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How do laser-accurate parts attach to a hand-welded heat-warped chassis? If rivet holes are added in the panels and tubes I don't see how they'd line up. Even with a jig, it's likely that the chassis's off up to 1/4", a big reason race cars use rod ends. All that accuracy seems like it's not applicable to a hand-welded chassis. How is this not an issue?

Even if rivet holes aren't added, it still seems like panel edges and chassis tubes are never going to quite line up parallel. Has anyone tried hand welding and riveting a complete laser-cut chassis and panels - and not using a 10-ton chassis fixture?

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Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

Interesting questions. I wonder if you included laser cut gussets with holes for pop riveting, to jig the chassis for tack welding? Maybe not practical, but might be worth a shot. Many of the gussets could be put back in and welded when the frame was completed.

Getting the kit this way and knowing things are accurate, would free you up a little bit to take more care on the weld up to get an accurate result.

I think there is also a bit of an answer in your question:



Someone is selling "flat pack" chassis kits on the UK site, I think we'll soon start hearing if they work. I have also seen people say they got their chassis within 1/32 inch, front to back. "With adequate care"...

I wonder how a robot builds a complex 3d shape like a space frame? I suppose they have an advantage because they can have three hands? Does it sort of force alignment of parts as it goes and know how to keep things true?

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
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All questions I will be asking next week. I was just "ass-uming" they were talking welding with greater accuracy due to the robot.

My smartalec response ("Indeed it is") to the...
>They say they can hold .001 tolerence which would be too good to be true.
...comment was a reflection on the technology of welding, not the technology of laser cutting. You're not likely to be welding these pieces together within a thousandth. For what we're doing, it's not that laser accuracy is too good to be true, it's that it's too good to be a factor. I've never had a piece come back from the laser shop that didn't fit, unless I'd screwed up the drawing.

I've stopped writing tolerances on my CAD files for weldment parts, 'cause when I'd write plus-or-minus-a-hundredth the laser operator would say, "Sorry, we don't have any way of cutting anything that sloppy."

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Locost builder and adventurer, and founder (but no longer owner) of Kinetic Vehicles

There is an old saying that if something sounds too good to be true it probably is. I would guess that you were talking with the salesman who was ezagerating just a bit. They would probably have a week into setting up the laser and welder not counting the construction of a Jig.

I worked in manufacturing for 35 years many of which was consulting and also part owner of a fab shop. One of my employers was having thier lunch eaten by the Japanese in bidding wars where they would get underbid. My response was to play name that song with them. Bid to the point that the project would be a loss then let the compitention get the contract. After a few of these bids would be more realistic, but keep in mind that you might get to eat one of the bids.

They would need enought time to develop a jig to insure squareness, which is generaly a tooling cost. If they can insure .125 tolerance from any one point to any other and that all tubes remain straight with a reasonable cost (less than $1,000) and build in a penalty for late delivery I'd say OK see you in a week.

This is tha basis for my frame jig which includes 40' of heat treated 4" I beam. Then you need to build fixtures to add to this.

What's a flat pack chassis?

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JSullivan

It is a bundle of all the chassis tubes precut to the proper sizes and ready to assemble.

I'm getting things a bit mixed up. If a company builds a big-ass fixture, I take back what I said about weld distortion. But if they're selling these "flat packs" kits to garage builders, I can imagine the yelling from builders who call, saying that the kit is crap and nothing fits. Then, the company says, "No, everything is exactly perfect; when we weld this exact same set of tubes <cough> in our 20-ton steel fixture <cough> everything fits perfect. It's your fault you can't weld accurate."

That's the kiss of death for a business, telling customers that it's their fault. (I'm speaking in general and don't mean my rant is pointing at any specific company.)

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

To help aleviate the problems KB58 brings up I would suggest a rather lumpy flatpack. Fully assemble and weld the top rails and bottom rails as well as any crossmember you can to allow easier setup by a novice. Pissing matches with customers in paticular in a community that corresponds as much as the 7s is a good way to become an ex company.

Look at the tailgate on most pickup trucks to see how it's removed. You open it to about 45* and lift the right side and slide the left side out of it's socket to remove it.

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Bill

Now I understand, thanx

What I was thinking about is pictured in http://locostusa.com/forums/viewtopic.p ... 0&start=15
by cs3tcr

Hi, i found this thread through google and was wondering how the American mongoose was coming along?

My names Craig and i'm building a Onyx Mongoose here in the UK. I got it to a rolling stage at the start of 2008 but due to buying a my first house with my fiancee I sold of a few parts to pay our solicitors fees. The parts being the engine and chain diff lol. and the car has sat in my new garage since we moved in last september collecting dust.

This is how it looked before i sold the engine.





It now looks a bit crap lol



There is good nes though as i have now bought an other ZX10 engine and i am now building a new LSD chain drive for it





Im hoping to have it back to a rolling/drivable stage in the next few months.

Few pictures i took of Onyx's own mongoose at a hill climb in 2007.

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WWW.ONYXMONGOOSEZX10.BLOGSPOT.COM

It's nice to see the interest.

Well, I am sorry to say we've had some set backs. My partner was killed in a car wreck which really put a damper on things. The economy hasn't helped either.

I have almost every facet of the car Americanized tho. I've made multiple changes to accomodate the parts we can get over here and to incorporate a cage-like structure so that the windscreen won't mousetrap on you in case of a roll over which also has the advantage of meeting the dreaded "broomstick test" by SCCA.

I'd really love to see some more detailed pictures of your car as we've been unable to get many pics from the original designer. There are many little spots that the plans don't show or don't show clearly. I have only the pics of his final car which was modified to meet a client's desires.

Interestingly enough the engine is the part that has changed the most often. We simply don't have any newer (as physically) small engines available over here with an inexpensive upgrade path to get us to the 140 hp mark as you do. And don't even get me talking about the price differential on engines over there vs. over here! It's the biggest cost differential in the car.

The D series Honda is very nice, but OLD and usually requires an expensive rebuild to be usable. The newer R18 engine is very nice, but has no upgrade path. The B and K series Honda engines are big and heavy. If we were to go there we might as well go to the Ecotec which has an upgrade path much further than any sane person needs and is available worldwide. In other words, the "stock" engine is still a toss up.

The car is physically bigger by a small amount to more easily fit 2 people and possibly fit a larger engine. I still haven't given up on a longitudinal mount engine, I just haven't found a way to do it inexpensively or without expensive adapters. Transverse is fine, I just think for the ultimate a longitudinal mount offers some advantages.

This site has been a wonderous help. Many of the little nit picky details have been solved by others. We've moved the steering column and steering rack up high which made for a more simple and cleaner path plus bought some toe room. This also makes for an easier conversion to right hand drive, left hand drive or center (single driver) .

Did you ever get to drive yours? About the only thing we've kept unchanged is the suspension. If you got to drive yours what do you feel were the suspensions shortcomings? What would you have changed?

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mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

I'm very sorry to hear of your loss. There is never an easy way to deal with it but i hope you are doing well.

Just let me know what pictures you want of the chassis and i will take them.

Have you considered the ford zetec engine? or the newer duratec? Zetecs over hear are very cheap as they have been going since about 1994. I know you guys have the focus over there but not sure what other small fords you have. Bike engines are an easy route to go as they are cheap and very compact and its very easy to make a reverse using an old starter motor. The engine i am using is a 1989 kawasaki zx10 with 137 bhp de-restricted. I picked it up for £80 bout $140-150 i think it works out as.

I never drove the car as i didn't have drive shafts in but i'm hoping it will be drivable before the end of this year.

Would also be nice to see some pictures of your mongoose. Have you bought the rights to the mongoose or just a kind of licence to build them in America?

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WWW.ONYXMONGOOSEZX10.BLOGSPOT.COM