Derek Cohen (in Perth, Australia)
Hi Mark

At the start of this chip breaker journey Warren made the comment that the reason he preferred a common pitch Stanley over a higher angle plane was because the lower cutting angle should leave a smoother, more polished finish. There have been a number of similar posts here in this vein, particularly from David. You commented earlier ...

It would seem to me that a high angle bed is going in the wrong direction, and would seem to me to be pushing and scraping the wood more than cutting. And although it may not cause tearout it is probably not going to give you as good a surface.

I chose a piece of Jarrah for testing that was all about surface finish. I commented elsewhere to David that the surface looked like end grain. It does, however have a grain direction. It is just extremely interlocked. It is not the type of wood I would use for building furniture. It is the wood from Hell. It does, however, quickly reveal which set up can and cannot leave a smooth surface finish.

It was apparent in earlier tests that the high cutting angles actually left the better surface finish to the touch. This is not as easy to see in the photos.

The conclusions I reached in this experiment included evidence that the chip breaker effect was real (hurrah!) but that there was a limit after which cutting angle appears to take over, or adds to.

I suspect that among some who do not use high cutting angles there is the equivalent misunderstanding experienced by those that do not use chip breakers appropriately. That is, that high cutting angles are for scraping and do not polish a surface.

The photo I posted of the BU infill shows a shaving that is clearly the result of shaving wood rather than scraping wood. It left a polished surface. All my other high angle planes - both BU and BD - do the same. Here in Oz high angle planes are fairly common place - just look to the success of HNT Gordon planes, an Aussie company that builds only high angle planes.

What I take from this experience is that I may be able to hot rod the performance of my double iron planes, particularly the couple of LN smoothers whose cutting angles (at 55 degrees) were not keeping up with the 60 degree BU designs.

Regards from Perth

Derek