12-Degree Versus 20-Degree Cutterheads for Poplar
From contributor T:
Contributor J has it right. The 12 deg. is best for poplar. I think the reason mfg. recommend 20 deg. heads is the horsepower, or lack thereof, issue associated with mass produced moulders. Never trust a salesman to tell you what he thinks you need. In addition who says you’re never going to cut oak or maple someday. Use the 12's, they are what I use and I cut a lot of poplar.
From contributor R:
The total geometry of the cutting tool is what provides you with the best finish and the longest lasting tool. This geometry is made up of the hook angle, the back clearance angle, the side clearance angle and the cutting tool diameter.
When we look at cutting different types of wood, we need to understand the material. The softer the wood is to cut, the more you want your tool to slice at it; the harder the wood, the more you want the tool to scrap at it.
With this stated, I normally use a 20º hook on poplar and soft cutting woods and 12º on harder to cut woods. Since the hook angle is only part of the overall tool, it is not uncommon to use a variety of hooks. For example, when I use 20º hook for poplar, I grind my back clearance around 27º. If I use 12º hook, I grind the back clearance between 30-33º. The bottom line is this, if you find a combination that works and you get the finish on the material you want, then there is no wrong tool. I always suggest that you try a few different combinations until you find the one that works the best for you.
From contributor M:
Or add dual angle heads to your collection that have both 12 and 20 degree pockets.
From contributor J:
Remember knives must be ground at the same angle as they will be run or the profiles will not be accurate!
From contributor Y:
12 deg. is for hardwoods. 20 deg. is for softwoods. Poplar is actually a hard wood but I mainly use 12. It depends on the knife stock you use also.
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