Why NOT plastic for a base plate?

Plastics are not that rigid and misalignment of the shaft during operation due to deflection would shorten the bearing life and could also cause pulsing of the rotor due to the air gap variations between the rotor and stator. The tension on the belt will cause a radial load on the bearing that could over time cause a permanent deformation of the housing that aluminum or steel would be able to withstand. Don’t underestimate how hot it can get inside the motor. The outside temperature is significantly cooler than the winding temperature, so depending on which plastic you choose, there could be deformation at a much lower outside temperature than you expect. This article explains what happens as temperature increases.

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The Effects of Temperature

The polymers we work with follow the same principles as the body: the hotter the environment becomes, the less performance we can expect.
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It sounds like you got a motor with a B5 style flange, that will be difficult to use as is. I think your best bet is to machine one out of aluminum or steel. Or hopefully you get lucky and can swap the existing drive end housing to the new motor.
 
If plastic were a good option you would see it used in the lower end Chinese machine tools. I'm with the others that would rather see you make it once with steel than have to re-do it later.

John
 
KyleG said:
My biggest concern would be bearing stress under the fastener heads, especially under the fastener in the slot. I think the plastic will yield when you tighten down that clamping bolt. Honestly, I would even hesitate to use aluminum for that reason.

My secondary concern is that the motor will twist/bend the plate due to the moment from the belt tension.

Sorry if the first response was a little short, I was on a cell phone.
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No problem with your first response, it actually made me think about it and that is why I wanted to know what your concern was. You gave a good reply.

I would also like to thank everyone else for their advice. It is good solid responses and I will use it to make my decision, don't know what it will be yet,but most probably steel of sorts. Cast iron would be ideal but I think that would hit my pocket hard. As soon as I have a minute, I am going to raid the local scrap yard.

Thanks everyone.
 
Well I decided to go with steel which most of you recommend and what the little voice in my head told me to use all along. I wanted to safe little money but sometimes you must just do what is best and fork out the bucks. Now I am on a mission to sorce for the best prices and the best possible way to build the baseplate. If I remember, I will take pics as I go and post them to keep you in the loop.

Thanks to all of your suggestions and advice.

Michael
 
It could be worth an inquiry or call to see if putting a slot in the motor flange would void the warrantee. I doubt it would because it wouldn't cause the motor to fail.
 
Geez guys, I wrote in Post 6:
My first thought was "cold flow", which is an issue with certain plastics to a varying degree.
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And yeah, it's a real thing. Between that and the heat, I wouldn't use it.
 
Cadillac STS said:
It could be worth an inquiry or call to see if putting a slot in the motor flange would void the warrantee. I doubt it would because it wouldn't cause the motor to fail.
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I had a look but it is not possible on this motor because the flange is not solid all the way around, only where the bolt holes are.
 
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