Est. 1998 — 27 years of woodworking knowledge
Re: Clarification
thomd [email protected]
>If you mean prepared like a power jointer sole, then you also have to relieve the sides like a rabate plane or the plane would not be able to feed properly on wide broads, and if you do that you have very different animal. On the other hand, as long as it was wider than the surface it was planing, it would remove consistant slices from an already perfect edge. Not the most useful cut, but probably as useful as some other planes we give shelf space to.
Obviously..
HC Sakman
>...that set up is meant for edge planing, not face planing, unless it's #10-1/2 instead of #5.
Chico...
Curiouser
Ellis Walentine
>I was intrigued by this challenge so I ran out to the shop and planed a 2-foot piece of Spanish cedar using a 5 1/2 and a low angle block plane. In both cases, after a dozen .0015" passes, I couldn't detect any gaps under my Starrett straightedge. That edge was dead flat.
Wonder what I'm doing wrong? It seems to me that when you start a cut, only the front sole is on the work and the edge is some depth below the surface of the edge. Your front hand is pushing down on the front of the plane and your back hand is pushing straight forward. As you push forward, however, at some point you change the vector of your tote hand so that you are pushing downward and forward. This brings the back sole into contact with the cut surface, and so, (theoretically, at least) you are turning the edge into a fulcrum. At some microscopic level, therefore, the front sole must be tipped up slightly in front. Thus, the bearing points must be at the front sole right at the mouth and on the very end of the rear sole. That changes the geometry somehow, but my mind can't really comprehend how, or if this phenomenon could result in the convexity you are describing.
For me, the jury is still out.
Great discussion, though, David. Thanks for pursuing this. It would be great to come up with something definitive on this subject.
And, while we're at it, we might want to analyze the dynamics of a Japanese plane sole, which is hollowed in front and relieved behind the blade, with or without a slight land at the back end. That has always mystified me, too.
Ellis Walentine, Host
Aha!
Ellis Walentine
>After reading my post, I realized that the rear sole first contacts the planed edge early in the cut, and the point of contact is close behind the iron. As you continue the cut, though, the point of contact moves out to the rear end of the plane. This transition alone would produce a convexity.
Does this sound reasonable?
Ellis
Re: Aha!
Paul Kierstead
>One would think so; in essence the rear would 'lift' the blade gradually. I'd *think* the longer the sole, the longer this lift, so the dubbed off edges some see would be related to the length of sole behind the blade.
Re: The edge planing experiment
Pam Niedermayer - Austin, TX
>The 30" C&W is just a bit less than 3" deep. I honestly think it won't bend, and if it did, I wouldn't like it. :)
Pam
Re: The edge planing experiment
Pam Niedermayer - Austin, TX
>Yes, of course, that's why I typed a smilie at the end of the message.
I agree that without care, the tendency is to plane a convex edge, perhaps more due to snipe than anything else; but that's why I've long taken care to try for sprung joints. This way even very long boards are manageable with much shorter planes.
So, my first planing from a few years ago confirms your experiment.
Pam
Re: More results
David Charlesworth
>Frank,
That is the result I get with my 5 1/2. Have not had time to try with smoother yet.
Glad it was fun and thank you!
David
Re: The edge planing experiment
David Charlesworth
>Mike,
your technique is pretty much the one I use (and was taught) to get slightly hollow sprung joint only my stop shavings are all nearly full length.
Both work well for the desirable slightly sprung joint!
best wishes,
David
Re: Aha!
David Charlesworth
>Ellis,
steady on with that running, not in the shop I hope ~;-)#!
Your analysis is very close to mine but I still can't quite make sense of it all.
I too want to think a bit more about Japanese plane sole variations.
Thanks,
David
Re: The edge planing experiment
thomd [email protected]
>I get it. I must test that. Wood is excellent on stiffness to weight though planes are pretty gutted. On the other hand I don't thikt his is a flex issue he that would hollow.
huh?
david.marcus.brown
>I'd be glad to toss in my findings but I'm not sure exactly what I'm looking for.
I thought about this a few years ago
Derek
>It was bothering me. I finally saw an analysis somewhere that put my mind to ease. If my memory is correct (and it might not be) here was the answer I saw that finally made sense (assuming a perfectly flat sole and a perfectly flat board):
1) As you start the cut, the toe of the plane is parallelto the wood and the cutter is below it so it cuts a shaving set by the blade depth.
2) as you progress past the point where the rear of the sole is over the wood and you are puushing down on it, the sole becomes angled. The toe is on top of the wood and still sets the depth. The rear of the sole rests on the lower cut portion of the wood. The cut depth is still set by the blade projection below the sole.
If the plane is not cutting ecause of too little pressure at the toe, I think we compensate and push harder. The key is that the portion just in front of the mouth is still riding on the wood surface though so the fact that the sole is angled slightly does not appreciably affect the cut relative to the original cut. The angular rotation is minute.
3) as the plane nears the end of the board, the depth of cut is still set by the projection of the blade below teh toe until the toe leaves the board, at which point the cut is done anyway.
Anyway - let me know if this makes sense. It is not original but I can't remember where I saw it.
Of course this is all theoretical. Our tools are not perfect and we are less so. We just compensate and use techniques that work for us. :>)
P.S. I have David's DVD's. I use his stop/through cut method when flattening boards. I don't have camber on my jointer though - just my smoothers and jacks.
My results...
Dan Clermont in Burnaby
>I don't have a true straight edge and my bench is covered in a project so I grabbed my LN 5.5 which mates extremely well on my flatness plate (well less then my 1 thou feeler guage).
I then hollowed my test board which was eastern maple 18" long and 2" wide. I was able to place a 1.5thou feeler guage between the plane and the wood. I then jointed the board and took ten more strokes. Using the LN plane and my feeler guage I was unable to put my 1 thou feeler under the plane. I was able to detect a wee bit of light.
I did the test twice with the same results and have a 4" raker light along the wall on the opposite end of my bench.
Dan Clermont
Re: Curiouser
thomd
>"And, while we're at it, we might want to analyze the dynamics of a Japanese plane sole, which is hollowed in front and relieved behind the blade, with or without a slight land at the back end. That has always mystified me, too."
Well the ones with the relieved sole aft of the blade are smoothing planes. They can be planing 4/10000", shaping is not the issue. They just have the two contact points required to line up the cut and work the mouth. Nothing else is required and if you deepen blade projection you run the risk of tweaking the sole relationship, and lifting the knife out of the cut. But that doesn't happen because you don't have any contact points on the trailing part of the sole.
On the other hand the straightening planes, need three points of contact to achieve a longi gradual curve, as near straight as possible, just like a regular jointer. My theory is that if you set the plane up so that for your prefered working shaving you have the three points of cantact in line (and they do use winding sets for just that purpose), then if you deepened the blade projection and teak the sole you create a curved sole that negates the additional surve a longer projection would normally produce.
That's a good theory and the degree of curve from blade projection can be controlled. But this is not a technocratic culture and the originators of these planes were pretty tight lipped. Some things may make sense without having anything to do with it.
Some other findings
Stephen Kirk in Quakertown PA
>I couldn't start with a perfectly flat edge from a power jointer, because I don't have one. But I was using my LA Jack to straighten some rough cut edges so I could rip them on the table saw. I would start out putting the straight edge to determine where the edge was off, and then work down any high spots. At some point, I can start taking nearly full length shavings, until I finish off any dips on the board.
Using the LA Jack on boards up to 6 feet long, I would notice that my final passes on a board that should have been flat would often leave the ends a bit low (as David suggested would happen). I hadn't seen the techiques of sprung joints, but did the same thing anyway to correct it. I'd take short pass in the middle, and then longer passes as I work my way out. I just adjusted the size and number of passes depending on how far out of true the board was.
After reading the whole thread, I developed a question, though. Most literature says to joint with the longest plane possible, but it seems that the ideas here, and some of the results, say that a flat edge is maintained better with a shorter plane. Or is it actually the case that if you start with a flat edge, you are more likely to maintain it with a short plane than a long one.
This is good, maybe it wasn't my rank amatuers technique producing the slight crown after all.
Re: The edge planing experiment
Sgian Dubh
>My short experiment yesterday proved somewhat inconclusive David. I straightened the rough edge of a couple of boards good enough that they could be glued with hide glue and a rub joint. Not a sprung joint, but straight. It took perhaps 5 minutes in total, including getting my tools out-- a trifling time really.
Then I took 20 strokes from the edge of each board to see what I ended up with. There was indeed a hump in the middle of the boards- slightly convex. Also the edges had drifted off square.
I was aware that I was drifting off square, and also that I was planing in a convexity. Even though I was aware of this I ploughed on in the name of seeing what happened. I got what I expected-- the humps and out of squareness.
The problem is (from my point of view) that in attempting to create a straight edge (or even a sprung joint) it's instinctive to make corrections as I go along. I'll take a couple of short strokes to remove a perceived hump (or perhaps bend the plane a bit) or I'll tilt the plane over a hair to square the edge again. I sometimes take a half width shaving to help bring an edge back to square. These corrective actions are so ingrained into my work habits that taking full length shavings just for the sake of it is completely unnatural.
So, in conclusion I think you're probably right about what happens. But the thing that bugs me is that it seems completely at odds to let what's obviously going wrong continue without doing something about it. I have a feeling that the configuration of planes (and their perceived faults) are a lot less important than the technique of the worker. Technique only comes with practice, sometimes years of practice, but once you've got 'it', it's almost impossible not to use 'it'. Slainte.