RC Tank Warfare community hobby forum

Louis, I so fondly recall the sounds our toy tanks made sixty years ago. I wish I could still make them unselfconsciously.

lol

You should know your Maybach from your Ford GAA

Ad Lav wrote: ↑Wed Dec 06, 2023 6:31 am lol

You should know your Maybach from your Ford GAA

Conan_the_Hungarian wrote: ↑Tue Dec 05, 2023 7:28 pm Here's my attempt at what you're doing, using the AHHQ kit. Mine uses the Tamiya kit electronics. You're much further along with the details. I've focused on getting the mechanical aspect working first. The work you've done thus far is superb.

Hello Conan, i can see you started with the fun part while i kept it for last. I always wondered why Tamiya did not integrate their recoil unit with their Sherman "full option" kit. I suggest you start your own build report so that we can see your progress.

Hi everyone,

The following posts are for the gun mount, mantlet and recoil unit


Anyone that built a Nick Aguillar conversion likely remembers some difficulty with the fit of the mantlet, creating the gun mount and getting good barrel elevation.

After studying the Takom mount and pivot that is built according to the original, its better to do something exactly like it. Instead of bastardizing the Takom mount, i decided to keep it for a static display of the 76mm gun, and create a new one.


If you plan to reuse and hollow the metal barrel, or use the plastic version of the kit, i determined that 8.5mm of the main section should be inside the mantlet. This calculation is required to give the proper length to the barrel, and figure out the situation inside the turret.



Here is the barrel next to the Heng Long metal recoil unit that has the trigger switch for the smoker. Still don't know what that switch does but i have seen instructions saying that it connects to the gun barrel smoke unit... We shall see soon enough. Before doing anything, the first task is to do calculations and a basic plan on the placement of the recoil unit, front and back, ensuring it fits inside the turret ring.


Matching the barrel to the recoil unit involves cutting and drilling.


After dissasembly of the main shaft, the tip section seen here will be cut, and the remaining part drilled to accept the base section of the Takom barrel.


The Takom base section is drilled a bit larger for 1cm to accept the smoker unit tube and create a good joint. The tube needs to coexist with the wire for the flash for that 1cm. After that, its just the wire as the smoke will travel through the barrel without need for a tube. The tip of the tube will be glued to the barrel base at the proper time, i don't need it in the way at this time.


The Takom barrel is inserted into the recoil unit main cylinder and permanently glued, solid and strait.


And the barrel is re-mounted on the recoil unit. I have removed the useless side pins and i now have two holes on each side to solidly install the recoil unit on the gun mount.


I have recreated in plasticard a simpler RC version of the gun mount plate to fit at the back of the mantlet. This part is critical, the back plate need to be square with the barrel. There are many angles and the back of the Takom mantlet is not an easy fit itself.


Installed on the mantlet. Take note that Takom provides two mantlets, one for WW2 and a post war version. This is good because the other one can be used for the static display of the gun.


continuing on following post

Side mounts are created and after a lot of dry fitting to determine the optimal position, the recoil unit is temporality glued in place with a couple of small drops of superglue. The unit is thoroughly tested with the control board. The recoil behaviour is analysed. I had to reposition the recoil unit twice.


The middle section at the joint had a recessed level that i have decided to fill with plasticard tubing and make it smooth. It helps the barrel repositioning itself inside the mantlet.


Be aware that the Heng Long TK 7.1 comes with a Deans T Plug for the battery. An adapter for a Tamiya plug was purchased on Amazon so that i can use my existing batteries.


Underside view of the recoil unit in partial recoil position.


The recoil unit is a bit loose at the cylinder, i placed a plasticard strip to make it tighter.


The base for the servo was being hit by the smoker trigger switch and creating a kick back on the recoil. I cut the base a bit. I have briefly looked at the gun barrel smoke unit, i do not see any connection for the plug of this switch... a mystery. Maybe it goes into the trigger switch port of the control board. TBD in a couple of days when i start setting up the TK 7.1


Analysis of the Takom mantlet is done to determine best placement and size for the elevation pivot.


The gun mount is reinforced, pivot parts added and then installed on the turret.


Take note that there is a plate at the back of the recoil unit, likely a stopper to prevent the servo gears from hitting the top of the turret. I determined earlier that it was too long at the back and not clearing the turret ring. It was simply bended to clear it.


continuing on following post

I have completed the static Takom gun, adding the coax machine gun and permanently gluing the rest, including the kit plastic barrel that is perfect for such display model. It’s a nice and very interesting model on its own, it would have been a shame to waste it. Got to design a display base for it. It is missing a muzzle, but i have a good one in storage somewhere.


The mount provides a good potential for the elevation.

Here at max depression.


Here at max elevation.


Something that i kept an eye on the whole time is the recoil vs turret ring. Because i used the Tamiya rotation wheel, it is quite small and limits the space for the recoil unit to go down inside the turret. It clears by bending the back stopper.


View of the mantlet, with temporary attachments.


The model as it stands today. Next step, gun elevation, coax mg, smoke units, and all weapons testing.


Regards, Louis

Hello,

Quick post for gun elevation


I investigated reusing the Tamiya barrel elevation unit coming with the donor chassis. I found the gears to be loose, providing imprecise and limited elevation. I have discarded it.


Going servo elevation on this one. The TK 7.1 has extra flexibility for servo elevation. The K2 button is used to set the servo low and high positions for gun elevation, which make configuration a 10 second task. Also much useful for DIY builds.

I earlier discovered the K1 button. I was in disbelief on the first recoil tests when the Heng Long recoil unit was recoiling in the wrong way... Pressing K1 reverses the servo. A small issue is that i inadvertently keep pressing these 2 buttons everytime i insert or pull a connector from the board. It buzz when doing so.

There is also the optional auto loading feature for the recoil, which automatically lowers the barrel for reload and reposition it at every shot.



Here is the turret with gun elevation. I used a powerful regular size servo at the rear for strength and stability. All the turret RC features are installed on the turret top. When i lift open the turret top halve, everything comes with it. Trying to install barrel elevation to the bottom of the turret like Tamiya did on the 105mm gun would create a lot of difficulties for the builder.

I removed the side rails on the recoil unit as it was in the way. In the end, this Heng Long recoil unit is expensive for what remains, and i still do not know what that trigger switch does, and i have seen much better recoil unit than this one.

People with sharp eyes will notice the remains of a lowered platform that used to go across the loader's hatch on the left side of the turret, added and removed when i tried to position the servo there. It proved impractical.


Max depression.


Elevating


Max elevation.


The turret interior as it stands today.

I added a couple of plasticard strips to make the recoil a bit smoother. Honestly, i think i could have done a better home made recoil unit with my aluminum tubing and plasticard plates. The trigger switch can be purchased separately. I won't be buying this Heng Long recoil unit again.


Regards, Louis

Louis,

Excellent solution!

Barry

Thanks Barry !

The following post is for the electronics and testing.

First, here is a video of the model in action.




The gun smoker tube was installed and glued in place after the LED was installed, no issues.

I have removed the trigger switch from the recoil unit. I determined it has no purposes on this build. I believe the gun barrel smoker is getting its signal to fire from its connector that is attached to the negative wire of the gun flash port. So, the smoker trigger switch is probably for an integration with a model that has no compatible gun flash port.

I have replaced the red LED coming with the unit by a yellow one that i think is better to represent the explosion, and it aligns the LED style fire with those installed for the 2 machine guns. As i could not run the LED across the barrel, i had to cut the wire anyway and re-install the LED from the tip of the barrel.


The coax machine gun before installation.


Overview of the electronics under the hood.


The TK 7.1 control board takes a lot less room than the Tamiya electronics that requires a receiver as well.

The gun barrel smoker small control board is connected to CN5 (Wifi transmission) and to the negative wire of LED1. There is no need for the recoil unit trigger switch. The control board in this setup does not need a loop on CN6 trigger in order for recoil to work.

Access to the electronics is very easy, nothing is piled on top of each other with no access to the bottom like it was before, everything is right there. The on/off switch is kept loose. It's actually simpler to lift the upper hull to turn on the tank and plug/unplug the battery than open the driver's hatch with the on/off switch under it.


The two smokers are installed at the back, under the speaker that is removable to access the units. I wish the smokers had a smoke volume control as they generate a lot of smoke in a interior set with no wind or ventilation.



The speaker unit is put on top. Having cut the bottom section and keeping it removable provides a lot more flexibility.


Overview under the upper hull.

Headlights to LED4
Tail lights to LED3
Turret rotation to CN3
Bow machine gun LED to LED5 and servo to CH5 and operated by the sideways button under stick 2.


Overview of the turret electronics. The turret halves fall into place with an almost seamless joint. I just need to add a couple of magnets in between to make them secure.


Coax machine gun is connected to L9, and automatically activated when unit is turn on. Be aware that adding a resistor to the LEDs create issues and seems to prevent the control board from recognizing that a LED is attached and it will not activate the second machine gun. My problem was solved when i attached a LED without pre-installed resistor.

Pressing K+A buttons on the remote alternates the control between the bow and coax machine guns when A is pressed.


Firing the barrel. As mentioned earlier, i replaced the red LED by a yellow one. Its a 3mm LED instead of a 5mm because there is a need to leave some room for the smoke to go through. The gun barrel smoke is a nice touch. This is the first time i install these and it was easy.