Making gussets

How to make FIA roll cage gussets.

Tools needed:
Jigsaw
power drill
Sheet metal sheer
Punch
pencil
graph paper
scissors
sharpie
welder
hammer
hydraulic press

Material needed:
36"X36" 18 gauge sheet metal

See the below diagram. Figure out what dimension you want for one of the distances based upon the angle between the bars to be gusseted.

For mine I chose to set the hypotenuse at ~5" for the 80 degree and 100 degree junctions. For the door bars I used around 7" for the hypotenuse.
The formulas for the remaining dimensions:
width = 2 * hyp * sin (angle/2)
height = hyp * cos (angle/2)

Once I had all the dimensions I drew out a template using graphing paper that was 1"X1" with 1/8" inner squares. Basically drew a line for the height, equal out each direction for a line for width. Then connected to outers. Draw a straight line down 2.35" and connect, that's the width for the bottom. Then mid point and go down to height. Connect and you have a template. The arc is going to vary for each. I used a spray paint can for the 80 degree gusset and a bondo can of around 8" diameter for the other two. Cut out the template and test fit it to your roll cage.

Decide where you want to have the center of the hole for the punched flaired hole. I did around 2 1/4" from the tip on the 80 and 100 degree gussets and aroun 3-4" on the 30 degree gussets. Mark and put a small hole through there on your gusset.

Draw out on sheet metal from your template. Remember if you draw many of them, to account for the width of the blade on the sheer between lines. Make sure to mark the center point for the punched holes. After you have all your gussets made up, drill all the center holes with a 1/2" drill bit.

Cut all the gussets out with the sheers. Use the hydraulic press to punch and flare the holes. Use your muscles to bend the sheet metal around a bar. I used a door bar that wasn't gusseted yet. 100 degree gussets will not bend fully around the bar once punched. This isn't a big issue.

Test fit to the junction to be gusseted. If you're doing all four on an X, likely two of your gussets should need trimming. Weld starting at the arc and pounding the gusset to close enough to weld. Weld for days to do the required number of gussets on a full FIA roll cage. If you want to skip all the previous steps and just jump to the fitting of the gussets and welding, check the for sale section. Also Tim Taylor makes some much nicer looking gussets than mine using more proper tooling so there may soon be a real retail outlet for his gussets as well. I don't really like making these and really don't like all the welding time, which is why I've offered them up for sale at or around what I would have been willing to pay to have someone else do them for me. Here's links to tools.

http://www.mittlerbros.com/Punches.htm
I used their 1 1/4" punch and flare with a hydraulic press. Got a different bolt that wasn't threaded and smoothly went through and put the whole setup on an old wheel bearing.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92115
It's Harbor Freight but it's worked well enough for me for 4 cars worth of gussets so far.

My ad on specialstage. There's a few more pictures there as well.
http://www.specialstage.com/classifieds/showproduct.php?product=353

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Grant Hughes

Hey Grant - Nice write up. Could you use a 1 1/2" punch for the holes or would that be too big? I ask because I picked one up from "IKEA" (yes IKEA of Sweden- no joke) for $7. They sell them for use with their stainless sinks.

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Scott Manley
Spokane, WA
86' XR4Ti
37

Sure. I'd not be worried about using a 1.5" punch. Just account for it by moving the hole a bit.

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Grant Hughes

Yup, they're miserable when they don't fit properly. Try this pattern for 100deg joints...it will work much better. Just change the scale on your print output until the 6" reference line measures correctly (it fits on a normal 8.5 x 11 sheet). If that doesn't work then just e-mail and I'll send you a .pdf that's full size.



I'm not planning on making anything other than 90deg joints at this point. I'm happy to make some .pdf drawings of other angles if the mods. want to host them in a hidden section like the escort prep manual. I'll even make the RA watermark in Kawasaki Green...

Tim

Here's a python script that uses cairo to render templates using this method: https://github.com/abstrakraft/gusset/blob/master/gusset.py.

The constants describing the template are near the top.