A Tutorial

The Um6b has a set of dropped grab irons on the side of the unit just forward of the cooling air intake that serves as a ladder to the roof.  They are pesky little dudes to make because they must be as nearly identical as possible. To be otherwise would make the oddballs stand out like a sore thumb. In addition they have to be mounted absolutely vertical and without variation, in line, one above the other. Eyeballing these babies is out of the question, at least with my eyesight ! The solution is a set of jigs and fixtures.  They are simple to make, don't require much time or effort and are cheap.

The first is this simple aluminum angle 1/8" thick by 1"x1" x4" long with a .025 hole that is 17" from the notch filed in the end. This thing makes 18" long grab irons. Bend the wire stock over the notch as far as you can (I use .0225 brass) using your thumb and forefinger.  It won't make 90 degrees so you'll have to adjust it with a pair of pliers.  Use the inside of the aluminum angle as a guide but be careful as all extruded angle isn't necessarily 90 degrees either.  When you buy it check, they won,t mind.
When you get it square, insert it in the hole and line up the unbent end over the notch.  Bend it the same way you did the first bend.

Sorry about the blurry photo but you should be able to see enough to get the idea. The bend should come out about like the next picture.

Square this new bend up with the pliers using the aluminum angle as a reference. When that's done turn the wire sideways and check that it is not twisted. You should only be able to see one wire as in the next photo.  This is critical.  If you get things twisted the finished grab irons will never look right.  Take the time to tweak them into shape.

In the photo below you'll see that I have made two notches in the edge of the aluminum angle. They are 18" apart. Just wide enough to hold the bent up grab iron, because we need to make another bend in both "legs" to get the drop in the finished piece. That bend has to be uniform in length.

As you can see I use another piece of angle to back up the grab iron while it is in the notches and then I use a flat needle file to hold it down and simply bend the legs over the edge of the angle. Voila! Consistant, uniform length bends. You have to make final adjustments to the bend angles with pliers as usual and all the bends must be parallel and square with each other or they won't set properly in the pre drilled holes.  We're not finished yet, because those holes are just as important as the grab irons themselves and we need a couple more jigs to get this done.

This is the drill guide.  It was made from .020 styrene and the cross member from .125 square styrene.  The blade should have been .040.  This was really too flexible but I made it work. Very carefull layout work pays dividends in the end.  I centerpunch my holes with a pin using a magnifying glass and am very carefull to make sure I drill the holes as verically as I can.  If you have a sensitive drill press, use it. These were done with a pin vise using a #74 drill. The thing is glued together with styrene adhesive.  Be absolutely sure it is acurately positioned before glueing.

This is how it works.  Notice the holes next to the guide below the grab iron.  It works!!  I clamped the guide in place with some small spring clamps. Probably a good idea.  If you tried to hold it with your fingers it would most likely drift.

This is the last piece of fixture you need. Simply a piece of .060 styrene about 15" wide to space the grab irons a uniform distance from the surface while glueing. I used CYA from the inside of the car body. If things are a tiny bit out of whack you can bend the wire into shape at this stage.  If it is a lot out of whack, pull the offending grab out and make a new one. When the adhesive sets, pull the spacer out,

and admire your work !  Still needed is the nut bolt washer detail at the top of each leg.

Does anybody really need this? I don't know but it was kinda' fun to do and so I may do some more as I progress with this model.  I notice some strange effects with the photo's. The grab irons are perfectly straight as is the roof line of the engine.  I don't do Photo Shop so don't know how to fix those things.  My wife is good at it so I might have her take a shot at it when she gets some time.  Might not be worth the effort. At any rate, the moral of the story is, jigs are simple and effective and mostly cost very little. Sometimes the effort to think of a way to do them is much more than the effort required to turn out the final product. Sometimes they are the only way.