Here’s a step by step build of the round TT scale window. I based the window size on the two vertical beams at the center of both the front and rear walls. I needed an outside diameter of .500”. The outer rim of the window was made .550” diameter. Gives a nice .025” lip on the round window. This is going to be an intensive picture post of 40 pictures. I took a picture of every important step in the procedure with a short explanation of each step. This second window didn’t turn out to be good enough to use. You’ll see why in some of the pictures. So let us begin.
The first thing I need was a piece of hardwood. I used a piece of rock maple in the lathe. It’s turned until the piece I need is round.
Once round the piece is cut off.
Next the round piece is transferred to the Sherline lathe for final sizing of the outside diameters, .550 & .500”
Using the rear wall to check if the dia. is correct.
Next, I drilled out the center to be able to get a boring bar in.
Boring the inside out to make the inside diameter of the window.
I didn’t pick any size for the I.D., just as long as it looked thin enough.
A large piece is cut off and will be used later as a jig.
I cut off the window to an arbitrary length. The allen wrench is used to catch the piece since it’s very fragile and I don’t want to get it caught in the chuck jaws. I have gotten my fingers whacked a few times on other projects. You learn not to do that after awhile. Pain is a good teacher.
Success, now it just needs a bit of light sanding to get rid of the fuzz.
And it fits.
Next up is the making of the inner frame and spokes, plus the small center window. I used .020” dia. phosphor bronze wire. In order to get a nice and round piece I wrapped it around a mandrel, in this case a Xacto knife handle, with a small hole drilled in it to hold the wire while giving it a turn and half. You always need to go a bit further when trimming to a good circle.
Next, cut off the excess approximately in the center where they will be joined.
Sorry for the out of focus picture. Didn’t set the lens to marco setting. This is what you should have after cutting the excess off.
Next, push the cut ring into that spare part cut off earlier. This will be used as a jig to get the wire cut so the two ends meet for soldering.
Notice the overlap, one end will be trimmed so the ends meet.
I use a pair of sharp pointed tweezers at the point of where I want to cut the wire. I usually launch the wire several times into the ether before I get it cut to length.
Another fuzzy picture. It shows how much needs to be trimmed.
Trimming it to length. Please point it away from your eyes.
And it’s a pretty good fit.
Next up is the making of the small center window. It’s made from a piece of 1/8” dia. brass tubing with four holes drilled through at 90 degree angles to give four spokes.
That’s one tiny drill, with a diameter of a little bigger than .020”.
Next the outer ring has the end joints solder together. I used a bit of rosin flux and a solder paste.
The first cross member is cut to fit into the center of the ring.
Next the brass tube which has been cut a little over .500” long is placed in a hole drilled in a piece of ceiling tile. The longer spoke is place through one set of holes and the ring is spiked down so it won’t move during soldering.
And here is where the problem began. I put a small drop of rosin flux and a couple of “to large of daps” solder paste.
And the result is a lousy soldering job. The part is too small to hold and file away the solder. I was going to make another one but for the sake of my sanity I decided to keep going.
Next the two remaining spokes are cut to length.
The two spokes should have been a bit longer.
And there you have it, one lousy soldering job. No excuse for that except I was in a hurry.
I filled the center with solder to hold the spokes on the inside.
Back to the lathe to trim the front excess off of the brass tube until the spokes are reached.
The center is drilled out to the I.D. of the brass tube.
The ring and spokes are cut off as close as possible on the back side without hitting the spokes or outer ring.
There you have it, a piece of waste due to haste with a topping of too much solder.
And the result is – it won’t fit. Back to doing another one.
I didn’t stop and redo the part since it’ll show what can go wrong. I’m going to make a better jig to hold all the wire parts for soldering. I should have made a jig like I had tone for making a radio antenna in TT scale for a fellow modeler.
That’s the route I’m taking to make another round window. I’m sure I’ll be able to use the jig in the future. Questions?