A Chequered Chieftain at #10

[Armortek]

Richard, I suggest that you skip dry moly on the pins.
If the model is a static model the dry lubricant will not make any difference. If the model will be an RC model then the dry moly will not last long anyway - especially if you are running over grass. In addition, there should be no need to lubricate the pins.

With regards to the sprocket rings and track horns - the tank has so much weight and there is so much torque in the motors that the sprockets and tracks will bed in quite fast.

Kian

[Richard Goodwin]

VM thanks for the advice Kian; good to know that the Manufacturer is keeping overwatch to us 'newbies' and providing guidance.

Could you advise what you did with the prototype in regard to the chamfer to prevent track climbing? My thoughts were around no more than 5mm deep with 2mm around the top of the teeth if necessary?

[Armortek]

We did not chamfer/ fettle either the tracks or the sprocket rings . that applies to both the prototype and the production validation build.

I would suggest building the hull up,fit the tracks and see now it runs (can do that without the motors - ie push it). The Chieftain track is fairly tight (unlike the Tiger 1 for example), so I think you will find the tracks bed in very fast.

[Richard Goodwin]

We did not chamfer/ fettle either the tracks or the sprocket rings . that applies to both the prototype and the production validation build.

I would suggest building the hull up,fit the tracks and see now it runs (can do that without the motors - ie push it). The Chieftain track is fairly tight (unlike the Tiger 1 for example), so I think you will find the tracks bed in very fast.

Again VM thanks for the advice; I wasn't looking forward to filing them further . I'll etch prime the sprocket rings now and give that advice a go when the opportunity arises

[Richard Goodwin]

Ok so I did think about this a little longer and whilst the advice is you don't have to, I made a personal choice and did. I suppose you can equate it to those that use grease within the drive unit - they prefer it! Anyway, I finally finished one track length today after stripping down some 60 tracks; filing, repainting and varnishing, not that it will probably stay there once running but you can't blame a bloke for trying! I did find that dry lubing the track pins made them go in so much easier and left the etch on the pin as opposed to scratching it off and that i didn't use that much when I grouped them together and sprayed in batches. Here's a pic of the finished track:

It measures just over 2.5 metres!

I've also been working on the return roller assemblies and a friend has TiG welded a couple of the boxes but more on that later!

Have a great Christmas everybody and try not file when you've had just the one!

[John Clarke]

That could be made into a nice Christmas decoration, few cards, sprig of holly or mistletoe

[Richard Goodwin]

Now a card holder I might be able to get away with

[Richard Goodwin]

As mentioned earlier, a friend of mine was sorting out the welding using TIG on a couple of boxes. Now soft soldering is ok but it does give a weak joint, also, its difficult to get a rough finish on it like the original hence this experiment with TIG. I decided to try this out using the triangular boxes since i'm not happy with the shape of them so if they end up getting damaged, it wasn't a big deal; it's easy to blow a hole in this thickness of material if you don't get the current right so if you are contemplating this, leave it to an expert in this type of welding!

Before welding, the boxes were beaten into shape to ensure the corner edges line up with each other.......

I'm really happy with the finish.......just what I was looking for Thanks buddy, great job!

The lids unfortunately will have to be soft soldered since there isn't enough material there to weld :roll

The other boxes and the mudguards will now also be TIG welded.

[Vince Cutajar]

Just like the real thing. TIG is ideal for sheet metal work.

Vince

[Richard Goodwin]

With my track building temporarily suspended, I've shifted my focus to the return rollers.

I started by deburing the main body and two bogie bodies to see if the roller body would fit into the slot. None of my 6 roller bodies fitted into either bogie so using a fine file, I took equal amounts off each side until it did fit in both bogie bodies. The body was then cleaned and degreased in preparation for the installation of the bush and bearing.

Using Loctite 648, the brass bush (EH0315)was pushed in and secured into the roller body. I would urge using the Loctite sparingly and ensure you use a small brush to spread it evenly over the bush and body. Depending on environmental conditions, you only have around 4 minutes or so if using this type of Loctite so don't hang about!

With the bush in position, I would suggest pulling a cloth with a little solvent on through the brass bush and out the bearing housing. This is to remove any excess loctite that may have been pushed out by the bush. Do not return the cloth back out through the bush since you could deposit Loctite within the bush and consequently, lock up the shaft!
Loctite 648 was used again to fit the bearing which is a push fit into its recess. With the bearing installed, a shaft was inserted and the bearing turned every 30 seconds or so to ensure that the bearing, bush and shaft were aligned and that the the bearing wasn't locking up due to excess Loctite.

With the Loctite set, the body was prepped for etch priming; the bearing is about the size of a UK one pence piece so using that as I guide, I cut out a piece of masking tape to cover the bearing and stuffed a piece of kitchen roll in the brass bush to prevent the ingress of paint.

After prepping the wheels, I wrapped masking tape around the outside diameter where the tyre would be attached too and removed approximately 1 mm from each edge to ensure a continuous edge for the paint. Etch primer was then applied to all parts.

Now originally I thought that the wheels were secured to the shaft using Loctite to ensure that they were locked to the shaft. Had I done a full dry fit beforehand, I would have seen that the wheels were locked in place by the M6 nut. If this nut loosens, then these rollers will be free to flap about with the potential to do significant damage. You could get around this by adding a strong Loctite to the nut but then this doesn't make it easy to disassemble for maintenance eg lubrication! Hot air guns aren't friendly to paint either! So when I do the final assembly, I'm going to Loctite the wheels to the shaft with 648 and secure the nut and the screw at the other end of the shaft with Loctite Purple. I'm not sure if this type of Loctite will work in this instance, only time will tell but i will be checking the running regularly when doing the initial running in just in case

[John Clarke]

Looks good Richard, as long as the shaft keeps turning in the bearing and bush, the purple loctite should be fine.

[Richard Goodwin]

The next update.....it would be road wheel assemblies next but since I want to do the excellent mods by John Clark on these and don't at the moment, have access to a lathe, I'll move on to the basic bogie assembly. No w,using my lessons learned from the return roller assembly, I'll do a full dry fit first!
So first, the drawing....

Then the parts....

So the first step was to prep the bogie body itself. All tapped holes were cleaned out using a suitable size tap, the body debured then rubbed down with 120 grit paper with the exception of the roller body slot where a power file (a new toy) with 180 grit was used. Be careful if using a power file, these things eat aluminium for breakfast as well as their own belts if you apply to much pressure! Finally, the body was washed in clean soapy water, rinsed and thoroughly dried. It would only need degreasing now before being etch primed.

With the bogie 'prepped' the first step was to construct the spring assembly as follows......
Screw in the spring stud into Spring Cap A (EH0205)
.

Install the smaller spring...

Then the larger spring.....

Finally, cap off with Spring Cap B (EH0206) and secure with the brass Stud Cap......

Now I do have a couple of questions for Armortek in regard to the Spring assembly so grateful if you could provide some guidance.....

1. Should the screw thread of the spring stud be totally engaged with Cap A? The Cap has the depth but there is around 5mm of thread currently exposed. I suspect the answer is yes and that the thread will need running through but grateful if you could provide confirmation of this before I proceed.

2. Is the brass stud cap done up fully to secure the springs in place? Again I suspect the answer is yes but would again appreciate confirmation.


With the spring assembly complete, install the control arm stops. Now the holes in the body are sufficiently large enough to allow the angle of the stop to be changed to ensure these run parallel to the control arm should it hit them. Its easier to install these now than it would be later and the final position can be adjusted once the control arms are installed.

Install the bushes into the control arms.....

then install the arms into the bogie and secure with two arm pins......do not fit the Nyloc nuts to secure the pins!

Install the spring assembly into the bogie ensuring that the claws of each control arm engage with the slot on the corresponding cap. Once fitted, you'll need to wedge up the control arms to keep the spring assembly captive between the claws. I used bits of 5mm plastic spacers on this occasion.

Finally, install the roller assembly. When I do the actual final assembly, I'll just install the roller body which will make painting easier.

Now the more astute of you that have been following the other more advanced threads would have noticed that I haven't modified the control arm with the double claw. This is because I'm waiting for the guidance in relation to the spring assembly before checking myself if there is an issue......just to satisfy my own curiosity!

[John Clarke]

I like the plastic pegs/pins, much better than my elastic bands.

Though I'm not fitting the springs until they've been given a top coat of paint, otherwise I'd miss areas.

[Richard Goodwin]

Me too John which is why I'm doing the following.

So have made quite a lot of progress wrt the bogies as you can see....

Every part has been 'prepped before being etch primed before any assembly has taken place. The intention here is to paint the complete assembly with undercoat and top coat and varnish the inside of the bogie housing, the spring assembly and the swing arms. Wrt the wheels, these will be finished painted and varnished on the inside faces before assembly to the wheel hub. Not been able to do anything wrt the hub since still waiting to get access to a lathe; hoping it will be soon! I'm also waiting for delivery of an M6 Plug tap for the end caps of the spring assembly which hopefully, once fully taped, will prevent the spring assembly catching the top of the bogie housing as per below...

In addition, I've also shaved a little off the right hand (twin claw) swing arm to ensure it will contact the bump stop before hitting the top of the bogie housing.....

Each bogie housing had a number stamped in the slot where the return roller sits ie 1,2 and 3 meaning front, middle and back respectively. Whilst I can initially not see any difference between the housings themselves, there is clearly a difference wrt the bits that are bolted onto them therefore, that number has been transferred to the rear of each assembly before fitment of the return roller....

I did have to take a power file to some of the parts, namely the bump stops, suspension arms and removal of the high spots from the swing arm castings. Now the wheel shaft and the brass bush holes run from one side of the swing arm to the other; the swing arms themselves are not interchangeable in terms of positioning so it is important therefore, that the bush and shaft are inserted in the correct side otherwise, you won't be able to fit the arm in the bogie housing...

As far as Loctites are concerned, I have used 222 for all fixings, 648 for the brass bush and 243 for the wheel shaft. For the brass bush, I ran 5 beads along the lower half of the bush, spread it around using a brush and then coated the top half with any surplus. The bush was then rotated as it was inserted to ensure even coverage. Any surplus was wiped off with a cloth soaked in a little solvent.

In keeping with my new policy of dry fitting beforehand, I fitted a complete road wheel assembly to a control arm....

After fitting a spacer washer to prevent binding as specified in the manual, I span the wheels assembly around and noted that it appeared to be wobbling when viewed full on. However, there is a little play between the hub and the wheels which enables the position of the wheels to be changed wrt the hub and after a little playing, the wheels were running true. I did only have two bolts fitted and the bearings were not secured in with Loctite, however; that said, a check of the open holes identified that they were all in line or thereabouts and i could insert bolts through all the remaining open holes! Just to double check, i repeated this three times with the same result.

[Richard Goodwin]

Progress update...........all the bogie parts have now been painted and varnished where required. Assembly day tomorrow methinks!

I did have a few problems when varnishing in that the airbrush kept clogging up and had to be fully cleaned before resuming. Anyone else had this problem and if so, how did you get around it? I'm using a 0.7mm needle in a Badger Anthem 155 airbrush with Vellejo Satin Varnish.

So whilst I wait for everything to harden up, I decided to take on the belly plate and straighten the rear end out in preparation for the mod. Out came the trusty old B&D workmate which incidentally, is over 35 years old! It just so happens that one side of the workmate is about the right size to support one half of the plate so the other half of the workmate was adjusted to support the other half and help prevent movement.

A quick check of the angle just in case I have to adjust

Out came the trusty persuader and a suitable block of wood and with the plate clamped to the workmate, the bend was almost straightened out.

A little fine adjustment was needed so a couple of plastic spacers were inserted under the end and gradual tapping applied until the plate was a level as it was ever going to be. You have to be careful when doing this since aluminium will work harden if you bend it back and forth and will be become brittle, so little and often is the recommendation here so you don't go back and forth to get it straight!

That'll do, cant expect any better using this method!

This was repeated on the other side. The straightening left a slight ridge on the outside where the bed had occurred. i initially started to use a power file to level this ridge out but soon changed to a hand file when it was proving a little difficult to control in this instance.

Time to order the plate to make the back end mod; 4mm thick should do it.