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Old Aug 09, 2014, 05:49 PM
Remote island inhabitant
epilot's Avatar
Faroe Islands, Sandoy, Sandur
Joined Nov 2000
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Geared 8.5mm motor - 72 gram thrust

I laser cut a gearbox today for a 8.5mm motor. The motor is a Chaoli 8.5x20mm, 11T brass pinion (V911 heli) and 54T gear (Syma X1 quad). It has a 1.5mm carbon shaft that runs in 1.5mm ID ball bearings. Once I find my 1.5mm silver steel I will replace the carbon with a hardened shaft. On a freshly charged 240mAh, 30C cell the thrust is 72 grams with a GWS 5x3 prop. Current is app. 2.1A. I'm quite impressed with the amount of thrust it delivers. The weight of motor/gearbox/prop is app. 8.5gram.

I have some other 8.5mm motor enroute from Banggood and will post test results when the motors have been received.

It's a lot of power for little money. The gear is $1, the pinon $0.29. Motors can be had for $2.50 - 3.00 - all from Banggood. The nice thing about the Syma gear is that it has a 1.5mm bore already so no need to ream it. The bearings were some I had left over from the Indoor Flyer days. IIRC they were about $1 each.

The gearbox is a bit different than previous ones I've made. The motor is held in place with a rubber band so it is easy to swap in case it burns out. A picture will have to wait until next weekend as my camera is currently in the UK where my daughter is visiting friends.

Together with the 240mAh cell and the new DSM2 compatible brick from Hobby King the equipment weight is 18grams. An AUW of 40 grams should be easily achievable so performance should be spectacular with all that thrust available.
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Old Aug 09, 2014, 07:33 PM
Registered User
Pakistan, Punjab, Rahim Yar Khan
Joined Apr 2011
97 Posts
That is a remarkable achievement, epilot!
Can you supply these motor/gearbox combos on commercial level to micro builders via ebay or directly?
It would be a service all micro builders would like to avail of.
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Old Aug 09, 2014, 07:49 PM
Remote island inhabitant
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Faroe Islands, Sandoy, Sandur
Joined Nov 2000
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I don't think offering them for sale is worth my time. Most people don't like gearboxes made from plywood and don't want to spend time on assembly. Besides, postage is very high from the Faroe Islands.
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Old Aug 09, 2014, 08:24 PM
confused poet
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USA, CA, Orange
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I would buy one if you sold them. But I am looking to make my own gear box so can you post a picture?

Hank
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Old Aug 09, 2014, 11:56 PM
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Pakistan, Punjab, Rahim Yar Khan
Joined Apr 2011
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Maybe you can put a link to commercialy available parts and drawings of the laser cut parts for the DIYers here.
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Old Aug 10, 2014, 01:03 AM
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I'm also interested.
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Old Aug 10, 2014, 01:45 AM
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72 is impressive.... i stick to 1s cus i like to push the limits of 1s brushed...
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Old Aug 10, 2014, 03:20 AM
Mack
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Australia, VIC, Mentone
Joined Jun 2004
541 Posts
In the past I have made gearboxes for 7mm motors from gears and pinions scrounged from toys, etc. the usual process was to have a piano wire shaft running through brass tubing which was glued to a section of hard balsa block. The block was sanded down until there was a good mesh between the gears and then the assembly was bound and glued to the motor.

I am currently using Hubsan spare motors and props from Banggood direct drive and they produce plenty of thrust. I'm not surprised that you are getting such good results, Epiilot. If you do not intend to go commercial with them more details of your method, especially the rubber band attachment, would be appreciated.
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Old Aug 10, 2014, 06:07 AM
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Pakistan, Punjab, Rahim Yar Khan
Joined Apr 2011
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Can you please attatch a photo of complete gearbox? A build sequence would be appreciated.
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Old Aug 10, 2014, 07:18 AM
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Faroe Islands, Sandoy, Sandur
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As I said in my first post, I don't have my camera at the moment. However I'll see if I can get a friend to take a couple of pictures later today.

I'm happy to share the drawing so anyone with access to a laser can make their own. I only ask that you do not do so for commercial gain. The plywood parts are very cheap to make but postage and packaging would be 4-5 times the value of the parts. I live on a very small island in the middle of the North Atlantic.

Gear: http://www.banggood.com/Wholesale-Sy...1-p-54197.html

Pinion: http://www.banggood.com/Wltoys-V911-...-p-929933.html

Motor: http://www.banggood.com/Hubsan-H107C...3-p-87563.html
You should buy the one with blue/red wires. There are many other 8.5mm motors to chose from at Banggood. You could also buy the V911 replacement with pinion already attached:
http://www.banggood.com/WLtoys-V911-...-p-913609.html

Bearings can be had from Homefly. I have hundreds of the 4OD, 1.5ID, 1.2W in stock myself so didn't have to purchase any: https://www.homefly.com/products.asp?id=9.
A brass tube or some turned brass bushes would work well as an alternative.

The gearbox alone is app. 1.2grams. This is the robust beginner friendly version. Some of my fellow pilots still crash a lot indoors. I will make a lighter version for myself - should be a tad under 1 gram.

Suitable cells are very cheap from DX: http://www.dx.com/p/502030-replaceme...0#.U-dUf2OK3oY
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Old Aug 10, 2014, 09:06 AM
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Pakistan, Punjab, Rahim Yar Khan
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Thak you. Very much. eflite. I couldnt have asked for more.
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Old Aug 10, 2014, 09:44 AM
confused poet
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Epilot

Thank you for posting that. Sorry I missed the note about not having a camera.

Hank
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Old Aug 10, 2014, 11:06 AM
Cap'n
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United States, OR, Springfield
Joined Dec 2013
228 Posts
The preformance of the Chaoli motors, is why I am trying to find 1S 3-5 amp brushed ESC's to work with my Lemon RX's.
Would be great rx/motor combo for indoor and UM scratchbuilts.

Alas, My efforts for the last month with the HK BR3A ESC, have failed and I have given up trying to use them.

Epilot....What ESC are you using with your geared 8x20 motor ?

Peter Mack...I also think the Chaoli 8mm motors would be great direct drive. They sure seem to do the job in my Hubsan X4 quad.
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Old Aug 10, 2014, 02:56 PM
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Faroe Islands, Sandoy, Sandur
Joined Nov 2000
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Dinghy, I've hooked it up to the new DSM2 brick from HK.

Here are some pictures of the gearbox. Last picture is of a ply mount I made for some gearboxes with 7mm motor that I bought cheap from China. They only have have a hole for a square carbon rod so I wanted a different mounting option for them.
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Old Aug 10, 2014, 03:17 PM
Cap'n
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United States, OR, Springfield
Joined Dec 2013
228 Posts
Thanks...... I was looking at that supermicro dsm2 brick....especialy since my efforts with the
stand alone esc has failed.

I saw a review that said that one of the onboard servos (rudder) is on the left stick.
So 3ch RET will require seperate servo for rudder, or transmitter mix, if you have a mixable tx.

Please let us know how you like that brick.....not much info about it yet, and no manual info, like range ???
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