Monday, 28 May 2007

The prototyping bug

I have to give credit where credit is due - and this little plane was was the most colaborative effort to date. It was sparked and defined by a good friend in California, partially informed by Wayne Anderson and Karl Holtey & confirmed by Larry Williams and Bill Clark.

The goal was to make a block plane sized smoother that was comfortable to use with one hand. There were quite a few givens right off the bat... bevel down, block plane length (5-1/2") and width, coffin shaped, a lever cap, single iron (3/16" x 1-7/16" high carbon steel), and high bed angle (52.5 degrees). This was not as simple as just taking a full sized No.4 and scaling it down. The front bun had to be big enough that it was functional, but not so bulky that it pushed the mouth opening too far back. The rear infill had to be tall enough that you could get a sense of level and plumb but not so tall that it bent the wrist in an uncomfortable way.

The paper mock-up suggested that everything would work, so I went to the next step of cutting the metal. Boy this thing was tiny!

I ended up using a piece of machined aluminum for mocking up the blade. It took a few cracks at the end treatment of the iron but I finally settled on a simple radius. It tucks very neatly into the hand.

Thanks should go to Ron Hock for helping with the irons. I called Ron to talk about blade thickness and he brought up an excellent point I hadn't considered. I had initially suggested using 1/4" thick high carbon steel for the blade, but in Ron's typically gentle way, he suggested it might be overkill and even a detriment. With a 1/4" blade, you are pushing the business end so far from the bulk and mass of the iron, that it is not as supported as it would be on a thinner iron. So thanks to Ron reminding me that once again, bigger is not always better.

I have had several opportunities to try Clark & Williams planes over the years and absolutely loved them. It did take me a while to adjust to how light they were, but they do share one important characteristic with infill planes - they are solid. Clark & Williams plane also proved that cap irons are not always needed - they work perfectly without them.

I had an opportunity to borrow one of C&W's small smoothing planes while I was working on this prototype. It was a wonderful model to have around and it confirmed a lot of information for me.

The irons arrived and I was able to tune one up and fit it to the plane the next day. It was well worth the wait as the first few shavings were perfect. I filed an almost ridiculous mouth on the plane - about .0015" - but it was able to do whatever I asked of it - so I left it. I can always file it open at a later date.


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