Heng Long M41A3 Bulldog High Speed Proportional Turret

[CanadianBulldog22]

Hello guys,

As an introduction to this forum I will document and post how I replaced the turret rotation mechanism very inexpensively and quickly. At the same time I machined some addition teeth in the turret sprocket to get 360 degrees of rotation. My mod involves modifying a standard servo to be continous rotating (not as hard as it sounds) and installing the main drive sprocket on the end of this servo. Then mounting the servo to the turret in the same location as the original mechanism. New turret has proportional control and can do full 360 in under 5 seconds.

Many more posts/pictures to follow,

Chris

[CanadianBulldog22]

Quick Update to my intial comments,

I ended up using a blue bird metal gear servo. I know this is extreme overkill but I had a spare one laying around and they are easy to modify to continous motion (from experience). You can use a smaller servo if you plan on doing a similar modification. Also I am sure there are other post related to servo and turret rotation. This is my approach, which I feel works best and costs the least. The picture attached shows the new mechanism. I used clear plastic reinforced with carbon fibre to make the mounting bracket. The key is to attach the drive sprocket dead on center on your servo, and ensure you mount the sprockets the correct distance apart. I wil explain in the detail in my next post.


Chris

[ALPHA]

Cool.. I've thought of a similar set up... but using micro helicopter servos...the only problem with the idea was what to do with the third wire...the normal motor for the revolution mech only uses two...

ALPHA

[MichaelC]

Cool.. I've thought of a similar set up... but using micro helicopter servos...the only problem with the idea was what to do with the third wire...the normal motor for the revolution mech only uses two...

ALPHA

ALPHA, in theory and perhaps Chris can show us, if you are using hobby grade radio, you just plug the servo into whatever channel you are using to rotate the turret, so it will be a completely separate set-up then using the main MFU and you don't have to worry about the third wire as it is not even hook-up to the MFU.

MichaelC.

[CanadianBulldog22]

Alpha,

Michael is correct. The most important piece of electronics you need is the RC5HL module from RCTankAustralia.com. This unit converts any standard radio transmitter to work with the MFU unit. You can then use any of your radios AUX channels to control the servo that will be used for the turret. There are many more benefits to using this module. For one, it is a true 2.4 ghz conversion, the HL tanks that come with 2.4 ghz are not spread-spectrum and are crap. I would suggest buying the RC5HL module as soon as you can.

[ALPHA]

Hey thanks guys...working on a couple projects I might try using micro servos on... the one I was going to use servos on is running the stock HL RX ...so there is really only one free plug that might operate a servo that would be the rotation...but even that is a two lead deal ...sounds like you all are using better systems...
I figured I would need a new different multi channel unit to use the servos... will probably make the investment in the spring ...after Crimbo expenses ...and proceed from there

Thanks for the Info Gents ...

ALPHA

[CanadianBulldog22]

ALPHA,

Don't use another MFU. They are useless. The only think I use my MFU for is the startup sequence, lights, and the airsoft control. Everything else is setup with my Turnigy 9x radio. You can get a Turnigy 9x radio for around $60.00 on HobbyKing.com. Buying a better radio and using that is a better option. Also, the (2) lead wires you are refering to is because the HL tanks uses geared dc motors throughout. The turret rotation, elevation, drive motors, and even the airsoft mechanism are all controlled with DC motors, which only required 2 leads. The (3) leads you are used to seeing on brushless motors allow for a third phase to be used as feedback (Back EMF, google it). On a digital servo (Like the blue bird i used) that is also a brushless motor, but with a tiny esc inside the unit, which outputs to a standard 3 pin (+,-,Signal) we are all used to. Brushless DC motors are always better.


Chris

[971wright]

Hi The other way is to use the Blackcap motor fitted to the BB gun ,use this in the traverse unit the traverse speed is almost double .You can also use this motor in the Tamiya traverse unit to increase the traverse speed but you have to move the clutch to the middle to stop it going off .

regards pete

[Saxondog]

Hi Chris, interesting modification. And great description of the benefits and electronics choices available to operate your modification.

I also would like to mention its ok to post a link when recommending products from other vendors in your post, just FYI Mate.

Thanks for sharing, http://rctanksaustralia.com/shop/index. ... oducts_new

Saxondog

[CanadianBulldog22]

ALPHA,

Pete has a good point. I forgot to mention the black cap dc motor is faster. This is still a DC motor and cannot be proportionally controlled. I will post a video to follow explaining why that is important.

Cheers,

Chris