Tuning a Stanley #140 Skew Block Plane
I use a vintage Stanley #140 skew block plane to tune tenon faces. For those unfamiliar with it, it has a skewed blade and a removable side.
The modern version of this is made by Lie-Nielsen, and is different in a few important areas, such as a lower bed angle (the Stanley is 20° while the LN is 12°) and a much tighter mouth (the Stanley, by comparison, positively gapes). One could also mention the better construction of the LN (bronze) against the Stanley (cast iron), as well as the better blade—1/8" A2 steel versus 1/16" HCS.
Garrett Hack remarked in The Handplane Book that "this should be an incredible tool, but mine has always fallen well short of expectations…it cuts poorly."
After all these negative factors one would have to question just who wants a Stanley #140 anyway! Well I did some time ago, and I know that there are many others who own and use one as well—and probably with the same mixed feelings I have had. But no more—we Stanley #140-ers are going to rise up and take our places on the podium. With a few tweaks, this can become a mean fighting machine!
I began tuning the #140 about a year ago. This involved: Leveling and raising the frog—unless the frog is level, the blade will end up canted to one side. The usual method of fixing this is to carefully file the high spots on the frog. Here, however, this will not work since, if you do this, it will lower the frog, effectively raise the bed angle, and widen the mouth even more. What we want to do instead is to raise this area, since then the blade will close the mouth nice and tightly. You can test this out by adding a little packing under the blade at the mouth.
To do this I used a little 5-minute epoxy. Place this on the frog and then seat the blade directly over this (making sure that you cover the contact areas with a little oil as a release agent first).
Press down carefully, and adjust from both sides until the blade is perfectly aligned with the mouth. This will close the mouth up as tightly as you desire.
The original Stanley blade was replaced by a LN Stanley Replacement blade, which was thicker and better steel. Actually, the main reason for replacing it was that the original blade was out of skew and I just could not fathom how to get the mouth-blade area right. The LN blade arrived and turned out to be slightly out-of-alignment as well! I have been living with this until now. It worked okay, not great, certainly not as well as I expected it to.
So now we turn to the latest mods.
I had built a (powered) jig to grind blades and this made it possible to awaken my plan to regrind the blade to the precise angle of the #140's mouth.
I measured it with a Starrett protractor at 69° and transferred this to the blade.
Since the LN has a cutting angle of 37° (12° bed plus 25° bevel), I planned to reduce the Stanley's bevel to 20° which, along with its 20° bed, would create a cutting angle of 40°, not so far off that of the LN.
But what happened is that I used a jig that I measure 20° on a straight blade, and this ended up grinding the skewed bevel at 15°! My first thought was to add a 5° micro bevel, but then I decided to try it out first and determine whether it would hold up planing hardwood. And it has(!), so the cutting angle of this #140 has dropped from 45° to about 33° (20 for the bed plus 15 for the bevel minus a couple for raising the mouth).
All this was to be carried out initially on the original Stanley blade before modifying the LN blade. As it turned out, the LN has not (yet) been touched.
Was it worth the effort? How does this modified Stanley #140 perform?
The mouth is now tight and square. But the proof of the pudding is in the eating, as is said.
I cut a tenon with my trusty Disston #5 (12" tenon saw), cleaned up the shoulder a little with my Stanley #93 shoulder plane, then set to work with the #140 (with side removed).
The result was effortless curlies.
Regards from Perth