I have an electric motor that has threads on the end of it. I'm interested in making a wood pulley to put on the end of it for use in a lathe. The only thing is that I'm not sure if I have the right tap or not. I measured, across the threads using a caliper, and got 9mm and using a TPI reader I got 1mm thread pitch. Does this mean that I need a M9 x 1mm tap to etch threads in the pulley so I can put it on the motor shank?
Measuring Electric Motor Shank Dimensions
electric motormeasuring
Related Solutions
Comparing those tables: Note that the speed switch in the circuit you show isn't using L.
A: L+2+3
B: L+1+3
C: L+1 (Maybe this is L+1+2 ???)
D: L+1+2+3
0: No connection (or no connection to anything but L)
1: 2+1 (possibly plus a connection to L)
2: 1+2+3 (possibly plus a connection to L)
3: 2+3 (possibly plus a connection to L)
Making them correspond with each other...
C is obviously equivalent to 0.
D is obviously equivalent to 2.
That leaves us with
A: L+2+3
B: L+1+3
1: 2+1 (possibly plus a connection to L)
3: 2+3 (possibly plus a connection to L)
We can make those match if we relabel the connections. If we just swap the labels on your terminals 3 and 2, then
A is equivalent to 3
B is equivalent to 1
If we renumbered them all (your 2 is their 3, your 3 is their 1, your 1 is their 2), then
A is equivalent to 1
B is equivalent to 3
Pick whichever you prefer; one will switch off-high-medium-low-off, and the other will switch off-low-medium-high-off.
As far as theory goes: I'm not sure either, but let's see what I can do with it.
3 (2->3) appears to be "slow" because power flows through the right half of the bottom coil, and then through the side coil, in series. More resistance, less current flow, less power.
1 (2->1) appears to be "fast" because the left side of the bottom coil, and the side coil, are powered in parallel. Both get the full house-current voltage applied across them rather than the reduced amount of power they got in series.
2 (2->1 and 3) is the tricky one. I am far from certain, so DON'T take my word for it. But I think what's happening here is that, since the middle and right sides of the bottom coil (1 and 3) are now connected to each other, that loop has a current induced in it by the motor's moving magnets, which creates a countering magnetic field, which acts as a magnetic brake to slow the motor... so fast with a bit of braking equals medium. Seems like an odd solution, but if I'm remembering my freshman Physics at all correctly it might actually be a reasonably efficient solution.
You might want to run this by the physics discussion, to get someone with more recent memory of electrodynamics to check and/or correct that last paragraph.
Gopher baroque...
It's pretty much up to you. Look at some pictures, find ones you like, make guesstimates.
When in doubt and looking for a ratio, there's always Phi (0.618) and 1/Phi (1.618) aka "the golden ratio" but you're still free to do with it what you will.
When you think you have an idea, grab some masking tape and mock up the outline on the ceiling (I'm assuming the ceiling is there, and flat, at the moment.)
While it would be difficult to mock up the whole edge, you probably can suspend a sheet of cardboard at various heights (I assume you are lowering the edge, not raising the center, as that's more structurally simple) to get a feel for how various levels for the lowered edge feel to you, standing under them. If you find that a 7'6" ceiling height (18" down from 9 feet) feels too low, better it's a piece of cardboard you can easily relocate than the whole framing system and drywall.
Best Answer
A little bit of research shows me that M9 taps are available in 0.5, 0.75, 1.0 and 1.5 mm pitch. This was a surprise to me. Your assessment regarding your measurements are correct, if your measurements are accurate enough.
To ensure one more level of success, consider to purchase a single nut of M9-1 and see that it easily threads onto the motor shaft. If it does, you can be confident that an M9-1 tap will do the job properly.
It is not unusual for a motor shaft to have a left hand thread. Purchasing a nut will also determine that aspect.
Consider that wood will require much more care when tapping such a fine thread. You will want very hard wood and also a sharp tap. Be sure to purchase the proper diameter drill to create a pilot hole in the pulley.
Additionally, you may want to use a nut insert, often known as a T-nut in place of tapping the hole. T-nuts are also available without the barbs, designed to be screwed to the surface.
If you are inclined to stick to wood alone, you can drill a hole slightly smaller than the appropriate size for the tap, then apply an epoxy that will soak into the wood, providing greater strength for the tapping process. Epoxy which takes longer to set will be stronger, that is to say, a five minute epoxy will cure quickly and be weaker than a one hour version.