March pump head alignment

[speshak]

I finally had enough close calls accidentally dumping water on my march pump and I decided to mount the pump in a box. I used the same method that I've seen online where the pump head bracket is removed from the motor and the enclosure is sandwiched in between.

All this is well and good, but the first time I fired the pump up after mounting I was greeted with an unholy screech of the magnetic cup rubbing against the head.

How did others get the alignment worked out? I tried making some hash marks on the head with a sharpie to figure out which side is rubbing, but even with that I am having a hard time getting it centered.

 

[BrewBeemer]

Your enclosure material between the motor and connecting backet must be parallel in thickness not a tapered material which I bet it is to easily remove from the forming die.
If tapered you will have to shim the thin side to keep the pump head concentric with the motor shaft.

On setting up the pump what I have found that works;
place the pump head with impeller installed facing up on a table align the stainless rear housing with its double screw holes.
Slide the SS rear housing towards each set of double holes and note how much out of alignment you can get the rear cover holes vs pump holes when the rear housing contacts the impeller magnet.
Rotate the rear housing housing 90 degrees and repeat until you find the best position allowing the same amount of misalignment when contacting the impeller magnet, marking pen the pump and rear housing for future assembly.
Next loosen the drive magnet set screw then pull the magnet away from the motor app 1/8" to 3/16" tighten to a light contact on the shaft, place the rear housing onto the connecting bracket and push lightly until it bottoms out or seats against the connecting bracket as this should also slide the drive magnet back towards the motor. Note this is why the snug set screw to slide the drive magnet back. Remove the rear housing and move the drive magnet 1/16" to 3/32" closer to the motor then tighten down the set screw. You should now have the rear housing centered around the impeller magnet as well drive magnet clearance from the rear housing.
With the drive magnet set too far away from the impeller the impeller will have more end thrust against the washer causing more wear as well less magnetic coupling drive strength driving the impeller. Hope this helps. End of novel.

 

[speshak]

I went and looked at my box again, turns out it does have a slight taper. I guess I'll be getting some thin washers to shim it up. Thanks for the detailed procedure.

 

[mariojr]

Is it possible to mount the pump to the tool box with the bracket and not introduce the problem of skewing the head when attaching it through the wall of the toolbox? I know you are looking to keep water off the pump, but a neatly cut hole would provide enough protection unless you plan on hosing off the pumpbox. Even though you may get the pump to work without any obvious problems, over time it may damage the pump, but that's just speculation on my part.

 

[BrewBeemer]

Yes a metal box with the same thickness wall material or cut out a plastic window and add a tin or thin alunimun plate to mount the pump onto.
I agree the above reply about "pump in a box" lacking cooling the motor properly. Added side holes with a 3/4' holesaw then add louvers mounted over then keeping water out.