Laser cut chassis tubes

[James-H]

We here at Manchester are currently looking at getting our chassis tubes laser cut for this year. Contacted a few companies who say that they require paper drawings of unfolded tubes or the same in a dxf format. Has anyone had any experience with getting tubes laser cut because we're not sure if this method will work? Surely a CAD file will be better to guarantee correct alignment of the two profiles relative to each other?
Are we better off finding a company that accepts a CAD file or does the unfolded tube method work just as well?

[Jersey Tom]

Many companies work off electronic drawings.

Iowa Laser works directly of Solidworks models...

[Mike Macie]

Places that accept CAD files usually charge an extra processing fee to convert the files to the format they desire. With a chassis these fees can be quite high. Unless you are confident in converting the files correctly, I would recommend providing a CAD file as it leaves less room for error on behalf of your team. This is one area I don't mind spending a lot of money on because it saves so much time.

[James-H]

By CAD file do you mean the solidworks/ProE (or whatever) file or the .igs or .sat file-the raw CAD data?

Cheers for the help.

[Mike Macie]

Originally posted by James-H:
By CAD file do you mean the solidworks/ProE (or whatever) file or the .igs or .sat file-the raw CAD data?

Cheers for the help.

I mean the solidworks/ProE part or assembly file. It all depends on the company your dealing with though.

[James-H]

Thanks again.

[MikeSadie]

A team alumni made a plasma tube-notcher and we used it last year. A flat pattern makes it much easier to run because the controller can easily interpret the dimensions as length vs angle. However, flat patterns were a PITA in solidworks; had to slice the tube lengthwise and unfold it using sheetmetal tools. We never had problems with misalignment or anything, and overall saved a ton of time and material over manual fitting.

[jrickert]

What size wheelbarrow of money does this require? Notching tubes by hand is something so miserable that surely it must be against at least a few international treaties...even for newbies.

We have long fantasized about the day when no more tube notching was required but always to scared to call and ask.

[Mike Macie]

Originally posted by jrickert:
What size wheelbarrow of money does this require? Notching tubes by hand is something so miserable that surely it must be against at least a few international treaties...even for newbies.

We have long fantasized about the day when no more tube notching was required but always to scared to call and ask.

Our team got a quote close to $3000. I think it's almost half that if you provide the correct drawings.

[Wes Johnson]

We were quoted $1500 by providing the proper dxf's.

-Wes Johnson

[Maverik]

How do you humble your freshman without manual tube notching?!?

[Mikey Antonakakis]

How do you get freshman to commit to the team?!?

[Mr. White]

Our chassis tubes are laser cut by an italian company for few money. Here are some pics..

http://farm4.static.flickr.com...8_0238b1f37c.jpg?v=0 (http://farm4.static.flickr.com/3070/2548195118_0238b1f37c.jpg?v=0)

http://farm4.static.flickr.com...8_d2d04e9f09.jpg?v=0 (http://farm4.static.flickr.com/3099/2548195438_d2d04e9f09.jpg?v=0)

http://farm4.static.flickr.com...8_58c210670d.jpg?v=0 (http://farm4.static.flickr.com/3018/2548195718_58c210670d.jpg?v=0)

If you are interested, we can provide the company contacts. Just send a PM to info(AT)firenzerace.it
See you..

[Wes Johnson]

Originally posted by Maverik:
How do you humble your freshman without manual tube notching?!?

Intense, grueling sessions of manual, slavelike labor.

But seriously, getting the tubes laser cut saves a heap of human capital and opens up feasibility in a lot of side projects, aka we've been doing new component and development testing on our 2008 car since the summer and will have two tests planned over winter break. (It rarely gets below 30F in SC).

-WJ

[Drew Price]

Mr. White,

Those self-jigging tabs are seriously sexy shit, I had not seen that yet. Very cool.

It was cool to see your car at West in '07, I was hoping that you guys would make it out to the U.S. again before I graduate, but it's looking more and more like I might get to graduate. Hrmph.

Best,
Drew

[Chris Lane]

Less than AU$500 for a good Tube Linisher and a few different size rollers and some spare belts. You'll be able to make a chassis of equal quality to a laser cut job. A bit more time is spent here though, but not a lot if the designs are done properly.

I however can understand teams would resort to the laser cutting method if their Uni's Health and Safety rules prohibit them from having this fairly scary piece of machinery.

[Mr. White]

Drew,

FSAE West was a great experience for us. We would like to come back there, but it's so expensive..

P.S. the tubes in the photo (84 tubes in total) were cut with less than 1000$, and the assembly was a child game

Regards

[James-H]

Self jigging tubes is an amazing idea.

How did you draw the extra tabs on the end to make them self jigging? Were they all done individually on each tube?

[Mr. White]

Yes, they were done individually.. You will spend some more time in design, but the savings in assembly time and the final dimensional precision are surprising

[Kurt Bilinski]

Does self-jigging really work? Welding heat distortion is a serious force to be reckened with. I've been welding on one end of a chassis only to hear a loud "Bong!" when a tack-welded tube lets loose somewhere. Once that happens the chassis isn't true.

I can see it would work great if the chassis is bolted to a 10,000 lb chassis plate, but the idea of self-jigging - by itself - seems very dubious. Has anyone taken a set of laser-cut tubes, tack-welded them together, finish-welded and really had it turn out square?

Simply welding on one side of a tube will result in the tube bending toward the weld, lifting each side several degrees. If any part of the chassis moves during welding, and every tube isn't already in place, it seems like have 0.001" accuracy in tube length isn't going to help if heat distortion means there's 0.073" less space for it to fit into.

I'm just trying to get a handle on whether self-jigging is as brainless as advertised - guess I'm skeptical.

[Drew Price]

Kurt, you're exactly correct. You can see the jig plates / fixtures holding the joints in place during welding, I am sure they just didn't up photos with everything clamped down.

I would never try to use those tabs alone to hold the structure, but it allows you to avoid having to do this (TU Braunschweig), with a structure to hold the tubes in place:

http://www.lionsracing.de/index.php?option=com_ponygallery&func=watermark&id=1285&orig=0&Itemid=32%27,%27saison_2007_lr07_rahmenfertigung_0 01%27,%27Rahmenfertigung%27,%27600%27,%27449%27


It lets you put the frame together and then use 90* angle plates, or clamps and paralells or whatever to put the jig together around the assembled structure, like in Firenze's 3rd photo, with the red block:

http://farm4.static.flickr.com/3018/2548195718_58c210670d.jpg?v=0


You'd never maintain good alignment with just the jigging tabs, but you should be at least torch annealing welded 4130 tubing anyways, and if it stays clamped when you do it you releive almost all the residual stresses from welding and everything straightens back out.

With a cool puzzle-piece jig like TU Braunschweig's you could use that whole assembly to send the frame out for heat treat too, just clamp the frame into that assembly.

Best,
Drew

[Kurt Bilinski]

Thanks, Drew.

Reason I ask is that in the Locost community (homebuilt Lotus Super 7 knock-offs) there's a perception that getting everything laser-cut is some sort of magic bullet for an accurate chassis. Well, it is, before welding starts. It's guaranteed that home-builders aren't going to jig the chassis or do any post heat-treat, either. Thanks for confirming that; without the other two steps, it's a waste of money.

[Drew Price]

Ahh, I haven't been following any of the Locost forums in quite a while, and hadn't seen any of that.

I always considered it as a killer way to save lots of time, and to do a nicer job with joint design, really easy to do complicated junctions at nodes if you aren't having to form the edges manually, or even in some sort of mitering saw. You can have everything come in on nice sharp corners:

http://www.lionsracing.de/index.php?option=com_ponygallery&func=watermark&id=1289&orig=0&Itemid=32','saison_2007_lr07_rahmenfertigung_006', 'Rahmenfertigung','400','400'

I don't think that having the tubing cut on the CNC laser is by default going to be more accurate, it's just that to get the same accuracy with other methods there is a significan time input. I always loved this photo of Helsinki's of the box full of tubing fresh from the laser house, it's a 'race-car-puzzle' kit! Just assemble, and weld up the seams, and you've got a car!

http://www.metropolia-motorsport.fi/HPF008_Making_of/album/slides/IMG_5839.JPG

http://www.metropolia-motorsport.fi/HPF008_Making_of/album/slides/IMG_5875.JPG



Best,
Drew

[Mr. White]

Laser cut is not for self-jigging.. it only helps jigging!

[PuJa]

We got our tubes back from laser cutting a while back now. The chassis was designed in SolidWorks using the weldment feature...then the tubes were individually unwrapped and saved as dxfs before being sent off for laser cutting.

When they came back they were all right...the only problem was that they did not fit around each other as beautifully as they did in SolidWorks. So out came the dremmel!

We've established that the problem was that we did not take account of the tube thickness in SolidWorks...does anyone know how you can take account for the thickness in SolidWorks (or if you even can) when you are using the weldment feature tool? Just so that the same thing does not happen again.

Overall the idea's worked very well and has saved us a lot of time.

Thanks http://fsae.com/groupee_common/emoticons/icon_smile.gif

[vandit]

i dont have much idea about weldment feature in solidworks ..... we use CATIA , and first we make a surface sweep along the line model of chassis..... then we give thickness option to surfaces already created.... i think there should be such option in Solidworks also ....

[PuJa]

Thanks shanky...I'll investigate that in SolidWorks!

[overdrive535]

PuJa, what did you spec your tolerances at?

[Wes Burk]

Our tubes were CNC cut for $1600, including material and a lot of bends in the tubing (which was a major part of the cost) by Cartesian Tube in ON Canada. http://fsae.com/eve/forums/a/t...25607348/m/431100411 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/431100411)

[Bazanaius]

Sorry bringing up an old thread here - but @PuJa:

I'd guess it would also depend on what setup the laser cutter has - if it's a 4 axis lathe setup then they may be able to do the cuts parallel to the tube you're trimming around (if that makes sense) and so the end will have a varying thickness that should slot up nicely to your other tube.

If they simply follow the profile and cut perpendicular to the tube surface, then you'll get the thickness issue, and as you rightly suggest you'll have to allow for the thickness of the tubes.

Did you ever find a convenient way of doing this in solidworks?

B

[James-H]

we did find a solution at Manchester-use a Laser Cutter with a few more axis. Should be getting the cut tubes back by the end of the week so we'll see if there is any improvement on last year!

[Dan B]

Originally posted by Bazanaius:
...If they simply follow the profile and cut perpendicular to the tube surface, then you'll get the thickness issue, and as you rightly suggest you'll have to allow for the thickness of the tubes.

Did you ever find a convenient way of doing this in solidworks? See my post at the bottom of the thread here:
http://fsae.com/eve/forums/a/t...25607348/m/193104413 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/193104413)

[Muad'Dib]

We got our tubes laser cut by Carrol Racing Development in California. They turned out pretty nice and the price was very good. The total cost was about $1200 including material and getting the rollhoops cnc bent. We had to prepare the solidworks files for them ourselves, they had instructions on what to do which were pretty good but I have to say it was one of the most frustrating processes I've ever gone through. It did take longer to get the tubes than I would have liked, especially because they didn't seem to realize that they were responsible for their supplier's slow downs but considering that the price was right and that they came out well I can't complain.

[Wes Burk]

For anyone looking to get a chassis kit outsourced, talk to Cartesian Tube Profiling in Ontario CA. We got our first kit for $1600 including everything, fit together like a puzzle. An estimate for our next chassis would have been $950, bent tubing costs by far the most. They have worked with SAE teams and wave their $1000 prototype fee for single time stuff like this. Cool guys.

[Wes Burk]

Oh year and Cartsian works directly from a SolidWorks model of the chassis, you dont need to do any work as long as your model is correct. Took them 1 week to get it read for us.