half blind dovetail kerfing tool.

[Pat Barry]

Stewie, this is incorrect. You would never want the kerfing tool to do this as it will cause the sides of the sockets to split.

I built possibly the first dedicated kerfing tool (that is not simply a scraper blade) and posted an article on it in 2011, and have used it ever since, with numerous posts on forums. Everyone must be familiar with it. It is made from a stainless garden trowel. The steel end is the thickness of a typical dovetail saw. The ends are squared off - a bevel, as on a chisel, would cause the end to slit the wood. The action is to compress fibres rather than cut them. Link: http://www.inthewoodshop.com/ShopMad...erfChisel.html

Regards from Perth

Derek

Edit to add: Stewie, regardless of these comments, you have made a beautiful tool - altogether nicer than Rob Cosman's version. (Incidentally, it was a Creeker who first made this design, not Rob Cosman. There is a picture somewhere in the archives).

I dont follow the concern related to "causing the sides of the sockets to split". The cleaving action is directed along the grain lines by the tool. Of course, overly aggresive hammering of the tool may be an issue, as would a tool that is too fat. Can you explain your concerns further.

[Derek Cohen]

Pat, indeed there are grain lines. If you plan to "cleave*" (which I warn against), then the wood will split with the grain. Remember how one makes drawbore pins? First you rive the wood ...



In this example, the wood splits nice and evenly because the piece chosen had obliging grain.

But what happens when the grain is not obliging, not straight? When this is what happens ...



The aim of the kerfing tool is not to cleave to deepen, but to deepen the kerf by compressing the fibres. The end of the steel is square for this purpose. If you wanted to cleave, then it would have a bevel, as with the chisel in these photos. A clamp is attached to the sides of the board to prevent any splitting as a result of the grain line running.

Regards from Perth

Derek



* Definition of cleave: split or sever (something), especially along a natural line or grain.
"the large chopper his father used to cleave wood for the fire"

synonyms:

split, split open, crack open, lay open,

[steven c newman]

Kerf tool has NO bevel......matches the kerf of the saw....no wedging takes place...

[Pat Barry]

Intetesting thought to compress the fibers. In practice though, I wonder how far you can gowith this.

[Ron Bontz]

Kerf tool has NO bevel......matches the kerf of the saw....no wedging takes place...

Correct. However one should consider excessive striking force can cause the wood to push outward as well creating that wedging effect and splitting the wood. You can only compress so much wood before it has to go some where. Normally this would not be a problem, but it did spur me to make a few with 20ppi reverse teeth. To facilitate removal of some of the compressed wood. ( Tedious though ). Since mine were designed to be held like a chisel or gent saw, depending on one's work methods, I tested mine, repeatedly, by beating it from the back into various wood species until it split the wood. The lack of a shaped plate was purposely done to extend the life of the tool. If you always strike it from the back you may need to square off the front edge from time to time. So hopefully it will out last most folks here as well as offspring. . I also have no doubt Tag Fried picked the trick up from some one before him and he before him, etc.

Stewie; Nice looking little tool you have there. I like the chisel handle look. Mine were based on my Gent saws. ( shared components ). Hope all is well. Best wishes.

[Jim Koepke]

Intetesting thought to compress the fibers. In practice though, I wonder how far you can gowith this.

Usually to the depth of you dovetail socket. My deepest was a half blind in a cedar 2X4. An old piece of a saw was used.

jtk

[Derek Cohen]

Usually to the depth of you dovetail socket. My deepest was a half blind in a cedar 2X4. An old piece of a saw was used.

jtk

As Jim writes. Go as deep as needed.

Below is a demonstration, in the video I recently posted. Go to the 30 minute mark. It lasts 2 1/2 minutes.

https://www.youtube.com/watch?v=QKMA...ature=youtu.be

Regards from Perth

Derek

[Brian Holcombe]

I agree with Stewie, while I understand one does not want to split the board, the wood in the kerf must part and compress into the sides, otherwise it is not going anywhere.

[Derek Cohen]

Brian, think of what occurs when a dulled nail is struck into wood. It does not split the wood as it penetrates - indeed, the aim is to prevent it doing so. What it does is act as a wedge and push the fibres to one side and below.

Regards from Perth

Derek

[Brian Holcombe]

Brian, think of what occurs when a dulled nail is struck into wood. It does not split the wood as it penetrates - indeed, the aim is to prevent it doing so. What it does is act as a wedge and push the fibres to one side and below.

Regards from Perth

Derek

This is almost verbatim what I describe above. If nothing else, certainly hairs are being split....in this thread.

The action is a splitting action, localized to the wood which you'd prefer sawn. If you drive it too far it will split the board, that is how I know it is a splitting action.

[Jim Koepke]

This is almost verbatim what I describe above. If nothing else, certainly hairs are being split....in this thread.

The action is a splitting action, localized to the wood which you'd prefer sawn. If you drive it too far it will split the board, that is how I know it is a splitting action.

To what grit does one need to hone in order to get in on said hair splitting?

It makes me want to say, "stop! Stop! You're both right!"

There is compression force sideways leading in to the force of splitting.

"It works a treat," is enough of an explanation for most of us.

A kerfing tool does a much neater and quicker job of a blind dovetail than using only a chisel to remove the waste. Derek may have covered something in his posts worth mentioning, making a center kerf in the waste of a blind joint also helps to make waste removal quicker and easier.

jtk

[Andrew Hughes]

I am tempted to try the kerfing tool some day. I still weigh how much time will I save and the risk of splitting a drawer front. I tell myself I’m good at fixing goof ups but I also don’t feel any need to get a drawer done in a half hour or hour.
Must be a personal challenge to dovetail fast.
Am I missing something

[Jim Koepke]

I am tempted to try the kerfing tool some day. I still weigh how much time will I save and the risk of splitting a drawer front. I tell myself I’m good at fixing goof ups but I also don’t feel any need to get a drawer done in a half hour or hour.
Must be a personal challenge to dovetail fast.
Am I missing something

Hi Andrew,

Do you have an old bandsaw blade, piece of saw plate or some other piece of flat metal?

Being a brave soul, my clamps are usually not used to prevent splitting mostly fir or other soft woods. (Note: Sometimes my clamps are used. After all, sometimes it just looks like it wants to split.) One thing in my favor is my pins are usually thicker at the edges of the pin board than many other folks show here.

My suggestion is if you have a piece of metal to use for a kerfing tool, then give it a try.

Mark out a socket on a piece of scrap, make the saw cuts including one in the middle, use the tool in all three cuts then chop out the waste.

The time you save will allow you to make more drawers or can be used on another part of the project.

It isn't only the time, it is less trouble and makes a neater joint.

jtk

[James Pallas]

It works okay. If you work with QS white oak for drawer sides and thin pins I advise you to take small bites and maybe clear some waste out as you go. And you can ask me how I know this. It will even start a split that you don't see until you make that last tap to seat the tail. Also make sure the edges are sharp to cut the fibers loose as opposed to smashing them down. And yes I know that it is not necessarily wise to use QS material for drawer sides.
Jim

[Tom Trees]

James you are suggesting tool maintenance, which I suspected...
Have you given the tool the same treatment as one would use for a cabinet scraper, without drawing the burr obviously.
How often do you give the tool a service?

Guessing someone's tried a pull stroke rip tooth profile, without either set or fleam,...
It must not hold up?
Thanks for sharing your story James

Tom