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Originally Posted by Hitman
What is exactly what you don't understand? If you have printed them already, you can post a picture and name them with letters (A,B,C,D...) and I will then tell you which ones goes where:hmm:
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I can't figure out what the problem is either. You show them together in the .pdf you distributed with the wheels, so it shouldn't really be a problem.
At least, I didn't have any issues, but then again I already had made two other wheels, and a couple of circular slide rules, so maybe I just made assumptions that happened to work well.
Just to help you out, indiana_jones, take a look at the pictures I posted of the wheel I assembled from Hitman's instructions.
To get started, and because you can use it as a stand-alone, and it's easier to assemble, build the backside first.
You will need the big wheel that is graduated from just under 6 to 90 degrees, the medium size wheel that has three scales on it (distance, speed, distance from inner scale to outer), and the small wheel that is marked 'Zeit'. You will also need one of the transparent pointers.
Print them out. I use cardstock, and laminate both sides, including the transparency (it gives it added strength).
Poke a hole in the exact center of each piece (the three wheels and the pointer). I use push-pins to make the holes, because I use push-pins as the axle for the wheels.
Take two push-pins. Using a pair of pliers, pull the actual pin out of the head of one of the pins. If the head breaks, try another one.
First put the smallest wheel on the push-pin that still has the pin in it with the face of it towards the head of the pin. Then put the pointer on the pin. Align the pointer so that it points upwards from the red line on the face of the small wheel. Glue or tape it in place (I use tape. That way I can reposition it if I screwed up).
Then, take the medium sized wheel with the three scales and place it behind the small wheel/pointer combo. Obviously, the face has to be towards the head of the pin. Then do the same with the large wheel.
Take a pair of wire cutters and trim the pointy part of the pin so about 1/2 inch (about a centimeter) sticks up from the back of the wheels. Test the pinless head on it for fit. If it fits reasonably tightly, take it off and put a little (just a little!) glue on the trimmed pin sticking up from the back of the wheels, then put the pinless head back on. If there is a significant gap between the back of the wheel and the bottom of the pinless head when it is assembled, trim the pin a little bit at a time until it fits, then glue it.
Viola!.
Here is how to use it:
Take two observations of your target separated by a reasonable amount of time.
Lets say they were 7000 yards at 60 degrees, and 5000 yards at 47 degrees. The amount of time that lapsed between the two observations was 5 minutes.
First, note the difference in degrees: 60 - 47 = 13 degrees. Align the middle wheel so that there are 13 degrees on the big wheel between the 7000 and 5000 range marks on the middle wheel.
In this example, the 5000 will be underneath the 28 degree mark on the big wheel, and the 7000 will be below the 41 degree mark.
We now have the AOB: At the second observation, it was 41 degrees. (it's kind of counter-intuitive that the AOB for the second observation is above the range mark for the first observation, but trust me, that is how it works).
Now we need to find the distance the target has travelled in between those two observations. Without moving the middle wheel, find the 13 degree mark on the outer wheel. Right below that is the distance the target has travelled, about 2400 meters.
Align the 5 minute mark on the small wheel with the 2400 on the inner scale of the middle wheel. You can now read the target speed, 24 knots, on the middle scale of the middle wheel under the pointer that comes off of the small wheel.
You now have the three things you need to input into the Vohrhaltrechner: Bearing, speed, and AOB.
This procedure works best if you are stopped or moving slowly, say 1 knot. There is a more involved procedure if you are moving, but that should get you started.
I did this exercise with my linear rule, as I happened to leave my KM wheel at home today.
So if I screwed up, I apologize in advance.
On edit: Yep, I screwed up the speed calculation. Should be 15.6 knots.