I have finished tack welding the lower section. I had some frustration with the welding; I kept setting the table on fire! I was able to get all tubes tack welded, but I don’t want to have the same problem when joining the top and bottom sections. So, I raised the entire lower 1 3/8″ above the table. I did this by taking 2X4′s and cutting them 4′ long. I then ran them through the surface planner to get all pieces a uniform thickness (1 3/8″) These blocks were placed under the tubes where they touch the table and screwed down to the table. I then clamped the tubes down with blocks and re leveled the entire lower section. The lower section is now ready to be joined to the top section. The jig for that is my next step.
These two pictures show the burn areas on the table around the tack welds.
Lots of burns from tack welding.
The next pictures show how I raised the lower section up 1 3/8″. This will make the next welding steps much easier, less burnings.
You can see here how the entire section is raised off table. I simply ran some 2x4's through the plainer and than cut them to about 6" and put them at different locations to support the entire section. The 2x4 blocks were screwed to the table and than the smaller blocks hold the tubes to the 2x4's. This worked great to prevent burning and allowed welding a little farther around the tube when tack welding.
Here are a few more views of the raised blocks and the tack welding.
Less burning with everything off the table.
Center section where landing gear will attach at ends of large tube.