half blind dovetail kerfing tool.

[Stewie Simpson]

The tool is designed for deepening the kerf depth on half blind dovetails. For those not familiar with its use watch the following video from 1.00min by Rob Cosman. https://www.youtube.com/watch?v=XY9MzSCvxc8

The design I made features an 0.025" saw plate gauge x 3 1/2" (length) x 1 1/4" (depth below spine). The 3/16" brass pins used to secure the saw plate, and handle fit, were 1st 2 part epoxied, then hammer peened to achieve a lock tight fit.

The pins used through the saw plate feature a pierced pattern commonly used by knife makers.

The brass parts received a final sanding to 1200 grit.

Lock-tite was used to secure the saw plate within the brass spine slot prior to pinning.

Time taken to complete this project was around 6hrs. (excludes handle).

Stewie;


http://i1009.photobucket.com/albums/af219/swagman001/half%20blind%20dt%20kerfing%20tool/DSC_0082_zpsa9n1khw2.jpg (http://s1009.photobucket.com/user/swagman001/media/half%20blind%20dt%20kerfing%20tool/DSC_0082_zpsa9n1khw2.jpg.html)

http://i1009.photobucket.com/albums/af219/swagman001/half%20blind%20dt%20kerfing%20tool/DSC_0083_zpsa4dywzgt.jpg (http://s1009.photobucket.com/user/swagman001/media/half%20blind%20dt%20kerfing%20tool/DSC_0083_zpsa4dywzgt.jpg.html)

[Kees Heiden]

Well done. It looks almost too nice to hit with a mallet!

[Frederick Skelly]

Hi Stewie,
I like the curved back and blade, and the pierced pins.

I watched the vid and still can't quite see how the tool works - does it just compress the wood when you hit it (which seems like it would be damaging), or does it cut it?

Thanks,
Fred

[Prashun Patel]

Quite beautiful. I admire the curved back too.

[Stewie Simpson]

Fred; cleave would be a more appropriate description.

split or sever along a natural line or grain.

[Phil Mueller]

Very well done, as usual, Stewie. Nice design. My Bonz is nice, but yours has more style.

Fred; it was a little nerve wracking the first time I put mine in the kerf, and gave it a few whacks. But it works wonderfully. I do clamp the board to keep the end pins from possibly breaking out.

Ideally, the thickness of the kerfing tool is the same as the tooth set on the dovetail saw. I’m assuming Stewie’s dovetail saw tooth set is near .025”.

[Jim Koepke]

Nice tool, mine, like Phil's, came from Ron Bonz.

How did you make the slot in the brass?

jtk

[Ted Phillips]

Your tool is really nice, Stewie! I've got one of Ron Bontz' Kerfing Tools (https://www.bontzsawworks.net/half-blind-dovetail-tool/). Wow what a nice piece of kit. Completely changed the way I cut dovetails.

[Jim Koepke]

Your tool is really nice, Stewie! I've got one of Ron Bontz' Kerfing Tools (https://www.bontzsawworks.net/half-blind-dovetail-tool/). Wow what a nice piece of kit. Completely changed the way I cut dovetails.

Ditto, well at least for half blind dovetails.

jtk

[Robert LaPlaca]

Stewie, that is a beautiful tool.

Jeez, I just use an old scraper (just like Tage Frid did) and rap the scraper with a 16 oz claw hammer..

[David Eisenhauer]

Nice work as always, Stewie. Looks to be a handy tool for blinder type dovetails.

[michael langman]

You did a nice job on your kerfing tool Stewie..
Looks like a very handy tool to have in the shop.

[Derek Cohen]

Fred; cleave would be a more appropriate description.

split or sever along a natural line or grain.

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/ShopMadeTools/KerfChisel.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).

[Stewie Simpson]

To maintain a kerfing tools edge, follow steps 2 & 3. You should end up with a bottom edge that's straight with sharp 90 degree corners.

https://3.bp.blogspot.com/-ekK7bARZOb4/VjMqcdM4nXI/AAAAAAAAHME/veqNmKNYUX0g4wHrmJmEK8cRZsuYrjo7A/s1600/CCI30102015_00000.jpg

Regardless of later designs; Tage Frid deserves full credit for his innovative idea of using a card scraper to deepen the kerfs on half blind dovetails.

pages 72 & 73. https://books.google.com.au/books?id=YXlDT6lZBCIC&pg=RA1-PA28&lpg=RA1-PA28&dq=tage+frid+card+scraper+half+blind+dovetails&source=bl&ots=lyw44_nEPf&sig=48Im0g1WHeA5tXigBOfK5Y51TM8&hl=en&sa=X&ved=0ahUKEwjDzrmJu_jbAhULHpQKHeurDc0Q6AEIbzAP#v=on epage&q=tage%20frid%20card%20scraper%20half%20blind%20do vetails&f=false

[Phil Mueller]

Thank you for posting that Stewie!

[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/ShopMadeTools/KerfChisel.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 ...

http://www.inthewoodshop.com/Furniture/Drawboring_html_m6ae4901f.jpg

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 ...

http://www.inthewoodshop.com/Furniture/Drawboring_html_m6e7e9d6d.jpg

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=QKMADs1MNpE&feature=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. :D

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. :D

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

[James Pallas]

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
It's been so long ago I forgot where I first heard about it. It may have been from FW when Tag Frid was around. I just used a cabinet scraper as was suggested. Like any tool I like sharp. I did experiment with a putty knife some. That was the days before so many thin saw plates. Ron' tool, Derek's tool and Stewie's tools all would seem to work, I never tried any of them. If I use a scraper now I don't use a burr of course. I don't think about it much because I've become a dreaded pins first person. I would also need to gather different scrapers for different saws. I just don't find it that difficult to clear the waste out and I get to clean up the pins anyway. Stewie's tool looks very nice. Classy tool to have in your shop.
Jim

[Derek Cohen]

In regard to maintenance, I built the kerfing chisel I use about 9 years ago. In this time, it has not received any maintenance (as one does a scraper blade). I have cut a lot of dovetail sockets in this period. I like the idea of treating the blade as per a scraper, as Stewie posted, but it has not been necessary. This may reflect the durability of the stainless steel I used.

Regards from Perth

Derek

[James Pallas]

In regard to maintenance, I built the kerfing chisel I use about 9 years ago. In this time, it has not received any maintenance (as one does a scraper blade). I have cut a lot of dovetail sockets in this period. I like the idea of treating the blade as per a scraper, as Stewie posted, but it has not been necessary. This may reflect the durability of the stainless steel I used.

Regards from Perth

Derek
Now Derek, we all know that you built your tool as a chisel because your a metal hammer guy now and you would beat up your tool and your hammer if you just used a scraper :p
Jim

[Tom M King]

Stewie's tool looks great, but I never have time to make such things. I tried one of these, since I had a new one, the steel is pretty good, and they come with pretty good edges. I don't know of any other than W. Rose ones that would come close to this quality though. If it fits, which it happened to do when I needed one, it works just fine in Walnut.

https://www.krafttool.com/products/by-category/w-rose/margin-pointing-trowels/by-sku/RO58-5

[steven c newman]

Carried one for 6 years...except mine was by Marshalltown...Use them enough, and the edges will get razor sharp.