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Discussion Starter · #1 ·
Starting on a new project, I have 3 350 engines built with kz440 pistons, so I'm going to do a series of 3 of these bikes, with a few different options, leather seat or race seat, headlight or fairing, paint or brushed tank. making the design mostly modular will make it easy to change the build options in the future

 

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Discussion Starter · #2 ·
finishing up the first tank, I used the solidworks model to develop the patterns, so the tank is accurate to the design, I don't need to have the frame or anything else built yet, it will fit because the drawing says so :)

the seat was 3d printed in a few sections and joined together, it will be sanded, filled, and primed to be used for molds to make the final carbon or fiberglass seats

 

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Discussion Starter · #3 ·
I pretty much finished the seat for building a mold, that just involved primer, bondo and sanding, the pattern then gets waxed, coated in PVA, flanged, and a mold will be built on it. I also set up the swingarm jig, it's a simple tool I modeled in solidworks so I can use it over again with a few slight modifications for different swingarms.




 

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Discussion Starter · #4 ·
my neighbor has a plasma table, I helped him get it set up and assist with troubleshooting things for him, so I get to use it when I need to, it zipped off the parts for 3 tank bottoms in about 30 minutes, saving me maybe 3 hours of templating and cutting on a band saw. everything fit up and welded together nicely, I may make some 3d printed templates to cut the edges of the tank to match the bottom, but it wasn't too much work to do it freehand. I will need to come up with something to secure the top of the filler cap to inside the tank, I'm thinking about making a 6 threaded hole flange that mates with the top side, but is split, so it can be taken out of the tank through the filler hole in case it needs to be replaced, otherwise the tank would be scrap if the bottom of the flange was stuck in there. The idea being, it will be simpler to just have the filler cap sandwich to the gas tank rather than weld it in and deal with the warpage that comes with that.




 

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Discussion Starter · #5 ·
I 3d printed some flanges based on draft angle from the 3d model, then started building the mold. I'll be trying prepreg for this seat, usually I do infusion for carbon fiber, but I'd like to try using prepreg more because it doesn't require as complicated of a mold, I can use my powdercoat oven to bake it since the ramp rate can be controlled. should be interesting.
 

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Discussion Starter · #6 ·
Started and finished swingarms today, machined the parts and bent the arms yesterday, but it didn't really take the whole day, so maybe 10 hours into 3 completed arms. Not bad, the goal here is to streamline the build process by A: building a series of basically the same bike and B: using tech to eliminate any trial and error typical in the "custom" build process. They're about 5.5lbs too, not too shabby.


 

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Interesting.
How did you figure out the frame?
 

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Discussion Starter · #8 ·
the frame is based a bit on a gt380 frame I built, I'm using 2x4 tube instead of round though, so it's more based on the cb350 frame but a bit sturdier. I modeled the cb350 frame and compared relative stiffness between the swingarm pivot and steering tube and the 2x4 is much stiffer, but doesn't have hot spots indicating excessive strain. for a 30hp motor, I think it's probably a bit overkill
 

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Discussion Starter · #10 ·
machining for about 15 years, product development and prototyping for about half that, I've been using cad since high school when it was cadkey, about 1996. I'm honestly surprised more custom builders aren't gravitating to parametric modeling and cnc/rapid prototyping tech faster, it really simplifies building, basically zero backtracking once you start building the bike
 

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I expect that the cost of entry (equipment) and time it takes to learn coupled with a general resistance to change.

There's going to be an increase in this sort of thing as the new generation of petrol heads brings their digital ways into the industry.

I can appreciate the new kit and skills as much as a guy who can use an english wheel.

Just got to be careful not to lose the old skills as the new tech comes in.
 

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Discussion Starter · #13 ·
I expect that the cost of entry (equipment) and time it takes to learn coupled with a general resistance to change.

There's going to be an increase in this sort of thing as the new generation of petrol heads brings their digital ways into the industry.

I can appreciate the new kit and skills as much as a guy who can use an english wheel.

Just got to be careful not to lose the old skills as the new tech comes in.
I think the open source/maker movement coupled with massive retooling in the cnc world will bring a lot of this stuff to custom builders without a big cost of entry, my favorite tool right now is my 1995 hardinge cobra42, a 12 tool slant turret lathe, cost $4k and with the help of the internet and general tinkering ability, I can load programs into it from my cam software just like a newer machine. my large format heated 3d printer is something I built myself, the controller software is all open source so all I had to do was figure out the mechanical stuff. the stuff that used to require a million dollar shop can now be done in a garage with a startup budget of 25k, stuff is really wild right now.
 

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Discussion Starter · #17 ·
none taken, this project is part of my plan to finish all my project bikes, I happen to have 3 350 motors already built, so that's where they're going. I also have a collection of xs650, 900ssie and an 848evo motor ready to go, so there'll be room for some more performance oriented bikes
 

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The only thing the CB350 had going for it in the day was everybody and their cousin had one, they were cheap and plentiful, but now they are neither cheap nor plentiful.
 

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Discussion Starter · #20 ·
nothing too eye catching to show lately, but I finished the frame design 100% including detailing all threaded inserts, tabs, etc etc. so I started machining the actual parts for them, just lots of accumulating pieces, then putting everything together. What I am hopeful about with the designing first, fabricating later process is that it will take a lot of the 95% finished project duldrums out, because once all the actual pieces are made, the bike will just go together like a kit.

 
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