BY
ROLAND KOEHLER
My method to make my own inline brackets has been the following for a long time now: (The numbers relate to the attached sketches)
1. Take rectangular or square brass tubing, 1mm wall thickness, outer dimensions as you need them - something around 10x15mm to 15x 20mm. Let them cut into precise rectangular "rings" of 15 - 20 mm height.
2. "Sharpen the motor shaft in a flat angle by letting it rotate against an also rotating cutting disc.
3. "Draw" a line around the tube segment: Put it on an even and flat surface - if you have take a clamp to fix it for better handling, let the motor run at 6 Volts, press it onthe surface as well, hold the sharpened shaft tip against the wall of the brass ring and "engrave" a line all around it.
4. Use a gauge to "draw" the center lines as shown by holding one arm of the gauge short under the edge of the ring, setting it to 1/2 of the outer dimension and scratching across the engraved line.
5. Drill the holes beginnig with a thin drill - sth. around 1mm - to see that the hole will be centered correctly, and go up to the final diameter in two or three steps. Drill through both sides if you are sure that the surface the ring is lying on is really even and 90° to the drill. Then work out the final shape as you like or need it.
If you do that with care, you get really exact brackets after your own specifications, and much cheaper.
The holes for motor fixing screws will be done the same way, with the gauge, as above.
Finally a thought to the inline principle. Because of the necessity of a really exactly centered rear axle and motor shaft inline brackets normally are made for one certain type of motor only resp. motors with equal height ( and with fixing holes on the same places if not to be soldered in ).
Example:
Sketch 7 - the motor is 15 mm high, it shall be even with the underside of the chassis and the clearance shall be 2mm. That means you must have wheels with a min. diameter of 19 mm.
Sketch 6 - the motor is 15 mm high as well, the wheel diameter must be min. 19 mm, too, but you want only 1 mm clearance. That means the motor has to be lifted up for 1 mm. During the construction of the bracket this would mean that you had to lay a 1mm sheet under the motor before "engraving" the horizontal centerline.
