Wednesday, October 10, 2012

Tuning up an infill plane

Crooked lever cap in the Mathieson
I know that infill planes have a reputation for being the Wood God's Harbingers of Immaculate work. The truth is that they are just as susceptible to hard wear and imperfection as any other tool that was created or used by man. 

My first infill plane was a dovetailed steel Mathieson smoother that I’m still having problems with. It took me two years to notice that the lever cap had been installed at an angle to the bed, and four more to notice that the screw for the chip breaker bottoms out in the groove in the bed. And the sole isn’t flat, or at least not flat enough.

The Musgrave was the second plane that I bought. It has a cast iron body that’s chipped on the back corners. The sole needed some flattening, but cast iron is soft, so this was easy to do. Once the sole was flat, I was able to use it, and to start learning just what these planes can do.

When I was just starting out as a woodworker, I learned to tune up Bailey style planes by working on Record and Stanley smoothers. Those are more straightforward: most of the work has to do with making sure the sole is flat, and that the parts are mating properly. Infills generally have no parts to take out, and no obvious interfaces to refine, so it took me a while to notice the subtle things that need to be attended to. Of the three infills that I own, the plane that has taught me the most about tuning up an infill plane is a dovetailed steel coffin smoother from Spiers. So I’ll describe my experiences with this plane, to date.

I started with the obvious: sharpening the blade, and tuning up the chip breaker. That led to me discovering problem number one: neither was squarely ground. I was a little surprised to see that, but it was easily resolved.

Once the blade assembly was ready, and I went to install it in the plane, I started having issues with lateral adjustment. Eventually, I noticed that the screw for the cap iron was way too thick; it was bottoming out in the groove in the bed. Apparently it’s not an uncommon thing for old infill planes to be paired with replacement blade assemblies, even if the screws don't fit the groove. So, that's why the discrepancy existed. (Noticing this on the Spiers led me to notice a similar issue in the Mathieson plane, too.  The discrepancy isn't quite so egregious, but was just as problematic.) Once I ground the screw down, the Spiers plane was a lot easier to set up and adjust.

That said, it wasn’t really taking good shavings. It took some inspecting to realize that the sole wasn’t flat. In fact, the surface in front of the mouth was not at all in the same plane at the surface behind the mouth: It was almost 1/64” off. Steel is much harder than cast iron to lap flat, so I had to take the plane to a belt grinder to (carefully) get the whole surface to be approximately co-planar. At that point, I could take shavings with it, but once I started dialing the thickness down, the shavings only came in at the corners of the iron. What that told me was that only the corners of the blade were engaging, and the middle of the sole was bellied out by roughly the thickness of those shavings. I flattened the rest of the sole with a file, and a machinist’s straight edge, until the shavings were perfect. This took some time.

With the blade sharpened, and the sole completely flat, the plane started functioning at a very high level. So all that remains is repair to the body and tote.

There was a crack in the handle. The other two infill planes I own each have a screw that is driven up into the handle to reinforce the rosewood. But Spiers used a steel rod, and I couldn’t thread it back out. The cracked handle was holding together just fine, but it was flexing, and needed to be fixed. It took me a while to figure out a viable repair: I used a dovetail saw to turn the crack into a saw kerf on each side of the handle, and then I glued a piece of veneer into those kerfs. Once the glue dried, there were no more gaps to allow the handle to flex. That said, the handle was still moving in relation to the rest of the plane, though.

At this point, I sent an email to Konrad Sauer. He asked for pictures, and pointed out that most likely, the handle had separated from the rest of the infill, and was pivoting around the rivet pin. When I got back in to look at the plane, it feels like this is exactly what’s going on. The options I have are to flood the cracks around the handle with glue, and hope it works, or to drill out the cross pins, pull the infill, and reconnect the handle. That’s where the process has taken me to date.

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I emailed Konrad back and mentioned that I was writing an entry about tuning up infill planes. I mentioned all of the above to him, and asked if he had any extra advice. This is what he said:

"The usual issue with an infill is the bedding. Most of the time, the bed of the plane is not coplanar with the metal block that is rivetted to the sole. This means the blade rocks or pivots on that point. Doomsday for trying to set the iron. The first thing to check is the bed. If it is flat (they rarely are) then you are in for a tedious PITButt job of finding a narrow file that has safe edges to get in there and re-establish a flat bed. All the time trying not to touch the leading edge of the mouth or the lever cap. And... you have to do this evenly because of you change it too much, the blade will sit differently and the front edge of the lever cap will no longer contact the top of the cap iron squarely. So now you have to either continue re-shaping the bed, or... file the underside of the lever cap. The best way to do all this is with the lever cap out - but that means pulling more pins. This task is by far the most challenging task - all the others are way easier. "

Given the importance of properly bedding the blade, and given the importance of the alignment between the infill and that metal block, I'm seriously thinking I should try for the glue injection method, as it seems easier, and not pulling the infull seems less likely to result in a misalignment between the bed and the metal block.

Konrad may have a good reason for having me pull the bed. And truth be told, I'd like to have the experience of pulling the plane apart. But I'm not sure that a little handle wiggle is good enough reason to take apart a plane that's working so well right now, if a simple glue squirt will fix it.

So, we'll see...




1 comment:

israel martin said...

Thanks James for your post, I thought I was the only one having problems with an infill plane. It is a lot of help.
Isra