modifying a chisel for dovetails

[Rich Luczak]

I've managed to acquire a plethora of chisels and am considering modifying some for use as dedicated dovetail chisels.

Any tips, hints, or pitfalls? Any suggestions on geometry?

[Jason Beam]

I have used some that were modified for dovetails and plan to do the same to my own.
I plan to shape the bevels on the side edges to fit into the crevices - basically eliminate that "square" facet and make 'em about 15 degrees from the back edge or so.

The other thing i'm going to do is skew a couple. I picked up two extra 1/4" chisels and will adjust their side edges like above, plus i'll skew their cutting edges. One to the left and one to the right. I grew very fond of the skewed chisels that I used in the class I took. I can't remember the angle that the ones I used were skewed at, i'll have to check. If memory serves it was to work well with the most common dovetail angles being used - I think that was either 1:6, 1:7 or 1:8 but memory's failing me at the moment.

[jamie shard]

This has your name written all over it!

http://www.hand-cut-dovetails.com/tools/8chisEgs/edges.html

[Mike Henderson]

I've used regular bevel side chisels and had no problems making dovetails. I did make two skew chisels (left and right) from some 1/4" Marples to get into the corners.

Mike

[Marcus Ward]

I ground a 1/4" chinese chisel into a triangle shape on a belt sander and then re-tempered it with a blow torch. (Retempering cheap 7$ chinese chisels from harbor freight yeilds excellent chisels but you'll need new handles. Maybe.) I should write a tutorial on how to temper those chisels. Anyhow, the chisel works great, cuts brilliantly, and is excellent for making those tiny little pin dovetails.

[Jason Beam]

I ground a 1/4" chinese chisel into a triangle shape on a belt sander and then re-tempered it with a blow torch. (Retempering cheap 7$ chinese chisels from harbor freight yeilds excellent chisels but you'll need new handles. Maybe.) I should write a tutorial on how to temper those chisels. Anyhow, the chisel works great, cuts brilliantly, and is excellent for making those tiny little pin dovetails.

Boy howdy, would ya??????? :D

I'd love to learn that :D

[Derek Cohen]

Hi Rick

There are several different types of chisels you can make/modify for dovetail use.

I saw and pare mostly, but when I chop (because the wood is too hard to pare) I use Japanese chisels. These hold an edge better than anything else I have used - for a combination of hardness and sharpness, nothing compares, even to the cheaper Japanese chisels. The downside is that the arris on the sides is not at sharp/narrow (e.g. like Blue Spruce - which I use for paring - or LN). So I ground down a couple of Matsumura dovetail chisel using a belt sander. The steel is hard and you must take it slowly on a lowish grit to avoid overheating.

Note that it is not necessary to use chisels with very narrow arrises - you can ckean out the waste in the corners afterwards. Just make sure that you leave room for this when you use a "thick" chisel so that you do not bruise the sides of the tails. Of course, a narrow arrised chisel makes for less cleanup and risk to the tail sides.

Now, "special" chisels ... These are divided into chisels for through dovetails and for half blind dovetails.

Through dovetails are helped with a coulpe of skew chisels. I have sizes in 1/4" (Blue Spruce) and 3/8" (which I made). You will be well served by a set in 1/4". The BS were made to my specifications, that is with a 20 degree skew, which is the same as I used on the ones I made out of worn down Bergs ...

http://i13.photobucket.com/albums/a262/Derek50/Chisels/Skewchisels.jpg

I would also have a strong and very sharp knife (I have a Japanese one that meets these criteria) to use when you need to pare away waste. Sometimes it is easier to do so with a knife than a chisel.

You can get away with skews for use on half blind dovetails as well, but a fishtail chisel here is really helpful to get into the corners. A square-ended chisel cannot clean out these corners.

This is a skew into corners ..

http://i13.photobucket.com/albums/a262/Derek50/Chisels/Dovetailfishtailcutting3.jpg

And this is a fishtail into corners ...

http://i13.photobucket.com/albums/a262/Derek50/Chisels/Dovetailfishtailcutting2.jpg

I have made a bunch of these over the years. Here is one I kept for myself. It is 3/8" wide ..

http://i13.photobucket.com/albums/a262/Derek50/Chisels/Dovetailchisel1.jpg

Blue Spruce now make these as well. Or you can get a Japanese version from Joel at Tools for Working Wood.

These is one more "chisel" you can make for half blind dovetails. I got this idea from Tage Frid. I call this my "chisel knife". It is steel of some sort (not sure) from a plaster trowel ..

http://i13.photobucket.com/albums/a262/Derek50/Tools%20that%20I%20have%20made/Chiselmarkingknife1a.jpg

I have used this to transfer dovetail marks or to extend the kerf depth - just make sure that you use a clamp across the board to prevent it splitting when you hammer it down.

http://i13.photobucket.com/albums/a262/Derek50/Chisels/HBDovetailchisel.jpg

Regards from Perth

Derek

[Paul Saffold]

Many thanks for that very clear and well illustrated post.

Paul

[David Keller NC]

"I can't remember the angle that the ones I used were skewed at, i'll have to check. If memory serves it was to work well with the most common dovetail angles being used - I think that was either 1:6, 1:7 or 1:8 but memory's failing me at the moment."

Jason - I spoke with David Jeske of Blue Spruce Toolworks a little while back on an unrelated topic. While on the phone, I mentioned that I had stupidly broken the very tip off of my set of BS skews, and needed to re-grind them, and asked him what angle he suggested. He noted that I had a pair of early (an interesting term for a modern tool, particularly to us tool collectors) set of chisels ground to about 45 degrees, and he'd switched to 25 degrees to make the tips a bit more robust.