1/35 M4 Halftrack(s) to RRC Tamiya, Testors

Post all your Smaller Scale RC Tanks, Half Tracks and Vehicles, including build threads here. From below 1/18 to way down as far as you can go, H.O. 1/87th scale or less. Even your Smaller Scale figures are welcome here.
User avatar
modler
Corporal
Posts: 497
Joined: Sat Feb 02, 2019 2:33 pm
Location: North Ridgeville Ohio USA

1/35 M4 Halftrack(s) to RRC Tamiya, Testors

Post by modler »

The 1/35 Testors Half Track model with 3 channel Track assist steering mod starts here.
viewtopic.php?p=347810#p347810

Latest Video here
viewtopic.php?p=347810#p347810

After working with the MTM gearbox in another project here viewtopic.php?f=33&t=33341I decided this gearbox was the answer for an M4 Halftrack and so I continue that build here separate from the Crusader build.

After the MTM gearbox is up and working with both poly tracks, I will upgrade the model to "Hobby Grade" DP radio remote control. As it is now, it is "Toy Grade" radio remote control with crude "Escapement" steering.

Here are some videos for this build...

MTM gearbox re-build and test
https://www.youtube.com/watch?v=kBy7XCbifjY

Gearbox mounted to M4 Chassis and test
https://www.youtube.com/shorts/1d_Wy4AniIY

Left track\chassis test
https://www.youtube.com/watch?v=ufJjediYq38

Steering assembly mounted and test
https://www.youtube.com/watch?v=0FOamfHicPA
Attachments
The chassis came from the Halftrack shown in this picture. It is a running model but is crude compared to what I can build now. The two parts may wind up back as 1 unit again.
The chassis came from the Halftrack shown in this picture. It is a running model but is crude compared to what I can build now. The two parts may wind up back as 1 unit again.
This is an Escapement stye steering box that has been converted to proportional steering box with Ultra micro servo.
This is an Escapement stye steering box that has been converted to proportional steering box with Ultra micro servo.
IMG_8419.jpg (83.58 KiB) Viewed 33007 times
busy workshop with lots of parts coming together
busy workshop with lots of parts coming together
figuring out which servo to use
figuring out which servo to use
steering box test fit
steering box test fit
The right side has been parched up and works good now
The right side has been parched up and works good now
Some Arizona (1984) sand in these wheels from sitting in my model junkyard in Tucson AZ.
Some Arizona (1984) sand in these wheels from sitting in my model junkyard in Tucson AZ.
the right side needs wheel bogie repair, can't find a new one of these at this time so will repair this one for now.
the right side needs wheel bogie repair, can't find a new one of these at this time so will repair this one for now.
MTM gearbox axle assembly modified to be a bit stronger as it is going to drive 2 poly tracks.
MTM gearbox axle assembly modified to be a bit stronger as it is going to drive 2 poly tracks.
Last edited by modler on Sat Jan 06, 2024 4:28 pm, edited 7 times in total.
User avatar
Herr Dr. Professor
Lieutenant
Posts: 3462
Joined: Mon Apr 22, 2019 10:48 pm
Location: Southern Wisconsin USA

Re: 1/35 M4 Halftrack to radio remote control with MTM gearb

Post by Herr Dr. Professor »

I can make a rather good guess at "proportional steering box,' but "escapement stye steering box" puzzles me. Both seem to use a tie-rod (rather than, say, trailing arms as on some 1950s Ford tractors). Can you explain please?
User avatar
modler
Corporal
Posts: 497
Joined: Sat Feb 02, 2019 2:33 pm
Location: North Ridgeville Ohio USA

Re: 1/35 M4 Halftrack to radio remote control with MTM gearb

Post by modler »

Herr Dr. Professor wrote:I can make a rather good guess at "proportional steering box,' but "escapement stye steering box" puzzles me. Both seem to use a tie-rod (rather than, say, trailing arms as on some 1950s Ford tractors). Can you explain please?
Why certainly Herr DR.
The earliest form of sequential (although not proportional) actuator for radio control was the escapement. Like the device used in clocks, this escapement controls the release of stored energy from a spring or rubber band.

An "Escarpment servo actuator" is a linear device (not proportional) that was used in early radio control planes to move the Rudder Left\Right in both extremes of movement and when not called to actuate the Rudder (or elevator, ailerons), will return to center or neutral position. These were used before digital proportional servos were available.

Back in 1977, when China mass produced radio control cars became available at the malls, They were elaborate, well made Toys that featured "Digital Proportional" speed and steering and were expensive. As time went by, They figured out how to make them less expensive with "Bang Bang" steering using a new form of steering "Escapement actuator". Suddenly most Toy grade cars had this style of steering actuator and to make them even cheaper, no more proportional speed control as now they went "full on\off and reverse.
Full on\off is also called "Bang Bang or escapement style speed control as well as BANG BANG steering which is full left or right when steering command is issued then returns to center position when steering command ends with a center position adjustment lever.

So basically, a R\C Escapement actuator is similar to a servo in its function. It has a few drawbacks compared to a digital servo but has one major advantage, it is cheap to manufacture compared to a digital servo. These are very common in
toy grade radio control vehicles.

For years, I would cut the Escarpment steering out of Toy Cars and use them in models like Half Tracks. I am now converting those steering actuators to "Digital proportional" servo steering boxes.

M4 Escapement steering box bottom view with "return to center" motion
https://www.youtube.com/shorts/N05PaKAiBXU

M4 Halftrack with Escapement steering and simple on\off speed control still works after ~2.5 decades.
https://www.youtube.com/watch?v=DQxX4auE9jI
Attachments
This steering Escapement has been converted to a Digital promotional steering box. Not scale looking but very robust and will last for decades. Scale steering looks better of course but is very delicate and hard to repair but has its place on a nice scale model that runs on a smooth surface.
This steering Escapement has been converted to a Digital promotional steering box. Not scale looking but very robust and will last for decades. Scale steering looks better of course but is very delicate and hard to repair but has its place on a nice scale model that runs on a smooth surface.
IMG_8419 (1).jpg (83.58 KiB) Viewed 32960 times
Halftrack build area is busy. A DP HT is in process.
Halftrack build area is busy. A DP HT is in process.
"Escapement" Elevator actuator from a Toy radio control plane.
"Escapement" Elevator actuator from a Toy radio control plane.
IMG_8441.JPG (84.9 KiB) Viewed 32964 times
"Escapement"  Rudder actuator from a Toy radio control plane that flew very well.
"Escapement" Rudder actuator from a Toy radio control plane that flew very well.
IMG_8439.JPG (76.42 KiB) Viewed 32964 times
"Escapement"  steering actuator from a Toy radio control motor cycle.
"Escapement" steering actuator from a Toy radio control motor cycle.
Adjustable center position on this  "Escapement" steering box. No digital TX trim here lol
Adjustable center position on this "Escapement" steering box. No digital TX trim here lol
Last edited by modler on Fri Aug 12, 2022 12:38 am, edited 3 times in total.
User avatar
Herr Dr. Professor
Lieutenant
Posts: 3462
Joined: Mon Apr 22, 2019 10:48 pm
Location: Southern Wisconsin USA

Re: 1/35 M4 Halftrack to radio remote control with MTM gearb

Post by Herr Dr. Professor »

Thank you! I clearly understand--and memory confirms---the "escapement" steering. In the late '70s, Ertl sold two RC toy tractors (JD 4430 and IH 1486) with such steering. It was painful to watch, the all-or-nothing movement causing some tricky handling. RIP escapement steering.

I recommend Modler's explanation, immediately-above, to anyone checking this thread. It's well-done.
User avatar
Captain Morgan
Recruit
Posts: 26
Joined: Sun Apr 17, 2016 8:02 pm
Location: Russia

Re: 1/35 M4 Halftrack to radio remote control with MTM gearb

Post by Captain Morgan »

Great job!

I'm starting to try myself in the "animation" of models in 1:35 scale:



https://youtube.com/shorts/V3WQe5LtYMs
User avatar
modler
Corporal
Posts: 497
Joined: Sat Feb 02, 2019 2:33 pm
Location: North Ridgeville Ohio USA

Re: 1/35 M4 Halftrack to radio remote control with MTM gearb

Post by modler »

Captain Morgan wrote:Great job!

I'm starting to try myself in the "animation" of models in 1:35 scale:



https://youtube.com/shorts/V3WQe5LtYMs
I like that Caption Morgan, I will be using that short phrase to describe what I do with these models :think:

Suspension really is difficult @ this scale but I see it getting implemented more in the future.
The variety of models available in this scale (1/35) is impressive and the cost of entry is reasonable. The workspace required to work on these models is less as well not to mention storage and display. Interested in seeing more progress on your model. And as they say in France, Make Them Move :D
Attachments
oh look, upper complete (unibody mount no frame) drive line removed with 3 screws. This is a feature I perfected along the way to 1/35 model work. They have to come apart like a real machine as apposed to being  glued in place like a "static" model
oh look, upper complete (unibody mount no frame) drive line removed with 3 screws. This is a feature I perfected along the way to 1/35 model work. They have to come apart like a real machine as apposed to being glued in place like a "static" model
IMG_8462 (1).JPG (94.17 KiB) Viewed 32908 times
second screw in here
second screw in here
first screw removed
first screw removed
now to remove "Escapement" steering box, which is held in place by two screws
now to remove "Escapement" steering box, which is held in place by two screws
old track drive assembly removed. It was held in place by 1 screw.
old track drive assembly removed. It was held in place by 1 screw.
it is time to upgrade this M4, let the disassembly begin staring with the old radio system.
it is time to upgrade this M4, let the disassembly begin staring with the old radio system.
well, this looks better. The MTM gearbox has opened up new possibilities for a more scale like appearance and operation of the stock tracks.
well, this looks better. The MTM gearbox has opened up new possibilities for a more scale like appearance and operation of the stock tracks.
This upper track assembly uses the stock 1/35 tracks. Now those tracks will be used on the scale chassis\rollers\sprockets\idler wheels
This upper track assembly uses the stock 1/35 tracks. Now those tracks will be used on the scale chassis\rollers\sprockets\idler wheels
yes it has toy parts in it from that era as that is the best I could muster skill wise at that time. You have to start some where.
yes it has toy parts in it from that era as that is the best I could muster skill wise at that time. You have to start some where.
This early attempt (1999) at a half track has a crude suspension as this track assembly floats in the body assembly.
This early attempt (1999) at a half track has a crude suspension as this track assembly floats in the body assembly.
Last edited by modler on Mon Jun 27, 2022 3:43 pm, edited 1 time in total.
User avatar
modler
Corporal
Posts: 497
Joined: Sat Feb 02, 2019 2:33 pm
Location: North Ridgeville Ohio USA

Re: 1/35 M4 Halftrack to radio remote control with MTM gearb

Post by modler »

Herr Dr. Professor wrote:Thank you! I clearly understand--and memory confirms---the "escapement" steering. In the late '70s, Ertl sold two RC toy tractors (JD 4430 and IH 1486) with such steering. It was painful to watch, the all-or-nothing movement causing some tricky handling. RIP escapement steering.

I recommend Modler's explanation, immediately-above, to anyone checking this thread. It's well-done.
RIP escapement steering. Lol yes may they rest in pieces.

As you can see the old M4 Is going to get an update 8) I can no longer stand to looks at it in its present form 8O

This update will reunite the well used frame to the well used body and will re-join the ranks of my favorite models Arizona patina as an extra bonus ;)
Attachments
Now to fit the body back on the frame. The front wheels are too wide apart and will be made to fit the fender wells.
Now to fit the body back on the frame. The front wheels are too wide apart and will be made to fit the fender wells.
IMG_8473 (1).jpg (89.52 KiB) Viewed 32905 times
These elements will be replaced with updated versions
These elements will be replaced with updated versions
IMG_8468.jpg (68.19 KiB) Viewed 32905 times
Here is the old drive line making its last appearance.
Here is the old drive line making its last appearance.
IMG_8466.jpg (48.66 KiB) Viewed 32905 times
these two assemblies will be reunited at last after 23 years.
these two assemblies will be reunited at last after 23 years.
IMG_8464 (1).JPG (98.68 KiB) Viewed 32905 times
Transformation in progress
Transformation in progress
IMG_8463.JPG (87.82 KiB) Viewed 32905 times
User avatar
Captain Morgan
Recruit
Posts: 26
Joined: Sun Apr 17, 2016 8:02 pm
Location: Russia

Re: 1/35 M4 Halftrack to radio remote control with MTM gearb

Post by Captain Morgan »

To manage the models, I have developed a smaller version of TCB (parent project - Open Panzer):

Image

I have not yet received the mini-ESCs for commutator propulsion motors to begin assembly.
Initially, I assumed that I would control the propulsion motors (geared N20) through the DRV8833 drivers, but this does not seem to work. I ordered small ESCs from aliexpress.
User avatar
modler
Corporal
Posts: 497
Joined: Sat Feb 02, 2019 2:33 pm
Location: North Ridgeville Ohio USA

Re: 1/35 M4 Halftrack to radio remote control with MTM gearb

Post by modler »

Captain Morgan wrote:To manage the models, I have developed a smaller version of TCB (parent project - Open Panzer):

Image

I have not yet received the mini-ESCs for commutator propulsion motors to begin assembly.
Initially, I assumed that I would control the propulsion motors (geared N20) through the DRV8833 drivers, but this does not seem to work. I ordered small ESCs from aliexpress.
Very interesting. I am an electrical designer (retired) and my specialty is in micro electronics. I am curious as to why it did not work. The impedance of the N20 cored motors may be too low (3v). Put a 22 ohm resistor in series with the motor and try again. Oh course this will limit the current to the motor as well as increasing the impedance of the N20.

Oh, you could try a coreless motor as they are higher impedance than cored motors and take way less current to operate. If you provide a link to the ESC you ordered, I will give you my opinion on them.
User avatar
Captain Morgan
Recruit
Posts: 26
Joined: Sun Apr 17, 2016 8:02 pm
Location: Russia

Re: 1/35 M4 Halftrack to radio remote control with MTM gearb

Post by Captain Morgan »

It didn't work because the parent project, which has an L298 chip, needs PWM, inA, inB signals for each motor.
I am not particularly strong in electronics, more precisely, it is often difficult to read the datasheet (English is not my native language). I think DRV8833 will not fit, what do you think?
So far, I have only learned how to design boards in EasyEDA, and then with the help of an autorouter.

I ordered these ESCs to control the RC outputs from the board:

Image

https://aliexpress.ru/item/1005003152945927.html
Post Reply

Return to “Smaller Scale Military.”