Darrell asked me to make sure that this was attributed to the"Museum of the Transmundane." A high quality write-up, hopefully we'll get to add some more exibits from the place...
The gory details:
In the spring of 1999 I had some time to putter away in the shop. You know, during that lull between the Christmas Gift Rush (which ends about Jan 31 around here ;^) and the impending hinting from SWMBO about all the other projects that are on that ancient dusty scroll labelled "To Do".
I rummaged about in the scrap metal bin and found a couple of old triangular files that had definitely seen better days. Ah, I says to myself, I can make something outta this! After I took dinner off the grill, I buried the files under the 'lava-rock' and left the heat on full blast while we ate. I went out after dinner and checked; 'twas a nice toasty orange-red colour. OK, Shut off the grill.
Once the kids were all abed I dug out the (hopefully) annealed files and tested them. Yup. Soft. I drawfiled the old teeth off one of them and then proceeded to lay out the new teeth. First try was 8 tpi, not very accurately laid out, but what the heck... Hey, did you know that it's hard to hold a triangular file in a vise and still be able to work on it; keeps wanting to jump out of the vise!
After about an hour and a half of filing I had a float. Not a thing of beauty to be sure, but it *works*, and I now have every confidence that I can easily produce a few more in whatever size & shape I need. So long as I have a couple of hours and some bandages for the blisters.
One thing I did note was that you should cut as many teeth as you can at one time. One pass with the file on each tooth. This produces much more even teeth than trying to file away the entire thing one full tooth at a time. The first half a dozen teeth are real mutants, but the rest are pretty good.
Afterwards I recalled something I read about saw sharpening, and checked out some FAQ materials I had, and sure enough (according to at least one authority) when filing teeth on a saw you don't do a whole tooth all at once. Spread the work out amoungst all the teeth a bit at a time and the results will be more even and predictable. Same applies to floats. Just goes to show ya, You re-learn something every day!
The second float blank sat on the bench for a while. When I laid out the teeth I tried 10 tpi, and I was a lot more careful with the layout and the filing. This one is also a bit wider, and it took longer to file, as there was more metal to file away. As it turns out I shouldn't have been so careful! The float chatters a bit in use, seemingly because the teeth are too even(?) The first one has teeth every which-way (different angles & sizes & profiles) and it produces a smooth fast cut. I'll try and mess up a few of the teeth on the 10tpi float and see if the performance improves.
For handles, I just grabbed whatever scrap I had laying around, and turned a couple of handles. I used pieces of copper pipe for ferrules (again, it was handy so I used it).
I may try hardening and tempering these floats, but I will probably
wait until I have another one to go with them. There's still that
big hunk of 3/16" O1 sitting around someplace in the shop... maybe I should
try a 1" wide float next time. With graduated teeth: 12tpi at the
tip to 8tpi at the base.