Vibration free DT750 for multirotor

by nherdananto | July 4, 2013 | (19) Posted in Tips

As all we know, that DT750 is the best motor for power/efficiency vs price, but the motor design with extra large bell makes it very prone to vibration.

After a long time working with this motor and using APM 2.5 with AC 3.x firmware, which is very much hate in vibration, this is what I could share.

Start with a brand new DT750 (easier to work with), and strip everything. there is a guide by tecdux, here

And then, follow FliteTest's tips to add a goop of epoxy at the end of the wiring to keep it safe.

Another that i found very usefull is to oil the bearings, i left them overnight in a small plastic with 10w motor oil.

Cut the extra long shaft, I run the bell on a drill, and while the bell spinning, i use dremel to cut it. and also I made a sharp pointy end on the shaft, with drill and dremel method, it will always 100% center.

Balance the motor bell. Even a brand new motor got unbalanced too. With the sharp point, I can balance it on a DIY mag-lev balancer. All you need is a good neo magnets.

This is what I got from balancing the motor bell. Also don't forget to balance the props too, lot's of guide out there

Assemble the motor bell and props. I like to use zip ties for this. It works very well and this will add a weak points for crashing, less damage for the motors and cheaper than dirt.

Yet again, balancing the assambled motor and props is also important.

This is my first article on FliteTest.com, and Please pardon my english. It is not my main language.

COMMENTS

earthsciteach on July 6, 2013
Great article! I'm about to do this with my Bat Bone tri. Thanks for the info!
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nherdananto on July 7, 2013
glad I could help.
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JustinTime on July 6, 2013
I'm not sure I like the zip-tie idea. If you hit the prop, on the ground or the wall, the zip-tie will break. How do you replace it? Take the bell off again?
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Captain Crash on July 8, 2013
make some kind of foam guard that's what i did . you can buy these thin sheets of foam called foamies for 2$ at Walmart . 1st rap the foam around the zip tie .second make a
small foam screen .
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nherdananto on July 7, 2013
based on my experience, I always carry extra prop (balanced) and extra zip ties when i'm going to the field. if anything happen, i just replace the prop..
balancing motor bell + prop attached is just something to do at home..

after doing this method for 4 motors, taking of the bell is just an easy job to do..
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Budge72 on July 9, 2013
I just received 4 new DT750's from Hobby King. I'm new to RC, so I was surprised that all 4 of the bells don't turn smoothly...they have stops in them. I don't know if this is caused by the magnets or by bad bearings. Is this normal for DT750's or for all motors like this?
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nherdananto on July 9, 2013
there's gap between magnets in the new DT750 motor bell, and lots of difference in epoxy filling. this could be the problem..

as for the bearings, i had my original bearing soaked in oil, an already flying for over 60 times, and still works fine..
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Budge72 on July 12, 2013
What did you use to balance your bell? In the picture, it looks like you shaved some of the bell off with a knife. Or is that CA glue added to the bell?
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nherdananto on July 12, 2013
i use layers of double tape for fine tuning.
if i need lots of weight balancing, i use david's zip tie method..
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Budge72 on July 13, 2013
Do you know if there is a flat spot on the shaft where the grub screw attaches the bell to the shaft? If not, I wonder if it's worth making one.
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Captain Crash on July 8, 2013
if their is vibrations isn't the company going to do something i mean they can use your idea .

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Cyberdactyl on July 8, 2013
Very clever alternative to mounting a prop on the DT750's!

Your magnet jig for the bell balancing is also great.
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twan1997 on July 6, 2013
Very helpful :D the zip-tie prop-mount is genius btw ;) I have both DT750 and DT700 motors, the DT700 does not have any vibration what-so-ever, so you might as well go with the DT700's instead of DT750 :)
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nherdananto on July 7, 2013
great to know that. but i'm picking dt750 for extra thrust at the same weight..
i'll try dt700 for my next project.. thanks
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Splatwillicrash on July 25, 2013
Great Article on the 750. I have some I would love to clean up for better performance and less vibration. Your English is more than fine, in fact is far better than most of the tech support people I have to deal with who were taught english and are paid a bonus to improve their ability.
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andre on August 1, 2014
I've been getting some pretty low flight times from my 750's on my tricopter.
I think I'll have to give this a test.
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Vibration free DT750 for multirotor