warping of chassis

[paul dae]

our chassis last year was made using a fixture table. Will cutting pipes on this chassis cause it to warp?

[MikeSadie]

If you stress relieved the welds, it shouldn't much. If the frame is as-welded, it will most likely warp. However, it is impossible to guess how much. Try constraining the area you are working on, and take note of how it warps, so you can account for it when welding new tubes in.

[Ppada]

If you chassis is stiff enough and you cut a tube and weld an other one before you cut the second then it should be ok.
Also if you had accuracy in your fixture table then it should be ok too...
And for last...
Weld the new tubes before you cut the old ones.

[paul dae]

how exactly do you stress relieve the chassis?

[Ppada]

With heat treatment depending on the material and the welds.

[Bazanaius]

I'm interested in how teams actually heat treat their chassis. What I've read on the topic suggests the piece needs to be heated in an oven-do teams actually place their whole chassis in an oven, or do you heat treat the welds as you go along? If so, what method do you use for this once your chassis increases in size?

Cheers, baz

[Drew Price]

You need to look at the difference between solution heat treating the welded frame, and post-weld stress relieving the frame, also known as annealing.

Annealing means you just have to heat the heat affected zones up to the critical temperature, which can be done with an oxy-acetylene torch and a way to measure the temp of the material (temperature indicating liquids or crayons, IR thermometers, etc.).

Solution heat treating involves achieving some temperature or series of temperatures, and controlling the heating and cooling rates, which will require special equipment, usually in the form of an oven.

Treating it all at once will also require a jig stiff enough to resist the frame relaxing as it's heated. Torch annealing you can usually get away with clamping to some simple reinforcements since you do one joint at a time without too much distortion.

This is a complex topic which merits some time with the search function. Old posts by Jersey Tom on metallurgy and welding and such are excellent reads. Read them.

Best,
Drew