Saturday, 27 July 2013

Chevrolet CMP 3 Ton Truck

During WW2, Canada produced these trucks in large numbers to British military specifications.   Many Commonwealth armies used the CMP truck as well as Russia.   The CMP was made in many variants and by most Commonwealth countries.   The models represent Chevrolet built CMPs.



The most difficult part of this build was the cab.   The many angled surfaces were a challenge to get right to get the correct look.   Radiator grill was represented by fine brass mesh.   The wheels came from the cheap toy semis mentioned in a previous post and were prepared in the same manner.


The springs, which are quite visible, are merely cosmetic and are made up in a simple jig as illustrated below.
Lengths of plastic strip are cut to the required length and then curved and held by pins in the correct curvature for the springs.   Shorter lengths are then glued and pinned until the spring is made up.   The differentials are made up from Insulin needle covers, glued end to end and detailed.
Basic construction was again 20, 30 and 40 thou plastic sheet with Evergreen strips and shapes making up the chassis memebers.



The tarps were made from fine cotton material, painted with a few coats of  acrylic paint with some thinned white glue to make them firm.   Not really happy with the look and I may redo them one day.


Saturday, 20 July 2013

Making Wheels Part 2

In this post I will describe the actual construction of the wheels.

   Cut your wheel rims to the required width.  Obviously this will depend on the vehicle being modelled but a good rule for trucks, is 5mm for front and 11mm for rear (Double Tyres)



     Sand faces of rims smooth and lightly file the sharp edge off rims.    Lightly sand internal and external faces.

    Cut tyres to the required width.  (for trucks, 4mm for front and 5mm for back)   This will allow about ½ a mm either side when tyre is placed on rim.

    Sand faces of tyres smooth.   File edges of tyres slightly rounded. 



    The next part is a little hit or miss.   You need to cut out a segment from the tyre so that when closed up, the tyre is a perfect fit around the circumference of the rim.      Trim to size. 



     Using the 20 thou plastic hole jig, insert the rim and then place the tyre around the rim.   I usually super glue one end and clamp with a peg.   This will only take a few minutes before you can continue progressively gluing the rest of the tyre onto the rim.   I use a cocktail stick to apply the glue and clamp as I go with a peg.  


    Fill any gaps with Squadron/Tamiya/Whatever Putty.   Allow to dry and sand smooth.


    Once you have finished your rim/tyres we can move onto the hubs and spokes.   Cut a length of 226 tube about 3/4” long (this will be trimmed to size on completion) and then two slices of 228 tube  about a mm thick.
     Glue one slice of the 228 to the 226 tube and allow to dry.   Repeat for the number of wheels you require.   



 The spokes are made up from plastic strip.   The key to success here is the ability to cut all these to the exact same length.   This is where the Chopper is ideal.   Some spokes have a little piece of semi round, rectangle or angle at the outer end of the spoke.   When cutting your spokes don’t forget to take this measurement into account.
  

   To obtain the length of spoke, measure the inside diameter of your rim, minus the outside diameter of the hub tube and then halve the resulting dimension.   Place your hub on the nail jig and centre your rim.   Cut two spokes initially and test fit.   Make any adjustments and cut remaining number of spokes (plus a couple spare!)


 To make up spokes with the little fancy bits at the ends just use a suitable spacer (washer, plastic offcut etc) so that when you glue the fancy bit onto the spoke, there is an offset.   This allows the spoke to sit straight over the ring on the hub and insets the spoke on the wheel a little.

     Working quarter about, fit and glue your spokes into the rim.   If you have measured correctly, they should go in very easily.  Most trucks seem to have had eight spoked wheels.   Some had 12 spokes.   If this the case, you may need to cut a slight taper on the inboard end of each spoke so that they fit around the hub more easily.

    Glue the remaining ring slice on the hub over the spokes and allow to dry.    When dry lift off and repeat for remaining wheels.   Allow to dry overnight before sanding/filing excess from hub tube.
    For wheels that have no hub i.e. the spokes go straight on the 1/8 axle, use the jig with the 1/8 hole.   A spacer (metal washer) is used to obtain the spoke offset.

A couple of notes.

You can obviously adjust the sizes of the wheels by using different diameters of conduit if you can get them.   You can also cut the rim down a little and cut and shut to the required size.   You would need to use a former of the required diameter to ensure they are all the same size.   The spoke sizes are just what I have used and again they could be varied.   Some spokes were flared from the centre outward, some were round etc, etc.
I have also used 40 thou plastic strip, curved around a suitable former in hot water for tyres as well.

A good website for a spoke calculator is this:   http://www.blocklayer.com/Scale-Rulers.aspx









Monday, 15 July 2013

Making Wheels Part 1

In this post and the next, I will illustrate my method of making spoked wheels for use with early armoured cars and trucks.   The tyres are made from plastic conduit and the spokes themselves from various thicknesses of Evergreen styrene strip.




The tools:

  


Precision Mitre Hand Saw.
Stanley Knife.
Emery Paper.
Files.
NWSL/Micro Mark Chopper – optional but definitely a should have.
I have since updated to the next generation of "Chopper" (metal based, replaceable cutting mat)
A Bench Sander/Linisher - again optional but very handy.


The Materials:

Electrical Conduit 25mm and 32mm  
Evergreen Styrene
214    1/8 Rod  - for axle
226    3/16 Tube  -   for hub
228    ¼ Tube   - for hub slices
242    2mm Half Round -   for fancy bit on end of spokes (if required)
294    3.2mm Angle  -   for fancy bit on end of spokes (if required)
143    .40 x .60 Strip   - for front spokes (trucks)
147    .40 x .156 Strip   - for rear spokes (trucks)
222   1/16 Rod   - for Model T spokes ?
Tamiya Extra Thin Cement
Superglue
Pegs, mini clamps etc.


2 x 6mm MDF 5”x 5”
1/8 Nail with head removed.
20 thou plastic sheet with hole just larger than your wheel rims.
Small metal washer(s).

Making up the Jigs

Find the centre of both pieces of MDF and mark.   Draw circles of diameters suitable for sizes of wheels you intend to make.
With protractor divide circle into eights (or divide the circle by the number of spokes required), drill 1/8 hole in one jig and 1/8 hole for headless nail in other jig.   Insert the nail into one of the jigs.   One jig is for wheels that require a hub to take a 1/8 axle and the other is for wheels that have a 1/8 hub i.e. like a model T Ford wheel.
  

Now that we have assembled the tools and the materials in the next post I will describe the actual construction.

















Sunday, 7 July 2013

Australian Matilda Hedgehog and Frog

The Matilda Infantry Tank, though generally considered obsolete by the British Army was still in use by the Australian Army right to the end of the war.   Used primarily in the South West Pacific Theatre, Matilda Gun, Flamethrower and Bulldozer variants were used.   The Matilda Hedgehog was designed as a "Buster Bunker" using a Naval anti-submarine mortar in a modified launcher on the rear of the tank.   The Hedgehogs, although very successful in trials never saw service as the war ended negating the need for them.



Matilda Frog

Matilda Hedgehog

The models were made from 20, 30 and 40 thou styrene sheet.   Various Evergreen strips and shapes were also used.


The running gear sponsons were constructed first.   Slices of suitably sized knitting needle were used for the road wheels and the track links were made up from individual pieces to replicate the pattern of the treads.


The lower hulls under construction.   A bonus with this style of tank is the much of the top of the tracks cannot be seen, so doesn't need to be modelled!


Balsa was used for the bows with superglued thread for the weld marks on the bows.   As can be seen, 6 Matildas were made, 4 as standard Gun tanks and 2 as what the Australian Army called "Circus Equipment", the Hedgehog and the Frog.


The turrets were a little difficult to make.   The main problem was to get the complex curves right.   Thin strips of plastic strip were laid alongside each other using the turret base and a line marked on the turret wall to achieve the sloping sides.   These were then sanded, filled and sanded again.   The main armament was made from knitting needle filed to shape in  a hand drill.   Auxiliary fuel tanks were made from aluminium tubing capped with plastic sheet.


The models were painted in Humbrol Bronze Green and the red fording depth decals are lining decal.



Tuesday, 2 July 2013

Ford Model T Ambulances


The Ford Model T Ambulance was first produced in 1917.   Ford made over 2,400 of these tough little vehicles during the First World War.   I myself have made 5!   The bodies and the chassis' were sent separately to France and then assembled for delivery to the Field Ambulance Sections.


The models were made again from 20, 30 and 40 thou styrene sheet.   Various sections of Evergreen styrene strip were also used.   The wheels were made from plastic conduit with plastic rod spokes.
Heat forming (where a male mould, less the thickness of the plastic used) is forced into a female mould which has a sheet of plastic heated over a gas ring attached) was used to produce the cab canopy, the ambulance body roof and the firewall behind the radiator.


The radiator grille was represented by very fine brass mesh.   I was unable to reproduce the classic Ford symbol!   The rolled canvas above the rear door opening was made from Milliput.


I decide to add interior detail to the ambulance bodies in the form of the two bench seats, stretcher and stretcher racks.   The rear tailgates are hinged (using hinges from Scale Link) and are fitted with the canvas pockets which protected the stretcher handles which protruded from the end of the vehicle.   These again were heat formed.


Steering wheels were made from cheap toy Jeep steering wheels and foot pedals were also fitted.


The ambulances were painted using Tamiya spray cans and the decals were homemade using white decal paper and red lining decals applied as crosses.