Tripod exanding and contracting with 3°C temp swings shooting timelapses at 5x?

Hi. I am trying to do timelapses at 5x with a D800 and a Laowa 25 mm lens shooting at 5x. I am also using a Cognisys Stackshot rig for focus stacking, but for the purposes of this question I don't think it's important as the problem is showing up with the D800 on the rail and also it just on a tripod head.

The problem is that something in the set-up is moving up and down by tiny amounts cyclically. I set up a Raspberry Pi thermometer and the camera movements seemed to directly correspond with the house temperature, which goes from around 19 C - 22 C in three hour cycles as the radiator system turns on and off. To verify this I turned off the furnace and the "bouncing" stopped.

At first I was using an aluminum Manfrotto tripod with the Manfrotto 410 geared head. Assuming that something in the set-up was expanding and contracting with the tempearture swings, I put the camera on the concrete basement floor and did a timelapse. The problem pretty much went away.

Back on the tripod, I did some experiments to see if the problem was coming from the tripod or from the subject on a makeshift table. My experiments seemed to suggest the former.

I tried switching heads, but the problem persisted. I read about how aluminum undergoes more thermal expansion and contraction for a given temperature change than carbon fibre does, so I got a carbon fibre tripod. This seems to have changed the nature of the bouncing, but it's still happening.

Does anyone have any suggestions for how to fix the problem of temperature swings affecting equipment when doing microscopic (at 5x) timelapses? Any ideas would be appreciated, thanks.

Here's a video of a timelapse done at 5x with the aluminum Manfrotto tripod and a Manfrotto MH804-3W 804 3-Way head of the chimney in the basement showing the problem:

This is a case where the only solution is a material that is less
sensible to environmental temperature conditions, changes…
a fat, beefy legged CF tripod.

agree!

Thanks for this! 

Thanks everyone! I ended up building a very stout platform out of rocks, sitting right on the ground. It helped a lot.