The Bridge City Toolworks KM-1 is a clever instrument for perfectly sizing a dado, groove, half-laps, or anything, really, if you treat it as an instrument for perfectly calculating an offset. Visit the linked page for Bridge City's description of it, or, if you're not the type to "read it for the articles", watch the video of how it's used.
I'm currently making a simple cabinet for inside a closet. This will be a wonder of plywood case construction with plywood shelves dadoed into plywood sides. That said, I will be using the KM-1 liberally to ensure that I get exact dados for the "nominal 3/4" and "nominal 1/2" ply.
In the demonstration video, the KM-1 is registered against a stop block on a fence used while cross cutting to create the half-laps. Naturally you can do the same on a table saw crosscut fence, but what if you're using the rip fence as I will since these sides are 4-5' long by 22" deep? All you need is a stop block of sorts for the KM-1 to register against.
When I documented how I did a walnut inlay into cork flooring, I described how I used the KM-1 with the Festool OF-1400 router to make the inlay groove exactly match the inlay pieces. Basically all you ever need is a stop block of some kind. This MDF jig for the table saw will definitely make the KM-1 easier to use when dealing with the rip fence.
Naturally, I like woodworking as a hobby, but an ice hockey tournament will easily get me out of the shop :)
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Thanks for sharing
I used the KM-1 yesterday for the first time and spent hours trying to figure out on how to use on a long board with repeat dado.
I will try your jog.
I just purchased a TM-1. How did you
come up with your stop block size and set up? I am trying to use mine on the BS and can't figure out how to place the stop block to get the cut. I am sure it's just a senior moment ;-) . How did you figure out the distance to set the stop block?
Charlie
Hi, Charlie,
Do you mean the KM-1 or TM-1? I'm actually in the shop right now recording a video on using the KM-1 on a tablesaw, bandsaw, router, mitersaw and the JMPv2. It should be out early this week.
If you mean the TM-1, I do have one, but haven't posted anything about it. The jig I used for the KM-1 is detailed in the video and likely will work fine for the TM-1.
There aren't a lot of hard numbers to the jig; my jigs are all of the easiest kind :)
I have the TM-1. I must have tried
hundred different ways and I can't get my head around it, probably be one of those"AHH HA!" moments, but until then it's a head scratcher.
How do you set the stop block? I mean, how do you come up with that initial distance before you insert the TM-1. That's the head scratcher.
I am sure I am "over thinking" it.
Works the same way as the KM-1. Set your fence for the first shoulder cut for the tenon. Then you put the TM-1 on the saw deck against the fence and clamp a stop-block on the other side. Make the first shoulder cut. Now flip the TM-1, bump it to the stop-block and slide the fence over to bump the TM-1. Make the second shoulder cut.
The only difference between the TM-1 and KM-1 is that the TM-1 leaves something the size of the calibration whereas the KM-1 removes something the size of the calibration.
AHH HA!
Thanks
Excellent! But do watch for the KM-1 video this week as the method of use is very very similar to the TM-1. You'll likely get some tips you can apply to the TM-1 there until I do a video of that.
I will definitely keep an eye out
for the video. The problem I was having was that I was not only flipping the TM-1 but also the work
piece... a little flip happy ;-0
After I picked it apart it all came
together, thanks again for the advise!