Re: Building a Magnetic Coupled Thruster.
Posted: Jul 10th, 2014, 9:48 pm
Thanks Bubbles that's I good idea I will look into that option as I go.
Next it is onto the motor mount. I cut another chuck of PVC and again after centering it in the lathe it is faced. Next I actually have to measure (no TLAR here) what will be the minor diameter of the threads for the mount. It's about 1.465" as you can see. Knowing the thread depth of 18TPI is about .07" I had to turn down the work piece to 1.535 for the major diameter before I can start the threading process. Next using the external threading tool again I thread the piece to match the housing. I quick test fit to make sure everything is correct before I remove the work piece from the lathe. Next I measure the original mount to determine the correct drill size (25/64") to use to match the center hole... and drill the corresponding hole in the center of the piece. This will only be used to mark the mounting holes in the new mount. Next it was over to the mill to cut a relief channel for the motor wires. Then using a 25/64" transfer punch to center the mount onto the work piece I use another punch to mark the center of each mounting hole. I then mount the piece in the mill and using a center pointer I line up the first hole. Next I use a center drill to start the hole. This will keep the drill bit from walking and also put a bevel on the hole face for the screw. After that I used a 1/8" bit for the through hole. I think the screws are actually metric so this will give me a little play when mounting the motor. I then repeat this process for the other three holes. I also drill two 3/16" holes in the mount, these will be used to screw it into the housing and later adjust the motor spacing. One last trip back over to the lathe and I use a parting tool to cut off the mount from the work piece. Here is the mount so far, it still needs a little clean up but its complete for the most part. I'm using a pair of needle nose pliers to test fit the mount in the housing, I will probably make a tool for this later on. I need to buy some longer screws before I can mount the motor.
Next it is onto the motor mount. I cut another chuck of PVC and again after centering it in the lathe it is faced. Next I actually have to measure (no TLAR here) what will be the minor diameter of the threads for the mount. It's about 1.465" as you can see. Knowing the thread depth of 18TPI is about .07" I had to turn down the work piece to 1.535 for the major diameter before I can start the threading process. Next using the external threading tool again I thread the piece to match the housing. I quick test fit to make sure everything is correct before I remove the work piece from the lathe. Next I measure the original mount to determine the correct drill size (25/64") to use to match the center hole... and drill the corresponding hole in the center of the piece. This will only be used to mark the mounting holes in the new mount. Next it was over to the mill to cut a relief channel for the motor wires. Then using a 25/64" transfer punch to center the mount onto the work piece I use another punch to mark the center of each mounting hole. I then mount the piece in the mill and using a center pointer I line up the first hole. Next I use a center drill to start the hole. This will keep the drill bit from walking and also put a bevel on the hole face for the screw. After that I used a 1/8" bit for the through hole. I think the screws are actually metric so this will give me a little play when mounting the motor. I then repeat this process for the other three holes. I also drill two 3/16" holes in the mount, these will be used to screw it into the housing and later adjust the motor spacing. One last trip back over to the lathe and I use a parting tool to cut off the mount from the work piece. Here is the mount so far, it still needs a little clean up but its complete for the most part. I'm using a pair of needle nose pliers to test fit the mount in the housing, I will probably make a tool for this later on. I need to buy some longer screws before I can mount the motor.