Thread: Plane (plain?) Geometry

Originally Posted by rsser

Yeah, good fun it is.

I certainly found the toe of the prototype A55 smoother too short to register reliably (had got it as one of Terry's bargain planes) but I'm no 'planesman'.

Ern - do you think that was the reason for the modification, then? I wouldn't expect 8mm would make a huge amount of difference on a plane that is 250mm long, but without trying it, I wouldn't know, so perhaqps that's all it took. It's a matter of balance more than actual length of the toe, so I can appreciate that a small change might make a big difference in some cases.

Anyway, you obviously know what I'm blabbing about wrt the length of the toe making a plane more or less convenient in use. You don't have to be a plane guru to know what suits you & what doesn't, in fact, the less experienced you are, the more you need a well-proportioned & well-balanced plane to begin with, I reckon. After all, trying to whack your first golf ball with a crude & awkward club probably isn't a good way to start if you want to be the next Tiger Woods, is it?

Cheers,

A while ago, I was using it to clean up a short board, & I had a deal of trouble finding a 'sweet' set to the blade. With a fine set, it seemed to stop cutting after a few strokes. To keep it cutting, I had to put more set on it than I really wanted, and because I was dealing with very cranky grain, this defeated the purpose. I checked the sole (dead flat, perfect mouth) and the lever cap (holding firmly) and could not figure out what was wrong.

Hi Ian

This is a classic symptom of a plane with a concave sole. The blade has to be extended to make a cut, and then the blade is unsupported at the mouth.

So first a bit of research - I pulled a few other planes out of the cupboard and compared toe length to that of the sole behind the blade. Since they are all of different overall lengths, I converted the mm to a ratio of toe/rear sole. A Clifton #4 comes in at 0.35. my new infill (pretty close to a Norris A5) at 0.34 and the little woodie 0.4. The hybrid came in at 0.57, i.e. the toe was actually longer than the part behind the blade.

I had a long think about the implications of this, and for the life of me, I can’t see why that should affect the plane’s ability to make very fine cuts.

I would argue that these ratios are incidental and not a factor involved in design.

For example, you could smooth a board with a long plane as long as the sole is flat. How many here enjoy using their LV LA Jack for this purpose. Alan Peters was reputed to use his #7 for all planing.

Of course there is a downside in using a long plane (it removes more material to reach the valley than a short smoother), but in theory a jointer could produce as smooth a finish as a block plane (all cutting angles held equal).

I would suggest that removing the toe of your plane essentially flattened the plane. I believe that Michael also suggested this.

Regards from Perth

Derek

Originally Posted by derekcohen

....I would suggest that removing the toe of your plane essentially flattened the plane. I believe that Michael also suggested this.

Hi Derek - thanks for your comments. It seems like we have a concensus. Much as I thought I had a flat sole (that was the first thing I checked), it was almost certainly not sufficiently so. I don't have a super accurate means of assessing flatness, and it is a bit tricky with wooden soles, I find . I guess it takes very little deviation to affect performance when using as fine a set as I was trying for. So the nose job worked largely because reducing the length has reduced the error.

It is a happy ending, because I prefer the look of it now - the original snout was too long & looked a bit odd. But the best part is that I can now use it at a set that is as fine as I ever need or wish to use.

All good!

Cheers,

Ian, yes it's plausible that Terry went longer on the production version because others too had difficulty registering the prototype.

Pity; it was a lovely plane otherwise.