I see why silicon carbide stones never got used that much..

[swagman]

12mm (2x laminated) glass, 1250mm x 300mm.

 

[swagman]

This afternoon I flattened the sole on my Stanley #5C, a fairly quick process with a corrugated sole. A quick resharpen of the blade, and set the cap iron clearance by eye to around 0.8 mm. Very nice shavings.

Stewie;

 

[ED65]

Who would that be? I suspect he is talking for effect, or he is an *****; no one can look at a plane and tell if it is flat enough.

My apologies, I'd forgotten the context so exaggerated how widely he meant this. The comment was only in relation to something like a jack plane.

 

[swagman]

A quick resharpen of the blade, and set the cap iron clearance by eye to around 0.8 mm.

Unless your dealing with reverse grain; the act of backing off the cap iron should eliminate most of the wear characteristics inherent within a closely set cap iron.

http://planetuning.infillplane.com/html ... study.html

This hollowing of the face is a result of the shavings flowing from the tip and being curled against the blade face by the cap iron. The pressure of these shavings is sufficient to wear away the metal in the region of high shaving pressure between the cap iron edge and the blade tip. Closer placement of the cap iron to the cutting edge and/or increasing the angle of the leading edge of the cap iron increases the shaving deflection (which Kato calls the “cap iron effect”) thereby increasing the pressure of the shaving and, correspondingly, increases the amount of wear on the blade face.

 

[D_W]

A quick resharpen of the blade, and set the cap iron clearance by eye to around 0.8 mm.

Unless your dealing with reverse grain; the act of backing off the cap iron should eliminate most of the wear characteristics inherent within a closely set cap iron.

http://planetuning.infillplane.com/html ... study.html

This hollowing of the face is a result of the shavings flowing from the tip and being curled against the blade face by the cap iron. The pressure of these shavings is sufficient to wear away the metal in the region of high shaving pressure between the cap iron edge and the blade tip. Closer placement of the cap iron to the cutting edge and/or increasing the angle of the leading edge of the cap iron increases the shaving deflection (which Kato calls the “cap iron effect”) thereby increasing the pressure of the shaving and, correspondingly, increases the amount of wear on the blade face.

This effect was relevant in the K&K study because they were studying cap iron data for commercial purposes (like for making a super surfacer). In practical use, this wear poses no issue, and you won't notice it.

You will notice that the plane stays in the cut longer into the sharpening cycle, though, and that the sharpening interval is at least twice what it would be in something like a 55 degree single iron plane with a similar iron. I had some concern, too, when I first read that, but it's not something you actually notice in practice, nor is it difficult to remove that wear when sharpening - no change in the sharpening routine is required.

 

[swagman]

David; thanks for your thoughts on the K & K study. While their is little doubt a closely set cap iron will help to reduce tear out on reverse grain, it does add considerable resistance to the planning stroke if your taking more than a whispy shaving. imo it makes far more sense to leave the cap iron backed off as a general rule, while viewing a closer set cap iron to combat tear out as an exception to that rule.

Stewie;

 

[bugbear]

12mm (2x laminated) glass, 1250mm x 300mm.

http://www.woodbin.com/calcs/sagulator/

The sagulator says that piece of glass would bend by 1.2mm (47 thou) with only a 20Lb load (how hard are you pressing) if it were only supported at the ends; that being the case the straightness/flatness of your grinding surface will be partially determined by the flatness of whatever the glass happens to be sitting on.

BugBear

PS all the materials that aren't named solid timbers are at the bottom of the sagulator material drop down

 

[swagman]

@250mm between load supports = 0.01mm sag @ midpoint load of 30lbs ACCEPTABLE

"beware the Ides of March" BB.

 

[D_W]

David; thanks for your thoughts on the K & K study. While their is little doubt a closely set cap iron will help to reduce tear out on reverse grain, it does add considerable resistance to the planning stroke if your taking more than a whispy shaving. imo it makes far more sense to leave the cap iron backed off as a general rule, while viewing a closer set cap iron to combat tear out as an exception to that rule.

Stewie;

If you continue along using the cap iron (and to some extent, it depends on how much heavy work you're doing with planes), you'll likely come to somewhere between. The K&K videos are not a good guide to setting a hand plane, but they were not intended to be, either. The university put together a separate paper for setting hand planes, and that paper emphasized that the cap set is a matter of situation (setting the cap iron on a japanese plane is a little bit more difficult, I think they'd have had an easier time with a stanley plane or any plane where the cap set can't be affected by changing depth setting).

AT any rate, for middle or coarse smoothing type work (like after jack work), you want to keep the cap set all the time. On something like a try plane and cherry, that might mean that you don't run into stop-you-in-your-tracks resistance until you are at the heaviest shaving you would've taken anyway - like a hundredth thick full width. That kind of shaving will be a disaster with anything less than good wood, but with the cap set, 2/3rds of the maximum shaving adds little more resistance than without the cap set, and the shavings stay continuous (which means the planing and resulting surface is predictable) and marks are easy to hit.

You can still bull your way through narrow work with the cap set back, but if the cap set off of the plane is a better setting than the cap iron set for use, then the cap is set too close. It's a problem/disaster preventer, but people gather from the K&K video that things like a set of cap distance = shaving thickness is good (it's too close) or that an 80% cap iron bevel is ideal for flexible use (it is not, it's inflexible).

If a super surfacer runs into extra resistance, the machine isn't going to care, but we do. I wrote about 4 years ago that the ideal set on a plane is one where the cap iron is a step off of very tight because it prevents large problems, and allows a thin pass or two to remove anything else. The same is still true - unless you have perfect wood that will allow you to be planing down grain on every stroke (then the cap iron is not needed). There is little wood like that at the lumber seller here.