Transport Tracks during a quick rebuild

[Liam Mahoney]

First of all, a very big thank you to everyone that has posted. I have spent so long looking at photos and getting inspiration from all of them.

Phil has asked about my transport tracks. I was waiting to finish the rebuild before posting but since my 6 month rebuild is about to start into the 3rd year I thought I might show a bit of what I have been playing with.

As I started into the rebuild I thought I would try a few different approaches to various aspects. The suspension was one that I thought would be interesting to develop. Design #1 I soon discovered is not so good - it locks nicely and works well but the glitch is that it is not as easy to set as I expected. Design #2 (not yet tested) is easier to lock and is more true to the actual design. It also gives a torsion bar length nearly 30mm longer than the first attempt, taking some load off the spring locks with slightly more wheel travel. Design #2 also gives the swing arm a longer and more supported pivot.

Here’s an overview of what I’ve done to date . . . . .

[Liam Mahoney]

The transport tracks - they are the original Armortek aluminium tracks cut down and fitted with new pins. I’ve had steel tracks made so I had 2 sets of the old tacks to play with. I intend to sell the steel tracks, they are not as detailed as Vincent’s Panther, but I have run them for over 23 hours in mud, gravel and sand with out any issues. I will post more details if anyone is interested.

[Liam Mahoney]

The road wheels and tyres were to replace the wobble wheels from the 2005 kit. Lots of bolts and nuts.

I still have a lot to do. I have never painted models before and I know that shows. Still much to learn.

[davidwilkins]

Hi Liam,

Some brilliant detailed work going into your tiger build, I really like your jig for holding and turning your model to different angles to work on.

Thanks for posting such detailed photos, these photos are very helpful to my own build.

Again thanks for taking the time to post on the forum.

Regards

David

[Phil Woollard]

Very interesting work you're doing there Liam, it's great to see the pics of what you are achieving.
You must try some period photography as your work will look totally convincing.
I never thought to cut down standard tracks to make the transport tracks, just imagine your tiger sat on a rail car ready to go off to the front, such a cool diorama.............keep the pics coming regards Phil.

[Liam Mahoney]

Thanks David, Phil
Yes Phil I have been toying with the photo options, and there has been mention of railcars on anther page that caught my attention

[Liam Mahoney]

Hi all
Per has suggested that I should show a bit more on how I made my bits, so here are the centre caps on the road wheels with the grease nipples which are made for an M8 socket head cap screw and an M6 flange nut. The grease nipple is a small section of 1.6mm copper tube with a 1mm copper rivet. I hope the photos make sense.

[Christoffer Ahlfors]

Absolutely brilliant Liam!
Thanks for sharing!
Are you using these hubs for fastening the wheels on the shaft?

Cheers,
/Chris

[Adrian Harris]

Very interesting to see how they were built up.

How do you get along with machining the cap heads, as they look like 12.9 hardened steel, which must have been a pain to turn ?

Adrian.

[Phil Woollard]

This is a video from Liam showing the gear change program that he has been working on.

[Stephen White]

Phil, that's certainly an improvement and is pretty convincing. Well worth experimenting. Thanks for bringing it to the Forum. Stephen

[Phil Woollard]

Clever guy is Liam, he said that when he's got a mo he will post explaining the system in detail .....phil

[Liam Mahoney]

Hi All
Sorry for the late reply, and thanks Phil for editing and uploading the Video - you have done a fantastic job on it.

Thanks Chris, I originally looked at using the hubcaps to hold the wheels on, I machined the bolt down and tapped an M4 on it, but after a lot more investigation I figured that the hubcap must rotate with the wheel . . . ? The locking tab for the hex which I guess is a nut of some kind, has a small bolt that locks it to the wheel spacer. I would really like to know how this system actually worked. So, no, they are just a hubcap that is pushed into the wheel spacer covering the bolt that holds the wheels on.

Hi Adrian, they are 8.8 I think, might be 10’s?? I use replaceable tip tools on the lathe and they machine quite well. The beauty of being untrained is that you don’t know what you aren’t supposed to do, so you give it a go anyway . . .

OK hear goes at trying to explain the programming of the controller.
It is all done with Open TX Companion. I programme the transmitter so that all the mixing is done before it is sent to the receiver. This system is for a single stick steering using a Turnigy 9XPro.

I looked at the problem as if it was a real vehicle, ie: the throttle operates the engine, in this case the sound card. Yes this requires its own receiver output, and the tracks (motors) which are on their own receive outputs (normal) are controlled from the mixing in the transmitter. This also gives me an additional safety system - the motors will not receive any signals until the correct switches are selected on the transmitter. Yes I can power up the tank without the transmitter turned ON and nothing will happen (not recommended obviously).

So the start up sequence is: one flick of the momentary switch (TRN), this is like turning the ignition on, it locks a latching switch within the programme which unlatches once the transmitter is turned off. The (TRN) is also used to set the sound card. Then the start switch is switched to ON (THR). Yes it seems back to front compared to a normal ignition, but the sound card is what dictates the switches. This switch system also adds safety for when the transmitter is turned ON and the switches are incorrect (which the transmitter will tell you) - everything will remain inactive. So once the start is ON the motor will start and you can use the throttle full forward to full reverse, basically neutral. Once the motor is running you can move the turret and can do a neutral turn, both of these actions are control by the throttle. For the turret the left stick sideways has a very slight curve meaning that full left will only give you a small output to the ESC on the rotate motor, then when the throttle is increased the mixing moves the output to increase as the rev’s increase. This is the same for the zero/neutral turn, moving the right stick sideways will set the motor outputs to a balanced turn, and then the throttle will increase the outputs proportional to the rpm, increasing the turn speed.

Time to move . . . just let out the clutch, switching the ELE will simulate the clutch by selecting the motor control curves for the gear selected. At idle in 1st, the tank will very slowly creep forward until the throttle in increased. The curve for first gear will give a throttle output from 0-100% with the motor output from 10-55%, so at full noise (full stick) the tank will only move at 55%. This gives most excellent control around the workshop as the ratio of stick movement to tank speed so low. Then into second gear – and is the interesting bit. This can happen at full stick, switching the ID0 to ID1 changes the output curves. The outputs to the motors and sound card during this change will drop simulating a slight kick (not too much to overload the drive train, I have steel track) then the rpm and the speed will increase at the rate determined by the second gear curves. In 2nd gear the throttle output is 0-85% and the motor output is 22-85%. Yes idling in second gear with the clutch out the tank moves quicker than in 1st. Then into 3rd - switch to ID2 which has throttle output of 0-75% (it would be a very powerful motor to rev to full rpm in top gear) and the motor output is 30-100%. 3rd gear is very tricky as the acceleration rates and turn radius make it very slow to respond.

Steering: I have different curves for the different gears and 2 radius turn circles. With the clutch out, move the right stick half way and the turn radius is quite large, move the stick to full sideways and the turn radius is reduced. First gear has a tight radius, 3rd gear is extremely large.

Acceleration: The rate of acceleration in each gear changes. In 1st gear the throttle and tank movement will closely follow the stick movement, 2nd is much less than first, and 3rd is even slower taking some 5-6metres to get to full speed. Deceleration is also slower in the higher gears – I’ve had a few moments where I have had to drop down the gears to stop in time . Switching off the clutch will be an instant stop! So when in gear the speed you move the stick has no real bearing on the speed that the engine revs and the tank moves, unless you are moving the stick very slowly, and the higher the gear the slower the engine and tank will accelerate.
I think that makes sense…

I will try for a better video over the next few weeks,
Thanks
Liam

[Stephen White]

Liam, thanks. It looks to be a major advance but......my quick look at Open TX suggests that it only supports half a dozen TX types, mainly Turnigy and Taranis. Since most of us use Futaba or Spectrum, does that means your work can't be ported to those TX? In hope. Stephen

[Stephen White]

Having said that in haste, I also see that the Turnigy 9XPRO sells at a ridiculous (..ly cheap) price and has a long list of features, including a port to install a rotary encoder. I can't see the waveform though, so is it compatible with the Armortek modules? I presume yes if you're using it?

Stephen