Bridgecity Jointmaker: I must have this!!!

[Shawn Buonarosa]

Floyd , any chance you could show me a picture of the design you are describing? I'm having a hard time visualizing it.

[Floyd Mah]

Here's a photo of my saw. It's slightly dark so that you can see all the parts.

The image shows the view through the top of the table saw, with the front of the saw on the right and the back at the left, the top of the image has the right side of the saw opening.

At 9 o'clock, you can see the table saw arbor. Crossing from 3 o'clock to 9 o'clock, across the bottom, you can see the remaining teeth of the circular saw blade. At the top of the picture, you can see the Japanese saw blade, attached to the circular saw with the metal bar running across the middle of the image. You can also see one of the slots in the Japanese blade that I used.

The components of the table saw are:
Pivot of the arm raising and lowering the blade at the top right corner. The raising arm extends down to the arbor diagonally behind the blade.
The trunnion bar (left one) can be seen at the bottom of the image. The trapezoid at the bottom right is the flange which holds the red saw insert (throat plate). Behind it is seen a wooden block, fastened to the trunnion bar with the pair of U-bolts. You can see the wingnuts on the top leg of each U-bolt. Embedded in the wooden block is the bolt which holds the end of the new lever arm nearest the front of the saw, the other end of the lever arm is fastened, with the wingnut and small bolt, to the bottom of the circular saw blade. You can see some of the circular saw is cut away to avoid hitting the bolt holding the new lever arm. I did offset the new pivot slightly towards the front of the saw about 1/2" to improve the clearance from the blade. The center of the new pivot is at the same level as the trunnion bar.

The parallelogram is formed from the two lever arms, the swinging end of each lever arm is attached to the circular blade: one to the saw arbor, the other via the wingnut. The stationary end of the lever arms are fastened to the trunnion. This arrangement keeps the Japanese saw teeth at a constant angle relative to the table top, despite changes in the distance of the blade above the table. It is important to measure and drill carefully to keep the parallel arrangement so that there is no binding in the movement of the various parts.

[Brandon Davis]

Floyd? First, thanks for the picture.

Question: Since the lever arm is basically to keep the modified circular saw parallel to the table top, would the same effect be achieved by locking down the belt movement from the electric motor?

Please do correct me if I'm missing something here.

...it also seems to me that some kind of manual control working off the [disconnected] electric motor would also allow you to precisely tilt the modified saw blade in the same way the BCJM is slanted (low front to high rear) ...you could just pull the belt, I s'pose, and re-"lock" it (with the speculative "locker") ...which blade angle may make the "manual sawing effort" a bit less, since the entry to the cut could be at a similar angle to what I see in the Youtube video.

[Floyd Mah]

The easy part: The tilt mechanism of the table saw stays intact, so that you can continue to use that to angle your cut.

The normal operation of the height mechanism is just to raise and lower the arbor with that lever. Since the circular blade is intended to turn, the usual operation of the saw allows the blade to rotate freely. Just securing the arbor (for example by holding onto the belt) doesn't maintain the blade in the same position relative to the table top as the lever arm is raised and lowered. You can adjust the belt each time a height change is made, but it's much simpler to incorporate the new lever arm to do that adjustment for you automatically.

My experimentation with this arrangement shows that your basic consideration is the length of your cut:
Long cuts (across wide stock) requires lower blade angles, since you have more wood under the teeth at any given time.
Leave the wood over the blade when adjusting for subsequent passes and raise the blade just enough for the lower end to be short of the maximum height of the kerf. This keeps you from cutting too aggressively and also avoids deforming the blade by trying to cut too much at once.
This tool would also be useful to make repetitive, starter cuts, when a cut deeper than the capacity of the saw is planned, so that another saw can be used to manually finish to the final depth. It just starts your cut at the right angle and correct location.

[John Schreiber]

Floyd,

You've come up with a good idea and you've done a good job explaining the concept, but I want to know how it works for you. Are you using a sled? Can you get those super precise cuts? Is it as good a JMP, or what's the difference?

[Floyd Mah]

I have tried it with a Delta tenon jig. It seems to work well with it. The reason that the Japanese saw blade works well is that once you start it, if you maintain your direction and angle, the blade pretty much will do what you want. Since the only difference between the stability of this homemade version and the JMP is how the blade is fixed, the variability is introduced by the degree of wobble in the circular saw arbor. A circular blade uses centrifugal forces to stabilize it so there isn't too much run-out. You lose this with this setup, so it depends on the tolerances of the arbor. I suspect that if you don't try cuts that are too deep, you can probably get good, reproducible results. I can place cuts on tenon stock approximately 2" thick about 3 mm apart.

The tenon jig runs on only one guide, so I think a sled would be, by design, more accurate. I'll probably try to put together a sled and see if I can get better results than with a miter gauge (which I have tried briefly).

[Kevin Groenke]

The word on the street is that Bridge City is finally shipping the JMP.

I got an email from a cohort indicating that Bridge City told him their first run of 300 units was complete and that they would begin shipping today in the order that pre-orders had been received.

According to the information received, 280 of the first run of 300 have been pre-ordered leaving 20 available. BC will not be making any more till they have orders for another 300.

Somebody at BC suggested that anyone interested should purchase one of the twenty left and if not satisfied, return it within 90 days for a full refund [less shipping i assume]. A box of five spare blades runs around $100, the tool ships with a rip and coarse x-cut.

I didn't pre-order till November, so we're a ways back on the ship list, but I'll report when we get it and try to post a review once we get some time to work it out.

-kg

[Dave Lehnert]

I had the chance to use the JMP at the Popular Woodworking shop with the owner of Bridge City Tools. It is a tool you have to see and feel in person to understand it's quality.

I love the table saw idea above. I think we all have tried to figure out a homemade vs of the JMP.

As a side note- A few years ago I purchased a 100 tip saw blade form Penn State Woodworking. I can put that in my table saw and get cuts a smooth as glass. You would not believe the quality of cut.

[Chris Padilla]

BCT was at The Crucible in Oakland, CA, for the recent Lie-Nielsen tool event and I was able to give this tool a hands on whirl.

I have to say: extremely impressive! The japanese saw blade cuts as smooth as glass. The kerf bent box is something to see in person...simply amazing.

[Doug Shepard]

...
I didn't pre-order till November, so we're a ways back on the ship list, ...

Mid-August for me so I'm a little ahead of you but I dont remember when they first started taking pre-orders so how far back in the queue I am is anyone's guess. I think they also took a number before you could actually do it on their website too. I'm crossing my fingers that I get it soon enough to use it a bit on my part of the SMC Keepsake Box collaboration.

[Berl Mendenhall]

Jameel,
I've just spent the last hour reading your thread on Oud building and your web site on Iconic Art. You are exactly the type of craftsman who should own one of these saws (I don't care what they cost). The kind of work you do takes craftsmanship to a different level.

I am new to Sawmill Creek (only a few weeks) but I've enjoyed every visit. There are some incredibly talented people that post here. Most of us do what we do alone. We spend countless hours working alone at our benches. These forums are a way to socialize with people we would never have a chance to meet. Reading your post has made my day, you are a true artist.

Berl Mendenhall

[Peter Quadarella]

I have to admit I lust after a Jointmaker. I could make one large tool purchase this year, but ~$1500 is a lot of money to spend on something like this. I'm not even sure how much I'd use it.

[Chris Padilla]

Some pics from The Crucible in Oakland, CA, at the Lie-Nielsen Handtool Event.

I wanted to add that the cross-sectional piece of oak molding in my hands is about a 1/16" thick and glass smooth on both sides coming directly off the BCJ.

[Jameel Abraham]

Berl,

Thanks for the nice comments. The Creek is a nice place indeed. I haven't been posting much lately, but I do try to keep up on what's happening around here. I don't have a JMP yet, but it's still way up there on my want list!

[Dave Lehnert]

When talking to the owner of BCT he is more than aware of the high cost of the tool. Made the comment that he would be willing to sell the patent to a company that could build it cheaper.

This type of tool IMHO would fit well in the Lee Valley line. Bet Mr Lee could shave off a few buck on the manufacture of something like this.