What difference a chipbreaker

[mat]

Compare a bevel down vs a bevel up plane with a high angle blade. Both have the same angle of "attack"
What difference does the chip breaker make? Is this compensated for by the ability to produce a narrow mouth on the BU?

I apologise if this has been covered somewhere. I did a search and the answer is not easily found.

[derekcohen]

Mat

Generally chip breakers - or cap irons - are unnecessary in any format if the blade is a reasonably thick one. In my book all they do is add mass to a thin blade. High bed angle BD planes benefit especially from not having one as they would get in the way of shavings being expelled.

Regards from Perth

Derek

[mat]

Derek
thanks for your response.
Are you suggesting that chipbreakers do not play a significant role in chip formation?

[derekcohen]

Hi Mat

Chip formation occurs at the cutting edge. A cap iron may stabilise a blade to reduce or eliminate chatter, but it has no part to play in the formation of the chip type, per se (i.e. in determining whether one has a Type I or a Type II chip) in common circumstances.

For the cap iron/chip breaker to influence the formation of the chip, it effectively must become a part of the blade. Research in Japan revealed that the chip breaker must be within 0.1mm from the knife edge to effect any change. Beyond this distance and there is no effect.


Regards from Perth

Derek

[mat]

Derek

That's exactly the information I was after.

[pjr]

hi Matt, and here is Brent Beach's section on Cap Irons if you feel like a bit of further reading.

The Sharpening FAQ - Fads and fallacies

[derekcohen]

Start with ..

Shaving information
Shaving Formation

Then there are two studies to read.

1. Yamagata University
Chipbreaker Study

2.Oregon State University
http://ir.library.oregonstate.edu/js...s_Chip_ocr.pdf

Regards from Perth

Derek

[pjr]

Excellent, thanks Derek, I don't remember seeing the Oregon State University one before

[Mr Brush]

pjr - thanks for posting that link ! Lots of very interesting and useful stuff on sharpening collected together in one place.

[RossM]

I love reading Brents stuff - forget the anecdotal opinion or outright luddite bias! Always good for a bit of controversy, especially from the "you are lazy unless you learn to sharpen freehand" brigade.

So, you can disregard my claims for variety of reasons, but not because they are wrong. In particular, you can continue honing without a jig on your favourite piece of stone and continue to think you are getting great edges. In fact, you are not. All irons honed without a jig have inferior edges. All plane irons honed without a back bevel have inferior edges.

And here he has a summary of some of the more controversial conclusions he has reached:

You will find a number of apparently outrageous claims in <Brent's> pages. Some of the more controversial:

• Any company Advertising flat backs as a feature of new plane blades does not understand the geometry of worn blades and is dooming their customers to dull blades and planes that don't work as well as they could.
• If you sharpen your plane blades like I do, stropping can only dull your blade. Put another way, if stropping helps then you should think about changing the way you sharpen.
• I suggest four bevels on a plane iron, when many people say two is enough.
• I urge you to try back bevels, when no commercial jig allows you to do this easily.
• I claim my shop-made jig is better than any commercial jig.
• I claim that inexpensive sheet abrasives are better than the best waterstones or diamond paste.
• I say you should use a jig, while so many say you don't need one. In fact, I say that using a jig will reduce the time you spend sharpening.
• I say all tool steels, from O1 to M2, can be brought to the same initial sharpness, while replacement blade sellers still make claims about superior edge sharpness of O1 steel. May 2007 - new results on initial sharpness.
• I say you can (and perhaps should) use a bench stone to grind the primary, when others depend on various powered grinders.

Great food for thought (& reasons to maybe change what you do - unless you really like grinding away at the metal)

[derekcohen]

I'm sorry, I think that (the quotes you refer to) is all poppycock.

I respect the research that Brent has done, and his work has described many important issues in sharpening blades. So please do not misunderstand me when I say that you have to be careful how you interpret his conclusions.

In the real world his sharpening methods suit whom? Blunt blades if you do not follow his methods? Oh please! There have been generations of woodworkers over hundreds of years who have have blades that are sharp enough to go good work, and do so efficiently.

It is more about "sharp enough" and "efficiency in sharpening". One must find a method and use it. My own personal preferences are not necessarily going to suit another, and I am not going to get adament that it is the best method around. I freehand blades when I can. In all likelihood the edges are not as keen as Brents', but mine take seconds to do, and do not interrupt the flow of my work. I find his method too obsessive.... now. In the past, when I was starting out in woodworking with handtools, his recommendations would have helped. Now they are excessive.

Regards from Perth

Derek

[pjr]

I love reading Brents stuff - forget the anecdotal opinion or outright luddite bias! Always good for a bit of controversy, especially from the "you are lazy unless you learn to sharpen freehand" brigade.

haha, yes, it's the outright luddite bias in me that loves his stuff!

[RossM]

Knew I'd get a bite

I agree - there is efficient & there is obsessive. However, there are plenty who are obsessively inefficient!

But Derek, you contradict youself when you say ALL the quotes there are poppycock. It is hard to refute his evidence - it just comes down to what suites an individuals method of work, which I think is what you are saying.

[jimbur]

I'm sorry, I think that (the quotes you refer to) is all poppycock.

In the real world his sharpening methods suit whom? Blunt blades if you do not follow his methods? Oh please! There have been generations of woodworkers over hundreds of years who have have blades that are sharp enough to go good work, and do so efficiently.

It is more about "sharp enough" and "efficiency in sharpening". One must find a method and use it. My own personal preferences are not necessarily going to suit another, and I am not going to get adament that it is the best method around. I freehand blades when I can. In all likelihood the edges are not as keen as Brents', but mine take seconds to do, and do not interrupt the flow of my work. I find his method too obsessive.... now. In the past, when I was starting out in woodworking with handtools, his recommendations would have helped. Now they are excessive.

Regards from Perth

Derek

Nicely put Derek. The way things are going with sharpening it will only be a matter of time before someone moves on to saws. Sharpening with files will become anathema and a moderately quick job will become a nightmare with shaped stones etc ad infinitum.
Cheers,
Jim

[rsser]

Hmm. Well I take Brent's point that the 'wear bevel' is a rounding over of both the planes that form the edge, so if you've lapped the top/back to the nth degree, when it comes to resharpening you have to take enough steel off to get past it back to the flat on that side.