[PSUBS-MAILIST] MK 2 Brushless Thruster

[Alan James via Personal_Submersibles]

Hank,the motor is an outrunner & the whole can of the motor rotates apart from the back section, so I can't locate the motor tight in the housing. Thanks for the thoughts on the precision machining of the pin holes, that confirms what I was thinking. I can drill the holes over size if I use the bearing, as the pins only stop the motor rotating & the slop will only be noticed going from forward to reverse.The shaft from the seal compartment has to go on the high side as any water that gets in will sink.Cheers Alan



      From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Saturday, April 2, 2016 1:40 AM
 Subject: Re: [PSUBS-MAILIST] MK 2 Brushless Thruster
   
Alan,If you put the new channel at the bottom instead of the top-when you fill the motor with oil, the air will be push out of the seal cavity.  The way you have it the air will burp out and it will be messy to fill.  Pins should always be tight or they will wear.  Four pins will be a bugger to drill and fit precisely.  If you go with the rear bearing you only need one pin that is a bit bigger.  Machining a bearing seat is easy with one pin to hold it.  Or you can eliminate the rear bearing if the motor is tight in the housing.Hank 

    On Friday, April 1, 2016 3:05 AM, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
 

  Updated version with Hanks suggestion of a channel directto the motor cavity.I have also added a bearing at the wiring end of the motor shaft.I am not sure about this. It would be easier engineering wise, to locate the motor ina central back bearing & have the holes for the locating pins a bit over sized,rather than a tight fit. That way they would only serve to stop the rotation of the back section of the motor. According to my propeller calculator, adding anothershaft bearing will reduce the power output by 1.5%.Alan

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