radio controlled Matchbox lorry.

  1. optima21 Forum Supporter

    Messages:
    2,663
    Location:
    halifax, England
    this is a "little" project that I've recently started on, while I wait for a boat to build which is a bigger project. when I say bigger, it's only 18 inches long and looks like this

    [​IMG]

    only thing is that I want it to be radio controlled and with a live steam engine. It'll be over 20 years since I played with radio controlled models and technology has moved on with that and it looks like 2.4Ghz, but why does it seem that different manufactures have different ways of having the transmitter communicating with the receiver.

    so having a look at the systems available, I decided to go with flysky because they make a tiny 4 channel receiver which is 25mm x 11mm, and their standard receivers and transmitter are cheap too, I decided to go for i6s transmitter. later after looking it what batteries to use to power the radio gear in the boat, I realised that the receiver works down to 3.3V so it can operate from a single cell lipo battery.

    Ive also recently been watching 1/87 scale models that are popular in germany like these and find them fascinting to watch.



    so when looking for lipo batteries I was looking at drone junkies website and found that they do electronic speed controllers and micro servos that both work on single lipo batteries.

    so the receiver I got was this one

    https://www.dronejunkie.co.uk/flysky-4ch-pwm-receiver-compatible-with---fs2a-afhds-2a

    the electronic speed controller is this one

    https://www.dronejunkie.co.uk/dasmikro-1s5a-micro-bi-directional-esc

    and the servo is this one

    https://www.dronejunkie.co.uk/22g-servo

    so that's the small low voltage radio control gear sorted, with the receiver on the left, the servo in the middle and the speed controller on the right (with a pound coin for scale)

    DSC02142.JPG

    as for the motive power a 3V N20 sized motor seems like a good choice and there are a couple of options to gear it to a suitable speed, one option is to get a geared motor and use a bevel gear on the back axle, the second option is to use a motor without gearbox but a worm and worm wheel on the axle and this is the option I went for as it is more compact, but the worm gear is prone to stripping if speed changes are done to fast.

    so the 3V N20 motor came from here, as they are slow speed

    https://www.componentshop.co.uk/n20-dc-motor.html

    and the 14:1 worm wheel and worm came from here

    http://www.nigellawton009.com/Tenshodo_Gears_Single.jpg

    and what model should I convert to radio control, well I do like the look of Foden Steam lorries so the answer for me is one of the varients of a Matchbox Y27 Foden Steam lorry, so this is the one I decided on with the radio gear and a lipo battery

    DSC02107.JPG

    so the first thing to do is to take it apart

    DSC02114.JPG


    the first thing to do was to put the wheels in a lathe to true the tyres up. the tyres are hard plastic, but cam be trued ( if they dont give enough grip I've got some neoprene rubber to make some new tyres)

    DSC02117.JPG

    and the bore in the front wheels were enlarged and some bronze bearings were press fitted in place. there is a drill in the tailstock chuck and the bearing is a loose fit on that and the drill is also a loose fit in the 3 jaw chuck, doing it this way should help keep the alignment correct

    DSC02118.JPG

    the first maching on the chassis was to remove the front axle mounts and cast in springs, I would have liked to keep them, but I think a flat mounting face for the front axle/steering would be better. the top of the rear axle mounts were also faced off to make the top of the chassis square.

    DSC02120.JPG
     
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  2. mtt.tr

    mtt.tr Member

    Messages:
    1,381
    Essex England
    This will be interesting.
     
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  3. eLuSiVeMiTe

    eLuSiVeMiTe Forum Supporter

    Messages:
    9,662
    Location:
    Bedfordshire England
    Another project il be watching with interest.
     
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  4. stuvy

    stuvy Member

    Brilliant little project I love radio controls Iv still got one in the garage, its a Sebastian loeb xsara rally car and
     
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  5. roofman

    roofman Purveyor of fine English buckets and mops

    Messages:
    6,581
    Location:
    North West
    Wow that's brilliant :thumbup:
     
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  6. optima21 Forum Supporter

    Messages:
    2,663
    Location:
    halifax, England
    my first challenge was to fit the motor and and transmission. so the first thing I did was make a bush to mount the worm onto the motor spindle, so the bush is 1.5mm o/d and 1.0mm i/d , seen here testing the fit of the worm

    DSC02111.JPG

    the the axle holes were aligned, the easiest way to do this is to fit them on a rod in a chuck and then mount the chassis on a plate in a drill vice and then the axle holes are drilled out and bronze bearings fitted as the axle needs to be a sliding fit it the bearings (these were lapped against the axle which was cut from 2.0mm piano wire).

    DSC02121.JPG

    A hole was then milled in the chassis so the motor can be fitted to drive the back axle. the motor will be vertical due to the space available

    DSC02126.JPG

    and the next thing is to bend a bracket to mount the motor, it was bent from 0.6mm thick brass. the holes for mounting the motor were done first, then first right angle bends were done between 8mm square hss lathe tools in a vice, but to get the top hat section I used this set up, the ruler underneath is use as a shim to get the height right. the holes for mounting to the chassis were drilled after it had been up.

    DSC02135.JPG

    and the competed axle/motor assembly, and yes it seems to work, one advantage of having plastic wheels and a plastic worm wheel is that they can just be pushed onto the axle without anything else to hold them in place. I tried it by connecting it to a battery without a front axle and with a metal stapler for ballast and runs across the floor so it looks like I'll be ok with the motor/ gear set up.

    DSC02138.JPG


    if I need a higher gearing ratio, I can get a 22:1 ratio worm and wormwheel from here

    https://www.scalelink.co.uk/acatalog/Sundry_Items__Lead_Foil__Chain_Etc_.html
     
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  7. Migmac

    Migmac Member

    Messages:
    3,409
    Location:
    Kintyre. Scotland
    You’ve got my attention too
     
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  8. arther dailey Member

    Messages:
    3,244
    Location:
    Southampton England
    fascinating , look forward to more
     
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  9. ibrooks Member

    Messages:
    1,052
    UK Lancashire
    Liking the truck........ but the flag is upside down on the boat.
     
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  10. eLuSiVeMiTe

    eLuSiVeMiTe Forum Supporter

    Messages:
    9,662
    Location:
    Bedfordshire England
    Good spot. Wasn't paying attention to the boat.
     
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  11. colnerov

    colnerov Member

    Messages:
    3,239
    Location:
    Nr Gatwick UK
    Perhaps it's in distress.:whistle:

    Following with interest, although it's too fiddly for my sausage fingers.

    Colin
     
  12. optima21 Forum Supporter

    Messages:
    2,663
    Location:
    halifax, England
    tell me about it, I had to find some tweezers to hold the M1.4 screws that hold the motor in place.....Im fine with 10BA screws though which are about 1.7mm

    originally I was thinking about using 4.8V 1/2 aaa cell ni-mh battery packs for the power supply for the radio gear for the boat like this

    https://www.ebay.co.uk/itm/122165361905

    but then found that you can get 800mAh pp3 sized lipo batteries that can be charged from a usb plug, so they look to be a good option with a 5V regulator

    https://www.banggood.com/OKcell-9V-...ry-for-RC-Toy-p-1022214.html?cur_warehouse=CN

    but a review of them may say otherwise as Im thinking that the DC boost converter may not be able to give enough peak current for the radio gear and the capacity is really less than 400mah



    so back to the lipo battery for this lorry, I decided to go with a branded one as Im pretty new to the technical details of lipo batteries and they seem to be less tolerant and more fragile if handled wrongly compared to nimh and nicad batteries.

    I decided to go for the largest one that would fit into the lorry, and got a 480mah 3.7v lipo

    https://www.dronejunkie.co.uk/mylipo-480mah-37v-40c-80c-red-jst-plug

    and being a single cell charging is easier, so show below is the battery with a couple of chargers and a voltage display

    DSC02148.JPG

    so top left is a single cell usb charging lead, which has been disassembled as I read that some are just resistors, but this one appears to be a 3.7v 600mah supply,

    https://www.ebay.co.uk/itm/264485443640

    I wont be using that and ordered a generic TP4056 usb lipo charger (top right), but as standard they have a charging current of 1 amp, which is a bit too high so by changing 1 resistor you can change the charging current, mine should now be about 500ma

    https://www.ebay.co.uk/itm/143018042735

    you can also get a newer version of these that has a circuit protection board built in so they disconnect the lipo cell when they get down 2.4v to prevent damage to the cell.

    https://www.ebay.co.uk/itm/272986428636

    but didnt get one as looking at the lipo discharge curves I'd prefer it to be higher probably about 3.3v as this should also give the cell a longer life.

    [​IMG]

    so I may make a low voltage cut off later using using a schmitt trigger using an op amp to drive a 3v relay or mosfet, but until then I have a small voltage display which is small enough to fit into the lorry.

    and being a removal waggon there is plenty of space in the back, so I'll need to cut a hole in the floor of the truck body to clear the motor, I can the stick the receiver and speed controller to the floor and make a platform to mount the battery and voltage display, and the "canvas" top is to remove to plug and unplug the battery.

    DSC02150.JPG


    so far this is the easy bit, the front axle and servo fitting are a bit more complex.
     
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  13. dobbslc

    dobbslc Forum Supporter

    Messages:
    4,619
    Location:
    Hertfordshire UK
    Love that! Tiny stuff my eyes aren't good enough for.
     
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  14. optima21 Forum Supporter

    Messages:
    2,663
    Location:
    halifax, England
    so next on the list of things to do is to make some working steering. there are various German websites where you can buy 1:87 scale parts off the shelf, including steering for 4 euro's but the 15 euro's delivery is a bit steep, and the scale is slightly wrong.

    https://modelisme.shop/epages/0d0ec...c28d-f13d-493d-9dc2-9fb4695e2062/Products/LTS

    so its a case of making my own.

    in the end I decided to have a beam axle, with the hubs pinned though that and the pins also secured the spindle for the wheels, and as this is a welding forum I thought I'd use some welding wire, and 0.8mm mig wire seems to be a suitable size.

    so the hubs were made as a pair from 3/16 x 1/8 brass to be cut from the ends of the bar once finished. after drilling the 2mm hole of fitting the spindle, I then cross drilled it with the stainless steel spindle in place with a spacer on that to give the correct clearance for a wheel. I started drilling a pilot hole of 0.6mm before taking that to the finshed size of 0.8mm, lets say luck was on my side as no drills were snapped while doing this. holes for the steering rods were also do now.

    DSC02153.JPG

    the hub then some milling done on it to get it to the finished shape, the end mill used here is 1/8 diameter

    DSC02168.JPG

    once done the hubs were cut from the bar and faced in my milling machine. they were clamped between two 1/8" square tool bits in my vice

    DSC02173.JPG

    the beam axle was also made from 1/4x1/8" brass and an the pivot holes for the hub were drilled first ans then a the ends were milled to give the axle its H section again using an 1/8 end mill.



    DSC02164.JPG

    a small recess was then milled on the back of the axle as there will be a pivot there, but may have clearance issues with a servo arm later.

    DSC02166.JPG

    and finally drilling the hole that the axle will pivot on. although it looks a bit dodgy, it was the only way I could hold it

    DSC02167.JPG

    and now we have the assembled axle, hubs and spindles together with a wheel and pound coin for scale (again)

    DSC02179.JPG

    and the individual parts

    DSC02182.JPG
     
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  15. rtcosic

    rtcosic Member

    Is that an 87/1 pound coin?

    Magnificent! I couldn't see those items clearly let alone machine them.
     
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  16. optima21 Forum Supporter

    Messages:
    2,663
    Location:
    halifax, England
    now its time to fit the front axle to the chassis but first you need to work out where to fit it and sort out clearance issues. the front mudguards need to be thinned down to give enough clearance for the wheels, so this was done with a dremel, and they were thinned down to about 0.8mm, on some places they were originally about 1.5 mm thick. using a marker pen so you can see where you're grinding away.

    DSC02184.JPG

    then checking the gap that will be needed between the axle and chassis, and clearance for the wheel turning, turns out 4mm was about right

    DSC02193.JPG

    then a mounting bracket for the front axle needs to be made, here is its being milled to mount the axle in. the milling cutter is 2mm dia.

    DSC02194.JPG

    the completed mounting is then glued to the chassis after fitting the axle to check for clearance in the muds. the two holes for fixing the mounting to the chassis are then spotted though to make sure they will be drilled in the right place.

    DSC02200.JPG

    the holes are then drilled though and the chassis is turned over and the holes are then counterbored with a slot drill so the screws have a flat face to mount to. I wouldnt normally screw the component being machined to a piece of wood so that I can clamp it in place, but it seems it was the only way to hold it in place.

    DSC02202.JPG

    and we now have a working front axle and steering, the axle can also pivot up and down 2mm, just to make sure 4 wheels remain on the ground. its not a pretty as the original cast in leaf spring, but it work which is more important. a drill is used as the axle pivot as I havn't yet decided how I will do the final version.

    DSC02203.JPG

    DSC02206.JPG

    and from the side the axle location looks pretty good too

    DSC02207.JPG

    next its time to fit the servo to operate the steering, so I needed to drill a couple of holes in the servo arm to fit the steering arms. I ended up sticking the servo arm to a piece of wood with double sided sticky tape, finding the centre of the hole that goes though the servo arm (using the shank of a drill in a drill chuck) and the screwing the servo arm to the piece of wood. the two holes for the steering arms were then drilled.

    DSC02210.JPG
     
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  17. arther dailey Member

    Messages:
    3,244
    Location:
    Southampton England
    great work, thanks for taking the time to take and upload pics. :thumbup:
     
  18. optima21 Forum Supporter

    Messages:
    2,663
    Location:
    halifax, England
    the pics are the easy bit, the hard part is working out what you want to do and how you go about doing that.

    so the next thing is working out how to fit the servo as the space is a but tight

    DSC02214.JPG

    and working out how to clamp the chassis so you can machine it too ends up like this

    DSC02217.JPG

    and after machining it for the servo. the rear mounting took me a while to work out how to do it was it was directly on to of the crossmember of the chassis, and a bit too fiddley to make a suitable bracket, so I ended up milling a recess in it and gluing a piece of H section over the edges and seems to be a working solution.

    DSC02224.JPG

    and with the servo fitted

    DSC02227.JPG

    and the finished steering assembly (just making sure it will fit together) and space is pretty tight but it does fit together very nicely.

    DSC02229.JPG

    and the completed installation for the motor/gearing and the steering

    DSC02230.JPG

    DSC02235.JPG

    and I couldn't wait to try it out so I has a play earlier and I was impressed with it as goes pretty well, its speed is about 1m every 3 seconds, and the turning circle is about 10 inches. It doesnt need to be fast as its not for racing, but its slow enough that you dont crash it. so all I need to do now fit the body back on and sort out the cosmetics of it, so it'll probably be 2 or 3 weeks before I do an update.
     
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  19. stuvy

    stuvy Member

    @optima21

    I think this has to be one of my favourite projects Iv seen on here for a very long time keep the updates coming
     
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  20. arther dailey Member

    Messages:
    3,244
    Location:
    Southampton England
    agree with that , although think the toe in is excessive:whistle:, joking aside great to see the quality of work and more so the infinate patience taken. :thumbup:
     
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