half blind dovetail kerfing tool.

[swagman]

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;

 

[Just4Fun]

Yours is a good-looking tool. A job well done. I take a simpler approach to workshop tools. I had a horrible tenon saw I didn't use so I cut it up to make other things such as a scraper. I took a short (2cm) section cut off the end of the blade, including the back of the saw. I just put this in the kerf and hit what was the back of the saw with a hammer. I haven't used it a lot but it seems to work. Of course it doesn't look nice like yours does and your approach keeps your fingers away from the hammer, but I figure if I can hit a nail I can hit my "kerf extender".
I do admire nice home-made tools like yours, but not enough to make them myself.

 

[dzj]

" I took a short (2cm) section cut off the end of the blade, including the back of the saw."

Luxury!
Just kidding, I use a similar setup.
Oh, and well done Stewie, a fine looking tool that is!

 

[MikeG.]

I'd need to be making blind dovetails all day every day to justify a (very pretty) tool like that. I use a thin piece of steel which I put aside as a potential cabinet scraper but found to be useless, but if the wood is soft enough I tend to just use a Stanley knife.

 

[StraightOffTheArk]

Thanks for posting this Stewie - it's (yet another!) trick I was unaware of.

You've certainly created a handsome tool there - most impressive - I shall have to have a go at my own (rather less handsome) version.

 

[Argus]

Very nicely made.
Now and then I make drawers with half-blind fronts and I've always used an old piece of a card scraper, cut down, held with pliers and knocked in with a hammer.
I believe that I got the idea from watching Jim Kingshott at one of his demos back in the 80s.... he probably watched an old feller in the 40's.....
But you've given me an idea for something a little more elegant the next time I make some drawers..

 

[Derek Cohen (Perth Oz)]

I believe that I got the idea from watching Jim Kingshott at one of his demos back in the 80s.... he probably watched an old feller in the 40's.....

The first time I saw this technique was in the late 80's in a video by Tage Frid. He used a section of bandsaw blade.

I built a tool dedicated to deepening a saw kerf for dovetail sockets, and posted this in 2011: http://www.inthewoodshop.com/ShopMadeTo ... hisel.html

I called my version a kerfing chisel, and have demonstrated its use many times in builds over the years. You would have seen this in my current thread on the Apothecary Chest, and in the video on the joinery/cabinetmaking forum (around the 30 min mark)...

The kerfing tool that Rob Cosman began selling a couple of years ago (made here very nicely by Stewie) was not actually designed by Rob or, rather, I was aware of this design several years before Rob began making his (it is in Sawmill Creek archives).

Regards from Perth

Derek

 

[Ttrees]

I was gong to ask you about that in your video Derek...
Can you tell us if its just a ground down chisel?
And if so is it tapered, a side profile of the tool would be interesting to see.
Tom

 

[D_W]

I've used a card scraper and a dead blow mallet for this without issue. If I ever don't have a crap card scraper to use for it, I'm sure part of an old saw plate would suffice.

Still try to minimize the amount of force and potential wedging with this type of setup, though - it just feels potentially catastrophic.

 

[Ttrees]

I would be also very interested to know what the maintaince is of this tool is...
Do you treat is as you would with a normal cabinet scraper, without drawing the burr?
Thanks folks
Tom

 

[Argus]

I would be also very interested to know what the maintaince is of this tool is...
Do you treat is as you would with a normal cabinet scraper, without drawing the burr?
Thanks folks
Tom

No, Just a squared piece of steel plate that is very slightly slimmer than the kerf of the saw and is ground square at a right angle .

You have already cut a diagonal line with your saw between the extremities for the tail to sit in.
When tapping the blade down the saw line, you are not cutting.... if anything you are compressing a small amount of end grain, extending the diagonal saw-cut into the dovetail corners in order for a chisel to follow in and clean down to the corners.

A blunt squared end is less likely to split the work, which is the last thing that you want because you are effectively tapping a wedge down into end-grain.
As well as a cabinet scraper and bits of worn saws, I've seen a large broken hack-saw blade with the teeth ground off used for this purpose.



.

 

[Just4Fun]

Still try to minimize the amount of force and potential wedging with this type of setup, though - it just feels potentially catastrophic.

I would expect the risk to be greater in harder woods. It has not been a problem on the few occasions I have used it on soft woods, but can anyone comment on the effect on hard woods? Any problems?

 

[Argus]

I only use hard wood. Never had any problems either cutting with chisels or driving a scraper plate in with a hammer.

 

[Derek Cohen (Perth Oz)]

I was gong to ask you about that in your video Derek...
Can you tell us if its just a ground down chisel?
And if so is it tapered, a side profile of the tool would be interesting to see.
Tom

The link I posted has all the details.

I made the kerfing chisel from a stainless steel garden trowel ...

The steel plate was ground down a little, not much, to 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. As mention, the action is to compress fibres rather than cut them.

Regards from Perth

Derek