Magnets went for a wander in the can

[Don McGill]

Bummer, been flying the first gbV1.1 I made for a couple weeks now. All was good till I had a minor collision with my bottom side. Seemed all that was wrong was broken motor mount and one magnet popped loose. Fixed that and flew her many more times. Always flew it on a 2cell lipo. Decided to check how many amps it would draw on three cell and it would not even start up, just chattered, then a puff of white smoke. Shut it down right away, checked for shorts, none, figured that must have been only half the smoke and continued to use it on two cell no problem. No problem till tonight that is. Flew it for a while, was really high up and shut off motor. I do have the brake enabled on the esc (thunderbird9). Had a really hard time restarting motor, but it finally did, seemed sluggish so brought it in. I found almost half the magnets let go and were cuddling up to other magnets, not so cosy looking to me. When I set up the magnets, I filled the space between the backside of magnet and can till no space left with thin ca. Only filled the backsides, not between magnets or below magnets. That is my sad story of my deceased first 17T 26awg that was nearly a two week nightmare to build. Would like some criticim and suggestions before I start on another one, thanks.

[olmod]

If you are going to be doing a few more motors you might consider using Loc-tite 480 or 438, 430. they do a much better job than normal cyno's ;)

[BeavrdamElectric]

Clean the can and magnets with acetone. If you mark the face of the magnets just use a small dot.

Good Luck!

[ImaBiggles]

If you are going to be doing a few more motors you might consider using Loc-tite 480 or 438, 430. they do a much better job than normal cyno's ;)

480 is the black CA that has an extra binder - what the heck is 438 and 430? - I can not find info on them.

OK finally found 430 - gelled CA - still can not find 438

[podavis]

There's a risk that loose magnets were rubbing on the stator and may have gotten hot enough to lose strength. The motor will draw more amps, make more noise and have less power. If the motor 'sings' and/or drains the battery faster, look for witness marks on the magnets.

[olmod]

480 is the black CA that has an extra binder - what the heck is 438 and 430? - I can not find info on them.

OK finally found 430 - gelled CA - still can not find 438
soz for the typo :o its 638

[Don McGill]

Thanks for replies so far, got some acetone last night. Will check amp draw to see if there is a change when I fix this one as well.

Could not find Loc-tite 480 or 438, or 430. Checked the TSC, Canadian Tire and Walmart. They all do carry loc-tite products, just not these specific ones. Will keep looking for the loc-tite 480. Does it wick in behind the magnets like the thin ca, or do you have to apply it to can and add magnet afterwards?

[applejack]

I 'borrowed' this technique and it has worked well for me where there is a gap between installed magnets. First, clean the inside of the can with an active solvent to remove any oily residue - sand lightly with a fine wet/day paper. Install the magnets using just a drop of thin CA applied at the edge of the can to wick behind the magnets. Allow several minutes for the CA to develop strength then fill the space between the magnets with a medium density balsa wedge. Ideally, the balsa will compress a bit when you slide the wedge in place. I then use enough thin CA to saturate the balsa wedges and apply an extra drop to wick behind the magnets. This adds almost no weight and sure seems to anchor the magnets in place.

[olmod]

Thanks for replies so far, got some acetone last night. Will check amp draw to see if there is a change when I fix this one as well.

Could not find Loc-tite 480 or 438, or 430. Checked the TSC, Canadian Tire and Walmart. They all do carry loc-tite products, just not these specific ones. Will keep looking for the loc-tite 480. Does it wick in behind the magnets like the thin ca, or do you have to apply it to can and add magnet afterwards?
just place a drop on the edge closest to you in between each pair of magnets it will do the rest ,a spin in a dremel inside a card board tube helps the ballance and penetration.oh and protects the eyes.