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Making a 4mm Radio Control Truck


Grasslands
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This story starts with the O gauge layout ‘The End Of The Line’ and Giles work on developing a 16mm Radio Control Truck (http://www.rmweb.co.uk/community/index.php?/topic/18108-radio-controlled-road-vehicle-and-powered-gantry-crane/)

 

When I first saw this truck I was fascinated. Searching the net indicates that the Germans have managed to make radio control vehicles in HO (1:87), thus it should be possible to create a radio control truck in OO (1:76).

 

 

 

As our UK model market generally lags behind our German and American cousins, I thought it best that I take the plunge and see if I can construct one.

 

I have purchased a complete starter conversion kit (which arrived from Germany today) and I now need to start preparing to construct the vehicle.

 

The first steps will be trying to understand the German instructions (a challenge!!!!); understanding all the components; and finding a suitable OO truck for the conversion.

 

Any thoughts or experience from anyone who has gone down the same path are very, very welcome.

 

Tom

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Sorry I have no experience to share, but I'm interested to know what is in the kit you bought from Germany?

 

When I read the title of this Thread I thought you might be converting one of the Faller mechanisms to radio control.

 

I wonder would it be possible with an N-gauge bus?

 

...R

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Sorry I have no experience to share, but I'm interested to know what is in the kit you bought from Germany?

 

I wonder would it be possible with an N-gauge bus?

 

...R

My conversion kit was bought from here:

 

http://www.sol-expert-group.de/1-87-model-building:::48.html?XTCsid=tnbq8b2g43ik0kgm6pr3t55en5

 

It wasn't cheap to say the least, but my thinking is that once I understand all the components required I can significantly drop the price of the next one.

 

I will add some pictures of the kit in a bit.

 

As for N-gauge - at the end of the second video there is an N-gauge lorry wizzing around.

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I thought RC 1/87 trucks had been available for years in Japan  and world wide in toy shops  .Mini gear made them .no experience of them .great modelling ,

I was looking at some videos of mini gear produced ones last night. I thought there were some RTR ones around, but many of the You Tube videos show high geared examples, I am hoping that the gear reduction on my kit is sufficient for some scale speeds.

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Hi RJS1977 - I hope that the gearing on this one should be geared down low, but there is only one way to find out!

 

So the next stage is to try and understand what is in the box.

 

imag0414lr.jpg?w=625

 

I recognise a few of the parts in the box from previous radio control cars I have built (granted they were far, far bigger). I recognise a servo (and it is only 1.5 x 1.5cm!!!!).

 

img_9983lr.jpg?w=300img_9987lr.jpg?w=300

 

img_9988lr.jpg?w=300img_9989lr.jpg?w=300

 

 

The receiver is also shockingly small. The largest thing about the pack is the radio controller, which will easily squash the car. It seems that radio control has come on since I last dabbled. This new controller sends out a signal in Ghz rather than Mhz and seems able to be 'programmed' to the radio control receiver. No more of that band 1-4 crystal nonsense. This sounds like a step in the right direction. It apparently also means that you do not need such long aerials on the models, which I suppose has helped push miniaturisation forward.

 

My immediate concern is the wheel sets. This kit is designed to convert a lorry. I didn't realise that it is designed for a lorry with a double tyre axle on the rear wheels, this might limit what I can convert.

 

I have three vehicles that may become the final RC prototype. The ground clearance is really good on the pick-up truck, but the wheels that come with the pack are much smaller than it's current tyres. They are a much better fit to the NCB lorry, but that might be more tricky to convert.

 

Anyone one know if the die-cast models below have friction fit wheels? It would be nice to retain the original wheels if possible.

 

imag0420lr.jpg?w=300

 

imag0419lr.jpg?w=300

 

imag0418lr.jpg?w=300

 

The next step is to decipher the german component list. Let's put google-translate to the test.

 

 

 

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That website seems to have lots of interesting parts - such as small gears and motors. I haven't seen gears like that anywhere else, in spite of a lot of Googling.

 

I suspect the Deltang receivers would easily fit in 00Gauge vehicles. They come with a motor controller and I think they can be programmed to operate a servo for steering. I guess the mechanicals are more of a challenge than the electronics.

 

...R

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That website seems to have lots of interesting parts - such as small gears and motors. I haven't seen gears like that anywhere else, in spite of a lot of Googling.

 

I suspect the Deltang receivers would easily fit in 00Gauge vehicles. They come with a motor controller and I think they can be programmed to operate a servo for steering. I guess the mechanicals are more of a challenge than the electronics.

 

...R

 

Hi Robin

 

Yes the receiver is certainly small (picture below).

 

It looks like I will have two free sockets once the motor and servo are wired up, so I suppose you can rig up a couple more servos to operate hydraulic pick-ups etc.

 

post-3486-0-04479600-1380392588_thumb.jpg

 

I have managed to get the wheels off the AEC truck, they are held on by an abrasion-like tip to the axle.

 

post-3486-0-21049700-1380392675_thumb.jpg

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Are those 4 white things sockets for servo connectors?

 

If so I presume the ESC is separate from the receiver.

 

The Deltang units have the ESC incorporated in the receiver board for about the same size board as in your picture. However on the Deltang boards the connections must be soldered on - makes for more trouble but a smaller board.

 

Will the system you have work from a single LiPo cell?

 

...R

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If weight is a concern perhaps a BT models truck would be better as they have plastic bodies. The new Oxford Scammell Showtrac also has a largely plastic body.

I've been looking at the website and I see that there is a kit for converting a Siku model truck to remote control. As Siku are diecast models it should not be a problem converting diecasts.

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Are those 4 white things sockets for servo connectors?

 

 

The Deltang units have the ESC incorporated in the receiver board for about the same size board as in your picture. However on the Deltang boards the connections must be soldered on - makes for more trouble but a smaller board.

 

 

...R

For £28 you can buy the DelTang receiver/esc pre-wired, which makes it really easy..... I'm a fan of the Deltang stuff, and can recommend it.

 

I think the motor/gearbox shown will have no problem at all with a die-cast body (depending one the ratio selected). I've been playing with a Ford Pop, and a similar motor gearbox, and power isn't a problem.

 

 

As a general rule, scale 'toys' are not a good starting point for a scale performing model

 

Mikroantriebe is another source of 1:87 RC components

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Are those 4 white things sockets for servo connectors?

 

If so I presume the ESC is separate from the receiver.

 

The Deltang units have the ESC incorporated in the receiver board for about the same size board as in your picture. However on the Deltang boards the connections must be soldered on - makes for more trouble but a smaller board.

 

Will the system you have work from a single LiPo cell?

 

...R

  

 

For £28 you can buy the DelTang receiver/esc pre-wired, which makes it really easy..... I'm a fan of the Deltang stuff, and can recommend it.

I think the motor/gearbox shown will have no problem at all with a die-cast body (depending one the ratio selected). I've been playing with a Ford Pop, and a similar motor gearbox, and power isn't a problem.

As a general rule, scale 'toys' are not a good starting point for a scale performing model

Mikroantriebe is another source of 1:87 RC components

Just incase it wasn't clear, the receiver that came with my kit is a DelTang model. The kit also came with a speed regulator.

 

The model will work off one LiPo cell, but i suppose it would be possible to wire up two for extra running time. When the kit arrived one of the first things I thought was 'How am I going to charge that battery?'

 

I am glad I did a bit of research on LiPo batteries last night, as it seems they have quite a specific way of charging and draining. This website was very helpful: http://www.rchelicopterfun.com/rc-lipo-batteries.html

 

Any one have any experience of wiring up multiple 1 cell LiPo's in series (if it's called series)?

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Great to see that DavidT's products have reached Germany.

 

This link http://www.shdesigns.org/lionchg.html may be useful for LiPo charging at "normal" speeds. The model aircraft community puts far more stress on its batteries than scale model trains and trucks need.

 

I've built a small circuit following the concepts on that web link which I use to charge the single cell LiPos in my trains. I can adjust the voltage to overcome the voltage drop in the rectifier which is necessary because a loco could be placed on the track in either orientation and could also discharge into another loco. With a multi-turn potentiometer very accurate control of voltage is easy.

 

...R

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I wouldn't wire up your batteries in series - low voltage is your friend here! By operating at single Lipo voltage of 3.7v, you'll get slower motor speed (which is a good thing) and the rest of the electronics will still operate.

Your battery is 180mA, which should be fine for around four hours work. My lorries (at 1:43 scale, 7mm) have 220mA batteries, and they will do at least five hours exhibition duty before requiring recharge - and they have larger motors and more vehicle weight.

 

Wiring batteries together, either in series or parallel complicates charging significantly (balancing) so is better avoided unless you can remove them and charge them independently, or buy pre-built 2xbattery packs.

 

If you need longer duration, buy a larger battery.

 

You'll find these little motor/gearboxes immensely powerful for their size.....!

 

Good luck, it's great fun!

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Your battery is 180mA, which should be fine for around four hours work. My lorries (at 1:43 scale, 7mm) have 220mA batteries, and they will do at least five hours exhibition duty before requiring recharge - and they have larger motors and more vehicle weight.Wiring batteries together, either in series or parallel complicates charging significantly (balancing) so is better avoided unless you can remove them and charge them independently, or buy pre-built 2xbattery.

Hi Giles

 

Thanks for the input. Wow i never thought that the battery could last that long.

 

I do not have loads of time tonight, but here are some pictures of progress

 

post-3486-0-92842300-1380494072_thumb.jpg

 

post-3486-0-06724700-1380494082_thumb.jpg

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I thought I would provide some description and photos about my progress from last week.

 

As you can see from the above pictures, I chose the Oxford Die-cast AEC pick-up truck, mainly because of the ground clearance beneath the chassis. The main risk of using this truck is the difference in size of the AEC trucks wheels compared to those provided with the conversion RC kit.

 

Wheel removal

 

The Oxford Die-cast wheels are held onto the axle with an abrasive tipped axle (not quite a thread, but more a cross hatching).

 

This meant that a bit of gradual pulling (using a pin vice and brute strength) releases the wheels. The Oxford Die-cast tyres are made of a similar rubber to those provided in my kit, which should be great for traction.

 

2013-09-28-17-12-14lr.jpg?w=579

 

Motor positioning

 

2013-09-28-16-38-56lr.jpg?w=625

 

The next job was to provide enough space for the motor on the die-cast chassis. I cut away at the rear of the chassis with a mini drill armed with a disc cutter. After losing about five disc cutters, I managed to clear a nice space for the motor.

 

2013-09-29-12-59-50lr.jpg?w=625

 

2013-09-29-12-58-43lr.jpg?w=625

 

2013-09-29-12-58-55lr.jpg?w=625

 

I soldered a small bit of wire to the brass gearbox, which acts as a simple harness to keep the motor inside the chassis.

 

2013-09-29-17-54-26lr.jpg?w=625

 

Building the front axle

 

The steering axle is a lovely, simple kit. I didn’t realise that the kit is made so that the axle will move across the x, y and z axes, so I am very pleased (as I thought I would have to adapt it for up/down movement). The plastic is also very rigid, with little chance of distortion, it looks laser cut.

 

The wheels supplied are quite small and the rear wheels are constructed to take a double tyre (which would look a bit silly on non-lorry models). In order to fit the AEC’s original wheels I replaced the kits brass axle pins and converted new ones out of the AEC axles. I didn’t want to risk widening the holes in the steering kit to take the wider AEC axles, so I milled down the AEC axles with a mini drill and a file.

 
2013-09-29-16-03-06lrps.jpg?w=625&h=424
 

Picture above - To the left - newly milled axles, made out of the AEC axle.To the right - the kits original brass plunger axle.

 

2013-09-29-16-46-44lr.jpg?w=625&h=352

 

Fitting the steering axle

 

2013-09-29-17-29-26lr.jpg?w=625

 

I decided that the steering column needed so much space beneath the body that it would be better to cut away the front of the AEC chassis and fit it directly to the cab. I also removed the mud guards, so the wheels wouldn’t collide with them.

 

Thoughts on progress so far

 

It was at this stage that I started to realise that the wheels were too far stretched out from the steering axle. This gives the impression of some monster truck adaptation, which I quite like.

 

2013-09-29-20-41-00lr.jpg?w=625&h=352

 

The problem is that the rear axle is fixed in the motor gear box, and is nowhere near as lengthy as the front one. Thus when the back wheels go on, the final product will look a bit stupid. So my next task will be to carefully de-construct the steering axle and re-mill the front axles until they are a bit closer to the body.

 

I have ordered some spare axles (just in case).

 

Expect an update soon.

 

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Thanks for all the great pictures. I'm looking forward to the video of the finished product.

 

Be very gentle with the wires from the motor. I broke a wire off a similar motor and when I opened it up to see if I could solder in a new wire I lost one of the brushes - tiny hair-thin wires. I think if I get another motor I will put a drop of epoxy where each wire exits the body for added durability.

 

...R

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Thanks for all the great pictures. I'm looking forward to the video of the finished product.

 

Be very gentle with the wires from the motor. I broke a wire off a similar motor and when I opened it up to see if I could solder in a new wire I lost one of the brushes - tiny hair-thin wires. I think if I get another motor I will put a drop of epoxy where each wire exits the body for added durability.

 

...R

 

Thanks Robin, I will watch those pesky little wires. a drop of glue sounds like a good idea.

 

I have managed to bring the front wheels back into the body now and I have also fitted the back wheels.

 

This evening the truck had it's first proper trial using my gaugemaster controller on low voltage. There was previous discussion about the diecast truck being too heavy. The opposite is the case, as it really needs a fair bit of weight over the back tyres to make sure there is minimal slippage from the tyres. This won't stop it running, but it will impact how it runs on uneven surfaces. I wonder how I can put a good weight on the back without having to convert the pick-truck into a box van. Suggestions appreciated.

 

I could also do with some help RE: wiring, but will post up the wiring diagram another day.

 

I cannot do much else until my battery charger arrives in the post.

 

Night

 

Tom

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Your tyres appear to be hard plastic that would give poor grip. As an experiment you could try putting a small rubber band around the driving wheels (like traction tyres on the trains). If that works, and if you can't get suitable alternative wheels it may be possible to put a groove in the centre of the wheels into which an o-ring could fit and protrude slightly.

 

Also, I wonder if you might have better low speed control with the Deltang controller so that the truck wouldn't try to start too quickly.

 

...R

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Hi Robin

 

This AEC truck actually has rubber tyres. I decided to retain them because the softness of the rubber was about the same as the tyres that came with the kit.

 

The rubber band idea is good and I will try that later.

 

I have a few videos of the car driving around on my desk (without a steering servo) which I will post up soon.

 

I can always try doing this:

 

 

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