Building steering columns is pretty easy if you just look at a few pictures of the ones that are sold on here. There are a few decions that need to be made before building one. Do you want the column to have a slide or allow the whole column to push back as the car bellies? Is the column going to be used in multiple cars with different box splines?
If the steering box is behind the engine cradle then only one u-joint is needed at the box and one heim to attach to the bar. I would not put a slide on one of these colunms as they do not seem to push as far back.
If the steering box is in front of the engine cradle such as on GMs(excluding caddilacs) and 80's and newer fords 2 u joints will be needed. One at the box and one close to the firewall. You will also need 2 heims to attach to your bar and hold to column from pivoting. If you want a slide it will need to be between the 2 u joints and make sure there is enough slide. Also with a slide you will need something to hold the steering shaft from moving back and forth, you can use collars that can be bought, but we have been using heater hose with hose clamps. This provides for some give if the slide gets collapsed all the way and is cost effective.
A few things to remember:
1. Dont start out with the steering wheel to close to you as it will come back if you do not have a slide on it.
2. Make sure that your top heim is as close to the steering wheel as possible at the beginning of the derby so there is not too much leverage and you will bend the column.
3. Use cold rolled steel when building.
4. Make sure your bottom hiem is not to close to your u-joint or it will slide back and hit the hiem and once again bend the column.
5. Make sure it is not to close to the a frame to begin. If your cage gets pushed over it will bend the column and lock it up.
6. Build a solid cage to frame and weld rockers good to avoid #5.
7. If you want to switch out the column from car to car with different splines on the gear box you can roll pin the bottom u-joint.
8. Have the column as straight as possible on the ones with 2 u-joints before the demo to avoid too much strain on the joints as the car bellies.
Money savers. (I have build columns cheap and expencive and they all work great if thought through properly)
-Instead of hiems, on columns with 2 u joints, you can use 7/8" nuts. ( you need a heim on the columns with one u-joint just at the box to allow for pivoting).
-U-joints off of factory columns work great on the top u-joint.
We have came up with a new design that we are going to try this year I think and see how it works but these are the things we have ran into and have experianced. I hope this helps a little. And I am a firm believer in columns now. Almost every car I have junked in the last 2 years have been sky high and I could still steer.