Setting the Chip breaker on a Lie-Nielsen #4 Smoother

[hbmcc]

Until a WoodNet Forum member suggested I modify my Lie-Nielson chip breaker for a tighter separation from the blade edge, I had assumed my ~1/32” spacing was about the closest for reasonable handling of curly grained woods. To control grain tearout any better my assumption was to use a frog angle higher than the standard 45-degree pitch for smoothing planes.

The suggested modification included reshaping the forward edge of the shallow angle of the factory chip breaker by “blunting” it to a 50 to 80 degree angle; then polishing the face edge. This modification together with moving the forward edge to a tight tolerance from the blade edge would probably eliminate the need for a higher pitched frog.

Before tackling the chip breaker remodel, I tuned up and sharpened the blade of my Bronze #4 smoother. I pushed the factory finished edge of the chip breaker to the blade edge as close as I could freehand. The separation was about 0.015” to 0.020”.

Note, I am using feeler gauges and comparing edge-face reflection. I would trust adjusting a VW bug’s valves in a muddy ditch at night before guaranteeing the gap in this plane blade scene. So take the dimensions with a dose of salt. However, the measurements are more
accurate than a “hair’s breadth”.

The blade shaved curly Western Big-leaf Maple quite nicely. There was no tear out, and the finish was relatively smooth. A scraper would be needed to finish the surface.

Using my diamonds and sharpening guide, a tentative shaping of the forward edge of the chip breaker was done. I use the same sharpening guide for blades and chisels. The edge was shaped to a quarter round of about 0.020” inclination from blade contact point.

Shaped chip breaker over blade with less than 0.020” separation.

The blade was re-honed and returned to the tool. Separation of the blade and chip breaker edges was approximately 0.20 inches; slightly less. Since both pieces of metal are polished one surface needs to be dyed, even if only to mount the chip breaker. The plane handled the contrary grain pretty much the same as previously with factory milled edge.

Moving the chip breaker to a separation less than 1/32 from the blade edge will increase physical resistance to planing significantly. At about 0.030 inch gap there is rougher surface than at about 0.020” and still little if any grain tearout. For me, keeping the blade/chip breaker gap at just under 1/32 inch is easiest to set visually, and more convenient to working effort. A second plane with higher pitched frog might be beneficial.

On a smoothing plane of traditional Stanley bench design, I will try to maintain a 0.020” to 0.030” chip breaker separation from the blade edge. This gap worked very well with most woods I encounter, without a lot of work effort. I would only modify the chip breaker’s face and slope by hand with great hesitation due to potential damage. These are my observations, and possibly useful to others.

[PaulC]

Sorry, I read this a few times, and still can't pull out your conclusions. Are you saying that you found no benefit to re-shaping the chip breaker? Or are you saying the breaker can be 0.20" back and still work? And why do you use dye?
Thanks for sharing your experience, I want to understand.

[Mike Brady]

I'm glad to see some application of these various tuning tips by some forum contributors. Its is a very compelling topic and one I too am investigating.

Chris Schwarz says that there are three options (beyond a razor-sharp iron) for tuning a Stanley (Bailey) type plane: A tight mouth setting. A higher angle frog. A close set cap iron, also know as a chip breaker. According to him, you can use any two of these together; but not all three. Using all three hopelessly clogs the plane. Since most of us have just the standard frog on our planes, we will most likely try the tight mouth / close set cap iron approach. I do have one smoother with a 55 degree frog, so I will try that in tandem with either a tighter mouth setting or the altered, close-set cap iron. Any interesting results will be posted.

[hbmcc]

PaulC said:

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Sorry, I read this a few times, and still can't pull out your conclusions. Are you saying that you found no benefit to re-shaping the chip breaker? Or are you saying the breaker can be 0.20" back and still work? And why do you use dye?
Thanks for sharing your experience, I want to understand.

---

Hi, Paul. My bad... Over clarification.

A sharp iron and tight gap, just under 1/32 inch, will produce a nice surface without grain tearout. In my normal woods. Tightening the gap will increase resistance to pushing the plane.

I found no compelling reason to modify the LN chip breaker. Tight gaps in the 0.020 area felt the same, polished CB or not. For what they are worth, you can see the results and have good dimensions to assess.

There was great trepidation in messing with something that I could easily damage. I couldn't bear to grind any more off the CB. Different story if I dropped the CB on a concrete floor and bent the crap out of it. Now that the CB edge is shaped and polished I can move on.

The image of the blade and chip breaker is selected because it does show the two surfaces. I was fighting 'old people' eyes, what seemed all one reflective surface, and two plates sliding around which had to be perfectly aligned to produce a parallel gap.

[hbmcc]

I don't think that I would agree with your relayed 3 points; that is, 2 but not three premise. It might be that the third application has little influence when used with the other two. Things won't blow up or go south if all three adjustments are made.

For instance, my polishing up the mouth and removing milling burrs and points that trap chips. I did it to have a tighter mouth opening. Probably immaterial to the effectiveness of cutting, but the modification will allow chips to pass easier. Even though I set a tighter chip breaker gap I would do the same thing with a higher pitched frog or back bevel and have the same results.

[Corneel]

I would say that 15 to 20 thou is still a bit far from the edge to see much effect. It is normal to feel more resistance. In other words, the extra resistance indicates that something is happening. You can definitely set it too close though, where it is aproaching the kind of resitance you feel with a high angle plane.

Do take these numbers with a huge grain of salt though, measuring them without a microscope is problematic, but I don't suggest anyone to use a microscope! Better to look what happens. When you still have some tearout, you might want to set it a little closer. When the shavings appear to straighten it indicates a nice setting, but this depends a lot on type of wood, grain direction and thickness of cut.

I can't comment on problems with bad eye sight, because my eyes are still fine. And yes you can combine tight mouth, high angle and close set chipbreaker, but it is an excersize in futility. Just the close set chipbreaker alone is fine allready in most circumstances.

[Mike Brady]

These are not my thoughts, but those of Chris Schwarz. He maintains that utilizing a tight mouth, a close set chip breaker, and a 50-55 degree frog all at the same time will jam the shavings in the plane. By close set, he is talking about a range of .005 to .009 set-back with a chip breaker that has been micro-beveled at 50 degrees. Any two the above should yield tear-out free surfaces. The downside is that those surfaces may not be as glassy smooth as desired.

I have not done any personal testing of these settings, but plan to.

[Rob Young]

Corneel said:

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I would say that 15 to 20 thou is still a bit far from the edge to see much effect. It is normal to feel more resistance. In other words, the extra resistance indicates that something is happening. You can definitely set it too close though, where it is aproaching the kind of resitance you feel with a high angle plane.

Do take these numbers with a huge grain of salt though, measuring them without a microscope is problematic, but I don't suggest anyone to use a microscope! Better to look what happens. When you still have some tearout, you might want to set it a little closer. When the shavings appear to straighten it indicates a nice setting, but this depends a lot on type of wood, grain direction and thickness of cut.

I can't comment on problems with bad eye sight, because my eyes are still fine. And yes you can combine tight mouth, high angle and close set chipbreaker, but it is an excersize in futility. Just the close set chipbreaker alone is fine allready in most circumstances.

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You can get MUCH closer Bruce. Like under 0.01". Too close the the shavings become "crispy bacon" shaped. At just the right distance, they stream out.

This description is one of many showing up on the web as to how to reliably get the very close distances.

I've also done it by using a cutting gauge to make a cross-grain trench. Then drop the blade in the trench and slide down the cap iron and secure. Some cap irons like to slip forward a bit during tightening so work accordingly.

[AHill]

Mike Brady said:

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Chris Schwarz says that there are three options (beyond a razor-sharp iron) for tuning a Stanley (Bailey) type plane: A tight mouth setting. A higher angle frog. A close set cap iron, also know as a chip breaker. According to him, you can use any two of these together; but not all three. Using all three hopelessly clogs the plane. Since most of us have just the standard frog on our planes, we will most likely try the tight mouth / close set cap iron approach. I do have one smoother with a 55 degree frog, so I will try that in tandem with either a tighter mouth setting or the altered, close-set cap iron. Any interesting results will be posted.

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Schwarz made these statements before he discovered the chip breaker setting method. As Warren (wmickley) has pointed out, that method is not new. It's been used almost as long as there has been double irons (chip breakers). As previously noted, the ideal setting to tame tearout is as close as you can get it and still see the blade. We're talking 10th's of millimeters here. It does appear, however, that the OPs setting achieves the desired results, as the shaving do have that accordion-like quality.

[Mike Brady]

Rob, the cutting gauge idea is clever. The Schwarz uses feeler gauges. Something about standing your razor sharp iron on edge next to spring steel does not appeal to me. At least the wood yields to steel.