Jointer planes with skewed irons?

[Eric The Viking]

This thread https://www.ukworkshop.co.uk/forums/#p1005575 raised a question for me:

I've never seen a jointer length plane with a skewed iron, and I noticed while watching those wonderful Japanese planing competitions they don't seem to use them either.

So have I just missed them (and they do exist), or is there a good reason why they have never been made?

I ask because, like many people, I tend to skew the (Bailey-style) plane going over difficult grain. With a #7 on a narrow edge this is not productive! Recently I ended up using a #4 instead (with a Japanese iron). It worked, but not wonderfully well, so I was wondering...

E.

 

[Racers]

There are lots of other way to control tear out, back bevels, close set chip breaker etc and bevel up jointers so I don't think a skewed iron is necessary, and it might be difficult to keep it going straight because of the sideways drag.

Pete

 

[DTR]

I thought it was best* to avoid skewing the plane on difficult grain because it lowers the effective cutting angle? (conversely, skewing works well on end grain for the same reason)

*of course, there are no hard and fast rules. The timber will make up its own mind.

 

[Eric The Viking]

I thought it was best* to avoid skewing the plane on difficult grain because it lowers the effective cutting angle? (conversely, skewing works well on end grain for the same reason)

*of course, there are no hard and fast rules. The timber will make up its own mind.

Tough call - trading a high angle against taking a shearing cut.

I confess most of what I do involves cheap softwood (of necessity). Most recently, I was squaring up the bottom of 100-year-old skirting, most awkward piece was 4.5m long. The wood is horrid - looks like it was unsorted (i.e. worse than fifths). There are places where I can hardly believe they managed to get it through the spindle without it shattering into a splintery mess. It has lots of dead knots in awkward places for the detail of the moulding.

Happily I didn't need 4.5m of die-straight accuracy, just a smooth enough line to get a good tight joint (using about 20 biscuits and 18 clamps for the glue-up).

It worked, but I had to give up on the #7, as I said. The #4 is a war-finish Record, with its normal frog (have never measured the angle - guess I should really), but I don't think it's Middle Pitch!

Skewing it over the worst knotty bits definitely helped. Whilst getting the saw marks out I managed at least one complete shaving (i.e. 4.5m), but it was very, very curly!

So should you hone/setup differently between avoiding tearout on a wide surface and jointing an edge?

Appreciating the comments...

E.

PS: just found this blog post by Paul Sellers whilst Googling. I need to re-read it carefully later (got to dash now), but on a quick skim-read it seems to raise more questions than it answers.

 

[Racers]

Set your cap iron so you can see the merest sliver of reflected light from the blade 0.1mm or so, and you should get crinkly shavings ejected vertically from the plane and no tear out.
It will work for every surface.

Pete

 

[Eric The Viking]

Set your cap iron so you can see the merest sliver of reflected light from the blade 0.1mm or so, and you should get crinkly shavings ejected vertically from the plane and no tear out.
It will work for every surface.

Pete

Thanks Pete - that I will try!

Happily I have some nice steel in all my Bailey-style planes, so can get a good edge as a starting point, too.

Later,

E.

 

[D_W]

As pete says, learn the cap iron, it guarantees the most certain results once you master it.

A skewed iron is ideal for cutting across endgrain, but not up to par with a cap iron in long grain.

And learning to use it is free, and a progressive skill (you just get better and better with it to the point that it becomes clear why it eliminated alternative designs.

 

[Racers]

Thinking about it 0.1 is far to far away, it should be the thickness of your shavings or less.

Pete

 

[D_W]

Not intending to start an argument here - the cap iron set should be slightly larger than the thickest shaving you'll take with a given set.

For example, if you're intending to take a 3 thousandth shaving to normalize a planed surface to your plane (not a bad idea, actually, to start with a shaving a bit thicker and not dawdle with a whole bunch of cautious thin shavings right away),
* the cap iron set should be somewhere around double that if you have a normal cap iron setting (i.e., your leading angle at the front of the chipbreaker is 50-60 degrees or so)
* when it's optimally set, the chip should straighten out coming out of the plane, it may end up perfectly straight, but it will be a straighter version of a chip, nonetheless.
* you can usually take a set like described above, take your thicker shavings and get a good surface and then make one pass, possibly two after backing off to a thin shaving, and have a completely bright and clear surface.

On very rare occasions, the wood may still have tearout with such a setting, and you might want to tap the cap iron a tiny bit closer (or take apart and reset if needed) so that the chip straightens out on a thinner shaving.

All of this becomes reflexive once you have familiarity with the plane you do it with, and you'll find that 99% of the time, you won't need to reset anything.

If the shaving bunches or accordions, the cap is set a bit too close for the thickness of shaving you're taking. Feel the planed surface, if it's still smooth and shiny anyway, no problem. If you are working softwoods, you can see that the top layer of fibers is a bit crushed when the plane is set like that, though. And if it's closer even than that, the surface will feel rough as the cap iron is smashing the shaving back into the surface and creating a jam and scraping type of cut rather than just holding the chip down and severing it off cleanly.

You may also have one on standby that is ultra close set, but I think it's nicer to use one plane - it's uncommon to have to reset the cap iron before sharpening next time.

 

[bugbear]

PS: just found this blog post by Paul Sellers whilst Googling. I need to re-read it carefully later (got to dash now), but on a quick skim-read it seems to raise more questions than it answers.

Er. Yes. That post is majestically unhelpful. I'm not sure even Sellers himself knew what actual point he was making. It just rambles all over the place. I suppose I can't fault him for not justifying his conclusion, given that it's not even obvious what his conclusion is...

BugBear

 

[Cheshirechappie]

About the nearest thing I can think of to a 'skew jointer' is a badger plane, which was intended for the specific purpose of cleaning up large rebates. I'm not quite sure how that fits into the debate, though, especially as 'normal' wooden rebate planes were made both skew and straight across.

 

[D_W]

About the nearest thing I can think of to a 'skew jointer' is a badger plane, which was intended for the specific purpose of cleaning up large rebates. I'm not quite sure how that fits into the debate, though, especially as 'normal' wooden rebate planes were made both skew and straight across.

Badger fits for large rebates in this because it is intended to cut with and across the grain. The across the grain cuts on a rebate necessitate a skewed iron to get a decent finish.

 

[swagman]

the cap iron set should be slightly larger than the thickest shaving you'll take with a given set.

DW offers some excellent advise here regarding the set of the cap iron. A message that is not often explained very well by others.

Stewie;

 

[Eric The Viking]

Reading all this with great interest. There's been some real gold dust so far.

Thanks everyone, but that's not me closing this off - far from it - feel free to add anything.

By way of continuing...

... I haven't with every plane, but with most of them I've squared off the cap iron then ground a bevel on it so that only the very front edge presses on the iron, the idea being I can then slide it down as close to the cutting edge as I can. The newer cap irons, Stanley particularly, were pretty rough, and originally had really "interesting" shapes, a couple were arched across so that only the extreme sides pressed down. I thought this distorted the blade horribly, and left a gap under the iron in the middle where it was most needed.

So they're mostly now almost sharp in their own right, so as to exert pressure evenly across and right at the bottom end. It sounds like this is the right thing, but I did wonder about a slight camber so the middle was pressed down a bit harder.

Thoughts?

E.

 

[David C]

Eric,

If I understand you correctly, you are talking about some tiny bump on the underside of the C/B edge.

I think this would be a bad thing and might cause shavings to get trapped under the outer edges.

However as I almost always use slight camber on my blade edges, I also prepare slight camber on my C/B edges. This is worked on the bevel side just as when sharpening a blade.

It is also good to polish the upper surface of the C/B near to the edge.

David Charlesworth

 

[bugbear]

It's fairly obvious, either by experiment or analysis, that the cap-iron must be parallel to the edge to at least the tolerance of the distance you're trying to set it.

In other words (e.g.) if the blade edge is straight, and you wish to set the cap iron within 1/100" of the edge, the cap iron must be straight to 1/100" or better.

If the blad is cambered, the leading edge of the cap iron must be identically cambered (within tolerance, as above).

This adds a new factor, not normally mentioned, to cap iron tuning and fettling.

So I though I'd mention it.

BugBear

 

[D_W]

No radius on cap irons (again, not trying to start an argument with any of this):

Here's why (aside from the complications of profiling a cap iron that geometrically will not tolerate doing that without flattening the hump out):
* there is never a point where the cap iron protrudes past the mouth
* the misconception that the iron needs to have camber to avoid a situation where it overlaps the iron is due to not getting a good grasp on first bullet point - first (anywhere the straight cap is past the end of a cambered iron, the iron will not be in the cut or the middle of the cap iron would have to be. )
* on a cambered iron, the cut will feather toward the edges. The projection from the cap iron will be greatest in the middle where the cut is thickest and finer at the edges. That's probably desirable, but it's difficult to take a very very thick shaving and straighten it out in the first place

the only exception to this is moulding or coving planes that are intended to cut a recessed cut in a flat surface.

Work with a cambered iron is generally done downgrain or cross grain, and the cap is not needed as much for that, and if there is some tearout, you can always get it in the next two steps. Smoothing and try plane work, that's not so much the case - you want all strokes in that work to be through the grain's length and overlapping.

 

[bugbear]

No radius on cap irons (again, not trying to start an argument with any of this):

Here's why (aside from the complications of profiling a cap iron that geometrically will not tolerate doing that without flattening the hump out):
* there is never a point where the cap iron protrudes past the mouth
* the misconception that the iron needs to have camber to avoid a situation where it overlaps the iron is due to not getting a good grasp on first bullet point - first (anywhere the straight cap is past the end of a cambered iron, the iron will not be in the cut or the middle of the cap iron would have to be. )
* on a cambered iron, the cut will feather toward the edges. The projection from the cap iron will be greatest in the middle where the cut is thickest and finer at the edges. That's probably desirable, but it's difficult to take a very very thick shaving and straighten it out in the first place

the only exception to this is moulding or coving planes that are intended to cut a recessed cut in a flat surface.

Work with a cambered iron is generally done downgrain or cross grain, and the cap is not needed as much for that, and if there is some tearout, you can always get it in the next two steps. Smoothing and try plane work, that's not so much the case - you want all strokes in that work to be through the grain's length and overlapping.

Yeah - your first two points are (as you imply) fairly obvious, especially the first one. But these two points, taken together, lead to your third - that you may not be able to get the cap-iron as near to blade edge as you might wish in the deepest part of the cut.

Of course, if you choose to sharpen (steady!!) such that the blade is straight across, with just the corners relieved, this is all academic, but some people do camber even their smoothing pane irons, albeit not by much.

BugBear

 

[D_W]

I'll summarize as such - if the cap iron gets close enough to the mouth of the plane on a cambered iron so that it's almost in the cut, it will be too close and the shavings will bunch up and literally scrape the wood ahead of themselves. The cap iron itself will always be plenty far from the cut, more than the thickness of the cut and thus up from the mouth of the plane a bit.

It's one of those things that we can easily overthink, but the best setting for the cap iron other than for a plane that is expected to leave a finished cove is straight across and it works well whether the irons are clipped or gradually cambered across their entire width (which is a matter of thousandths on a smoother and a little more on the next more coarse plane).

 

[David C]

BB,

I am one of those who chooses to have very slight camber on my smoothing irons.

My c/bs have been similarly cambered for years, and I can confirm everything works just fine.

Not suggesting that it should be done, just that it can be done. I suspect there are very few people who share the camber fetish.....

best wishes,
David