Building the Chassis Jigs

Scrap Jigs

First "professional" jigs

Because this looked like a lot of busy work, my first thought was to have the chassis jigs built by a local machine shop. So I bought the metal and had it sent directly to the machine shop and went over the drawings with them. They kept asking me how big various things were, when the dimensions were clearly right there on the drawing. Then it became clear they didn’t know how to deal with dimensions in meters. They asked me how to convert a dimension from meters to centimeters. “You mean like move the decimal point two places to the right?”, I’m thinking… This was not looking promising. Eventually I went home and tried to come up with a set of orthographic-projection drawings, with hidden lines removed, that they couldn’t possibly misinterpret. I soon gave up. When I went to pick up the first two jigs the next day, the list of errors was long and creative. Mounting footprint on one reversed, vertical tube holders cut too shallow and not in line, overall height incorrect, horizontal alignment out of spec, etc., etc.

Sigh. I called a local aerospace-engineer type that I know and asked him if he knew a good machinist, and he directed me to a local guy who I visited the next day. We met a couple of times and he is indeed capable of handling the project; in fact, I decided it’s really below his capabilities and ended up building the jigs myself, saving him for building actual car parts.

Cut Pieces

Lots of cut pieces waiting for welding, drilling, & milling

I needed a good, strong right angle to hold the pieces in place while welding. The bandsaw table served perfectly.

Welding Jig

Welding the angles onto the uprights. Chassis table is very useful here.

Drilling Crossmembers

Drilling the chassis table crossmembers on the milling machine.

Trial Fit

First trial fitting of the chassis jigs onto the chassis table. Top rail guides not yet cut; other tube guides not yet in place.

Welding Verticals

Welding tube guides for vertical tubes. Sample tube keeps things in alignment, along with very careful tack welding.

Jig Set

Almost-finished complete set of chassis jigs

Subframe Pins

Chassis table crossmembers were drilled for pins to hold front subframe during welding.

Stretched Bolt

3/8" bolts should be tight. But not this tight.

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2 responses to “Building the Chassis Jigs

  1. Hi mr. Ludemann,

    I am a student engineer from Canada and I am also a member of my school’s Formula SAE team. Formula SAE is an international open wheel racecar competition between colleges and universities. For more information please refer to http://www.fsae.com.

    This year we are building a tubular spaceframe for the first time and we are interested in building a welding jig similar as the one you used for your F1000 car. I would appreciate if you could tell us what were the positive and negative points about the jig you used and if you have any tips to give us to help us make a good tubular chassis.

    Thank You

    Denis Latulippe
    Formule Polytechnique Montréal

    • The positives for my jig table are that it is easy to build, rigid, straight, and has adjustable leveling. One thing that I would consider doing differently is making the main table able to rotate about the longitudinal axis. This is because I’ve found welding upside-down is nearly impossible, and yet I’d like to be able to weld the bottoms of the joints while the car is still fixed to the jig table. To do this, you’d have to make the main table frame out of closed-section, or box, tubes to get the torsional rigidity you need. Also, it would be difficult to get that table structure perfectly planar. Somewhere on the web I found someone who did it this way.

      -Jim

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