Tuning wooden planes

[Mike Holbrook]

So I have put together four wooden planes, kits I got from Steve Knight before he stopped making them. The bodies are together but I am having some problems finishing them up. I bought 3M Stikit sandpaper (4.5 " x 30') form Highland Woodworking. I got 180 & 320. I think I should have bought 100 & 220. The 180 works great but is too slow for flattening bottoms, tops & sides. I think the 220 is as low as I will need to go. The 180 makes a good finish, probably good enough for most purposes, especially as it wears down.

My big problem has been getting the blades making the kind of shavings I want. I have been working the blades the seat for the blades & the wedges that hold them in place. So far though I seem to get a rough cut that kinda bounces across the surface of the piece being worked, digging in & leaving horizontal cuts in the surface. I think my blades are sharp & flat enough, so I think the problem is in how the wedge and wooden seat hold the blade in place. I have adjustable mouths (sliding wooden block) so I don't think the mouth opening is the issue. My mouths are about as perfectly square to the sides of the plane as I think I can make them. The Jack plane is the one I have basically finished but can't get operating like I want. So the others are sitting there in rough form waiting for me to figure out what my design/finishing issue is with the Jack plane.

Steve cuts the seats for the plane blades a little concave so one can file off the two high spots on both the top & bottom of the plane to get them even. This is my best guess of where my problem lies. It is hard to get inside the blade seat with a square/etc. to check how the two sides are relating to each other. I have been trying to check that relationship with my flattened plane blade, since it is made to fit in the area and has been flattened. The blade seems to be lying flat & snug after I drive my wedge in, but....I decided that the whole area did not need to be perfectly flat as long as the blade fit and seemed to be level, this is my best guess of where my problem is. I am a little concerned about grinding away too much wood in the plane seat though.

I have worked my wedge so that when driven into its slot above the blade it can be driven to within 1/4-3/8" of the end of the slot. The friction marks from driving the wedge into the opening seem to be in the correct place & about even on both sides.

Does anyone have suggestions about what I should try from this point? I seem to be circling, reworking the same things without improving anything.

[David Keller NC]

Mike - The traditional way to do this is with lampblack - one candles the blade, then inserts it into the plane and taps home the wedge. Then the blade and wedge is carefully removed, and spots on the bed that are darkened by the lampblack are carefully shaved down with a planemaker's float.

This is the way you should do this - trying to square up the bed of a plane with measurement tools and chisels is incredibly difficult, even for an experienced planemaker. The lampblack procedure and a float is far easier. If you don't have a float, use a coarse mill file or a rasp - it's a bit slower than a float, but it will allow you to true the bed of the plane without the small inaccuracies that will inevitably result from the use of a chisel.

And, it goes without saying that you don't have to use a candle - a magic marker will work just as well, as will machinist's layout fluid and any number of other thin marking inks and dyes.

[Mike Holbrook]

Thanks David, very helpful. I just went and found my Starrett Layout Dye, which I have used to find problems flattening plane blades & working blade bevels. It just did not occur to me to try that with the plane blades.

I am wondering though. The blades Steve sent me are concave on the back sides, apparently by design. I had read that one did not need to grind the entire back flat but just make sure it was ground such that it laid flat. Now that I think about it though I wonder if having both the plane seat and the plane blade convex might make everything to hard to tune? I am not excited about all the grinding it would take to get the backs of all those plane blades flat but if that is what it takes....

[Terry Beadle]

Regarding the concavity of the back side of the blades: Try putting a couple strips of masking tape on the center of the blade bed and remounting the blade. This should make seating the blade more difficult. If it doesn't, then put a second layer of masking tape on the first layer and try again. I would be very surprised if it take two layers of masking tape to properly seat the blade.

The blade should not be just trapped by the wedge edges. It should also be seated to the plane blade bed fairly tightly. This is a key element to properly seating a Japanese blade in a kanna die and it applies to a American woodie equally well IMO. If this solves the problem, then glue a very thin piece of hard wood such as rock maple to the plane bed and once cured, use the marking die suggested to slowly scrape the high areas away until the blade is seating properly.

I would also try a 15 degree back micro bevel on the blade. If that alone solves the blade cutting issue, then that should indicate that the cutting angle of the blade is not set correctly, ie too low as in below 22 degrees or so. This is probably not the case though as Steve's blades that I have in service were 25 degrees or more.