Manufacturing Space Frams

[Colin]

After being heavily involved in the manufacturing of two sae cars with space frames i would be very interested to know the methods of other teams use of both jigging and fishmouthing tubes. We have used both milling and laser cutting to different degrees of success. Personly I belive that the jigging of the chassie is of great importants to the performance to the car and is a consideration often left to the last minute during the project.

Full Boar Racing

[Colin]

After being heavily involved in the manufacturing of two sae cars with space frames i would be very interested to know the methods of other teams use of both jigging and fishmouthing tubes. We have used both milling and laser cutting to different degrees of success. Personly I belive that the jigging of the chassie is of great importants to the performance to the car and is a consideration often left to the last minute during the project.

Full Boar Racing

[leclercjs]

For the jigging part, I was of the member who builted the frame this year for my team. Next year, I'm the one who will be in charge of construction. I know that a lot of the top teams in detroit used a metal jig and tried to stay it in place by putting different tube or metal junctions so the frame is exactly to the specs of your CAD drawing. Next year car jig will be constructed with this method. I think it is the most accurate way to have a frame as straigh and precise. This year, we used wood for the jig and it resultwed in a frame which have deformation and errors at certain places!!!
Not really good when you try to install your suspension mountings!!!

Jean Sébastien Leclerc
Dir. Formule SAE Poly 2004
http://www.fsae.polymtl.ca

[Frank]

colin,

the easiest way to keep it straight is use SHS or RHS for the pickup mounts, and jig 'em down to a surface....

after seeing 2 1/2 frames, i really believe its better to use SHS/RHS as much as you can, or at least everywhere you have mounts that need to be aligned

regards,

Frank

[Tim]

One word, "demmeler", these tables are the best things since sliced bread. We also have a tube notcher that uses a drill and a hole saw. It works a treat and very accurate.

But the chassis is only as good as the people who are building it

[Colin]

That dammeler table looks good, this year we welded big c section stands onto our jig table, bolted alumunium blocks to them and sent the hole lot to a cnc place where they had a mill big enough to fit the whole table on and got all our suspension pickup points machined in one go. the rest of the jig is made of lasercut plates that locks togeather.

Full Boar Racing

[JCMarshall]

I've helped build 1 1/2 chassis' One of the more straightfoward jobs I think.

Here is how we do it.
1)Pull the dimentions of each bulkhead from CAD and build each one on a flat piece of MDF.
2) Stand each bulkhead in position over a big piece of MDF attached to a sisemic block (ok my spelling is a problem), This large MDF sheet also jigs up the suspension points.
3) fill in the gaps with the rest of the tubes.

All our fishmouthing is done with angle grinders and many hours of filing, I am very picky about the fishmouthing as you should be, I only wish some of our other team members were (Sam, your 'supertube' was famously shithouse). After this years chassis construction I could write my name on a grain of rice with an angle grinder (correct spelling and all).

We tried using a 1 inch mill bit to do the fishmouthing a couple of years ago - waste of money for a poor first year team, the setup time was way to long, not to mention the tubes were just mashed (not suprising on 0.7mm wall tube, like trying to mill ally foil.)

Get a good welder to do the job, I was supprised how shit some of the welding on the cars has been in the past couple of years (angle grinders hide nothing). Also if you get a good welder there is more chance he will be able to fill the huge gaps between tubes when other team members could not be bothered doing a proper job on the fishmouthing.

Thanks,

Pat.
UQ Racing

[Sam]

Sam's super tube was a work of art. it just didn't fit properly, that's all http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Sam Graham
Engine Group Leader 2003
UQ Racing

[Colin]

I don't like the sound of MDF much, sounds a bit to flexable. we used aluminum to jig the chassie last year and this year it is all being cut by laser out of 4mm steel.
Last year we did all our fishmouths on the mill wich gave great results but was very time consuming. This year all the tube was cut by a laser cutter(we like laser cutting lots)wich seems like a resonably cheap and quick way to do it if you can get all the drawing files out alright

Full Boar Racing

[Jackson]

We used to use one of those "hole saw" jig things. They are crap -- They made the drill press vibrate all over the place.

We use a really crappy mill that we have next door for fishmouthing-- we just mount the tube in a vise, a hole saw in the mill and rotate the head to whatever angle we need.

Of course if you need angles like 80 degrees, it becomes an angle grinding job, but if you are a decent welder, that can be fixed such that nobody will ever notice.

Of course we haven't ever made a formula car, but we have had sweet baja cars for quite a few years with 1-1/4" 0.049 wall tubing.

Brian
Washington State U

[Scott Wordley]

we use hack saws, die grinders, hole saws and beer to make our chassis. we dont care if the chassis is up to 4 or 5 mm out in places so long as the pickups are spot on (+- .5mm), so thats where our jigging effort has gone. you'de be suprised how good your tube fit up skills get after getting a few chassis made. We dont bother even using a bench for a lot of it- we just check the diagonals a lot and let welder's intuition pic a weld order to pull it back square.

we just had a bit of luck getting a t-slot mackine bed (750*2400)from a factory near us for our next chassis and we're making a whole lot of jigging arms to slide around on it. A table like that usually costs about $1500-$2000 so for two slabs of beer we were very happy.

Therefore beer is the key to a good chassis.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[Mick_P]

Scott,
Dont get me wrong champ, but you dont 'care' if the chassis is out 4 - 5mm as long as the pickup points are within spec?
How can you say that your chassis analysis is representative in relation to the actual car when you add up all your 4 - 5mm errors? That could go way out of hand when you look at 20 - 30 error points that are between 0 - 5mm out...

Not having a go mate - I would never have a go at anyone who attempts FSAE, but I dare you to email Claude Rouelle your last post...... http://fsae.com/groupee_common/emoticons/icon_wink.gif

Mick Partridge
Swinburne University
2004 FSAE
Dynamics Leader

[Scott Wordley]

Firstly, Bob jumped on my computer and wrote that last post.

I think Bob gave you the wrong impression with regards to the build quality of our chassis. His main point was that he considers the location of the suspension pickup points to be most important and therefore we direct most of our effort towards getting them absolutely right.

I know that he redid some sections of the chassis several times to get them right so I wouldn't take his 4-5mm comment to literally.

Furthermore our chassis is now finished, weighs 27kg and should be good for 3500Nm/deg. I'll let you and Claude know once its tested, because we think its tops. By the way, if it comes down to a choice between finished now and out by a mm in a couple of place, or finished in a month, spot on, and costing twice as much I would take the first option any day.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[This message was edited by Scott Wordley on July 11, 2003 at 01:07 AM.]

[This message was edited by Scott Wordley on July 11, 2003 at 01:10 AM.]

[Colin]

i definatly believe that the pickup points are critical to get right. but makeing sure the rest of the chassie is right has advantage's in that things like firewall and seat that are designed in cad will still fit the car properly. The extra time spent getting the chassie right can easly be made back when mounting the rest of the components on the car. We also try and make our jigs as riged as possible to avoide weld defermation. wich can largly be compensated for by weld order but not toatly

Full Boar Racing

[Scott Wordley]

We compensate by not building directly from CAD, we usually build directly off the chassis and make minor adjustments to the CAD if needed.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[Disco]

Scott,
I've heard you guys are using a integrated sump as part of the chassis? Is this true? If so, does the 27kg include the weight on the integrated sump?
Cheers
Steve

[Colin]

scott do you find that making stuff to fit the chassie means that the order in wich you manufacture stuff is sort of set because you have to have the chassie built before making alot of other stuff?

Full Boar Racing

[Bob Wright]

Colin,

Yes and no. We make the roll hoops, put in side structure, make the front of the chassis, make the rear chassis off a jig, make engine plates then bolt front and rear together and put in the roll hoop supports and side structure. All our suspension is made off separate jigs obviously.

When I talk about not building directly from CAD I'm talking about the fiddly stuff like mounts which interact with other areas. For instance plumbing hardlines for the cooling system, intake mounts, radiator brackets, the bodywork etc. For tricky stuff like this we will always build off chassis, using CAD as a guide.

There is nothing more frustrating than building something in isolation only to find the package won't go together.

Add to that the fact that we always change our mind on stuff and it helps us to have a whole of flexibility in our build process.

Disco,
Yes we have an integrated sump this year which is getting build right now and the 27kg does include 1kg of additional weight for it.

Bob Wright
Monash University
Australia
http://www-personal.monash.edu.au/~fsae

[Erik C]

Rapid Prototype http://fsae.com/groupee_common/emoticons/icon_smile.gif

In all seriousness, I spent more time on the suspension mounting fwd and aft sub frames, then on the misc tubes connecting them. I found it easier to manufacture the smaller sub frames on a more precise and accurate jigging table then on the full size jig used for the other points. As for tube coping, I tried printing flat patterns and then using them to align the correct angles. However, after a couple of chassis, you can get close with just a paint pen and a tape measure... oh and a Wiz machine...

www.adamaircraft.com (http://www.adamaircraft.com)

[Bob Wright]

is there anyone out there who has actually attempted to add heat to a material and noticed what happened? Ive built a couple of these chassis' as well as a whole lot of other tube frame stuctures and have learned a lot of tricks to keeping them looking like you intend them- which is fair enough, but my main point was about realising where your time is best spent.

It simply doesnt matter if your chassis is out a few mm here or there so long as your pickups are right. What are you seriously thinking will happen? Do you think if a well triangulated node point moves a bit and causes the tubes going to it to missalign a fraction of a degree that its going to cause the chassis stiffness to change by any noticeable amount?

By the way, I know a guy who restores old lotus spaceframe chassis (18's and 21's mainly)which were gp winning cars and he's never seen one come out of the factory that was anything close to straight (up to half an inch in places). The old lotus factory is another good case in point with chassis and suspension jigs made up of things that looked like hacked up chipboard. Anyway the point is the picup points were spot on and thats all that matters so long as everything else is close to speck.

If your conserned about real and modelled stiffness being slightly of because chassis nodes are a bit off, then you are obviously mad for trusting fea that much and if you want to know the difference between your 'perfect' model and the 'real' model in fea, then grab the node points and move them around a bit and notice there is little if any all difference.

ps

just wondering who builds your chassis's at swinburne. I want to know what they're doing that nobody else can.

pps

laser cut tubes for a one off car- get off the bongs!

Bob Wright
Monash University
Australia
http://www-personal.monash.edu.au/~fsae

[Bob Wright]

I forgot to mention one thing. I just read (again) what mike partridge wrote from his high horse mounted atop his ivory tower and have decided to find out where he lives and run over his dog or cat in my car (repeatedly)

cheeeers, and watch your back.

Bob Wright
Monash University
Australia
http://www-personal.monash.edu.au/~fsae

[Colin]

Bob
So goiing by what your saying since you can never really get a welded structrue true to design why even bother trying. Sound's like you've got a massive case of the couldn't be F*$cked.

I never claimed we had the greatest chassie in the world but in response to your question "Who builds the chassies at swinburne", I do. I've been TIG welding for about 8 years and learnt at work from some of the best stainless steel welders around. Last year we built the chassie in 5 weeks, including jig design and manufacture and it was close enough to the design that the extensive fire wall we used due to our fuel tank location was right first time straight from the CAD model. no cutting and trimming required at all, thats just one example of how a good chassie can save you time.

"laser cut tubes for a one off car- get off the bongs!". Have you even looked into this. A good rotational laser cutter can get 100 odd tubes cut in a day with a lead time of about a week for well under $1000. and they are spot on. I don't know maybe you just really like grinders, personally i've got better ways to spend my time.

Prehaps you got the wrong impression of what i've been saying. I started this thread because i was intrested in methods of improving the speed of manufacture and quality of build of the chassie for following years. So chill out dude mo need for rudness, maybe you need another bong

Full Boar Racing

[Frank]

Our welder has passed about 200 or so AS1554.5, AS 2885, and AS 1210 coupons.

He purged the structure this year (1 inch OD * 0.7mm, 0.9mm, and 1.2mm 4130).

We didn't even bother with post weld flame relief, except in a few places, where thicker bits of brackets joined thin bits, example.. wishbone inserts, seatbelt pickups, pedal box mounts..

What the guys from UQ didn't say in the previous post is... that we use a block of concrete that has, cast into it, a large cast iron plate. The plate has slots in it ( a seismic block for mounting engines and dyno's on). It is essentially like a huge milling table, very rigid.

A sheet of MDF gets bolted to the top, and marked up. The pickups are jigged first, then the intermediate tubes get welded in place.

Colin, i'm not sure that 5 weeks is so quick... and $1000 is a fair bit of cash.... but anyhow.. out of curiosity, what file transfers do you use for these "rotational laser cut" tubes?, and how long does the data preparation take?

Frank.....AINDT Level 2 Radiographer

((That's welder's x-ray technician in case anyone is wondering.... no bongs))

[This message was edited by Frank on July 16, 2003 at 06:31 AM.]

[Colin]

Frank your welder sounds awesome way better than me, i wish we had someone with that expierence I wrote what i wrote in response to the monash bloke who replied to me as if i had no idea at all what i was on about.

In response to your question about the lasercutting the files where transfered as .dwg and it took our cad guy an day to get all the files togeather. We got a cuts done for free for sponsership but the quote we got was for $600.

Sorry mate i wasn't trying to big not myself i was just a pit annoyed about the response from bob.

look forward to seeing your car this year

Full Boar Racing

[Frank]

reply...

sorry mate, have come home from a shit of a day myself... have edited my post, this time a little more conservatively, and respectfully....

question two?.. so its a quick process to get the CAD data to them..

ok.. autocad... hmm

and i'm wondering can you do both ends at once?.. ie can it get the indexing correct?

regards


Frank

[Colin]

all good mate
our car was designed in solid works but from what the cad guy said once he had worked out how, it was really quick to unrap the tubes flat and change them to a dwg.

the laser cutter can move over a length of about 4 m so it just makes one cut at one end and then moves up the bed the required amount and makes the second cut. because it never comes out of the chuck for both cuts the orentation of the second cut is spot on. The operator then pulls the tube through the chuck for the next cut. I went out to see it and the whole process is very quick. the only problem is when really thin tubes ie under 10mm are cut as an end stock is required to stop the tube shakeing

Full Boar Racing

[Frank]

sounds good to me....

shall have to go check the process out some time

kind regards

Frank

[Mick_P]

Bob,
Settle the hell down mate. i am new to this game and was just asking a question about matching actual to modelled data. I know that there is always differences - this aint a perfect world.
Oh, and I dont own any pets so your luck is out there mate.
Its obvious that everyone has different standards when building the cars, good luck to all with whatever wy they do it. You Monash boys look like you are on the money. Hope she works out well.
Wont open my mouth again asking questions around here....

Mick Partridge
Swinburne University
2004 FSAE
Dynamics Leader

[Snow]

Bob,
I believe my good mate Mick P was saying that you guys at Monash sound like you don't care enough about this project for us to take you serviously as adversaries in this competition, and i will use last years car (although it barely ran, can we call it that :-o) as an example.
Get off YOUR high horse, oh yeah, and learn to spell, you are at UNIVERSITY are you not?
Watch your back, please, who do you think you are talking to.
To everyone else in FSAE land good luck with the car, look forward to catching up with you at this year's comp.

Michael Snow
Chassis leader
Swinburne 2004

[PatClarke]

Okay okay guys, enough is enough. Public slanging does nothing for anyone and for the FSAE in particular.
Healthy competition is a good thing, but lets keep it civilised, lay off the threats and concentrate on the job at hand.
So shake hands and come out fighting....at Tailem Bend in December !
Pat Clarke
Tech Advisor (and umpire ?)
FSAE-Australasia

Rudeness is a weak mans imitation of strength

[Rich]

Bob,
Isn't the whole point of this forum to generate debate?
The point Mick raised is fair enough regarding your post. Manufacturing repeatability wrt tolerance stackups is a realistic consideration. I'd rather have a process that'll produce an end result within as small a tolerance as practicable, especially when it comes to the time savings with supension tuning and the resultant handling quality.
Making personal threats in your last post just because someone raises a question is pretty distasteful not to mention piss weak.
Maybe slowing down on the beer might improve your disposition.
cheer

[Frank]

hmmm,

aussie holiday stress

i have the solution!!! beer and bongs !!! http://fsae.com/groupee_common/emoticons/icon_smile.gif

regards all

Frank

[Michael Jones]

Wow, the Aussies have not only taken over, they've gone completely mental. Good to see.

---
Cornell Racing
http://fsae.mae.cornell.edu

[Mick_P]

Not a big bong man myself Frank but a few beers could help the cause. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Mick Partridge
Swinburne University of Technology

[Charlie]

Too bad Michael, I think its a bad sign for us because it's probably from overwork. http://fsae.com/groupee_common/emoticons/icon_wink.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Disco]

Pat,
Can you actually lose points for bringing the FSAE competition into disrepute?

Disco

[Frank]

OMG... if you can, i'll be in a LOT of trouble

[PatClarke]

Hi Disco,
If I were a judge you would =] But in Aus I am the tech advisor, so I have no clout....well not much anyway.
Pat

Rudeness is a weak mans imitation of strength

[Bob Wright]

wow!

havnt read the forums in a while- I think you got me a bit wrong, you see: I WAS JOKING.

It just sounded a little bit patronising being refered to as 'champ', and that it was good that we were 'having a go' and all that so I responded in a way that (to me anyway) could not be taken as anything but a joke. I seriosly did not mean any of that stuff- even about the laser cutting. Further to that I have on numerous occasions commented that the 2002 swinburn car was one of the best finished sae cars ive seen.

no offence meant (quite the opposite really when you consider that i began my response by trashing my own work-which is NOT as bad as i said by the way)

I think you Swinburn guys are all right- no matter what they say. http://fsae.com/groupee_common/emoticons/icon_smile.gif

Bob Wright
Monash University
Australia
http://www-personal.monash.edu.au/~fsae

[Mick_P]

Cheers bob - i apologise if i came across a bit sarcastic.
http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Mick Partridge
Swinburne University of Technology

[eon]

struth!!! Fella goes on leave for a few weeks and the world goes nuts..

I'm more interested in the methodology of contruction than in the technology.

When building any spaceframe (ANY spaceframe buildings cars planes etc etc) you have to consider the whole "process". Depending on your methodoligy (fancy jigs simple jigs tig mig etc ) your aim is to come out with a product that is strong and within spec.

When you build a spaceframe you are building a pre-stressed frame, pre-stressing can affect variables along the lines as to wether some nodes are truly rigid or behaving more like mechanisms.

How well the frame handles load/unload cycling, torsionally rigidity etc is the main aim of this process.

We had to replace the roll hoops with heavier walled members.. (on the Steel City Racer 01). Because the chassis was built from the cab out .. we lost torsional rigidity due to the fact that the stress built in by the manufacture process was no longer present - removing the hoops had relieved the chassis.

As for accuracy ... your chassis your only reference point for everything that happens in your race car.. if your reference point is not accurate then your nothing else will be.

BTW laser cut tubes... sounds awesome!!!

Steev in da gong!! http://fsae.com/groupee_common/emoticons/icon_wink.gif

[BrendonD]

I'd like to thank the spambot for making me aware of this thread, it was really good up until the second page haha.

[Adambomb]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by marryjosephs:
According to me its a great concept where you are trying to manufacture space farms.Its very much required for animals to stay in a free area. </div></BLOCKQUOTE>

SPACE FARMS, GREAT SCOTT! I suppose dog transport would be a challenge in space. Curious what that highly specific address in the location is, I'm sure these guys are from DC. http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif

[ESaenz]

i should add this to fav things about sae... lol