One file to rule them all - and in the Ebony dust bind them.
Over the last 8 days, I have fit the front buns and rear infills of 7 coffin smoothers. Two XSNo.4ss's, three No.4ss's and two A5ss's. Six of these planes have Ebony infills. Needless to say - my hands are disturbingly filthy. The fitting process goes something like this;
1). Waste out the bulk of the infill using saws (thanks again Mike!).
The above shoulder cut that defines the overstuffing still feels “dangerous” - even after 100+ times.
2). With the bulk removed - I turn to files, rasps and chisels to further refine the shape.
3). Once the footprint is close - I add in my 1/2" wide, by 3-3/4" long shoulder rebate plane to get the fit of the shoulder to mate perfectly with the sidewall. There is still some refining of the footprint involved - but at this stage it is a bit of a dance between fitting the footprint and the height of the shoulders of the overstuffing.
The above photo is one of many tests of the fit between the overstuffing and the sidewalls. The thing that makes coffin shaped planes a bit tricky is there is very little wiggle room with regards to the fit. On a parallel sided plane, the infill can be slid in from either end. With a coffin plane on the other hand - it needs to drop down from the top.
Take an A5. The handle is already shaped, the bed angle is established, the slot for the adjuster is cut and the section of wood that connects the top of the handle to the bed is already defined. There is really not much of an allowance to move the infill forward or back before any of these aspects will be fatally compromised. Anyway - it requires all of my wits being present to do this task.
Back on topic. Until now - the rasp and file stage took the longest. I was typically using about 6 different files and rasps for this stage, but it was never quite perfect. One of the issues was finding a tool that would remove material quickly, but do so in a very clean manner. Generally - this is not done with rasps. I love rasps - but the cutting action leaves deep V shaped grooves as opposed to a file which leaves a more level surface. Rasps are great for stock removal - but it is sometimes difficult to accurately gauge the depth of the bottom of the V shaped cut. When fitting infills +/- .003" can be the difference between the perfect fit and disaster. So I turned to files because the surface was more level. The trouble with files - they are much slower and tend to clog up much more quickly - especially when used on exotic woods.
Enter this file made by Toshio Fukazawa.
This was unlike anything I had seen before. The teeth one side were completely unfamiliar. They were not like a rasp or a file... but rather a bit of a blend of the two. They had peaks on them that was rasp like - but they were still flat-ish like a file.
The other side was a little more familiar - like a fairly aggressive single cut file. Another nice feature was both edges were safe - and very well done.
I have had this file for several months now, and when I got it home (it was a gift from a very good friend), there was a rear infill and front bun for a No.4 to fit. I decided to quickly try the unhandled file - just to see what it would do. I was blown away. The toothed side removed wood so fast - I could hardly believe it - but what really got me, was how smooth the surface was. I tried another pass - just to make sure. Same thing - rapid stock removal with a super clean surface. I could hardly contain my excitement. I took of my jacket and kept going. What would have taken 6 rasps and files I was doing with a single tool at twice the speed. Once it was shaped, I flipped over the file and tried the other side. This side was very different. It too cut very quickly, but left an almost polished surface. There was absolutely no clean up after this side. I had both infills fit in record time.
Back to these 7 coffin smoothers. All 7 of them were fit using this single file in conjunction with my Wenzloff saw and small shoulder plane. This process has become much quicker, more accurate and consistent - thanks to this last missing tool being added. The only thing left is to find out where to get a few more of them.