Well, I didn't fall down a well, I've just been sidelined with a couple of items including one significant change to the tunnel structure. I started on the tunnel next because it was: 1) about the most complicated substructure in the vehicle; 2) in the middle of the chassis and hard to get to once the side rails were up; and 3) I thought it would stabilize the un-welded chassis once removed from the build table for final welding. The idea was to fully weld it up outside the chassis and then put it in place and then weld fully to the lower crossmembers at front and back.
As I started to build the tunnel, I found some members had too many complex angles and required finer cutting on the bandsaw than was really practical. Some of the RHS joins had to be cut, ground or filed appreciably by hand and I decided to redesign and simplify the structure excepting the bottom rails, which were already completed.
Redesign really meant doing a new model in 3D because I no longer had a license to the software product I used for the original design. It also meant developing some new techniques because the old software handled RHS and tubular materials extremely well, but the new software does not and has no facility to build space frames at all, unlike the first software used. Long story short, I took quite a bit of time to do the above along with handling some real-life interruptions to do other family-related things.
Attachment:
Small-2nd-Gen-Tunnel-ISO.png
Age does bring some degree of caution based on experience. So, when I had the narrowest part of the new design tacked together, but not tacked to the lower (old design) bottom rails, I decided to revisit the folks at Oceanside Driveline to make sure I could get the drive shaft through from the back. I'm sure glad I did. We took a new spline and yoke, the parts I'll need to use for real, and tried to put them through the redesigned structure. There was about 0.030" extra clearance on one end and about 0.040" too little on the other end. I can't make it wider without going past the outside faces of the already-built lower rails, which would cause problems with the sheet material for the sides when affixed later.
Attachment:
2nd-Gen-Tunnel-2.jpg
I can force the pieces apart just enough and the tack/weld them in place, but it is close, probably way too close because even a couple coats of primer and paint may be enough to cause a problem. So, I'm going to re-think this again. In truth, I believe I could do a redesign in 1/2" x 1/2" RHS of 14 gauge just for this narrow part and do fine, strength wise. I don't expect huge forces in this part of the tunnel. That would give me a whole half inch of additional clearance, but cause some issues where the half inch RHS has to join larger 0.75" and 1" RHS pieces at front and back.
Attachment:
2nd-Gen-Tunnel-1.jpg
Anyway, I'm going to take a day and give it a think-think. I really don't want to throw away the all time, work and material put in thus far, but it may be the best decision long term and I may just make a wider tunnel.
Cheers,
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