Welding aluminum screw on caps "warping"

[MoMnDadGTR]

I just got into aluminum tig welding a year ago and do a pretty descent job still very green though, lately ive been making some coolant over flows with a 1.5" screw on cap for filling, and i keep warping them and the cap wont screw on once im done welding. its a shame because i make these great pieces then i weld the cap on and completely wreck it because the lid wont screw on...the 2" screw on caps i weld i havent had an issue with them warping but once i get down to a 1.5" for some reason i warp them every so often. sometimes they dont warp sometimes they do, i realize im self taught and am propably missing something....any tricks from the mates would be appreciated? im using all vibrant pieces for my fabrication fyi. cheers mates

[MoMnDadGTR]

this is a picture of what im doing, thats the 2" lid sitting on top in that picture but im trying to use 1.5"....
 

[robbo_rb180]

I've had the same problem with small pieces too and found doing shorter welds on opposite sides and letting it cool abit before starting again.

[MoMnDadGTR]

On 17/01/2022 at 7:06 AM, robbo_rb180 said:

I've had the same problem with small pieces too and found doing shorter welds on opposite sides and letting it cool abit before starting again.

Thanks good buddy. I tried this today and it worked great. Your a good mate.

[MoMnDadGTR]

This was what it turned out like. Definitely letting the piece cool down lots between welds and cranking my heat worked well for me...cheers mates. No more warping for the maple leaf warrior!!!!! 

[robbo_rb180]

nice work.
What thickness material you using? 

[MoMnDadGTR]

On 18/01/2022 at 4:31 PM, robbo_rb180 said:

nice work.
What thickness material you using? 

I have been using a few different sizes, I started with thicker stuff when I was learning but now that I’ve tried a few different sizes I prefer the 2mm stuff as it’s quite a bit lighter than the 2.5-3mm stuff I was using and it still plenty strong enough for little trinkets like catchcans/ over flows, power steering reservoir etc. Intercooler pipe is 2mm thick as well that I use.