A while ago on the “Hand Planes of your Dreams” thread there was a video pointed out that showed how the angle of the chip breaker affected the planes performance. The thing it didn’t show was how the mouth affected performance as well. It showed that a 80 degree angle on the chip breaker works better than a 50 degree. I checked and most of the planes I have were pretty close to an 80 degree bevel anyhow. At some point I’d like to see if the angle really makes a difference.
I have noticed a big difference if the chip breaker is not smooth. I always polish the ends of the chip breaker. Pitting doesn’t seem to have a huge affect, as long as its not deep, and its cleaned and well polished.
I did a little testing on the relationship between the gap between the breaker and the blade, and here is the results I came up with. I’ve been asked a lot about how to set the chip breaker. Here is a proven answer.
First I started with a no name plane, without a frog adjuster nut. Why? I’m not sure. Remember this guy? This proves no frog adjuster is needed to be successful and a no-name plane can produce superb results.
Next I made sure the front of the chip breaker was honed at 80 degrees. It was already pretty close, so it didn’t take a whole lot of work.
Now this probably isn’t the most scientific experiment you’ve ever seen. I used my $1 flea market calipers. Its more important to watch the relationship than the actual numbers.
First I sharpened the blade and set it like I normally would.
I buckled up a piece of pine and gave it a try. Not bad, but not perfect either.
At this point the mouth is .06” and the gap between the blade and breaker is .09”. The results are not terribble but I can feel the plane is not working as it should. The plane is hard to push and the shavings are inconsistent.
So lets open up the gap between the blade and breaker to .20”. You’ll notice moving either moving the gap wider or narrower or raising and lowering the blade changes the width of the mouth, so it takes a little trial and error to get it right.
Now the mouth is .07 and the gap is .20”
This isn’t working all that well. I can feel the plane is hard to push. The shavings are a little inconsistent and I can’t get an even cut. So I closed the gap between the breaker and the blade. I could immediately feel that plane was working easier.
I started to see as the gap between the chip breaker and the mouth were closer to the same measurement, the shavings came easier and thinner and more consistent.
I found if the measurements were close to the same the plane worked ok, but as the measurement grew so did the thickness of shavings. I found if the mouth was wider or narrower than the gap between the breaker and the blade, then the plane pushed harder and the shaving were inconsistent.
I then grabbed the bedrock 604 and set the mouth to .03” and the gap to .03”. It was already pretty close to that anyhow, it didn’t take much movement of either measurement.
I found that .03” produce the best results. Any less than that for the mouth and the shavings didn’t want to come through, and any less on the gap between the breaker and the blade and it started to make dust instead of shavings.
That’s all I had time for today. When I get some more time I’m going to add a few more test and see how hardwood changes things.
A few other points to note. When you planing for real, you’ll want to skew the plane a bit, so don’t expect you shavings to all be nice and even and always consistent. The most important point is no tearout.
Also note, this is for a smoothing plane, but could apply to a jointer as well.
As always, comments welcome, good bad or indifferent.
Day 2, lets try some hardwood.
So I grabbed my favorite restore project, my Millers Falls #10. Its the primary plane from this blog. The first thing I did was give it a try on a piece of red oak.
The chip breaker was set to .05”
the mouth was .07”
It push hard and I could tell it was going to do well
I left the chip breaker set to .05”
I moved the mouth to .04”
it got better, but was still hard to push. Its oak so I expected a little harder than the pine, but you can tell when its cutting like it should.
Next I moved the chip breaker as close as my eyes allowed. I think it wound up about .015” to .02”.
I set the mouth at .02. As you can see, it worked really well
I then took a half turn on the adjustment screw to open the mouth up a little
I tried the same setting on a piece of pine. Its still working well.
So I know know that the chip breaker set close works well on hardwood as long as the mouth is set close as well.
To verify this I grabbed one of my latest #3e restores. I set the chip breaker as close as i could. I noted the chip breaker had a concaved end, which meant it was set close on the outside edges, but not the center.
It was ok, but not great, so I took the chip breaker out, and went to the stones to straight out the chip breaker. When I was done, it was square.
I made sure it was square, at about 80 degrees and polished. I’ve known the polish makes a difference.
So after the fix, set thew chip breaker about .015” – .02 and the mouth about the same.
Tried the same setting on the pine. Love those sweet shavings.
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