Jointer Plane Blades

[Andy Kev.]

I read somewhere that the jointer plane blade should always be ground dead square. The reason for this is fairly obvious when jointing edges etc. However, I find myself using this plane more and more often for general flattening of boards and it occurs to me that for this sort of purpose the usual very fine camber would be most suitable. One obvious answer would be to keep two blades.

Out of interest are there any generally accepted views on this? Is my instinct to get a second blade sensible? I realise that one answer to that is to do whatever you're comfortable with but I'm interested in knowing if anybody else has addressed this matter and what they have decided on.

 

[woodbrains]

Hello,

Funnily enough, most people I know DO camber their jointer blades. The camber is so small that it should not affect jointing edges. In fact David Savage (wrongly IMO) says that jointer planes must be cambered. It works for him obviously. Having said that, I keep all my iron dead square across except for smothers, but I am less common than camberers, who seem to do everything.

Two irons for a jointer is handy, though, but I'd not worry about the camber making any odds to edge jointing.

Mike.

 

[deema]

Well this is my theory, the panel always dries out faster at the surface than in the middle, by using a slight camber I compensate for this and prevent the edges of the joint being in tension.

The camber helps me immensely when correcting any out of square situations by moving the plane over towards the heighest side.

 

[D_W]

I can't say what pundits say here or there, but I've generally kept slight camber on a jointer, even if being used for match planing, and I've not had any matched planed boards separate or show even the slightest gap.

If the amount you want to camber has no effect on the work, then the work dictates regardless of "perceived possible maybe" problems.

 

[undergroundhunter]

Both my metal jointer and wooden one both have pretty much straight blades with the corners knocked off. This way I can joint with them and use them on flat panels. My smoothers are also sharpened this way.

Matt

 

[Sheffield Tony]

Having said that, I keep all my iron dead square across except for smothers

Interesting, that's the exact opposite of what they taught us in 'O' level woodwork (my only formal woodwork qualification ) back at school. There it was camber for the jack, straight with rounded corners for the smoother.

I camber them all by virtue of sharpenig with a well worn oil stone, but I've come to like them that way.

 

[Beau]

Hello,

Funnily enough, most people I know DO camber their jointer blades. The camber is so small that it should not affect jointing edges. In fact David Savage (wrongly IMO) says that jointer planes must be cambered. It works for him obviously. Having said that, I keep all my iron dead square across except for smothers, but I am less common than camberers, who seem to do everything.

Two irons for a jointer is handy, though, but I'd not worry about the camber making any odds to edge jointing.

Mike.

I trained with David and the reasoning for the cambered blade is to have the perfect glue line. The camber is very slight but by having the edges of the boards fractionally concave makes the outer edges sit very tight together. We also would plane the edge of boards concave in their length for the same reason. I have stuck with his way and it works.

 

[Corneel]

Wood is compressible enough not to to worry about a little bit of camber. And indeed it seems you can get tighter edge joints when the edge of the board is a little hollow.

Anyway, camber makes the proces of getting the edge true and square quite a bit easier. You can use the camber to vary the amount you remove left or right. I first heard this method from David Charlesworth, and it is indeed pretty usefull.

 

[David C]

I have always used a slight camber when edge jointing.

David

 

[woodbrains]

Hello,

Funnily enough, most people I know DO camber their jointer blades. The camber is so small that it should not affect jointing edges. In fact David Savage (wrongly IMO) says that jointer planes must be cambered. It works for him obviously. Having said that, I keep all my iron dead square across except for smothers, but I am less common than camberers, who seem to do everything.

Two irons for a jointer is handy, though, but I'd not worry about the camber making any odds to edge jointing.

Mike.

I trained with David and the reasoning for the cambered blade is to have the perfect glue line. The camber is very slight but by having the edges of the boards fractionally concave makes the outer edges sit very tight together. We also would plane the edge of boards concave in their length for the same reason. I have stuck with his way and it works.

Hello,

It is not the fact I disagree with clambering jointer irons, I know it works if you choose to do it. It is David Savage's insistence that it MUST be camberd that I do not agree with. In fact if you read some of his musings, he actually claims it is difficult/impossible to correct out of square edges unless there is a camber. It is a good job he didn't tell me this sooner, as I've managed to get dead square edges from an un-cambered try plane for 30 odd years! I'm afraid much of what Savage says is a bit spurious. There is no advantage to the edge of the boards whatsoever with a cambered iron, perhaps to the craftsman's technique if that is what he chooses, but none to the work. The camber is so slight, it just doesn't matter, in fact, and that is all. Claims that it helps tighter edges is just a bit of creative theorising. If you think about it, a cambered iron on a 2 3/8 wide jointer, should be so slight so as to not lose much if any cutting width. Joint a 3/4 in wide board and the hollow produced would be immeasurable.

Mike.

 

[D_W]

Beware of blogging gurus.

 

[Beau]

Yes not suggesting is does not work with a straight blade but never done this myself.

"If you think about it, a cambered iron on a 2 3/8 wide jointer, should be so slight so as to not lose much if any cutting width. Joint a 3/4 in wide board and the hollow produced would be immeasurable." Agreed but I don't set up my blades to cut the whole width. I set the blade with a camber and only use part of it's potential cutting width. Once one part is a bit dull then adjust to use an unused part. Pushing a 2 3/8 blade cuttings it's whole width would be beyond me on hard timbers. Can't say I often have much wood to remove with a plane anyway as try to get board straight and true from the planer and just looking to remove ripple with a few light shaving with a hand plane.

 

[woodbrains]

Yes not suggesting is does not work with a straight blade but never done this myself.

"If you think about it, a cambered iron on a 2 3/8 wide jointer, should be so slight so as to not lose much if any cutting width. Joint a 3/4 in wide board and the hollow produced would be immeasurable." Agreed but I don't set up my blades to cut the whole width. I set the blade with a camber and only use part of it's potential cutting width. Once one part is a bit dull then adjust to use an unused part. Pushing a 2 3/8 blade cuttings it's whole width would be beyond me on hard timbers. Can't say I often have much wood to remove with a plane anyway as try to get board straight and true from the planer and just looking to remove ripple with a few light shaving with a hand plane.

Hello.

Ahh, yet another useful technique if you find it so. There is so much variation in how we all use tools.

Mike.

 

[ED65]

However, I find myself using this plane more and more often for general flattening of boards and it occurs to me that for this sort of purpose the usual very fine camber would be most suitable.

I think that a very fine camber being usual needs to be addressed. I don't think it is the norm and it's possible the majority today don't camber blades (even when they should ). In terms of what was traditional advice a perusal of vintage woodworking guides shows us that their guidance on when to camber, and by how much, varied nearly as much as the advice on the setting of the cap iron*.

"General flattening" is a bit broad, but if you're in effect using your jointer as a long-bed smoother then obviously remove the corners at least to help prevent track marks if it's the last plane that will touch the wood.

*Which I can now confidently state, having collected a bunch of quotes from every book I could lay my hands on, was all over the shop!

 

[Andy Kev.]

Thank you all very much for your replies. It looks like the case has been made for a very slight camber on the edge of the blade and there's no need for me to get a second one.

ED65, my process for flattening currently is as follows: take out everything big with a jack plane equipped with a fairly viciously cambered iron. Once the board is approximately flat I get it truly flat with the No 7 and finally I use my low angle jack, with its lightly cambered iron as a smoother. Then, having got the two edges square and having marked the line for the second face, I repeat the process on the other side although I might not use the heavily cambered jack if there is not much wind i.e. no great variation in the distance from the rough surface to the marked line. If there is such a variation I scrub it down to about 1/16 from the line then use the No 7 and LA jack. This method works a treat.

 

[bugbear]

It is David Savage's insistence that it MUST be camberd that I do not agree with. In fact if you read some of his musings, he actually claims it is difficult/impossible to correct out of square edges unless there is a camber.

Pick a guru, pick a technique! Jim Kingshott said jointers must be straight...

BugBear

 

[D_W]

However, I find myself using this plane more and more often for general flattening of boards and it occurs to me that for this sort of purpose the usual very fine camber would be most suitable.

I think that a very fine camber being usual needs to be addressed. I don't think it is the norm and it's possible the majority today don't camber blades (even when they should ). In terms of what was traditional advice a perusal of vintage woodworking guides shows us that their guidance on when to camber, and by how much, varied nearly as much as the advice on the setting of the cap iron*.

"General flattening" is a bit broad, but if you're in effect using your jointer as a long-bed smoother then obviously remove the corners at least to help prevent track marks if it's the last plane that will touch the wood.

*Which I can now confidently state, having collected a bunch of quotes from every book I could lay my hands on, was all over the shop!

I don't think that we can gauge what works well by what most hand tool users are doing, only because I think most people don't get far enough into hand tools to differentiate what works really well and what doesn't.

As far as texts, I don't read too far back too much, but I'd bet if we examine what people are doing to finish plane for the last 125 years, it's not their final surface, anyway.

It's difficult to prepare wood from rough and plane a finished surface without leaving marks if an iron doesn't have camber on it, and it's easier to work left to right or right to left on a panel that is ready for smoothing using a plane that has some camber on it, because it's a little bit more forgiving for lateral adjustment.

The arguments that work can't be done one way or another or that it's really difficult to true edges with a straight blade - that's goofy.

 

[Derek Cohen (Perth Oz)]

And just to muddy the waters ...

I have two jointers I use most of the time. One is used with a straight blade for shooting edges on the bench or for match planing. The other is used with a slight camber for jointing edges individually, and traversing or flattening panels.

No such thing as one-or-the-other. Both have their place.

Regards from Perth

Derek

 

[Beau]

I would be interested in how a straight blade is used to square up an edge so done a couple or drawings to how I guess you do it and how I would used a cambered blade. The advantage of the cambered blade that I see it is the plane stays in full contact with the wood while changing the angle you are planing. Hope you can make out what I am getting at from these drawings.

 

[Derek Cohen (Perth Oz)]

There are two methods I would use to square up an edge with a straight blade.

First, if the edge is uniformly canted to one side, then simply angle the plane and level the high side, before planing down the centre. Stop when you achieve full shavings.

Second, if there are high spots along one side or the other, mark these high spots clearly, then take them down with a block plane or smoother, finally finishing with the jointer taking full shavings.

Regards from Perth

Derek