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Nick
Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
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There are two techniques I like to use:
Place two screws in opposite holes, preferably use cap head screws and screw them all the way in to make the measurements more accurate. Using a caliper, measure across the outside of the screw heads and then the inside. Add the measurements together and divide by two to get the spacing between the holes or the bolt circle in this case.
For that motor with an offset shaft, the best measurement option is to not measure anything at all! You can buy or make a set of screw-in transfer punches that mark the motor mount with the screw locations. Here are some commercial screw-in xfer punches:
The type with a hex head are more accurate and faster to use. You can easily turn a point onto the head of a screw; its easier if you make the point larger than the one shown. For small screws, screw on a number of nylock nuts and grip the nuts in the lathe jaws.
When using more than three xfer punches at the same time, its important to get the points aligned at the same hight or not all the punches will make a mark. I like to cover the area with several layers of painter's tape , which is softer on the punch points and leaves a mark with little pressure on the part.
For that motor, I would drill a hole the diameter of the motor shaft and use that to position the motor. Then you just press the motor into the mounting plate and there should be six tiny punch marks. If one or two punches do not transfer, just drill the ones that did and screw the motor lightly to the plate, the remaining punches will now transfer in the correct places. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
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Sat Jan 10, 2015 4:00 pm |
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