Kong Head Toybash part 3

At the end of the last post I decided to add a few more nurnies to the front of the cab and have now done so completing the construction process by finalising the primer.

Then it was into photoshop to come up with a suitable colour scheme. I wanted to go bold with the colours for this truck and looked over a number of vehicle concept art pictures I have collected from the internet for inspiration. Here's what I arrived at as a very rough paintover of the primered side view;

I went to the auto parts shop and purchased some spray cans in the appropriate colours. The first can I tried was an old one that had been sitting on the shelf for quite some time. On pressing the trigger an ooze of thick goo came out of the nozzle. I shook it up some more and tested the spray on a piece of wood and it seemed to come good so I started spraying the model... the spray coming out was not a fine mist but a series of thick blobs. I tried the other similar colour I purchased and it was a newer can and sprayed a perfectly fine mist. So one side ended up with a thick textured finish and the other was more like I was expecting. This ended up causing me problems as the too thick acrylic lacquer paint and the perfectly fine primer will start coming straight of the styrene when you pull off the masking tape. It seems to dissolve the primer styrene bond interface and the stuff will almost fall off which it did in several places. Everytime I removed some masking I had to repair the paint, the model needed and got more and more heavily weathered through the process. The other issue is that I am trying to complete this model and at least another before exhibiting them at the Perth SupaNova event coming up in nearly a week and a half, so there is a deadline. I am taking some holidays before the show to get them done and I dont need any more disasters besides the fact thet the weather has not been conducive to paint drying.

The model is now pretty much done except for a voltage booster board from Hobby King to power the 12 volt lighting from a 7.2 volt battery. I have had the board on back order for a number of months and still no show.

Here is the result of the last few days;

On to the next model for completion.
More soon...

Toy Bash Truck part 3

Part1, Part 2, Part 4, Part 5


I made up pairs of headlights using some Cree Led aluminium penlight torches I got from China on Ebay. The torches worked out costing about $4 each which I thought was a pretty good deal. They claim they put out about 1000 lumens, I suspect it may be a bit lower than this but they are incredibly bright for their size and only use 1 AA battery at 1.5 volts. They conveniently unscrew at the business end making for a really nice lens and reflector housing, and are easy to mount and solder some wires to.

 

I wired them up 4 in series thus requiring a 6 volt supply. The battery for the chassis is 7.4 volts so I am employing a Turnigy Ubec which can deliver a switchable 5 or 6 volts at 3amps from any input battery between 2s or 6s which in LiPo battery speak means between 7.4 and 22.2 volts. These 4 penlights are only pulling 1 amp from the battery so there is plenty in reserve.

The Ubec is wired to a little adapter which is made from a deans connector plug and socket soldered back to back with the feed wires coming off the positive and negative at the join. The join is then covered with some suitable heatshrink. It is a convenient way of plugging it in between the battery and the speed controller. The lights are wired to a servo extension lead with one end cut off and the appropriate end plugs into the servo style female connector on the output of the UBEC which stands for ( Universal Battery Eliminator Circuit). In the old days of RC you used to have an extra separate battery for the receiver, servos and any other electrical systems it is this legacy battery that is supposedly being eliminated by the UBEC.

The lights are switched by a push button toggle switch mounted on the side of the cab which when painted will just look like a  random bit of detail. It probably would be cooler to make a switch that can be controlled from the transmitter, I am only using 2 of the three channels, but that was laying around in a box so I used it. I like to use whatever is to hand where possible.

The cockpit has been started but still has more work to come. A 1/16 Bruder Toys man sits in the seat. I'm thinking of making some sort of space helmet and converting his rolled up sleeves to be more space suit like.

I made up some tanks from PVC pipe end caps and the next size up pipe which has had a slice removed from its circumference to bring it closer to the outside diameter of the caps. Mounting pieces were made from 10mm foamed PVC, first a hole is made of the same diameter of the pipe and then sections are cut to suit. these slightly domed end caps are getting hard to find. All the new stock at the hardware store have totally flat ends which are not as interesting a shape and I can make those myself easily enough with a disc of flat sheet.

The chassis was shortened at the front to fit the body work that has been built, but yet to be detailed. The olive green radiator looking shape is a leftover spare part from a Tamiya Wild Willy Jeep kit.

More soon...

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...

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...