About this Blog

This is about the combination of two interests, Radio Control vehicles and Science Fiction models. Its also about vehicle design. The models have to satisfy two main precepts.

1. The vehicles have to work, ie be driveable, but not nescessarily win any races or rock crawling competitions.

2. The main thing is that they have to look cool.

Saturday, 30 May 2015

Toy Bash Truck part 2

Part1, Part 3, Part 4, Part 5

I finally completed constructing the chassis.The creeper chassis plates have been extended by some aluminium angle and channel section. The plates are held apart by some 6mm and 8mm aluminium rod spacers that have been drilled on the mini lathe and threaded at both ends to accept M3 cap screws.

The shocks have been mounted to the link mounting points on the axles with the links moved inboard. A piece of silicon fuel tubing has been inserted as a flexible bush into the hole in the shock shaft to allow some angular movement.

The top of the shocks use the mounting system that is included with the Hot racing shocks. These include a couple of silicon O rings and an aluminium ball shaped insert to allow for angular movement.

A styrene tray was made by heating some styrene with a hot air gun at specific points and bending it onto a wooden form one bend at a time. The trick is to shield the parts that need to remain flat so that only the plastic at the bend area gets heated. It is secured to the frame with some philips headed plastic screws salvaged from some old toy or appliance dis-assembly. The battery, speed controller and receiver are held on with self adhesive velcro. The battery is further sandwiched by some yellow EVA foam cut from a child's learn to swim surfboard.

The speed controller is a Castle Sidewinder 3 which can control both brushless and in this case a brushed motor using two of the 3 connectors. It can also be programmed through a Castle link and USB cable from your computer. It is set to crawler mode which gives a no delay reverse which I like as well as a drag brake at idle. The rear steering servo connects to a Hobby King servo reverser then to a Y connector with the front steering servo giving 4 wheel steering. Due to the 4 wheel steering it has a very small turning circle and is very maneuverable.

Unfortunately as expected the top heavy body tends to flop over to one side or another as can be seen below.

A solution to fix this was to attempt to make a sway bar. After some fiddling about this was made from some 2.5mm piano wire and a couple of small brass plates. Only the rear had enough room to fit this as the motor gets in the way at the front.This turned out to be entirely successful at curing the flop. A small DuBro collar secures the ends of the sway bar into the original shock positions on the axle. The piano wire is pretty old as can be seen by the surface rust, it'll need cleaning and possibly some paint. The hole that the sway bar pivots in has to be slightly bigger, preferably elongated into a slot to allow for the fact that the pivot position does not match the apparent pivot of the 4 link suspension. Its needs some play to compensate.

Here you can see the result of adding the sway bar with a nice level body.

I think the body probably sits a bit too high overall, but there's not a lot I can do about that at this point. I am going to add a bunch of tanks hanging down at the sides which may cure that perception. There is still some more volume to add to the body work at the front so that will help as well.

I completed the detailing of the top and nearly finished the rear.

The yellow part of the rear platform was originally from the top of the cabin of the dozer. The dark grey checker plate floor was from one of the rubbish trucks. The two black shapes that say Dick Smith upside down on them are the servo cases of my very first radio control unit from about 1980. They've sat in a box for nearly 35 years waiting for the right spot to glue them. Got a small amount to add to the back and then finish the front before the grey primer to see how its all looking.

The chassis also needs some paint. The worst part about that is having to dis-assemble and then re-assemble everything over again.

More soon...

Friday, 22 May 2015

Creeper 6X6 part 2 chassis

Creeper 6X6 part 1 is here

The original post for this from 2011 got accidentally deleted while I was trying to add a link to the next part, so I am going to recreate it here for a part 2.

Here is the Venom Creeper as it is supposed to be, a rock crawling RC vehicle supposedly to compete with the Axial  Rock crawlers. It was not as successful and has since been discontinued and for a little while back in 2011 they could be had new quite cheaply. I got a couple of the kits thinking I could attempt to make a 6X6 chassis. Others had already done this reasonably successfully so I had a go. One thing I particularly liked was the anodised aluminium beadlock rings which are very sci fi in design. The other aspect to the Creeper axles that i liked is they have a switchable diff lock, which means you can either have a working diff for tight cornering or a locked diff for better traction on rough terrain. As I have little regard to the "crawling performance" of these vehicles I thought they would suit my application just fine.

 I started by designing the chassis framework on a CAD program Deltacad.

This design was then printed out onto paper twice and spray glued to some 1.6mm thick lengths of aluminium angle. All the radiuses were then drilled out, after center popping them, using the radius centers marked on the printout. Then using a scroll saw and a lot of blades really designed for wood I cut out the rest of the material that made up the holes in the truss structure. Much careful filing later I had a pair of frames that the rest of the venom assemblies could bolt to.

 What you see here in these pictures is circa 2011. I eventually swapped out the shocks and their mounting positions many times over until I had a suspension system that could hold the weight of the top heavy body without flopping to the side. The added on rear axle is connected to a creeper frame cut in half, with many spacers made from 6mm aluminium rod on my Unimat 3 lathe.

It was quite a fiddle to get it all to work without binding or fouling, especially the front wheels which are turned for steering.

More recently with the new stiffer shock setup there is not the same amount of articulation as shown in the previous photos.

I then turned my attention to the body design and did a number of rough thumbnail sketches. After choosing the one i liked ( at the time, but ultimately abandoned and replaced) I roughly modeled it in Maya to get a sense of the volumes and proportions.

I then built a wood and plywood frame as a basis to start hacking into some 2mm styrene.
However I didn't really like what I had done and it sat around till this year 2015 when I did another thumbnail sketch that got me enthused and cutting plastic.

more soon...

Thursday, 21 May 2015

Toy Bash Truck

Part 2, Part 3, Part 4, Part 5

More than a year ago now I was looking at the toys in a discount store that may have interesting plastic shapes and found this rubbish truck toy which was not too expensive.

A little bit later I purchased a Bruder large tracked dozer thinking It might be fun to try and use the tracks for something. The cool thing about the Bruder range of toys is that they are all at a standard scale of 1/16 and reasonably accurate to the subject at least as far as most toys go. The pain of the Bruder toy range is that they use no screws in the assembly, its all tabs into slots with barbs that make it fiddly if not downright difficult to pull apart. Anyway it sat around in a box in bits for quite some time.

Some months later I found another of the rubbish truck toys for $3.50 at a thrift store or charity shop as its more commonly referred to in Australia.

Many more months later (only last week) I had the idea to see what would happen if I put them all together. Here is the result of that toy bashing.

Its basically the dozer cabin, back to front, joined to the combination of the two back ends of the rubbish trucks joined end to end, split down the middle and widened. A pile of 2mm styrene ties it all together. Parts off the dozer and the truck are re-purposed for detail bits and pieces along with a few kit parts, a small amount of foamed PVC and more styrene and assorted evergreen strips and textured sheet. A few of the urethane cast parts have also been employed here and there. It has a wooden frame underneath for reinforcement.
The wood is superglued to the plastic parts with thick superglue. The plastic is sanded with very coarse sandpaper to roughen the glossy surface so the superglue has something to mechanically bond to. All the PVC and Urethane parts are also superglued with a sanding treatment first.

The chassis, which is still to be completed, is based on a Venom Creeper seeing as I had a few parts still left over from the Creeper 6X6 project.
Here is the body work balanced on top of the chassis so far to give a rough idea of the way it will sit.

The yellow lump at the back is from the rear of the bruder dozer, here upside down. There is some work still to do at the back and quite a bit more to do at the front including adding a driver figure and fitting a seat. The original cockpit has been cut up as it faced the otherway. I may be able to adapt the existing seat for re-use, its not a sinple exercise at it was all molded in one at an angle with the rest of the interior. Much butchery has had to take place to extract it.
The wheels and tires are the old Axial Rockster beadlocks with Rock Lizards which, true to form, I have had sitting in a box for years waiting for a project to come along.

You can see how messy the bench gets with all the butchering and sanding of parts to get them to fit. I think I'll have to have a clean up before going much further.

More soon...

Part 2, Part 3, Part 4, Part 5

Monday, 18 May 2015

Hardware Shipbreakers

In the post about making your own PVC wheels I hinted at some concept art  and in particular the vehicle design that I found inspiring. Here it is.

It is from a proposed game originally called Hardware Shipbreakers, now Homeworld Shipbreakers. As far as I know it is still in development, though this artwork was released some years ago now.
The hardware of Shipbreakers is some of the most convincing designs I have seen, really believable they look like they could actually work. Many sci fi designs I see look cool but could not in any way work, particularly off road. You see many so called all terrain vehicle designs with close fitting wheel arches, where there is nowhere for the suspension to go. It looks cool on a road race car where there is not any where near the amount of suspension travel, but would be totally impractical offroad.

As is common for me, a project is usually determined by the tyres I can find. The tyres come first and the design follows. The RC4WD Interco Super Swamper series 40 tyres  arrived and the PVC rims I made just before I stumbled across this artwork. They would be perfect for a vehicle along these lines. One of the concept art illustrations shows the scale of the vehicle.

From this image the massive RC tyres scale out at 1/64 scale. I don't really want to work at that small a scale so I figured 1/35 scale would be more suitable which, although halving the apparent scale, still makes for a humungous machine. To visualise the size of the vehicle at 1/35th, double the height of the figure near the front wheel. 1/35 scale also has the advantage of all the military kits and figures in that scale for kit bashing parts.

I started with some thumbnails and then roughly modeled the one I liked in Maya to grapple with the proportions.

From the screen grabs of the rough computer model I drew up a CAD version in DraftSight to get some dimensions. I then used Delta Cad to print out the CAD drawing fullsize over a number of A4 sheets which then were stuck together with masking tape, lining up the pages using a light box.

This is going to be the largest model by far of any of my projects with the body at 1070mm long and 475mm wide. I am not sure if my idea for powering the model like the Space truck project with a 540 motor and gearbox in every wheel will work with this size of model and the massively bigger circumference of these tyres. I think I will have to at least use a 200 rpm final drive rather than the 400rpm I have for the space truck idea. I think a 750 sized motor would be nice but I don't see any planetary gearboxes to fit, well not on my budget anyway. Below you can see a drilled out Traxxas 17mm hex fitted to the 6mm shaft of the motor. There is a flat ground on the shaft and a 4mm grub screw secures the hex onto the shaft.

Below you can see how the offset was allowed for in the construction of the rims so that the motor sticks out and can be mounted at the end of the suspension arms. On the far right is a rim assembly before getting trimmed. A ring of pvc gets removed from each of the inner and outer rims on both sides.

Here is a complete painted wheel with its skull design re-drilled Axial beadlock fitted. It doesn't look that big in the photo, it's ridiculously big in reality.

I still have not begun to figure out the suspension or the steering. For the latter, probably a high torque servo will get buried in the arm of each of the front wheels.

At least it is now after looking at the concept art it's fairly obvious why I painted the PVC wheels yellow.
More soon...

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