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chisel plane theory

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chisel plane theory

#1

chisel plane theory

ydb1md

>I�m building a chisel plane and I was thinking about the bedding angle, the angle on the iron and the clearance angle between the iron & the wood surface.

I�m probably going to bed the iron at 20* -- 15* seems to shallow for wood. In terms of the clearance angle, the goal of a chisel plane is to shear anything off that�s above the plane of the wood. Wouldn�t you (in theory) want a back bevel on the iron that matched your bedding angle, which would give you a clearance angle of zero? Or, at most a clearance angle of a degree or two? This would minimize the irons tendency to dig into the workpiece.

I can�t recall having read anything on this topic before. I know that a common complaint about chisel planes is that they tend to dig in and they have no support in front of the blade. Minimizing the clearance angle behind the blade should help to minimize these tendencies.

What do you think?

Dave

Re: chisel plane theory

#2

Re: chisel plane theory

Frank D. in Montreal

>Hi Dave,

I'm not sure the lower angle or less clearance would stop the digging. Take a bevel-up spokeshave and a bevel-down spokeshave...both can dig even if the bevel-up has a clearance angle of 0�. Hopefully someone with more knowledge can explain.

Here's what a chisel plane with a clearnace angle of 0� looks like (they work well too, but still dig in occasionally:


img

Re: chisel plane theory

#3

Re: chisel plane theory

mikew

>Hi Dave,

A couple thoughts--take 'em for what they are worth. Just thinking aloud...and the thoughts are related to a BD chisel plane.

Clearance angle *may* be an issue once the edge gets a little beat up or begings loosing its sharpness.

Which brings up the thought about bedding and bevel angles. A chisel plane, at least how I use them, tend to get the worse jobs--scraping glue. The bevel has to be less than the bedding angle, and to provide for some wear, I would say you are looking at 5 degrees less than the bed.

That makes for a 15 degree bevel. My thought is that will result in too fragile of a bevel, at least for scraping glue.

Well, that's my initial thinking. I'm spent for the day now!

Take care, Mike

Re: chisel plane theory

#4

Re: chisel plane theory

Dave Thompson

>I think I'd agree with Frank and Mike. There is nothing in front of the blade to stop it from keeping the grain from pulling the blade down and in.

I use my chisel plane for glue scraping.... it does an excellent job of that. It's important to keep the weight on the back of the plane to counter balance the digging in tendency. I suppose length of the plane may help in a leveraging sense.

good luck,

Dave

Re: chisel plane theory

#5

I never understood...

HC Sakman @ Victoria, BC

>...the exact purpose of chisel planes. Dog-leg, paring or firmer chisels will to better job any day than the best chisel plane. I never got the hang of chisel planes myself.

Chico...

Re: chisel plane theory

#6

Re: chisel plane theory

paul womack

>Here's a technically intersting solution to zero degrees.

http://www.leevalley.com/wood/page.aspx?c=2&p=32664&cat=1,41182

It's an early manifestation of LV's magnet fixation.

Although I suspect a cranked parer is just as good.

BugBear

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