Subtleties of shaving deflection

UKworkshop.co.uk

Help Support UKworkshop.co.uk:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Corneel

Established Member
Joined
19 May 2010
Messages
1,520
Reaction score
1
Location
The Netherlands
It's now more then a year since the Kato/Kawai video was republished. I'm sure everyone has a lot of practice now, and might have found some little practical tricks. Let's share some experience.

For me, the single most difficult thing is preparing the capiron so it sits flush with the back of the blade with no light showing through. When you use the capiron very close to the edge, any small gap is an entry point for the shaving to pry it open and shove itself under the caprion. Most every capiron in my shop wasn't flat enough. I could have bought precision machined LN capirons and been done with it, but being a cheapskate I choose to repair the old ones. They usually are convex, so I start with narrow pieces of sandpaper on a glassplate to make it concave first. Using somewhat wider pieces I slowly work the concavity flatter until I am done. Check often, it's easy to go too far and recreate the convexity again.

With some capirons it is very difficult to adjust it very close to the edge. Especially when tightening the screw, the capiron seems to move again. I don't really have an answer for this. Sometimes it is a problem with the screw being off to one side, so putting pressure on one side only. Or the capiron just slips around because everything is too smooth. Roughing up the caprion at the top end might help a little bit. If nothing helps I tend not to use that plane anymore or use it as a jackplane.

With the capiron resting nicely flat on the back of the iron, it's time to think about the angle of the leading edge of the capiron. I know that the Japanese video encourages to use a very steep angle, something like 75 degrees. I've seen older German documents where they even use a 90 degree wall. So first this was were I was heading. Problem with such a steep leading edge is the increased effort of pushing the plane. And I don't know exactly what happens to the wood when you put so much pressure onto it.

So I have been experimenting with much lower angles lately. This on advice from Caspar Labarre, a Dutch cabinetmaker with a deep interest in historic woodworking methds. In my Stanley smoother I now use a 45 degree angle. Of course, you need to set the capiron closer to the edge, compared to the higher angled capiron. But it pays of in much reduced effort to push the plane.

In my wooden smoother I even use a lower angle, about 35 degrees. According to Caspar you have an extra mechanism in a wooden plane. The shaving curls forward and hits the wear of the plane, then curves back and forth between capiron and wear until it exits from the thoat of the plane. These curls have friction between these two walls and thus help to support themselves. So you can get away with less support from the capiron itself, because you have this extra support higher up. I don't know if it really works like this, but I do know now that such a low angle works. You have to set the capiron really close to the edge of course. Pushing the plane now feels as if there is no chipbreaker effect going on at all, but you still have the benefit of no tear out.

I happen to have two 49 degree planes with a double iron. I didn't do any structural analyzing of these, but subjectively I'd say they perform a little better on very curly grain.

In none of my planes I use a very tight mouth. Bailey style planes benefit from the extra support under the blade when you pull the frog back. And a really tight mouth in a wooden plane is a rare occurance, not often found in the wild. Because the chipbreaker effect is so strong, I don't feel faffing around with all kinds of combinations of tear out reduction methods is worthwhile. And when everything gets too tight around the mouth, clogging is just waiting to happen. But I'm sure others will feel different about this.

Hope this encourages some discussion. As usual everyones opinion will be different, which isn't a problem, but do expect a ribbing when you post downright nonsence. :mrgreen:
 
If you consider the scale of the Kawai Kato film, it is clear that the 70 degree bevel need be no more than 0.2 to 0.3 mm wide, maybe even less. The film shows no mouth, but I have used the technique on a plane with a mouth of 0.004 inches. No sign of any choking.

As I have said many times before, almost all chibreaker edges need work, L-N, Veritas, IBC, Hock & Clifton. A small clearance angle underneath is helpful, maybe 1 to 2 degrees. Black felt tip helps with the checking, and a fine diamond plate or dead flat oilstone is good. I find paper does not give precision flatness and unhardened steel digs holes in waterstones fast. 45 degree top edges can be worked in Eclipse honing guide.

David Charlesworth
 
Thanks David. Usefull stuff. Do you think with such a very small 70 degree bevel, the effort of pushing the plane is lessened?
 
Corneel":w866d4qi said:
For me, the single most difficult thing is preparing the capiron so it sits flush with the back of the blade with no light showing through. When you use the capiron very close to the edge, any small gap is an entry point for the shaving to pry it open and shove itself under the caprion.

I havent seen the video/film you refer to, but the comment I have quoted here reminded me of a snippet in George Ellis's Modern Practical Carpentery where he describes a way to elinimate your problem. As I recall, he advocates using a burnisher type of tool drawn across the edge of the cap iron after t is fixed to the cutting iron, to close up that gap. I reckon similar to when you prepare a scraper by changing the shape of the edge with a burnisher. Its as if he does a simplle type of cold forging, to force the sharp edge of the cap iron/chip breaker right down tight to the cutting iron
Just a thought.. :idea:
 
Most of my cap irons are set 0.5 mm or farther from the edge... I never fettled them...
I personally think getting a tight mouth is easier and more efficient. All you need to do is put in the blade, stick a shaving or piece of paper between it and the mouth and push the frog as far as you can with the screw. Done in about a minute, no flattening, etc.
 
Ah yes, but in a Bailey plane you need to remove the blade assembly again to tighten the frog screws! I also wonder, do you have to change the setting when changing the cutting depth? My beloved wooden planes don't have adjustment, while the mouth is invariably too wide for tearout reduction. And then, the cursed chipbreaker tuning is a one time job. After that, setting the chipbreaker close to the edge is not really troublesome in most cases.

But if it works for you, that's fine!
 
Cottonwood":3c6jdwze said:
I havent seen the video/film you refer to, [...]

Here's the video. You should really watch it, it is very tranquile with the softspoken Japanese voice, and these flowing shavings are a bit hypnothising. :lol:
http://vimeo.com/41372857

Thanks for the idea about the burnisher. I read about it on Chris Schwarz's blog, but didn't understand really what he ment.
 
Corneel":kyeaup1b said:
Cottonwood":kyeaup1b said:
I havent seen the video/film you refer to, [...]

Here's the video. You should really watch it, it is very tranquile with the softspoken Japanese voice, and these flowing shavings are a bit hypnothising. :lol:
http://vimeo.com/41372857

Thanks for the idea about the burnisher. I read about it on Chris Schwarz's blog, but didn't understand really what he ment.

Hi Corneel :D
I did indeed watch the video earlier this morning, fascinating viewing. It occured to me that the way the chipbreaker works is sort of like the way a cleaving brake works to split logs, where you control the degree of runout so the split goes centrally and you end up with 2 equal boards. Am I right in thinking that those extreme chip breaker angles are designed to start bending the shaving up and out of the mouth ASAP, before the shaving develops enough thickness and tensile strength to tear the grain with a counter-levering ssault?

Also, I went to have a look again at George Ellis's book. What he advocates is to assemble the iron and chipbreaker, then use a bradawl or broken file to draw across the join of the 2 pieces of metal and shave off tiny slivers, until no light is visble between the 2. If you want I could type out word for word.
cheers Jonathan :D
 
Corneel":2rrgu56o said:
Ah yes, but in a Bailey plane you need to remove the blade assembly again to tighten the frog screws! I also wonder, do you have to change the setting when changing the cutting depth? My beloved wooden planes don't have adjustment, while the mouth is invariably too wide for tearout reduction. And then, the cursed chipbreaker tuning is a one time job. After that, setting the chipbreaker close to the edge is not really troublesome in most cases.

But if it works for you, that's fine!

With a Bailey, you half-tighten the frog screws (as in tight enough it won't flop about or get moved by hand pressure, but loose enough that it can be moved by the adjustment screw), put the blade in, adjust the frog, remove the blade and fully tighten the frog screws. The frog does not move when you're removing the blade because the screws are half tight.
I set the mouth tight with my thick replacement blade in the plane. When I have to take a deeper cut, I switch in the thinner original blade, which opens the mouth up again. So no, I don't really have to move the frog when changing the cutting depth. It is really just a one-time job ;)
 
Thanks for explaining Sam. Seems to be a usefull method.

David, yes I haven't been very consistent with my screennames. It is in fact the same, Kees being the germanic form and Cornelis is latin. Kees is my name for daily use.

Jonathan, as far as I understand, the shaving is kind of pushed back into the wood. When you bend a springy curl of wood and press on the topside, there will also be a force on the underside of the curl. That's what happens, as far as I know. From my recent experiments I conclude that you don't need to bend the curl very far, a 35 degree bevel on the capiron of my #6 is enough to prevent tearout in a range of woodtypes.
 
Wonderful video, thank you! If you have time please also check out the guy who uploaded it http://giantcypress.net/ Wilbur Pan is a very readable blogger, passionate woodworker and a nice guy to boot. He has some of Matthew's WSH content on their too.
 
Surely back-cutting the chip breaker where it sits on the blade so that only the leading edge touches would make sealing the joint between the two easier? Although after seeing the film the chip breaker needs to be more substantial than on most planes.
 
I presume you must be employing a large hammer to get a 35 degree front edge on a Stanley or record curved c/b ?

They were clearly manufactured with 45 degree front edge in mind.

David
 
No, I used the grinder. Plenty of metal down there. But maybe it would have been smarter to bend it a little first.
 
Back
Top