The Saga of the Sons-in-Law

To begin with, the previously reported progress was a bit premature. I discovered that the aileron hinge I thought was complete was fabricated incorrectly.  I welded the bushing into the end of the tube and trimmed the tube around it.

It is not supposed to be that way.  As we go through today's post, I will demonstrate the way it is supposed to be installed.

Aside from mistakes resulting from mis-reading the plans, there have been production problems.  Drilling 3/8" holes, perfectly aligned, in the tubing proved to be a very challenging task.  There is a video on the EAA site that shows a gentlemen fabricating a v-block out of a couple of pieces of angle iron and then duct taping that to a piece of wood.  I believe this approach would work fine when drilling aluminum tubing, which is the case in the video.  It simply does not work when trying to drill steel tubing.

I discussed the problem with one of my sons-in-law who is an industrial engineer.  He described the method they use in his company.  It involves a basic v-block with a bushing attached to it to guide the drill bit.

I looked into this arrangement and found that it either required a rather substantial outlay of cash, or machine tools to which I have no access.

But applying the principal of keeping things rigid, I developed the following process, beginning with the acquisition of a pair of v-blocks, which took an inordinate amount of time getting here because they were coming from New Jersey at the height of the winter storm that hit most of the country.

Some of the photos I took today did not come out very well, so you will have to settle for narrative for the time being for some of the steps.  In some cases I will use the fuzzy photos.

The first step is to center the v-blocks in the drill press.  This is accomplished using an appropriately sized drill bit run into the center of the "V" and securing the vise.

In order to keep things rigid, and avoid a drill bit wandering around center before getting a grip, I used a center drill swiped from my Unimat (a small model makers lathe) to drill a pilot hole.  The center bit is designed to drill a countersunk hole in the end center of a piece of round stock for turning on the lathe.  It is a small bit with a fat body so that it does not flex and wander around.  I apologize for the fuzzy photo.

This pilot hole is centered 3/8" from the end of the tube to correspond to the outside diameter of the bushing.  Why would I choose that dimension?  Continue with the saga and you shall see.

The next step, without disturbing the alignment, is to enlarge the hole with 1/4" bit, which corresponds to the guide point on my step drill.

Once the top hole is drilled the bit is advanced to drill the bottom hole.  This is the place I took a bit of a chance.  The 1/4" bit is chucked in the drill press as short as possible to reduce flex, plus, I was hoping that the upper hole would help serve as a guide and steady rest for drilling the bottom hole.  It worked.  The top and bottom holes ended up exactly aligned.

After drilling the 1/4" hole I replaced the drill bit with the step bit.

And enlarged the top hole to the required 3/8".  I then flipped the tubing over, aligned the bottom hole (now on top) using the guide portion of the step bit, re-clamped it in the v-block, and enlarged the bottom hole.

The holes ended up perfectly aligned.  It seems like a lot of steps, but it really doesn't take very long.

The next step is to draw some lines extending the outside diameter of the hole to the end of the tube. What did we ever do before Sharpies?

And cutting out a slot whose width corresponds to the outside diameter of the bushing.

The reason this is done is because once the bushing is tacked into place, the ends of the tube will be heated up and bent around the bushing.  Below is the bushing ready to be tack welded in place.  It is cut long to facilitate welding.  Once welded into place it will be trimmed back to correspond to the outside diameter of the tubing.

And here comes the contribution of the second son-in-law.  As I was attempting to tack the bushing, my welding helmet would not work properly.  I have a self-darkening helmet. It darkened as soon as I struck the arc, and then promptly went back to clear!  It would oscillate back and forth.  I obviously could not use it that way and hope to hang onto my eyesight.

In discussions with another son-in-law, who happened to be visiting, he pointed out that the helmet is solar powered and perhaps all it needed was some recharging.  We shall see.  I have the helmet sitting in a window so it should have an opportunity to recharge while I am at church tomorrow.

Not wanting to abandon all progress, I tacked the bushing in using oxy/acetylene.  After I bent the ends around the bushing, I went ahead and finished up welding the bushing in place with the gas.

The above is the bushing finish welded, ground down to the proper length and reamed 0.250"

I had previously fabricated the brace, but I didn't have a useable bracket.  So I needed to make one of those up.  Here is the blank set up in my cheapy little Harbor Freight brake, which works quite well if you don't push it too hard.

Checking the first bend.

Set up for the second bend.

Checking the second bend.

And here are all the parts in the jig ready for tack welding.  We will see if charging the helmet works. I would rather tack this up using the TIG than the gas.

More as it happens.  Hopefully I am on the road to steady progress.