Sunday, December 4, 2011

Dec 1 - Cleaning and Welding the Reservoir

December 1st was another day with big plans. The reservoir tube was finally cut to spec. It was time to weld again. But first the tank needed to be cleaned out. Below you can see the specks of rust from the light rain that was falling when I carried it into the shop.

Mr. Lyons suggested that I clean off the inside with Scotch Bright. As I did, I noticed a lot of black dust coming off of the tube. It collected as a dusty shadow on the ground. I'm glad this stuff won't be running through my tractor.

Scotch Bright getting dirtier
Junk from the tube interior
To keep the interior from degrading I coated it with WD-40. This will prevent rust while I'm finishing the production.

Next I took the angle grinder to all the surfaces that I was going to weld (to take off the mill scale). Then I ground a chamfer into the flanges. This is a small angle that will allow fill material to flow between the surfaces that I will weld.

Ground and ready for welding
It turns out that professionals assemble gas tanks and other water tight things using TIG welding. TIG is a stick welding technology that gives extensive control over a weld. You apply heat and add material separately. This means that as you weld, you can backtrack and fill holes.

I decided to use TIG instead of MIG for this job. First I welded the large flange to the standoff tube. It went well except for a mild burn to my leg and a crater from my attempt to weld without any shielding gas.

The first section of the weld. The tip of the TIG gun is visible shown.
You can see that the chamfer leaves a gap between the flange and tube.
This is what happens when the shielding gas isn't turned on.
Fortunately you can weld back over the spot pretty easily.
I finished the flange and then welded the tube to the tank. I forgot to get a picture of that. I'll include that next week. I'm pretty happy with the product, the welds look good and are almost certainly air tight and very strong.

* Timesheet updated