bench plane v block plane

[paulc]

Is it correct to put a bench plane blade in bevel down , and a block plane blade in bevel up ? why the variation and what difference does it make to cutting action? thanks

 

[Alf]

Is it correct to put a bench plane blade in bevel down

Depends on who's definition of bench plane you use, but by and large, yes. Except when it's no...

and a block plane blade in bevel up ?

Yes (although there's probably an exception to the rule somewhere - but we'll soon find out... :roll: :wink

why the variation and what difference does it make to cutting action? thanks

Ah, one of those deceptively simple questions full of traps for the unwary trying to explain it. Anyone better at theory want to take this one? :? Oh well, I'll take a stab at it. Despite the current move towards high angle blades in low angle planes, the historical reason for bevel up planes was to get as low an angle of attack as possible, which tends to give better results on - principally - end grain. If you imagine tilting a blade, bevel down, as low as a low angle block plane you'll see pretty quickly the bevel of the blade is going to be rubbing on the work and thus stopping the edge making the cut. Okay, you say, so just grind a shallower bevel to give more clearance angle then. Alas no; make the bevel too shallow an angle and it's too weak and will fold over, break and be generally no bloomin' use. Soooo, instead flip the blade over and then you've all the clearance you could possibly want. Hey, you say, so I can do any blade bevel angle I like then, right? Ah, no. Now, instead of the pitch of the frog defining the angle at which the edge meets the wood, now it's the angle of the bevel. Erm... try the "tech" link under the High Angle Blade on this page which has a better chance of making that clear than I have. Derek's good at explaining this sort of thing, so with luck he can unwind the confusion I've just made for you...

But, after all that, you rightly point out "what about standard angle block planes? With a 20deg beding angle and a 25deg grind, that's an effective cutting angle of 45deg, just like a bevel down Bailey". Good question. Imagine a block plane with a bevel down iron sticking up at 45degs. Got it? Right. Now, how d'you hold it in one hand...? :wink:

Cheers, Alf

 

[Derek Cohen (Perth Oz)]

Despite the current move towards high angle blades in low angle planes, the historical reason for bevel up planes was to get as low an angle of attack as possible, which tends to give better results on - principally - end grain

I agree Alf. My take on this is that "small" block planes (such as the Stanley #60-1/2 and #65) were basically all that the cabinetmaker of old needed for paring end grain on boards.

Two points are to be noted: (1) The thing about end grain is that it does not easily tear out. (2) A low cutting angle will shear timber strands while an increasingly high cutting angle will increasing move in the direction of a scraping cut.

So bevel up planes were developed to cut at low angles on end grain.

Where, then, did the Stanley #62 and #164, the forerunners of the LV and LN LA Jack and Smoother, respectively, fit in? As I understand it, these planes were used primarily to smooth large end grain areas, such as butcher blocks. Not something that the everyday carpenter/cabinetmaker did. And they were expensive in their time, which is not going to make them a desirable addition to a toolbox when their use was so limited. In their original format, such planes were not suitable for planing face grain since there was a constant threat of tear out. So the #60 and #65 was a better choice. But over the last decade we have seen greater experimentation taking place in woodworking. Perhaps this has something to do with the increasing popularity of handtools among hobbyests? The #62 and #164 have been reborn, with HA blades suitable for face grain, and now we are seeing the development of the "bevel up" plane progressing quickly and bevel up plane ranges beginning to take off.

Mmm, I have not said anything about bevel down planes, the standard set up on bench planes. Perhaps it is sufficient to just add that planing face grain is the domain of the bench plane, and this process requires a higher cutting angle. The nominal cutting angle for Stanley bench planes is 45 degrees (which is fine for most straight grained timber). But why bevel down? Because the bevel up design was fragile in the "old days" - thin soles and weaker iron construction. The bevel down design, which used a thick frog to support the blade at a steeper angle, was much stronger. So this became the default design for a higher angle plane.

Please note - this is just my musings.

Regards from Perth

Derek