a (knock-off) jig for getting perfect half-lap joints on soundboard braces

[Bob Hammond]

Hi, there's a company that makes extraordinary hand tools at extraordinary prices: Bridge City Toolworks (no, it's not located in the City of Bridges - Pittsburgh, PA).

Anyway, they make a clever jig that they call a Kerfmaker(TM) that works very well The tool is excellent, but the price is extravagant if you don't need it for everyday work. It's not a complex thing to make, and knockoffs have been constructed. I made my own version (and then did the literature search), and then discovered that over at Lumberjocks.com one can find several threads that describe 'shopbuilt' knockoffs. It's a great idea that you can use to make your own jig for your own purpose, but don't try to sell it.

[David King]

Bridge City is (among others) Portland Oregon. That's where the tools are made anyway. I had to watch the whole video to figure out how it works. You can make as many of these as you would like as long as you don't use the trademarked name. These sorts of story gauges have existed for hundreds of years so I doubt anyone could patent them now-a-days.
I think if I needed one for everyday use I would just buy it, the price seems pretty reasonable to me for the amount of work it would entail and then getting all the parts anodized to boot. If I just needed something like it for occasional use it wouldn't take long to do out of hardwood.

[Bob Hammond]

David, you got the idea of it, and you understand that the idea of it has probably been around for a long time. That said, there's a thread on the lumberjocks site that describes how to make 'disposable' gauges for a particular purpose.

As for a city of bridges, Pittsburgh, and the surrounding area, is the place to go if you want to admire the artistic development of bridge-building. If you want the amusement park experience, take the expressway from the Pittsburgh airport to the city. You ride along on a cement highway through green forested hills, and then you enter a tunnel into a mountain, and then suddenly emerge onto a big iron bridge while admiring the downtown landscape. Whoever thought of this entrance to the city was a genius.

[Nate Scott]

Several months ago, the Museum of Contemporary Craft here in Portland had an exhibit on hand tools that featured a bunch of stuff by Bridge City. There was a lot if space given to their design process with many one-offs and prototypes along side production models. As someone who is mildly tool-obsessed, I found it very interesting indeed, and I gained a new respect for the high level of engineering and craftsmanship behind their products.

[Geoff Wight]

I am about ready to do a X brace joint, so when I saw Bob's post it got me thinking.
So I put this together.
Worked perfectly the first time on scrap.
I still need to make a small sled to hold the braces at an angle before I can do the real thing.

[Markus Schmid]

Nice knock-off Geoff!

You can make as many of these as you would like as long as you don't use the trademarked name. These sorts of story gauges have existed for hundreds of years so I doubt anyone could patent them now-a-days.

Some details of this Bridge City gimmick are patented indeed. If the claims would hold up at court is another story though.

The drawings in the patent are quite useful for making one's own "kerfmaker".

[Greg Steil]

I'd love to see more pictures, since I have no clue how this would work.

[Mario Proulx]

Watch the video on the Bridge City Tools site...

[Murray MacLeod]

You ride along on a cement highway through green forested hills, and then you enter a tunnel into a mountain, and then suddenly emerge onto a big iron bridge while admiring the downtown landscape. Whoever thought of this entrance to the city was a genius.

Was this not the vision and creation of my fellow countryman Andrew Carnegie?

[Bob Hammond]

Murray,

Andrew Carnegie was possibly the greatest gift from Scotland to America, but this bridge was constructed long after Carnegie's time. Also, Carnegie was a ruthless industrialist, but he became a great philanthropist. Here's a link to the Font of Popular but Uncertain Wisdom:


http://en.wikipedia.org/wiki/Andrew_Carnegie (by the way, in Pittsburgh, the name is pronounced Car (as in automobile) -neg (as in negative), GEE (as in the letter g substituted for 'k' in the work 'key')

Since we going down the lane of history, about 20 miles north of Pittsburgh is the small town of Saxonburg. Saxonburg was founded by the John Roebling family, who built the Brooklyn Bridge in New York City. About 15 miles further north is Butler, where a famous military vehicle was conceived, designed, built, and delivered to the Aberdeen (i.e. Maryland, USA) Proving Grounds in about three months in 1940. You may recognize its candyass descendants as the Jeep. Incidentally, one of the oldest surviving 'jeep' 'Bantam Reconnaissance Cars (#2271') was found in a knacker's yard in Scotland. It served with the British 8th Army in North Africa and Italy, and was shipped back to Scotland where it rusted in the junkyard for 20-some years before restoration. Hmm, if you find another one in Scotland, then grab it - it's one of the Holy Grails of automobile & military history.



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