Do bevel up hand plane blades dull sooner?

[george#1]

I have a couple of Veritas bevel up planes and a Stanley #6, all with PM V11 irons. I have used the Veritas planes extensively, the Stanley only briefly. From time to time I have seen discussions online where woodworkers have observed that their bevel up planes seem to stay sharp only a fraction as long as their traditional bevel downs. Just wondering if anyone has any thoughts on the subject, without really getting into my particular tools. Hopefully Derek Cohen will chime in as he seems to have a lot of experience and can articulate his thoughts well.

[Derek Cohen]

Hi George

I find this an interesting subject, and I have done a number of comparisons. Still, this is only my opinion ...

I believe that plane blade wear has three issues: the way the wear bevel affects performance, the affect of the clearance angle, and the effect of the bed angle in creating wear.

As discussed, the wear bevel is on the "wrong" side of the blade for a BU plane, and this should create more work when honing. In practice, the effects of the wear bevel are more subtle than commonly argued, and most would not experience an issue.

The same may be said for clearance: the low bed of a BU plane creates a clearance angle of 12 degrees, compared with the BU plane on a common angle (45 degree) bed, which has 15 degrees when the blade is honed at 30 degrees. So, hone the BD blade at 32/33 degrees, which Steve Elliott argues for, and clearance angles are the same.

Then we are down to the bed angles of the two planes. I will say more about this below.

Essentially, one might say that the higher the bed angle - that is, the closer one moves to a scraping angle - the greater the resistance encountered by the blade moving forward. For example, think of the burning fingers when pushing a card scraper - the heat is generated by the increased resistance to the high scraping angle.

BD planes with high beds - HNT Gordon (60 degrees) and LN or Veritas Custom with 55-degree frogs - are harder to push than beds with common angles, which is evidence of the resistance mentioned earlier. The bevels on these planes may be 25-30 degrees (note: 30-32 degrees is far better than 25 degrees for bench plane), and they will show more rapid blade wear.

BU planes, such as LA smothers, have a low bed (12 degrees) but are typically used with high bevel angles (40 - 50 degrees). Since these do not start out as "sharp" to begin with, they are more vulnerable to wear. The higher cutting angle also increases resistance and wear. More or less than the BD plane? It's hard to say. In my experience it is about the same.

What I want to emphasise is that it is not simply a BU/BD issue; rather, there are a combination of factors. Bed angle plays a part: When one compares (as I have) a BU shooting plane with a 25 degree bevel (= 37 degree cutting angle) against a BD shooting lane with a 25- and 30 degree blade (= 45 degree cutting angle), the BU plane far, far outlasts the BD plane. In short, the lower the bed angle, the lower one aspect of wear.

A BU plane with a 25 degree bevel will outlast a BD plane with a 25 degree bevel, however this is not an apples vs apples situation.

Blade steel has a part to play, of course. O1 steel is going to last about a quarter of the time of A2 steel, which will last half that of PM-V11. The latter blades have carbides that resist abrasion, which O1 does not.

Look at the factors involved as an interaction rather than individually. For example, a board that is softwood and straight grained does not need a plane that has anything more than a common angle (45 degrees) and does not even need the chipbreaker to control tearout. Even O1 steel will last a long time here. But switch to interlocked hardwood, especially if it is abrasive (contains silica), and you had better be using a blade with greater resistance to abrasion to sustain edge life. Plus the interlocked side then requires tearout control measures. Now you have the choice between a high cutting angle (more wear) and a closed chipbreaker (less wear). The high cutting angle choice is divided into two groups again: BU and BD. Both wear similarly, but the BU is easier to set up.

Do people seek a plane based on its duration planes for edge holdings? I suggest that one chooses the plane one prefers using, and if the blade lasts long enough for the task at hand, then all is good. This should be adequate for most.

Hope this explains the situation.

Regards from Perth

Derek

[george#1]

Thank you, Derek. I sharpen the BU jack at 30 and the smooth at 35 degrees so I'm really not using high angles. I feel like the blades should be sharper longer. My Veritas spokeshave is bevel down and also PM V11 steel. That stays sharp for hours even when hogging shavings and cutting end grain. I realize a plane is pushed with more force but still. That made me wonder if there is something to the theory of bevel down staying sharper longer. Glad to hear you say that you have not found a noticeable difference. I like my BU planes because I can put in a blade and have it set up to take the shaving I want in a few seconds (and I guess I like them because they're paid for). The Stanley #6 takes forever to set especially trying to adjust laterally. I will looking at jointer planes and trying to decide between the Veritas BU and something bevel down. If the consensus here is that blade life should be the same I would feel very comfortable with the BU.

[AHill]

The short answer is that 95% of all plane users will not notice the difference between wear of a BU or BD plane blade.  There is a lot of discussion on the "wear bevel", which occurs on the non-bevel side of a BU blade.  For those who might use planes all day long on harder and/or more abrasive woods, you may notice over time the BU plane blade does not get as sharp between subsequent sharpenings.  This is because the wear bevel effectively rounds over the edge and it cannot be corrected merely by honing the bevel.