chip-breaker problems in a wooden plane

[chris carter]

I have a couple wooden planes (jointer and jack) I made using the cross-pin method. They’ve always worked spectacularly as single iron planes. The ONLY problem with them is that occasionally when grain reverses on me on the face of the board I can get some wicked splintering tear out (more than you would want to remove with a smoother). After learning all kinds of techniques to minimize it, it can still rear it’s ugly head. So I decided recently I would convert them to double irons. I started with the jointer. I took out a recess in the bed to accommodate the screw, made a thinner wedge (since the chip-breaker adds thickness obviously), and I made a little recess on the back of the new wedge to accommodate the tiny bit of screw that sticks through the chipbreaker. I’ve gotten everything to the point of testing before I go for visual aesthetics. Everything works PERFECTLY, with one MAJOR problem.

The problem is that when I advance the iron with my hammer, the chip-breaker winds up sliding back. I’m not exactly sure how to fix this. I rubbed some rosin on the underside of the chip-breaker which helped, but it’s still impossible to advance the iron without increasing the distance between the chip-breaker and the edge of the iron. I have ruled out everything else. It’s only when I advance the iron with the hammer. Obviously, I know from a physics standpoint why this is happening. I just don’t know how to fix it. Obviously there are double iron woodies, but I’ve never used a wooden bench plane other than the two that I made. So I’m not sure how they get around this problem.

Any advice greatly appreciated. I did prepare the chip-breaker and like I said, the plane cuts great. The only issue is the advancing the iron without the chip-breaker sliding back.

EDIT: just a point of clarification. When I advance the iron, the iron goes forward, but the chip-breaker does not advance with it (it advances a little bit, but it does not keep up with the iron).
IMG_20210803_145613863.jpg

[Andrew Hughes]

I have a couple wood planes that do that same thing. I just tap the chip breaker forward my wedge isn’t longer then the breaker.
Good Luck

[Jim Koepke]

You might want to consider friction. The friction of the wedge against the chip breaker is greater than between the chip breaker and the blade.

You may need to make 'fingers' at the sides of the wedge to reduce friction against the chip breaker.

Is the chip breaker held tight against the blade? From the screw to the front edge of where the breaker meets the blade it can be mostly open. From the screw away from the blade it should be without gap.

jtk

[Steve Voigt]

On a traditional (not Krenov) woodie, this problem occurs when the wedge tips extend beyond the high point on the cap iron. For a traditional plane, I would prescribe the following fix:

- With the double iron assembled, hold a straight edge across the length of the cap iron. Note the two high points--one at the top of the cap iron, and one just above where the curve begins. Mark the lower high point with a sharpie.
- install the iron and wedge, and observe whether the wedge protrudes beyond the high point.
- If it does, trim it back, and trim the abutments to match.

I don't know whether this would work on a Krenov plane, but it's worth a try.
Edit: I just looked at your picture. One problem is that you are using a modern style cap iron, which puts far less pressure on the cutter than a traditional cap iron does (because it has less spring). That might be a difficult problem to overcome.

[chris carter]

Thanks for the feedback everyone.

Jim: upon closer inspection, I think there is a very very very minor amount of twist in the chip breaker – can only see it when held just right against the light. Just enough to cut down probably significantly on contact with the iron. I’m going to try untwisting it and see if that works. When I added rosin it helped, so hopefully going down this path of more friction through more contact will be the way to go.

Steve: Thanks for the details. The I made the wedge shorter and it didn’t help, but you bring up an interesting point about the style of chip breaker. When I bought it the description said it was designed for wooden planes. The seller sells a lot of plane parts so I took their word for it, but that doesn’t mean descriptions are accurate. It’s pretty thick and while it flexes, it doesn’t flex a lot (although when screwed down to the iron it is definitely concave with the bump and the tail end higher than the middle. If removing the tiny twist (see above) doesn’t work, then I will grab a more flexible chip breaker from one of my transitionals. They are both 2” wide (this one is 2-3/8), but at least it will likely tell me if the style of the chip breaker is the issue.

I’ll try and report back on these fixes.

[Rafael Herrera]

To increase the friction between the chipbreaker and the iron, roughen up the highlighted inner surfaces in the attached picture. Use coarse sandpaper.

If the iron and chipbreaker do not mate properly, you can find replacements on ebay easily. Ohio Tool, Auburn, and other American makers manufactured double irons with the screw no protruding too much from the face of the chipbreaker.


temp_picture.jpg

[chris carter]

Update:

Today I modified the other plane, a jack, for a chip breaker. For this one I had a different style of chip breaker – a classic Stanley Baily type with the thin piece of metal and a rounded hump at the end. That one went rather flawlessly. It did not seem to exhibit the same problem, or if it did, it was so minor as to not really matter. With that success I went back to the 26” jointer with the older chip breaker. The mating surface of this one wasn’t very flat so I spent FOREVER with 40 grit sandpaper on a piece of marble and then finished up on DMT coarse stone. Then I put in some deep scratches with the 40 grit sandpaper for traction as recommended in the post above. It helped a little, but it still exhibits the problem. That said, I think it’s “good enough.” The reality is that the closeness of the chip breaker doesn’t matter as much for a jointer/try as it does for a smoother or something. I’ll just set it a hair tight before I set the cutting depth and it should end up in the right general ballpark. Realistically, I rarely adjust the iron in the jointer. I set it and it never really moves until I sharpen it up. If it bugs me down the road I’ll try the same style of chip breaker I used in the jack.

[Robert Hazelwood]

I've noticed this happening before when doing a lot of adjusting, so I try to minimize the amount of iron adjusting I have to do after installing the wedge. If you set the plane down on a clean flat bench, and just set the iron down so that the cutting edge contacts the benchtop through the plane mouth (now theoretically at zero cut depth), then gently insert the wedge by hand and give it a few taps to seat, then the cut depth usually ends up about right for a try plane. If adjustment is required its very minimal.

Also think about how close you really need the chipbreaker to be. After learning about the CB I was setting everything very tight, over time I've relaxed it some. That makes it less sensitive to any slight movement that comes from setting the plane. Also a nice rounded profile on the front of the chipbreaker (like you see on a Stanley or old-school woodie) makes it a little more forgiving as well.