You're totally right, a chamfered edge there would make the weld a bit easier, less heat required to get a good weld. The downside is that we then move up to 5 axis toolpathing, which increases the cost and complexity dramatically. If we can get a solid weld with MIG, the only downsides are a larger heat affected zone. We decided on this going in, so I did all the chassis design and FE analysis at an as-welded strength of 32ksi. Basically, if we had done full chamfered 5-axis cuts and TIG all around, we could have made the chassis 4-5% lighter while nearly tripling both our setup and more than doubling our marginal costs.
With our frame weight, it would have saved about 8 lbs. Not including supplies, the labor and shoptime cost would require the kit price to go up to about $8k from $6k. Is 8 lbs worth 30% of the kit cost? Nah. I'll just cut back on the soda.
It's all about the big picture. We're not building art pieces that you'll never see in real life. We're comfortably down to 1500 lbs with these things, so our focus is on manufacturing and repeatable quality rather than stringing out every ounce of performance. It's not going to change the world if no one can buy it. I firmly believe this idea can be executed well enough and with enough value to see thousands produced. The UK already has ~400 Exocets scampering around since it was released in late 2010. I want to make the US version attractive to more than "kit car guys".
Whoo. All parts have been cut. Flat metal parts are bent. All that remains is the main roll hoops, which are being bent right now. The finnicky Italian tube bender needed to phone home, but we've got that figured out now.
The parts in this picture are all 101ksi DOMEX EHS steel.
Quick video of bending the front wing mounts
Sexy fab'd parts are sexy.
Wow. I'll be staying tuned for the meaty fab intensive parts. Looks so far above and beyond any "kit car" parts I've ever seen.
I've seen the "wiggle" cuts referred to as puzzle joints. They are rather common in cnc-routed plywood parts for stitch and glue boat kits, increasing glue area and eliminating the need for a scarf joint, plus self-fixturing.
I don't recall seeing it coupled with an un-cut face in a ductile material like steel, makes for a neat solution in this near-serial production.
Mr_Estrotica wrote:
Wow. I'll be staying tuned for the meaty fab intensive parts. Looks so far above and beyond any "kit car" parts I've ever seen.
That's the point. Let's bring kit cars out of the 1950s, shall we?
Keith, if you're reading this, 2147. That's how many parts I picked up today in our little boxtruck. FM and our UTCC car [u]should[/u] be welded by the end of the week. Bodywork will take a little longer.
I love that we're going to go from CAD model to UTCC car in 19 days. 
Warren v wrote:
That's the point. Let's bring kit cars out of the 1950s, shall we?
That is something that my friends and I have talked about many times. This leads me to ask about your body panel manufacturing. That is one thing that we have seen little improvement on since the 70s on my Kit cars. One of my friends has LOTS of experience with vacuum forming plastics and can't understand what anyone is still using fiberglass. This is probably a question/conversation for another thread but I am curious what you take is on it.
Jordan
singleslammer wrote:
This leads me to ask about your body panel manufacturing. That is one thing that we have seen little improvement on since the 70s on my Kit cars. One of my friends has LOTS of experience with vacuum forming plastics and can't understand what anyone is still using fiberglass. This is probably a question/conversation for another thread but I am curious what you take is on it.
Jordan
Interesting question. The vacuum formed plastics I've worked with are cheap and easy to form, but would likely loose their shape when exposed to the heat of an engine bay, brakes or exhaust.
singleslammer wrote:
Warren v wrote:
That's the point. Let's bring kit cars out of the 1950s, shall we?
That is something that my friends and I have talked about many times. This leads me to ask about your body panel manufacturing. That is one thing that we have seen little improvement on since the 70s on my Kit cars. One of my friends has LOTS of experience with vacuum forming plastics and can't understand what anyone is still using fiberglass. This is probably a question/conversation for another thread but I am curious what you take is on it.
Jordan
Your friend is a man after my own heart, and is absolutely right. Now that we have brought chassis manufacturing into the modern age, the rest of the kit is to follow. We are pursuing this, but it's realistically at least a year away. Large vacuformed panels are difficult to form properly without temperature controlled molds, and temperature controlled molds usually mean machined aluminum. Even with our awesome manufacturing connections, this would put the mold cost in the $50k-80k range. Each set of bodywork would cost us ~1/6 of fiberglass production, but that's one hell of a wait to break even. I'm certain the kit car industry still uses 1960s fiberglass techniques because you can build molds and get your first part with very little equipment and initial investment. There's not much of a guaranteed sales volume to offset large upfront costs, either. Now, the game changer would be if stepper motors, control electronics, linear actuators, etc had suddenly gotten much cheaper in the last 5 years, if you have the ability to manufacture large machines, and if you have a crazy engineer that plans to build all the equipment needed... That would be interesting, wouldn't it? If we keep selling kits at this current rate, we should be able to afford this venture. If we are successful in being able to produce bodywork in this manner, the cost would be low enough for all previous Exocet owners to swap out their cars to the new bodywork. I can't wait to see that happen.
If your friend wants to give any insight into the process or act as a mentor for the project, have him email me. My email address is my first name @exomotive.com (I don't want to type it out due to spambots).
In reply to nderwater:
Good design, heathy gaps to stave off conductive heat, good airflow to wisk away convective heat, and reflective films to reflect radiant heat are all proven in the world of vacuformed powersports vehicles.
In reply to Warren v:
warren
don't get too ahead of yourself in terms of what's being brought ahead. You have brought tube chassis manufacturing to the 21st century. And that's totally awesome. But chassis have been unibody desing since the 60's- including racing cars with composite panels. Still, for tube design making, very, very advanced. You guys may want to look into making race chassis from scratch- there is a market for that.....
For the rest- I also want to hold back how far ahead you can make this. While this isn't the leading edge of making chassis, for the number and type of cars that they are making, this is really advacing the product a lot. Going much more costs quite a bit- which is why you see glass construction in applications like this- molds are easy to make- even with a big CNC mill. Cost for the stuff is reasonable, and labor isn't too bad. Maybe the technique for making the panels can be updated- but going from that to something else could require a lot of man hours. (exactly what Warren pointed out in terms of cost).
What I warn Warren and his staff- DO NOT UNDER VALUE your time. Whoever did the CAD work in the first place so that they can be cut needs to get a huge bonus. You've already posted that you all know the skill of your welder. But to the rest- one can't undervalue their time so much that they lose oodles and oodles of $$ just to make a few people happy.
Having said that- this has to be one of the better cost projects from a design standpoint. The backbone of the chassis and powertrain was done by Mazda- and by far, that's the most expensive part. Vs. other kits- there's no worry about suspension desing, fabrication, attachement- etc. Huge time savings. So they can (and clearly have) put most of the time and effort into a very clever chassis, and a very, very elegant way to make it. It's very cool.
(Not having done a chassis from scratch, or even onto a jig- I can't imagine how many fabrication hours this saves- it's got to be enormous)
In reply to alfadriver:
Unibodies are great, but properly design tube frame with predominantly axially-loaded tubes offer 90% of the stiffness/weight ratio without the millions of dollar of tooling and development. If we were building a $100k+ car or aiming for volume numbers in the many thousands per year, a unibody would make sense. The scope completely changes from what we're trying to accomplish.
I did 100% of the CAD work myself. Not even going to add up the hours, but it's well into the thousands. Labor of love, and I do other contract engineering work to pay the bills. I also consider this one hell of a portfolio item for my design engineer career.
In reply to Warren v:
I hope the people you are working with recognize the huge effort you put into this, then. It's one thing to cad out that frame, but it's another to understand what you are going to use to make it, and then put the effort into the cad work. Just the tabs and angles are cool.
Your work is saving a ton of time and money- both to the consumer and the builders. pay yourself.
In reply to alfadriver:
I'll do alright if we sell these things en mass. I made the mistake last week of looking at a few offer letters from when I graduated last year, but I'm young and stupid, right? Might as well do what I love when I have no commitments. Startup mentality.
Anyways, my immediate goal is to get this one and FM's chassis done. Welder is working on the chassis as I type. 
The saga begins!
Dat fit:
(There are tabs at every arm of that crazily-shaped shear plate.)
...singularly sums up the exocet xp3...
I emailed my friend about your interest in plastics. He worked for Disney for a few years doing exactly this. We are also in the process of designing motorcycle accessories using sheet metal and advanced construction techniques. Got to love startups!
Took twice as long to find the damn tubes as it did to put it together. We have a designed tube rack that holds a dozen of each part number, but since we're right about to move, I don't want to put 2k lbs of steel in that rack just to take it back out. Thankfully we now have a few boxes set out for XP-3 and FM's chassis.
Note of success: we haven't even plugged in the bench grinder yet. The angle grinder was used to clean off the table. The tubes that are placed against an already-welded joint actually have cutouts for the previous step's welds.
I work at a plant that makes specialty plastics for auto industries. If you want more info let me know
Cotton
SuperDork
7/9/13 3:52 p.m.
That does it. I'm looking for a donor car.
So when do you start shipping?
In reply to wearymicrobe:
We've got a decent-sized preorder list to get through. I think our current lead time is around 8 weeks, but I'm not the sales guy. Email Info@Exomotive.com for any sales inquiries. It takes us 2 days to make a Sport chassis, which 90% of the orders are. The fiberglass work takes significantly longer. We still have yet to have a single "Base" chassis order, which makes me happy (harnesses > 3 point belts).
Not to be a used car salesman, but here's some insider info: this week would be a damn good time to get your orders in. We're negotiating with 4 different organizations/individuals that want to order 6+ cars each to start a few different racing series across the country (and another continent). Lead times will likely shoot up in about a week or two. The manufacturing process is designed to be parallelizable, but we have a lot of work to do in order to get there.
Pretty happy with the production fuel tank mounts. Simple bent parts, I actually just had them cut flat and bent them myself on our little manual brake. Three are the same cut pattern, the fourth is another. All together they weigh 0.84 lbs.
Your's truly standing on one:
The layout:
Beads:
Welder is pluggin' away on the top half. We weld the whole top half of the chassis in the jig to ensure that the subframe mount points do not shift from heat. Standard practice is to simply tack a chassis in a jig and then do the continuous welding on a rotisserie. The rotisserie makes it really easy to weld, but the downside is that you WILL get a crooked chassis. By doing the main structure completely in the jig, we get a very straight car. The previous cars have sat completely level on our jig table after all their welding was done.
