Edge Planing Trouble – Inconsistent Bow
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I am having trouble edge jointing boards. I have a #7 that is flat, but not machinist flat. When edge jointing, I usually end up with a sharp hump about 2-3″ from the end of the board I am planing towards. It is consistently in this location whenever I try to joint with this hand plane. I have tried planing hollow — not touching 1-3″ from either end of the board — but the hump remains. Is there anything with technique that I am missing or is it a problem with the tool?
Thanks.
Hi,
I had the same problem with my number 5 jack plane. I have corrected the problem by flattening the sole. In your case, my guess is your plane must be hollow. It is very important that the toe, the heel and the area around the mouth are on the same plane. Otherwise, when your plane start loosing contact with the wood (in your case, the toe is probably higher than the heel in reference with the mouth opening), you start diving in the wood. Since it is a number 7, you can try bending the sole while planing.
My two cents,
Good luck!
Like the No: 4 size plane, a No: 7 is, to my thinking, a finishing tool. It’s length and expected flatness is supposed to deliver fit-tolerances in the engineering spectrum.
Before we used synthetic glues, boards edged-joined used a method called a “rub-joint” which was exactly what the name implies. A ‘Jointer-plane’ made a dead-straight, dead-flat planed surface along the length of each board. Put side to side, the edge was exact; next it was glued using hot, animal glue which dried very quickly. Immediately the glue was applied the boards were assembled and rubbed up and down, then left. No clamps at all – a rub-joint. Although a jointing plane made the finished surface, the technique was not a single long stroke; it was achieved using minute adjustments and a straight edge.
If you are preparing boards to be glued edge-to-edge using clamps or the like, I’d recommend a good straight-edge, (spend a lot on an engineering-type or make your own in an hour or so) and a No: 5 fore-plane.
However, using clamps and the like, there are two jointing methods both requiring slightly different planing techniques; both need two boards to be folded together in the vice so that the mating surfaces are together. The first is used where the boards are the be clamped and here a minute hollow in the middle is beneficial so that the ends of the boards are under pressure to compensate for moisture loss later. The second involves the use of joiners’ dogs. In this case a portion near the ends are shaved away so that as the dogs penetrate the slight hump in the centre of the boards are compressed.
Paradoxically, neither of these methods demand a dead-flat surface end-to-end….. which is what a No: 7 is supposed to deliver. Just that the cross section matches, which is why you plane them both face-to-face.
I reserve my No:7 for finishing long boards that are presented to view…. Tables and the like.
I hope that this clears it up a bit. Paul Sellers has explained the clamp-joining method in lots of videos, also how to make a straight-edge from wood….. the technique of using joiners dogs is covered on You-tube by others, I believe.
Good luck
When you say there is a hump at the end, do you mean that the edge is straight until you get to the end, but at the end too much material has been removed? This is a very common problem and is part of learning to plane. It happens by putting pressure on the knob / toe of the plane as you move off the end. Do you find that the hump is a little closer to the end when you use the #5 vs. the #7?
Try this: Work a hollow in the center as you’ve been doing. Hold a straight edge to the work to make sure there’s no falling off at the ends…the very edge should be the highest points. You can use a yardstick for now. You may need to make a hollow in the center and then lengthen the strokes carefully to grow the hollow out to the two ends in order to get rid of the fall-off.
When you have achieved the hollow, take a pass with the #7, but when you get about 1/2 to 2/3 of the way across, take your hand off of the knob and just have your pushing hand on the plane, pushing via the tote. Push until the mouth moves off the far end. This makes it impossible to bear down on the knob. If you cannot get a shaving without pushing down on the knob, then you have a sharpening problem and fix that first. Remember, though, that with the hollow, you may not get a shaving in the middle until you’ve made some passes. So, if you don’t get a shaving in the middle, but get a short one at the end that gets longer and longer, then you are fine and there’s no sharpness issue.
Give that a try and see if it changes or eliminates the problem at the far end.
I have the same issue I think, but I would describe it as the boards trailing off in stead of a bump, as Ed described.
@Ed, @YrHenSaer,
Thanks for the pointers, will defenitely give it a go.Mic
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