Chassis and roll cage design, tube bending

How do you guys design your ch***is and roll cages? Auto-Cad, Solid Works, pencil and paper?

 

pencil and paper.

 

AutoCad.

 

Setting inside the car with tape measure, pencil, cardboard, tape, and yellow marking pen.

 

chalk on the shop floor.............I'm not kidding

 

That is a new one....

 

Same here. Plus, I made a protractor out of cardboard that's the same radius as my bent tube (die radius + tube radius = total outside radius), with marks on it that line up with the edge of the die. Hold it in place in the car where you want the bend, and measure the straight length from the die mark on your protractor to the floor, or to the next bend, or to the next tube. Lay out the straight leg on your tube, make your mark, line up with die edge, and go!

I think Mittler Bros (or other bender mfg) makes those protractors now, but you can make your own pretty simply, and they help a lot.

The chalk on the floor is good for laying out a big piece, like a main hoop, and making sure it's symetrical.

 

Solid works,seen your stuff at imts.Pretty nice equipment.Burl

 

The chalk on the floor works very well. I built many roll cages for offroad vehicles and that always works. They have a program called bendtec that works great also. You can build and rotate the image to see it from all angles. If you click on a joint you can print out the cut out for the notch and wrap it around your tube to get the perfect notch. Pirate 4x4 website has a great write up on the floor/chalk method. http://www.pirate4x4.com/tech/bendin_tube/

 

We use "Bend it" for Windows, available as a free download. It's about the easiest bending program you'll ever see, saves TONS of tubing from being mis-cut & mis-bent.

http://www.midmoracing.com/bendit.htm.................available here

 

I do a pencil sketch, usually to scale to give me a good idea of what I want and then I buy enough cheep muffler tube u bends to be able to build a mock up of the cage in the car. I cut and tack weld the muffler tube into the shape I am going to need bent, and make sure that it fits into the car and you only need to do the bent tubing. Then I take these muffler tube "templates" to the bender and have him make them for me in .120 wall and I have him add 12 inchs on each end so that I can trim to fit. May sound like extra work, but if you want the cage to fit really close making a tube template insures that the fit is tight and right.

Rex

 

Well, at work we spend hours on Autocad to design stuff that needs fixed by a bunch of guys with chalk on the floor.
At home I usually just go straight for snapping a chalk line down the center of the car, and go from there.

Eric

 

I bend eletrical conduit to make a patten then i copy it with roll bar tubing.

 

Must separate the 2 functions:
1. designing the structure - how big a tube, going from where to where?
2. how to make, cut & weld the tube

1. is engineering - has nothing to do with bend radius or CAD, much more FEA, and may give a design impossible to actually make or fit.
2. is fabrication only, and frequently results in a plan that p***es tech, look like jewelry, and does almost nothing else.

More: http://victorylibrary.com/brit/ch***is.htm

 

No, it's a very old one.

 

rule book in one hand and cardboard patterns in the other. Took tubing and pattern to a fellow with a bender and said bend me this with lots extra on both ends. it worked for me.
man I get nervous when i hear the word engineering. "Fabricate "gives me a much better feeling.

 

Been doing it so long that a piece of paper, pencil and a tape measure are the primary design tools. FWIW, chalk on the floor is one of the most accurate ways to "see" your design. You would have to be born before 1950 and doing cars since 1956 to understand fully.

Frank

 

Seen your equipment at some of the trade shows. Looks pretty good. Where is it made?

 

All the above (well, except the Cad part); did the chalk on the floor deal again just recently.

Depending on the application one method will lend itself better than another but they all work for me......

Al in CT

 

Depends on what machines you are talking about.

 

All out tube benders, notchers, weld positioners and power hammers are built right here in Wisconsin.

 

I use solidworks.

 

check this out

http://www.bend-tech.com/video/pro_bt_cage_demo01c.wmv

 

I usually buy about 50 ft more tubing than I need.

 

I use a tape measure and 20 years of experience.

 

That bend-tech program is impressive Shane, how do one go about getting a copy of it?

 

No you wouldn't. I'm not even using pen and paper anymore. I stick a big tape measure inside the car where i want tubes, cut a piece that long, mark center. Find center in the car, hold a test bend up where I want my tube to make a turn, measure from car center to test bend ref mark, mark that on the new tube, use by angle finder to figure how much and commence bending. Check the fit, reset centers and do it again. I don't remember the last time I drew it on paper or concrete.
Some things you just need to feel.

 

pencil and paper

 

The race car cages I have done are the conduit to fine tune tthe desing and scratch paper and chalk on ther floor.

 

Current project has wall to wall seats which required side bars start above seat shoulder, then to front edge of seat, then bent down and in to meet cowl bar. I also wanted to make sure they cleared quarter windows so I made a main hoop of 1-1/2" PVC with long elbows, then bent PVC side bars with torch and measured bend and ordered. I had to buy tubing and deliver so bender bent a s**** to determine bend allowance.