitchen is not in use...

[Jessica de Boer]

I'm probably over-complicating that but that should require precise positioning and precise blade moves to get the same angle, isn't it? However if it provides like 2 times less sharpening it worth trying...

I'm not that anal about it. It it's a bit less than 5 degrees I really don't care. I have however noticed the edge stays sharp longer.