Fishtail Chisel - Useful?

[Rob Luter]

I'm working on a project that will utilize half blind dovetails in a drawer front. Clearing the waste in the back corners of the sockets looks like a challenge. I don't have any skew chisels, but it looks like a fishtail might be a good solution. This will be my first foray into half blind dovetails. Is a fishtail worth it? Inquiring minds want to know.

[Jim Koepke]

For me a couple of shop ground skew chisels work fine. What helps more than fishtail or skew chisels is a kerf making tool:

429682

Derek made his own.

Before the Bontz model, mine was just an old piece of saw blade. They take a lot of the work out of half blinds.

jtk

[ken hatch]

I'm working on a project that will utilize half blind dovetails in a drawer front. Clearing the waste in the back corners of the sockets looks like a challenge. I don't have any skew chisels, but it looks like a fishtail might be a good solution. This will be my first foray into half blind dovetails. Is a fishtail worth it? Inquiring minds want to know.


Rob,

I have several, both Japanese and shop made. I use them because I have 'em. A couple of shop made skew chisels would work just as well and I expect Jim's kerf tool with a skew chisel would be more help.

ken

[Tony Zaffuto]

As Jim said, I use it (LN), because I have it. I believe the LN is O1, and has lower hardness, so it is easier to put a razor edge on. But, for getting the last bits out of a half-blind DT, my knife works just as well. Also, although I don't recall it it was on SMC or another forum, I over cut my half-blind DTs, so the waste to remove not much.

[Phil Mueller]

Like the others, I have it so I use it. I think a narrow left and right skew chisel would be more convenient...depending on the size of your dovetails. And I agree, the Bontz kerfing tool helps a lot.

[Warren Mickley]

I made a skew chisel for this purpose in 1978, but I soon went back to my old way. I use a 1/4 chisel to get into the corner. I use dovetail angles in the 8 degree range so the chisel doesn't cut too much into the back of the socket. I recommend holding off on a special chisel at least until you have a feel for making the joint. A 3/16 or an 1/8 inch chisel will work as well.

I also don't recommend a Kerf extender, knife, chisel, or whatever. I usually overcut the lines on the inside of the drawer. However with good technique it is not hard to cut the joint entirely with chisel.

[Prashun Patel]

I have the lie Nielsen one. I also made one from an old Stanley. I like them and use them. The skews (which I also have) are annoying to me because you need two. Also, I just find the fishtails more ergonomic for coming into the corners.

The lie Nielsen one I have is small and delicate so it works well in smaller pins where you might be concerned about splitting thin walls.

[Rob Luter]

I have the lie Nielsen one. I also made one from an old Stanley. I like them and use them. The skews (which I also have) are annoying to me because you need two. Also, I just find the fishtails more ergonomic for coming into the corners.

The lie Nielsen one I have is small and delicate so it works well in smaller pins where you might be concerned about splitting thin walls.

What size is your LN Prashun?

[Andrew Pitonyak]

Never needed one to do half blinds. Might be helpful, but I do not own one. If you cannot get into that corner, grab a smaller chisel.

[Prashun Patel]

3/8".

The acute angle of the fishtail chisel does really make it easy to poke right into the corner to release the waste. The clearance lets me get into the corner without harming the walls.

I probably only appreciate this chisel because I worked without it for a while. I second Warren's advice on that. Perhaps try making one on own before buying one. This will help inform whether you like it, and what size you might prefer.

BTW, does anyone else clip the inside corners of their half blind tails?

[Derek Cohen]

I'm working on a project that will utilize half blind dovetails in a drawer front. Clearing the waste in the back corners of the sockets looks like a challenge. I don't have any skew chisels, but it looks like a fishtail might be a good solution. This will be my first foray into half blind dovetails. Is a fishtail worth it? Inquiring minds want to know.

Rob, everyone has an opinion. None make it right or wrong - just preferences. Are they necessary? No ... but that is not the question.

In my opinion, I find the fishtail incredibly useful in clearing sockets.

Here are a selection: top down - Koyamaichi (the dubious honour of being the first made by Mr Koyama); Blue Spruce - fantastic, and one I made from a 1/4" Veritas O1 chisel ...

https://i.postimg.cc/Xv11HHtH/3a.jpg

https://i.postimg.cc/htQq6HKT/Chiselingcorners2.jpg

Regards from Perth

Derek

[Zach Dillinger]

I have used them but, like Tony and Warren, I always end going back to my old standby, deep overcuts with the saw and using a narrow chisel to clean up if/when necessary. It works fine for me. That said, it would be incredibly hypocritical of me to argue against the acquisition of a new tool (especially a chisel).

[Christopher Charles]

I have used skew chisels and a narrow chisel (3 mm). Like Prashun, I also put a slight bevel on the tailboard so removing every bit of waste is not necessary (bevel is hidden). I did just receive a Blue Spruce chisel like Derek's as a gift but have yet to use it, so have no grounds to argue against a new tool either.

[Mike Henderson]

I have the 3/8" Blue Spruce and also left and right skews. I don't use either very much - I find that I can clean out a half blind socket well with a narrow regular chisel. If you want to save some money, pick up two cheap 1/4" (or smaller) chisels and grind them to a left and right skew. Then see if you use them. If so, get a fishtail just because it's only one chisel instead of two.

If you want to purchase the skews I have, I'll sell them for $10 each plus postage. They're made from Irwin blue handle 1/4" chisels.

Mike

[Taylor Tools makes a kerf extender (https://www.amazon.com/dp/B07H549F7C/?coliid=I274WCYIT3P544&colid=2M1XMQFRF5982&psc=1&ref_=lv_ov_lig_dp_it) that's a bit less expensive than the Bontz or the Crosman. Like the Cosman, just available with the 0.025" blade.]

[Derek Cohen]

Hi must have bought up a huge stock of Crown handles. :)

Using my name for the tool, and copied Rob Cosman's design (although Ron also posted this design around the same time).

Regards from Perth

Derek

[Derek Cohen]

Commercial skew- and fishtail chisels work differently. They are not equivalent.

The skew chisels I have from Blue Spruce are beautifully made and work very well. However, they require a different cutting action from a fishtail chisel (one can modify the to work in the same way as a fishtail. More in a moment).

Many years ago, when Dave at Blue Spruce was getting going with his dovetail/detail chisels, I bought some of the first he made. The 3/4" I have was the first he made, and in fact he remade mine to 1/8" thick steel on my request. I also purchased left- and right skews in 1/4". At this time he had no intention of making skews, not a value here, and we began corresponding about their virtues. These are the drawings I sent him ...

Skew chisels, with a 20 degree skew (equal to about 1:5 ratio), need to be used with a cutting action, as they cannot enter the corners ...

https://i.postimg.cc/DZ9myT0h/Dovetailfishtailcutting3.jpg

A fishtail chisel, however, can be pushed into the corner quite easily ...

https://i.postimg.cc/0QTdghqM/Dovetailfishtailcutting2.jpg

This makes the clearing process much easier.

To modify a skew chisel to work as half a skew, the skew angle must be reduced to about 8 degrees (rough estimate).

Make your own. I used a grinder to transform a bench chisel into this ... using a handle I made for a marking knife (my first skew chisel). It worked extremely well ...

https://i.postimg.cc/LXcFZ4jy/Dovetailchisel1.jpg

Regards from Perth

Derek

[Hilton Ralphs]

[Taylor Tools makes a kerf extender (https://www.amazon.com/dp/B07H549F7C/?coliid=I274WCYIT3P544&colid=2M1XMQFRF5982&psc=1&ref_=lv_ov_lig_dp_it) that's a bit less expensive than the Bontz or the Crosman. Like the Cosman, just available with the 0.025" blade.]

That size seems perfect for a saw plate of 0.015" thickness with a kerf of 0.003" each side (total 0.021").

[david charlesworth]

I prefer a pair of 1/4 inch home made skews.

The angle Derek shows for skew chisel seems much too acute to me.

Mine are ground at a fraction less than 1:6 which is the angle I use for single lap or secret mitre.

My skew slides easily along the side wall before nipping the corner waste off at the roots.

I find that a fishtail sticks into the side wall and is less friendly!

[Derek Cohen]

David, that the angle of commercial skews is too acute is the point I was attempting to make. We are in agreement.

Do you have a reason why your fishtail “sticks” along the side of the socket? Is it possible that the chisel sides/lands are tapered and sharp rather than flat?

Regards from Perth

Derek

[david charlesworth]

Derek,

Agreement is good ~;-)#

I would have to check. My fishtails are L-N, though I have one Japanese one as well.

Best wishes,
David

[Rob Luter]

Well, after much contemplation I ordered a fishtail from L-N. Starting to prep my drawer parts in anticipation. I should be able to get all my tails done this weekend and perhaps the through pins on the back. It's the time of year for yard work so shop time will begin to dwindle a bit.

[chris carter]

I've never used one for half-blinds and I've never found myself wanting one. I just use a 1/4" chisel to get into the corners. If I can't get that last crumb in the bottom corner, I can just knock off a corresponding crumb from the bottom corner of the tail. After all, it won't affect the strength of the joint one bit and nobody will ever see it. So what's the point?

[Tom Bussey]

I think they are useful and here are some pictures of mine. If one is not to brand conscience they can be picked up at a flea market- antique store for a buck or two.

430057 430058 430059

[Mike Henderson]

I've never used one for half-blinds and I've never found myself wanting one. I just use a 1/4" chisel to get into the corners. If I can't get that last crumb in the bottom corner, I can just knock off a corresponding crumb from the bottom corner of the tail. After all, it won't affect the strength of the joint one bit and nobody will ever see it. So what's the point?

I believe that most people who do a lot of dovetails go this way. I certainly did.

If a 1/4" chisel is too big, use a 1/8".

Mike

[Derek Cohen]

I believe that most people who do a lot of dovetails go this way. I certainly did.

If a 1/4" chisel is too big, use a 1/8".

Mike

And almost all the people who say use a 1/8" chisel do not make "London" style dovetails (I have no idea why they are referred to as this) ... that is, very slim, pointy dovetails, where the sockets have little meat ...

http://www.inthewoodshop.com/Furniture/TopOfTheWorldToYou_html_m233f38e0.jpg

http://www.inthewoodshop.com/Furniture/ApothecaryChestFinal_html_23b3cc36.jpg

https://i.postimg.cc/pXbvBnnh/Buidinga-Bench4-html-m167fdf7a.jpg

https://i.postimg.cc/zvm9bcPM/55e28b74-db67-47eb-b272-0d2a59eaa6cb-zps940885c3.jpg

Try using a 1/8" chisel into the corner of the sockets, and you will likely cause damage. Yes, you can use a 1/8", but really now ... the fishtail chisels excel at clearing the corners of sockets.

It's like using a chisel instead of a router plane to clear the waste in a dado. It can be done, but why not use a router plane?!

Regards from Perth

Derek

[Rob Luter]

Then there’s the consideration one must give to my meager (but improving) skill set. I’m sucking less and less at this the more I practice but I’m willing to invest in tools that will help me flatten the curve, if I may use a topical vernacular.