Mortises in soft wood

[john hanes]

Hi all,

I have been lurking a while. I am a new woodworker and have come upon this problem.

I am trying to make mortises in soft wood (cedar). I have drilled out with a forstner bit to rough it out, but when I get to chiseling out, especially across the grain and corners, I can't get a good cut. It is hard to describe what is happening, but basically the chisel pushes out grain rather than cutting through it and I can't get square corners.

I am sure that a sharper and better quality chisel would help, but are there any suggestions?

I was thinking about drilling a small hole into each corner before roughing out with the forstner to help make the corner sharp.

Would a mortising machine or mortising drill press attachment run into the same problems?

Thanks all.

[Carl Eyman]

I made a couple of chairs out of pressure treaded pine. As you know it comes very wet; so the same sort of problem is possible. I found the mortising attachment worked well. Perhaps the fact the mortises and tenons were I/2" wide or wider helped.

Another idea is to use a router and a guide to cut them and leave the ends round. Or do the same by hand. Let us know what you decide.

[Steven Wilson]

Learn to sharpen your chisels.

[Donnie Raines]

Steve really is right on here...unless a dedicated machine was at hand. Click on the URL below for some tips on setting them up( the article is directed toward plane irons..but you can use it for this as well).

http://www.hocktools.com/sharpen.htm

[Jim Becker]

Steve really is right on here...unless a dedicated machine was at hand.

Steve is correct even for a dedicated machine! The chisels need to be honed even right after purchase and before you use them. This is even more important when soft woods are involved. ("soft" hardwoods or soft softwoods apply here!!) Since the fibers compress more easily, a chisel that is even remotely un-sharp will bend the fibers before cutting causing tearout and other visible issues. This is less of a "visible" problem where the whole mortise is hidden by the shoulders of a tenon, but really an issue when there is no tenon and the component slips directly into the mortise. But a mortise that is not cut cleanly may not glue as well as one that is neat.

[Dick Parr]

Welcome to the Creek John. Sorry I can't give any advise on the question since I haven't done any by hand, only by machine.

[Alan Turner]

John,
"Cutting" soft woods with a chisel is always a problem as the fibers want to crush instead of cut. Sometimes I use a 20 degree paring chisel for softer woods in order to get a clean "cut."
Alan

[Donnie Raines]

Alan,

The chisel that you are useing, is this considered a mortising chisel per say?

[Alan Turner]

Not at all. It is a paring chisel, which is typically sharpened at a much lower angle. The poster said he was drilling, and then squaring the corners, of pine mortises. I recently had to square corners on 44 mortises of a garden bench of Paulownia, which is way soft, and had to use a chisel that would cut and not tear. My mortising chisels are closer to 35 degrees, the paring chisels are closer to 20 degrees. But the wood was so soft that edge breakage was not a problem.
Alan

[Donnie Raines]

Thanks Allen. I was not sure what constituted a pairing chisel from a mortise chisel.....now I know.

Thanks again.

[Alan Turner]

Generally a paring chisel is longer than a bench or butt chisel. About 12" or slightly more. I like them that length since, which I am paring, say a tenon shoulder in a vertical postion in a vise, I can get my hip onto the handle, for both power and control. It is usually beveled as well. Sharpened at 20 to 25 degress, it will pare endgrain without tearout if really sharp. A Stanley 720 is an example. Here is a link to an ebay pix (not mine, just for reference) http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WDVW

Alan

[Jack Young]

All-

As a newbie myself, at least to good hand tools, I have learned the hard way that sharpening is the key ingredient to any success at all. I now have a Japanese "slick" which is a paring chisel, long and unbelievably effective in such as cleaning up the notches I'm doing in treated 4x4 stock to rebuild the front steps (about 10' elevation). But it takes sharpening, as do the A2 steel blades and irons on good planes, etc., and I know well that the first thing I must build as I clean out my shop space is a dedicated sharpening station. Can't really do the rest well until I do that. Don't know why, exactly, it took me so long to learn that.

Jack

[Howard Acheson]

While sharp tools are always safer, easier to use and produce better results, cedar is not easy to mortise. The wood fibers tend to compress before enough resistance is built up to cut.

I have made a number of outdoor projects with cedar and even my very sharp mortising machine chisels do not always result in clean, smooth sides.

[Bob_Hammond]

I'm in the midst of making a bench out of redwood with M&T joints. I made the mortises with a plunge router and a spiral upcut bit.

Then I round off the tenons to match the oval shape of the mortise.

If you don't have to have square mortises, it may be something to consider.

Bob

[john hanes]

Thanks all for the info. I am learning. I will learn to sharpen my chisels; I also think that I should learn to use my plunge router to make rounded off mortises. That seems that it would be the best way to go for soft wood.

John