Help centering my washer on stir plate

[TravelingLight]

I'm building a stir plate. Got it all constructed and wired up and everything. I was testing it out last night and it started fine but would throw the stir bar shortly thereafter.

I started out using some heavy duty velcro to mount the washer. My thoughts were this would allow me some leeway over glue in case it was off center and I needed to adjust it.

Here it is with the washer and magnets on.

I'm pretty certain a couple things are happening. For one, because of the velcro, the washer wobbles a bit since it's not all the way down flush with the center of the fan. Secondly, I wonder if I need a bigger washer, like at least twice the size of that one inch-ish washer I'm using.

That brings me to my ultimate question. If the washer is much bigger, like a 2" fender washer, does that make it much easier? My thinking is that if I'm using a bigger washer and get it as close as possible to dead ass center, then it won't matter much if it's off center by a cock hair or two. As long as the magnets remain equidistant from each other. Yes? This is frustrating as sheet.

 

[Gavin C]

I'm building a stir plate. ..

• Use a slow setting cement like this one.
  
• Position the washer
  
• Turn fan on slow
  
• Soft touches to the washer with a fingernail/pen/pencil/as the fan spins will center it perfectly. Just like a potter using clay.
  
• Once it's spinning and centered, turn off fan and let the slow setting cement harden.
  
• Magnets just sit right on the washer.

 

[Dfitz]

After I applied a 5 min. Epoxy I laid my washer close to center, placed a pencil point close to the edge of the washer and slowly turned the fan centering the washer. Try a little practice before applying epoxy.

 

[TravelingLight]

After I applied a 5 min. Epoxy I laid my washer close to center, placed a pencil point close to the edge of the washer and slowly turned the fan centering the washer. Try a little practice before applying epoxy.

So you held the pencil stationary, then turned and sort of let the pencil point slide the washer over to center? I think I see what you're saying...

 

[TravelingLight]

• Use a slow setting cement like this one.
  
• Position the washer
  
• Turn fan on slow
  
• Soft touches to the washer with a fingernail/pen/pencil/as the fan spins will center it perfectly. Just like a potter using clay.
  
• Once it's spinning and centered, turn off fan and let the slow setting cement harden.
  
• Magnets just sit right on the washer.

Excellent. Thanks!

 

[jwelch1103]

I used a contrasting Sharpie and made a series of concentric circles on the fan hub while it was rotating slowly, then used a wee bit of RTV silicone sealant to attach the washer to the fan hub.
After curing I used again a contrasting sharpie to make more concentric rings on the washer for magnet alignment.

 

[TravelingLight]

I used a contrasting Sharpie and made a series of concentric circles on the fan hub while it was rotating slowly, then used a wee bit of RTV silicone sealant to attach the washer to the fan hub.
After curing I used again a contrasting sharpie to make more concentric rings on the washer for magnet alignment.

I dig this idea as well. So you just started in the center, made a circle, then progressively worked outwards making new circles?

 

[jwelch1103]

I dig this idea as well. So you just started in the center, made a circle, then progressively worked outwards making new circles?

No, first I made a small circle that would be visible through the center of the washer then a larger circle(s) that would be visible outside the washer and used those as alignment marks.