RC India

RC Baazar => Wanted => Topic started by: Singh.Varun_v on April 04, 2021, 06:58:22 PM



Title: WANTED, MG90S
Post by: Singh.Varun_v on April 04, 2021, 06:58:22 PM
Please please please somebody help me..
I need mg90s full metal gear. For Chinook style bicopter.had some flight but every time servo failed(was plastic geared so everytime second main gear broke..) bought a lot of mg90s from Flipkart,robu, flyrobo and many sites but no one has all the metal gear.they all had only one (main in which horn is connected)metal gear rest was plastic inside the cover...

Please help if someone has these or any it only need to be full every gear made of metal , im ready to buy second hand also...

Full metal gear is mandatory.


Title: Re: WANTED, MG90S
Post by: o.kashelkar on April 04, 2021, 07:54:55 PM
I have full metal gear yeah racing micro servo. Cost is 3500. Let me know if ur interested.
WhatsApp on 8850107241


Title: Re: WANTED, MG90S
Post by: Singh.Varun_v on April 05, 2021, 08:03:36 AM
So pricy bro....cant afford that


Title: Re: WANTED, MG90S
Post by: Mohammed Naveed on April 05, 2021, 01:52:09 PM
Hi Varun Singh, Welcome to the forum!
I guess you are working on something similar to what Tom Stanton had posted on YouTube couple of years go!

Indeed you do need an all metal geared servo and the tower pro MG90S is not the answer to it!

Let me explain the way you should use to decide how to choosing a servo, let say you have a tilt rotor mechanism similar to what Tom Stanton has done in his chinook video. you are using a sunnysky x2216 880kv motor with 3s and a 10x4.7 propeller, the thrust data that is available on the Sunny Sky website says that the max thrust this motor can generate is 890g for the above setup. Consider the weight of the motor and the pivotable motor base. Let us assume this whole thing including the thrust generated to come up to 1000g (just for simplicity).


So from this we get to know that the load the servo needs to manipulate is max 1kg.

Now let us see the specs of the Tower Pro mg90s servo (specs taken from robu.in)
The torque data is what i am looking for:
1) Stall Torque @ 4.8V :1.8(Kg-Cm)
2) Stall Torque @6.6V: 2.2(Kg-Cm)   

What does this data mean?, well if you see your servo horn you notice small holes at certain distances. this is where the torque data comes in to picture, so if you measure a point (hole) 1cm away from the centre of the servo horn that point can support a load of max 1.8kg before failing (stalling). the further away you get from the centre lets say a point that is 2cm away the max load supported will become half of what can be supported at 1cm, so effectively it is going to become 0.9kg and the closer you are the more load it can support.

So if you have put the pusrods on the extreme end hole the max load this servo will be able to support will be less than 1.8kg, since i have the same servo i found out the distance from the centre to the last hole is 1.5cm (this was measured for the double arm servo horn)

Therefore at 1.5cm the max load this servo can support is 1.2kgs before failing. Another thing to note is if you change the voltage the torque also changes.

Hence from this i can conclude that since my max load is just going to be 1kg I can use a tower pro mg90s provided i choose the correct hole to mount the pushrod in.

The reason the servos fail is either due poor quality of parts or by using it wrongly, tower pro sold locally are all clones so some of them wont be of good quality, in an all metal geared servo if one component is plastic that part will fail after some use due to wear and tear.

I suggest you go with Hitec Servos, one of the best servos out there! I have servos that are almost a decade old been used on big models and have some what been abused, but they still work like a charm not yet have had any failure.

The HS 82 which is an all metal geared servo and pretty compact will work for you.

https://sumeetinstruments.com/shop/MOTORS-ACTUATORS-HITEC-SERVO/Hitec-Servo-India/Hitec-HS-82MG-Metal-Gear-Micro-Servo?sort=p.price&order=ASC&limit=100

I Have purchased many servos from them as well and also Rcdhamaka, these two are the official dealers of hitec in India

Regards,
Mohammed Naveed


Title: Re: WANTED, MG90S
Post by: Singh.Varun_v on April 05, 2021, 04:24:13 PM
Thanks for the reply Naveed, ihv searched some sites and found some MG servos but they are very costly and i cant afford that much...thats y ihv posted here so that if someone has the servo extra or at least their gears work i will buy them. Jusk knocking my door of luck.


Title: Re: WANTED, MG90S
Post by: o.kashelkar on April 05, 2021, 11:13:27 PM
Good servos comes at good cost too ..  :hatsoff:
I have both mg90s and fully metal gear. Let md know if ur interested


Title: Re: WANTED, MG90S
Post by: Singh.Varun_v on April 19, 2021, 10:08:47 AM
How much for mg90s????


Title: Re: WANTED, MG90S
Post by: Singh.Varun_v on April 19, 2021, 11:01:38 PM
How much for mg90s servo??


Title: Re: WANTED, MG90S
Post by: o.kashelkar on April 20, 2021, 12:08:15 PM
165 /each
WhatsApp 8850107241


Title: Re: WANTED, MG90S
Post by: Singh.Varun_v on April 20, 2021, 12:13:35 PM
Come on wapp