Wed May 19 2021

Adventures in tube tapping

I had a heck of a time locating the steel, powder coated triangle brackets. Found four in a bag...have no idea why there are four. Should only have two of these. Is it the right bag? They're the correct part number. After some time, I determined that the holes in the F-705 bulkhead for mounting these angles had never been drilled. So, I just pulled two of the four from the bag and match drilled them. Also temporarily installed the C-605 and the two little steel links after the necessary bending and twisting, of course.

With one of the little roller lugs clamped in place, I was able to position the latch tube appropriately in preparation for fabricating the pushrod. However, something was causing me trouble when positioning this roller lug.

This is really hard to see, but from below, I can see the roller lug is interfering with one of the side rails. It seems the roll bar is mounted at an angle, so the roller lug will also be mounted at an angle, but the aft end of the side rail was trimmed straight up and down. Not sure if I messed that up, or if it's an issue with the plans, but I'm going to need to trim that aft end at the same angle as the roll bar to prevent the interference.

Perhaps a better view?

Time to drill (#3) and tap (1/4-28) the end of the pushrod tube. I aligned the drill as straight as I could with the tube and drilled up to #3. Same when tapping.

Hrm...This looks off center. After checking with calipers, I determined it was quite well centered near the end, at least. But when I tried to screw this tube onto the clevis end, it wobbled all over the place. Clearly my drilling or tapping (or both) had not been straight. No worries...this piece of stock is a few inches extra long, so I can cut this end off.

Before cutting that end off or trying again on the other end, I decided to make a drill and tapping guide from a block of oak. First, drilled #3 all the way through.

Then drilled 5/16" (the OD of the tube) halfway through.

Now, with the tube shoved in the 5/16" hole, I can drill #3 using the oak block as a guide. There's no possible way this can be non-concentric, right?

What the actual fuck? How can that even happen? Fuck. Ok...all is not lost. There's still enough of this tubing length to make one more try.

After cutting off one of the fucked up ends, I clamped on a piece of angle as a visual guide.

Also, opted to drill up to #3 using some reamers instead of twist drills.

Argggggg! Drilled at an angle. Now this piece of tubing is scrap. Fuck. I give up for today.