Jerry Palmer
Member
- Messages
- 317
- Location
- Cedar Park, TX
I actually came across a situation where a few thousandths of an inch became important. A friend emailed me and asked me to check the width of the tongue created by my old Stanley #48 T & G plane as he found that his was making a tongue several thousandths inches wider (maybe .007) than the replacement blades he had gotten for his. For those unfamiliar with the #48, it uses two blades to cut away either sides of the edge of a board leaving a tongue in the middle. To cut the groove the fence pivots 180 degrees on an offset pin which moves the registering edge of the fence over so that one of the two blades is in position to cut the groove while the other is buried behind the fence edge. The inside edges to which the blades index is cast and machined at the factory so is not adjustable so the width of the tongue created is fixed. When he made a joint using his plane, the tongue would split the edges of the groove out when it was forced into place. Mine is a relatively new plane to me, so I had only tried it out a bit when I got it and hadn't gotten around to cleaning it. So happens that mine has replacement blades from the same source as his. When I tried mine out, I noticed that the tongue fit quite tightly into the groove, but it didn't split the sides out like he was experiencing.
Anyway, I broke out the dial calipers, cut a tongue onto a piece of scrap and measured it. Amazingly, to me anyway, was that the tongue I created was, with a couple thousandths variance over the length, the same exact width as he was getting, and yep, the blades were about 7 thousandths narrower than that tongue. The remedy to the situation is to tip one or both blades out about 1/2 hair at the top so that they are tilted ever so slightly inward at the bottom making a tongue that is a few thousandths narrower. Or maybe just intentionally kant the plane a bit or use a side rabbet to take a shaving off of one side.
But, truth be told, that is about the only time where I have found that a few thousandths made any difference what-so-ever in woodworking. I've done some segmented turnings on the lathe and used a large plastic adjustable protractor from a hobby shop to set the bevel angle for cutting segments along with a stop block and found that I could squeeze out the accumulated error over 24 cuts using large hose clamps in even very hard wood.
Anyway, I broke out the dial calipers, cut a tongue onto a piece of scrap and measured it. Amazingly, to me anyway, was that the tongue I created was, with a couple thousandths variance over the length, the same exact width as he was getting, and yep, the blades were about 7 thousandths narrower than that tongue. The remedy to the situation is to tip one or both blades out about 1/2 hair at the top so that they are tilted ever so slightly inward at the bottom making a tongue that is a few thousandths narrower. Or maybe just intentionally kant the plane a bit or use a side rabbet to take a shaving off of one side.
But, truth be told, that is about the only time where I have found that a few thousandths made any difference what-so-ever in woodworking. I've done some segmented turnings on the lathe and used a large plastic adjustable protractor from a hobby shop to set the bevel angle for cutting segments along with a stop block and found that I could squeeze out the accumulated error over 24 cuts using large hose clamps in even very hard wood.