Tear Out

[Harbo]

Interesting article in Popular Woodworking which refutes some of the commonly held views about hand planes and preventing tear out.
Namely the non effectiveness of skew planing, tight mouths and chipbreakers.
The remedy is sharp irons, high effective angles and the simplest of all timber choice.

Well worth a read

Rod

 

[kenneth cooke]

Interesting article in Popular Woodworking which refutes some of the commonly held views about hand planes and preventing tear out.
Namely the non effectiveness of skew planing, tight mouths and chipbreakers.
The remedy is sharp irons, high effective angles and the simplest of all timber choice.

Well worth a read

Rod

Thats fine if you just want to work with mild mannered timber which can seem a little pedestrian. Certainly, high angle frogs can help I have a York pitch LN smoothing plane which often is called into play on wild grain and yes a very sharp iron is essential and there is some validity in back bevels. I am not sure about the merits of skew planes either

 

[Philly]

I have found a high bedding angle (60 degrees is my favourite for smoothing) and tight mouth, along with a freshly sharpened blade, will tame pretty much most timbers.
Skewing the plane as you use it lowers the effective pitch - pointless if you spent the money to buy a high angle plane!!
Cheers
Philly

 

[bugbear]

Namely the non effectiveness of skew planing, tight mouths and chipbreakers.

I haven't seen the role of cap-irons defended w.r.t tear out in around 5 years - bit of a straw man.

BugBear

 

[ByronBlack]

High angle is the only method that has worked for me. In fact, I was getting so annoyed with a particular job, that I demanded that Philly construct me something that would save my sanity, it worked a charm!

 

[Harbo]

In the article CS states that the old maxim of keeping a very tight mouth and the chipbreaker as close as possible to the cutting edge does not really work in practice - Chris Schwarz now uses 3/32" - to prevent blocking.
An effective angle of 62 degrees copes with most tear out problems.

Rod

 

[ByronBlack]

In the article CS states that the old maxim of keeping a very tight mouth and the chipbreaker as close as possible to the cutting edge does not really work in practice - Chris Schwarz now uses 3/32" - to prevent blocking.
An effective angle of 62 degrees copes with most tear out problems.

Rod

Aye, the small coffin smoother I bought from Philly is at 60 degree's, and so far I've yet to find anything that it can't smooth. It has an almost scraper like action with uber-fine shavings.

 

[Karl]

It has an almost scraper like action with uber-fine shavings.

I believe this is the reason why a tight mouth is not necessary for tear-out free shavings. Chip failure and all that.

Cheers

Karl

 

[ivan]

Depends what you call 'close' and 'tight', I suspect. A setting of the cap iron of more than a handful of thou will have no effect on cutting quality. With the right angle on the chip breaker and settings of around 5 thou, you mimic the cutting geometry of a scraper plane, with the added benefit of a very fine mouth.

 

[bugbear]

In the article CS states that the old maxim of keeping a very tight mouth and the chipbreaker as close as possible to the cutting edge does not really work in practice...

I'd like to see those two strategies tested independantly, as well as working together (or not, of course).

Admitedly (see my previous comment) "chipbreakers" pretty much got dismissed 5-10 years ago w.r.t. tear out reduction.

BugBear

 

[Derek Cohen (Perth Oz)]

I haven't read the article yet, but gleaning from that written here, nothing I have heard is exactly new. For years we have argued that a high cutting angle is the most important factor in avoiding tearout. Further, as the cutting angle approaches 60 degrees, so the mouth size becomes increasingly irrelevant.

Finally, I thought that chipbreakers had long been debunked as affecting the performance of a plane since research (by Hitachi?) revealed they are required to be .05" from the blade edge to have a positive input. That research was done at least a decade ago.

Regards from Perth

Derek

 

[custard]

So if chip breakers are redundant, and it's really all about blade angle, then doesn't that argue in favour of bevel up planes, which then have the added benefit of better support for the iron closer to the cutting edge?

 

[Jeff Gorman]

Custard wrote:

So if chip breakers are redundant, and it's really all about blade angle, then doesn't that argue in favour of bevel up planes, which then have the added benefit of better support for the iron closer to the cutting edge?

Yes, but I think that a couple of contrary arguments are (a) adjusters less accessible and (b) the adjustment having too great an effect on the shaving aperture size.

 

[bugbear]

(b) the adjustment having too great an effect on the shaving aperture size.

One notes that the VAST majority of BU planes have easily adjustable shaving apertures.

BugBear

 

[Jeff Gorman]

WhiskyFoxtrot wrote:

(b) the adjustment having too great an effect on the shaving aperture size.

One notes that the VAST majority of BU planes have easily adjustable shaving apertures.

BugBear

Ah yes, but who wants to have to mess about both with the cutter and shaving aperture settings when working with very fine apertures on difficult timbers?

 

[bugbear]

WhiskyFoxtrot wrote:

(b) the adjustment having too great an effect on the shaving aperture size.

One notes that the VAST majority of BU planes have easily adjustable shaving apertures.

BugBear

Ah yes, but who wants to have to mess about both with the cutter and shaving aperture settings when working with very fine apertures on difficult timbers?

Well, no one (as you imply), but I suspect most people configure their "best" smoothing plane for small aperture and shaving, and leave it that way.

BugBear

 

[ivan]

Don't dismiss chipbreakers too soon - it's quite easy to fettle a LN chipbreaker with a 70 deg 'microbevel ' at the sharp end, and fit it 'thou' close to the blade edge. Been using a Clifton today with a 10 deg 'micro' back bevel, and the LN chipbreaker* setting does make a difference to tear out. The mouth will just pass a 4 thou feeler. Obviously if the back bevel is much over a shaving's thickness, you can't get the cap iron close enough. Simpler to ignore cap iron? But if you can find a way to lower effective pitch with no tearout overall surface finish improves, which may be useful.

* several of my Clifton 2 piece cap irons have too much backlash in the 'hinge' to allow them to be set consistently 'thou' close.