Thread: Building a Tamiya Missouri with Super-detailing

Here's the mast with the top platform soldered on. There are still seven more under-braces that need to be installed. And I was not happy with how the process of putting holes into the mast to give the braces something to grab onto.



I was attempting to drill the holes into the 0.062" mast with 6 evenly spaced holes and have those holes drilled at the angle the brace should sit. Not only was this difficult in concept, it was difficult in practice. The holes are not in an even plane, and it's hard to get the little pieces into place.

I have lots of brass rod, but only have two of the Eduard PE upper platforms so it has to be right.

I woke up this morning thinking about dealing with these holes. Oh... did I mention that I've received my carbide drills and already have broken 4 of them. The really small ones are almost too thin to handle without a sensitive drill press (which I don't own).

I remembered from one of my live steam books that English model engineers create an object with evenly spaced flats (like a miniature bolt head) with a filing jig which consists of a way to secure the lathe chuck at evenly spaced increments, and a set of rollers that flank the work piece on either side. The rollers are adjustable as to height to control the filing depth.

I realized that I have a way to space six sides (which is what I needed) by chucking the rod in my pin vise and clamping the pin vise in a drill vise. By resetting the 6-sided chuck I can file 6 flats. I needed to make small flats so I could make a punch mark and drill the holes without the drill wandering and slipping off the curve. Once all the pieces are in a little CA will round it all back out.

Here's the filing setup.



I first tried it with the bare 0.062" rod, but quickly found that the 0.021" holes wrapped around the circumference left almost no brass left and the holes started to run into one another ruining the work and breaking a couple of carbide drills.

So I figured, since I have to enlarge the top to fit the hole in the bottom of the platform, and the prototype mast has enlarged rings around the portion of the mast that all these braces attach that it would be okay to enlarge the diameter a bit at the upper end. With the forest of braces coming out, the enlarged diameter will not be noticeable. I soldered a piece of 0.062" i.d. telescoping tubing to the upper end.

I filed the flats, made an initial punch with a divider point, and then deepened the punch mark with the scratch awl and a modeler's hammer. Then I used a slightly larger carbide drill in a pin vise to expand the punch mark and make a good spot for the 0.021" drill in my Dremel's flexible shaft.

Here's the punch marks around the perimeter.



And here it is with the 6 holes drilled. They're not deep. I may have to go back and make them a bit deeper, but as you can see here, they're deep enough to support the 0.021" rod that's going to be the brace.



One other decision I'm going to try... drilling the holes at 90º and bending the rod to the angle, cutting the rod just a bit away from the bend. I think it will produce a more manageable assembly and probably more secure.

If the rod bend isn't sharp enough so that it looks funny, I can make a slight cut with the razor saw so the bend will be a little tighter.

Next time, I'll turn the end down to 0.070 to attach to the platform. I'll machine in up to the area where the braces attach leaving a ring, not unlike the real one.

Don't be afraid to do parts over until you get them the way you want. This model's going to be displayed in a very prominent place and should be the best I can make. I find I'm the most creative just when I waking up in the morning. I'll build something several ways in my head before doing it for real. Like Jack Nicholson, I will visualize what I want to do in my head many times before executing. I will build the entire model before I even start (not on this one...)