Bontz kerfing tool and a question- why not just use this, sans saw?

[Malcolm Schweizer]

IMG_1808.jpgGood day all:

I had the pleasure of trying out Ron Bontz's new kerfing tool. I compared it to the one I made from a surgical chisel that I ground down. Full disclosure: This was in part a trial for Ron, but my opinions are my own and based on my own results.

When the tool arrived it was not at all what I expected. I thought it would be a chisel style. I wasn't sure about the brass backed "toothless gent's saw" style of tool, but I was intrigued. On first impression, it is very well made. The brass back is thick, the handle is large, and the plate is 0.20" on mine. It is, as expected, a very well- made tool.

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I was at first a little timid about hitting this thing too hard, fearing it would bend the plate. My fears subsided and I soon found myself whacking away at it with a cocobolo mallet. I was amazed at how easily it went into end grain. Cross grain, as expected, took a bit more effort. No worries, as most dovetails will be done in end grain. (General statement there-of course there are many cases where they would be in cross grain, but typical half-blind dovetails would be end grain.)

First off, if you have never used one of these, the idea is that when making blind dovetails, this is used to finish out the kerf where the saw cannot reach. You saw first, then use this to finish out the kerf. That said- a question- do you need to saw first? This thing does such a good job, could you just hammer it in to make the whole cut instead of just finishing the kerf? Open to thoughts on that.

I decided to compare it to my home-made kerfing tool. I was surprised that this made a much thinner kerf. Here are some shots:

My home made chisel

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Bontz kerfing tool

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Mine versus Bontz- showing kerf.

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Mine vs Bontz vs saw kerf from LN 14ppi thin plate saw. ***edit- that image landed at the top of the page and I can't move it, so look up there.



Having trouble with image upload. Hopefully that last pic shows up.

Conclusion- I certainly like it better than mine. It goes in to end grain like butter. It is very well made. As I said above, I am wondering why bother sawing- why not just hammer out the kerf with this? It may take some practice. I will try that on the next project and see what happens.

By the way- this was a test on scrap wood. I wasn't really aiming at a line- I was just hammering it in to see how it worked.

[Jim Koepke]

I am wondering why bother sawing- why not just hammer out the kerf with this?

It may have a tendency to cause splits when used in such a manner.

My tool to finish a kerf in half blind dovetails is made from an old saw blade and works fine as long as there isn't a knot in its path.

jtk

[Malcolm Schweizer]

It may have a tendency to cause splits when used in such a manner.

My tool to finish a kerf in half blind dovetails is made from an old saw blade and works fine as long as there isn't a knot in its path.

jtk

True. I use mahogany so frequently- that's what I used for this. I should have considered that other woods might split- fir comes to mind.

[lowell holmes]

My Lie Nielsen dovetail saw starts it's own kerf
After I learned to use it.

I also have both Lie Nielsen carcass saws, They also start kerfs.

I also had Ron Bontz send me a 4"X20" saw plate and a brass back. I made a curly maple handle for it.
It is a tenon cutting delight.

[Jim Koepke]

My Lie Nielsen dovetail saw starts it's own kerf

Though this tool might work as a kerf starter, it seems to be more useful as a kerf finisher in applications such as half blind dovetails.

jtk

[Malcolm Schweizer]

Though this tool might work as a kerf starter, it seems to be more useful as a kerf finisher in applications such as half blind dovetails.

jtk

Yes- this is for finishing the kerf in half blind dovetails where the saw can only saw part of the kerf, or else it would not be a half-blind dovetail.

[lowell holmes]

I use a card scraper to finish the kerf. If I need to I will use a bevel edge chisel. My Lie Nielsen chisels can make translucent shavings.

[Jim Koepke]

When making my blind dovetails a third kerf is cut in the middle to help in extracting the waste.

jtk

[David Eisenhauer]

Exactly Jim. The bigger the dovetail, the more kerfs I add in. Sawing is quick and it definitely helps the following chisel work.

[Derek Cohen]

Just for reference, I designed and have used a kerfing tool (kerfing chisel) for several years now.

I designed this to be used like a chisel ...



Not to take anything away from Ron's tool, which is beautifully made, his is a copy of one produced by Rob Cosman about a year ago. Both Rob's and Ron's kerfing tool is similar to the concept made famous by Tage Frid, from whom I also got the idea.

Regardless of the design, Tage Frid's idea of hammering a scraper blade or a bandsaw blade was ... is genius. It makes clearing out half-blind dovetail waste much easier. Just be careful: (1) the lower edge of the blade is square, not bevelled (or it will split the wood), and (2) place a clamp across the board when hammering it in (also to present splitting).

Regards from Perth

Derek

[Ron Bontz]

Just for reference, I designed and have used a kerfing tool (kerfing chisel) for several years now.

I designed this to be used like a chisel ...



Not to take anything away from Ron's tool, which is beautifully made, his is a copy of one produced by Rob Cosman about a year ago. Both Rob's and Ron's kerfing tool is similar to the concept made famous by Tage Frid, from whom I also got the idea.

Regardless of the design, Tage Frid's idea of hammering a scraper blade or a bandsaw blade was ... is genius. It makes clearing out half-blind dovetail waste much easier. Just be careful: (1) the lower edge of the blade is square, not bevelled (or it will split the wood), and (2) place a clamp across the board when hammering it in (also to present splitting).

Regards from Perth

Derek

Hi Derek,
Just to be clear.
1) This is for finishing the kerf on half blinds. Not starting the kerf. I make them in 0.015", 0.020" and 0.025". Otherwise they would act like a riving knife, splitting the wood. I had heard of using a putty knife by a particular woodworker and I myself have used a putty knife like a chisel for 30 plus years.
2) I have had these available for a while now and I initially designed this a couple of years ago, almost 3 years now, at the request of an accomplished woodworker that builds 18th century furniture. Just didn't get them made. I had not even seen Rob's when I designed this as well as a couple of other versions.
No offense to Rob, but this is NOT a copy of Cosman's tool. Personally I think mine is better.
Please keep in mind, I do not make production anything so I do not have the resources to send out numerous free samples. My half blind tools are only made in small batches, using various wood species. The last batch of handles was bubinga, zebra wood and hickory. I did have the blanks CNCd.
I just happen to be chatting with Malcolm , had just finished a few of these half blind tools, and decided to send him one. Hopefully it will last many years. So Thank you, Malcolm, for the kind words.

[Malcolm Schweizer]

I probably led people astray with my question and pondering about using one without a saw because it was so easy to make a kerf. As Ron clarified, it is to finish a kerf in half-blind dovetails, not to start a kerf. That said, it took four good whacks to make a full kerf without sawing first. The kerf was clean and there was no splitting. I was using mahogany and just playing around with it. It made me think one could just hammer a dovetail out with this thing. It was pointed out that splitting may occur in other woods. I could see that. I will say, however- I may try it for fun.

It's a beautiful tool and works better than my home-made ground-down chisel. The whole thing is very substantial. Ron is an upstanding man. I bought a used saw from another creeker and Ron saw that I had bought it and wrote to tell me he would gladly answer any questions, and gave me some advise on using it. Ron got $zero from me for that purchase, as I had bought it used from someone else, but he stood behind his work. I also have bought a plate and saw nuts from him new. His work is excellent, and his integrity top notch. Thanks Ron, for your integrity and generosity.

[Derek Cohen]

Hi Derek,
Just to be clear.
1) This is for finishing the kerf on half blinds. Not starting the kerf. I make them in 0.015", 0.020" and 0.025". Otherwise they would act like a riving knife, splitting the wood. I had heard of using a putty knife by a particular woodworker and I myself have used a putty knife like a chisel for 30 plus years.
.... No offense to Rob, but this is NOT a copy of Cosman's tool. Personally I think mine is better.
...

Hi Ron

My apology if my post appeared derogatory. That was not intended. It is difficult not to reach the conclusion that your tool copied Rob Cosman since he has been producing the same design for a while before yours was made public.

Also, I know the tool is not to create a kerf but to extend one that is half sawn (at an angle, per half-blind socket).



What I need to emphasise for all is that a tool like this will split wood (especially in the hard and brittle woods I work with) if an attempt is made to create the full kerf. Importantly, one should nibble away at the kerf, rather than place the full length of the blade in the kerf and wack it down (I mention this in my web article). This is the reason for my design, that is, a narrower blade. The longer plate will tempt some to try it all in one go.

Regards from Perth

Derek

[lowell holmes]

I'm glad you guys made up. I admire both of you and always look forward to your comments.

[Robert LaPlaca]

Regardless of the design, Tage Frid's idea of hammering a scraper blade or a bandsaw blade was ... is genius. It makes clearing out half-blind dovetail waste much easier. Just be careful: (1) the lower edge of the blade is square, not bevelled (or it will split the wood), and (2) place a clamp across the board when hammering it in (also to present splitting).


Derek

Indeed, I have a VHS (remember those) tape of Tage Frid vintage 1980's by FWW showing how to hand cut dovetails, I learned how to dovetail from that video (Tage recommended pins first by the way). I have been using a card scraper since seeing that tip, Tage was a wonderful teacher.