EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: schembri_andrew on August 31, 2014, 06:37:05 am
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Hi!
I have a couple of brackets that I need to attach to a 12V pmdc motor. I was wondering whether drilling and tapping a couple of holes on the side of the case, in between the magnets ( of course ;) ) would affect the magnetic flux when I would insert the bolts? Maybe this would cause excessive heating or something. I have no room for mounting on the face of the motor and this is my only option. I would leave about 2mm of thread protruding on the inside. The motor will only be run for short periods of time.
Thanks a lot, Andrew
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No, but the metal shavings you put inside will not make the motor very happy, unless you first strip it and remove the magnets and the spring steel clip holding them. Mark the parts for orientation so you put it back together exactly the right way, or you will either have poor efficiency or it will not work or turn in reverse. After drilling and tapping clean the inside of the housing thoroughly and then place the cleaned magnets back, then reassemble the motor. Add a drop of clean engine oil to the bushes at the ends, or if they are bearings do nothing aside from wiping with a clean dry cloth. Make sure you get all the washers back in the same order and direction that they were when they came out. Brushes can be a bit fiddly but you often find there are 2 holes on the rear plate that you place a stiff wire through to hold them off the commutator during assembly so it makes putting it together possible.
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in order of preference:
A) machine a clamp by boring a hole in some aluminium, then cut a slot down one side, and use a perpendicular bolt to clamp
B) use hose clamps to hold motor in place
C) epoxy the bracket in place
drilling holes in motor is a recipe for trouble, and even if it works, its not too hard to put the screw in too far and damage the windings.