T8's 750 Cafe Racer Project

Here's a nice shot of the plug coming together. I sanded and primed the 3D print with Rustoleum red v2100 primer and it bonded really well to the plastic but just didn't build high enough to fill in the imperfections quickly. I had primed and wetsanded it several times and was making slow steady progress. It was starting to smooth out nicely with just a few small low spots. I wanted to speed things up so I went and bought some Rustoleum High Build/Sandable primer and what a mistake! I sprayed on a single coat and was devastated. Even though the red primer had cured for over a 24hr period the high build stuff turned it to goo. So, I had a high build primer (that dries quickly) sitting on a semi liquid base.. As the top layer dried, the bottom layer moved and shifted with it. It ended up looking like a desert after a rain storm.. Cracks everywhere. Needless to say I'd have been better off just taking the slow and steady road haha. In the end I was able to save the 3d printed part and start from scratch with a new primer. I stayed with Rustoleum but went with a purpose built sandable primer rather than a high build/sandable primer. I finally got it close to done and started to make a new front end that will become a part of the plug out of foam and body filler (just like last time). You may wonder why I didn't just 3d print the whole thing because I have the resources and the reason is that if you look closely at any of these old fuel tanks you'll see that they are not truly symmetrical from side to side. No two tanks are exactly alike and no side is an exact mirror image of the mating side. So, I chose to sculpt and form the front end to make it look symmetrical even though it won't be rather than having a perfectly symmetrical part butt up with an imperfect one and expose the dirty details. Anyways, here's a picture of the final profile/shape of the bike at the new shop. O yeah, so in other news I finally have a dedicated workspace. No more working in a garage that's meant for cars, no more working in barns, no more moving from place to place. I finally have a spot for a while! I also picked up a 1978 GS1000E from Rexburg, ID on Sunday. It runs.. Like crap. BUT it runs! I'm stoked to start working on it when I'm done with this one.

[mikerophone]

That is a thing of beauty. Nice work!

Really amazing!
How much does it cost to produce?

That's a loaded question! haha. To me it's basically the cost of material (which can be a number of different plastics) and is relatively cheap. That's because I design, model, and act as the engineer, tech, and printer operator (or Ben). We cut the middle man out.. err we are the middle men haha so we don't charge ourselves for our time. If you're thinking of doing something like this shoot me an email and I'll give you a realistic quote. I will say I have at least 5 hours in the design of my seat cowl. As simple as it looks, it's really quite a complex part. Then add to that the print time (which we got down to about 15 hours total) and setup. I'd say it would probably cost at or around $200 to have your part drawn, setup, and printed the first time then less with minor revisions and reprints. It's pretty cost effective if you're not quite sure about what you want or if you're planning on making a mold. I can honestly say I have at the very least 50 hours in this seat mold BEFORE we did the 3d print.. If we would have done this from the start I would have saved myself so much time and headache. (not trying to sound salesmany).. haha it's just true true

2nd Iteration










Don't mind the aluminum here. It's just there to keep the part from falling since we only had half done at this point.


As you can see from the side view of the bike the profile shape of the tail section didn't change at all. In this iteration I changed the overall width to sit on the frame better and line up so the outside edge of the seat is tangent with the outside edge of the frame tube. The top view shows that I kept the overall shape as well. What I changed is the outer portion to hide the frame better and I think it came out looking pretty cool. Form follows function and this is a good example of that. Anyways, I think this is it! Time to move onto the under-butt section and then the plug will almost be complete. I'm stoked to finish this bad dude up. Once the mold is made I will probably make the final part out of carbon fiber. When I have a final part, the electronics/battery will have a home! This means it's almost time to start her up and take her for a romp. I'm beyond excited.

[John Kat]

Really amazing!
How much does it cost to produce?

3d print
















Everything came out looking pretty good off the printer with the exception of a little warpage on one of the parts. I decided to make a few revisions so the new parts are on the printer now. Update on Monday.

Click for video

Here is the solidworks model of the seat cowling. For now it's done. My buddy has two 3d printers at his house that are just big enough to print this part. We're printing it in two halves. It's on the printer now until about 3AM so as long as nothing goes wrong with either printer overnight we'll be able to mock it up and see how it looks on the bike tomorrow. It's about a 10HR print job. The longer a print job is the more likely something will go wrong so cross your fingers with me and hopefully this comes out right on the first try. The nice thing is if it doesn't fit or we need to make adjustments we just make them in the computer and print it again. Once I am left with a part I like and that fits I'll sand and prime it until it's smooth and looks exactly like the final part should. Once it's all pretty, I'll wax it and make a fiberglass mold or in other words a reverse of the part. The fiberglass mold will be nice because I can experiment with different materials (fiberglass/carbon fiber) and make multiples if necessary. Hopefully it all works out. Either way I'll report tomorrow.

The seat is under its third rendition... I'm sorry it's taking so long to finish. We're going to 3D print the seat plug this time so hopefully we can eliminate any irregularities in symmetry. I'll post pics as we starting printing it up. Brakes are bled and working great so far.

Moar!!!!!!!!!

You should sell those. Some of the nicer headlight brackets I have seen.

A little nip tuck and boom, nearly done. I knew the body filler I had was probably a little expired but I didn't realize how bad it was until I went to the auto body supply store and bought some new stuff. The consistency of the old stuff was like cookie dough where the new stuff was more like pancake batter. It was has been so much nicer to work with, but I didn't want to waste what I had left. So all the major shaping and sanding is done. I just need to finesse it a little bit, fillet all the hard edges (I don't plan on keeping it so boxy, it's just easier to shape accurately that way) hit it with some primer, and finesse it again. Once that's done I can attach this to the front section that I have already started. I can't wait to lay fiber glass on this and get the plug done! This is one of the main things holding me back at the moment because without the tail section I have nowhere to mount the battery, wires, and other odds and ends. Also the sooner this is done, the sooner I can make a seatpan and get going on a leather seat! SO close!

Yep. Joined last spring, did you guys end up riding last year at all? If this weather holds, and isn't too wet, we'll have some nice early spring riding!

I know! It's a bit weird that spring seems to have arrived already.. I only have eight days on my ski pass this season! I'm not ready for it and neither is my bike haha

Interesting idea for the seat bump, Tate. Things are coming along nicely. I just sanded my tank down to the bare metal, too. Any thoughts on what paint system you're going to use yet?

I'm not sure what system I'll be using but I'm pretty sure that will be one of the things I have done out-of-house. I'm going to go to a shop here in town that I've had to some work for me in the past and see if they can mix the color I want. If they can do it they'll be the guys. Also, since you just sanded your tank down I would look into epoxy asap. It's something I didn't really know about when I stripped my tank but it's a great sealer so it will keep it from getting surface rust. It also adheres really well to the tank steel and primer adheres to it very well. In other words, if you're anything like me and won't be getting to it fairly soon it's the thing to do so you can get to it when you get to it.

Interesting idea for the seat bump, Tate. Things are coming along nicely. I just sanded my tank down to the bare metal, too. Any thoughts on what paint system you're going to use yet?

I've been plugging away at the .. plug. It's getting pretty close. I finished the wood skeleton last night and got some epoxy on it, then spray foamed it before I headed to work today. It usually cures within an eight hour period but because I didn't put it on in layers there were still some gooey spots in the middle. If you're going to attempt this yourself you may want to check this out

Here's what I learned:

Make the slots in the wood that hold the pieces together tight and widen them up as needed. If you can nail this part it makes everything line up reaaal nice and reduces the need for clamping when you glue it together.

Definitely glue what you can if you're going to use spray foam. If not you run the risk of the foam tweaking your part as it expands.

The space you have to fill is relatively small so I'd recommend spray foam rather than filling the space with blocks of foam that need to be glued into place.

When using the foam expect at least 1" of expansion. I learned this lesson twice so I would totally nail it if I had to do it again haha. This means don't fill your skeleton all the way up to the edges. Fill it until there is about an inch from the top of your foam to the outside of your work piece. The most dense and quickest drying layer of foam is the outside. If you can nail this the first try you won't have to deal with the goo even if your part didn't fully cure. The outside layer is really workable (sandable, cuttable, etc). In other words underfill it, let it expand and cure for about eight hours, if it's not up to height that's ok. If the gaps are large hit it with a light layer of foam, if they are small just wait for the body filler.

If you start roughing your part and you run into a gooey section don't touch it! Even though it looks like a cavity that won't fill up, as long as you don't touch it, it will expand and fill itself back up. Remove what you've cut and let the air hit it. Mist the gooey cavity with water from a spray bottle and sit back for about fifteen minutes. That cavity will fill right up and cure like a champ.

A two layer process may be the quickest and easiest. If you put a base layer of foam down, mist it with water, and hit it with a dryer it should be ready for the second and final layer within fifteen minutes. Spray the second layer on and mist it with water periodically and that sucker should be fully cured and ready to shape in about four hours. If you can get it right the first time this can be an easy and fun process. Remember not to overfill and give it enough time to fully cure. If you do that you won't even have to worry about the gooey cavity stuff.

Here is what it looked like right after I finished putting the foam on. Way too much


Here is what it looked like by the time I got home...



Once I started hacking away at the excess foam these are the cavities I opened up


This side was totally sunken it and I didn't think it would cure and expand by the looks of it, but after about ten minutes I took this photo and it had already filled in



Now it's all roughed out and ready for body filler. I'm going to let it fully cure overnight rather than move onto body filler tonight because it is still expanding slightly.