CAD Forum

Hi all,

This is an ongoing issue I have been encountering over many years.

What is the best way to model a frame for a race car chassis.

The way I've seen it done for over a decade is a 3d sketch driving a bunch of manually inserted parts (tubes). Usually a master tube is used to make the process a bit faster. That master tube is inserted for each tube centerline from the 3d Sketch, and uses the sketch to drive a profile. It also takes the file name and there's a feature that "cuts" that into the tube a few inches from one end. This will be straightened (unbent) by a laser cutting company with a program called Tubeworks or something similar. They will process the tubes to make them "laser ready" (normalized). Usually ensuring the part number feature is etched into the tubes and not cut.

Its always been a time consuming process and when I had first encountered it I thought there's got to be a better way. I eventually stumbled into Weldments and thought AH! This is the solution. Yet, that wasn't the case as it seems there is not a great way to get that part number into the side of each body. But I don't know that for sure.

Can anyone with insight on this issue, or with a lot of experience with weldments share their opinions... I have long thought Weldments was the solution to all the issues surrounding designing and manufacturing chassis... But without a way to link the bodies to a part number where you can have it etched into the tube when its being cut... I don't see this being a viable option.

*Note... chassis assemblies can have a hundred tubes, many of them being mirrors of the other side. And potentially having a dozen different profiles (diameters, wall thicknesses).Keeping a link (traditionally a etched part number) between the physical manufactured tube and the CAD model is an absolute requirement so that engineers, designers, manufacturers, and fabricators can all be on the same page.

Hello, and welcome to the forum. I use multiple body weldments often, and agree that would be a great option if it wasn't for the etched part number requirement. I just did some quick checking, and while I often assign "body name" cut list properties, I can't find a way to link to cut list properties with sketch text.

While I don't, many users model multi-body Parts and then break them up into individual Parts later. Doing that might be an option since you could then have the part number as a custom property and link to it with sketch text for etching.

Hopefully someone smarter than I am will have a better idea.

I don't know much about cars, let alone race car chassis, but if I had to model one, I would most likely proceed in a similar approach you spoke of.

There are a bunch of things you need to determine. Details are one of them, how much detailed do you need it to be, per say.

If I were to give it a try, I would create a part that would contain a 3D sketch of the "chassis".

I would then insert that part into a new part to build the tubular part of the frame and use the strength of the multibody environment. After that, it's free game pretty much.

The reason I would keep the sketch in a seperate part from the chassis is to keep the Skeleton Sketch as light as possible so that if/when it does require to be inserted it doesn't carry a load with it.

If possible, use 2D sketches instead of 3D. It'll be more stable.
It may not matter for round tubes.

The "weldment" is not really for welded assembly. More like building a frame from structure shapes (pipe, tube, channel, I-beam etc).
It is quicker to get a frame, mite and coped. As long as you don't need to add and remove "member" often. SW love to forget part order and all those miter and cope will go crazy.
You can use it as multibody.
You can also save every piece out and reassemble.
You can do it somewhere in between.
It'll take some time to learn how the software works and doesn't works.