Now all the bits are ready, we can join 'em all together. What would, in 21st-century geek-speak, probably be termed a 'critical point in the project timeline'. We're just damn pleased it looks like we're getting somewhere at last!
Time to make use of our trusty chassis jig: a stiff, 4"-square-tube frame that we made a few years ago. Athough it has been used for a couple of other people's projects - both round-tube racecar chassis - this is the first time we've used it in anger.
As you can see, it wasn't actually designed for a Model A chassis, but the addition of a couple of tubes tacked across the main sections give us some support for the chassis rails, while the rest of the jig offers a reference plane to clamp other bits to.
After much clamping, measuring, re-clamping, and re-measuring, we got the main rails in position. The rear crossmember was pretty easy to install - just cut to the right width (after double-triple checking our plans) - then tack it into place. The front one wasn't quite as straightforward, as the rails aren't parallel. More, careful, measuring gave us the dimensions we needed (also checked against our drawings), then mark out the crossmember and get hacksawing: a bit of fine adjustment with a file, and it fitted a treat.
Once the front and rears were tacked up, we cut a piece of 3" x 2" to size for the centre crossmember, and fitted that.
When we were happy with the tacked frame, we fully welded the three cross-pieces in place, releasing the frame from the jig afterwards for more measurement-checking.
Obviously, the frame wasn't going to be strong enough to use without some form of triangulation, so we cut to size and welded a pair of diagonal braces for the centre crossmember. The small gusset piece visible on the diagonal was welded on because the angle of the joint would have been too acute to access for welding without it - even with this, it wasn't exactly easy.
Because the weight of the car is supported by the rear crossmember, we also added some 2" x 1" tube gussets to brace the rear corners, TIG-welded in place as with all the other parts.
Here it is! One repro basic Model A chassis. A lot of work, buckets of sweat, and a few skinned knuckles, and this is the result.
Incidentally, we have had to take a bit of a guess on the centre K-member: because we are not using this chassis for the pickup, we looked at various other Model A chassis and used them as a reference. The tube is welded flush with the top face of the main rails because this type of chassis sits quite high off the ground, so the tail end of the transmission, and the propshaft, pass underneath.