Hand Tools Archive 2007

Subject:
Re: chip breaker/cap iron or not?

Wiley Horne
>Hi Mike,

Clark & Williams are of the opinion, especially with respect to smooth planes, that the combination of single, thick blade + tight mouth + 55 degree bedding angle + SHARP is the best approach to avoiding tearout and getting a nice surface in our typical furniture-making woods. I can testify that their system works, and works well. As a footnote, in using both 50 degree and 55 degree smooth planes from C&W, there is a perceptible difference favoring the 55 degree, in the more challenging boards.

Another up and coming maker of wooden planes, Phil Edwards of the UK, is also using the single blade/high angle/tight mouth approach successfully.

There has been some testing performed in regard to the effectiveness of cap irons in breaking the chip. Steve Elliott is of the opinion-- and he quotes testing by a Japanese professor as well as his own results--that the cap iron can be effective in breaking the chip, but only if it is located very close to the cutting edge, like 4 to 8 thousandths of an inch. Here is a link to Steve's thoughts:

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

Perhaps Steve will come by and discuss this further and bring us up to date on his work. His published thinking is that the chipbreaker, even when set very close, would be more useful in planing soft woods rather than hardwoods, and in planes bedded at lower angles.

The idea that the cap iron must be set within a few thousandths of the edge to be effective also jibes with the opinion of the Japanese plane gurus, one of whom has stated that "...the subblade has to be set so close that if it were any closer, it would be doing the cutting..."

So there is a body of opinion that (a) a cap iron is not needed to prevent tearout when taking thin shavings through a tight mouth, using a high angle plane; (b) a cap iron may break the shaving, provided it is set within a few thousandths of an inch from the cutting edge.

Note that there is a bit of a conflict in having both a tight mouth (say, 3-4 thousandths) and a cap iron located within a few thousandths of the edge. Everything would have to be perfect for the shaving not to clog the mouth. Plus, the closeness of the cap iron in this situation complicates putting any camber on the blade.

Now the foregoing discussion relates mostly to taking thin shavings. It has also been argued that the cap iron, in a bevel down plane, stabilizes the edge against deflection when taking a thicker shaving. Jack planes and fore planes come to mind. My experience using C&W jack and fore planes, bedded at 50 degrees with single blades and plenty of mouth clearance, is that you still do not get noticeable tearout. I would speculate that the reason for this is that the camber on the thick-shaving planes is also effective against tearout by making more of a shearing-type cut than a straight-bladed plane.

Conclusion: You'd be in very good company if you made your coffin smoother at a higher angle, with a tight mouth, and with a single blade. Also if you used a single blade on the jack plane, 50-degree bedding, and with camber of, say 6" to 8" radius.

Wiley

Messages In This Thread

chip breaker/cap iron or not?
Re: chip breaker/cap iron or not?
You guys are awesome
thank you all and 1 more thing
Re: thank you all and 1 more thing
We've got a few... *LINK*
Re: thank you all and 1 more thing
Re: chip breaker/cap iron or not?
Double Iron
Re: chip breaker/cap iron or not?
And let's not forget HNT Gordon planes *PIC*
Some thoughts but no new tests
Re: Some thoughts but no new tests
Update your WoodCentral email
Re: Some thoughts but no new tests
Clarification
Re: Clarification
Fine Shavings
Re: Fine Shavings
Re: Fine Shavings
Re: Fine Shavings
Fine shavings and thick shavings
Re: Fine shavings and thick shavings
No. 46 degrees is the steepest
Re: No. 46 degrees is the steepest
46 degrees is the steepest
Re: 46 degrees is the steepest
How to look at the post you are responding to
Re: How to look at the post you are responding to
Thanks
Re: 46 degrees is the steepest
Re: 46 degrees is the steepest
Oops, my bad, found the prefs. *NM*
Re: 46 degrees is the steepest
Re: 46 degrees is the steepest
Re: Fine Shavings
Re: Fine Shavings
Re: Fine Shavings
Re: Fine Shavings
Chris, I have a question for you,
Re: Fine Shavings
Re: Fine Shavings
I don't think so *LINK*
Huh?
Re: Huh?
Really Huh?
Re: Really Huh?
Re: Really Huh?
Question and correction.
I'd really like to hear Larry's/James' response. *NM*
Re: I'd really like to hear Larry's/James' respons
Facts
recanting?
???
Re: Facts
Re: I'd really like to hear Larry's/James' respons
Tread carefully
Re: Tread carefully
Re: Tread carefully
cap iron use- please help
sawing planes in half
that could work- thanks! *NM*
Re: cap iron use- please help
Re: chip breaker/cap iron or not?
Re: chip breaker/cap iron or not? *PIC*
Apologies Wayne...
Re: Apologies Wayne...
© 1998 - 2017 by Ellis Walentine. All rights reserved.
No parts of this web site may be reproduced in any form or by
any means without the written permission of the publisher.

WOODCENTRAL, P.O. BOX 493, SPRINGTOWN, PA 18081