Chieftain MK3 Build

[Marco Peter]

Little children standing in the way.

[David Battson]

Very nice, but I'm trying to imagine what sort of forces are you expecting on the splash guard?

Hi John, if I knew the answer to that one I'd try and avoid the situation in the first place. Unfortunately I'm rather conflicted with this hobby, as much as I like to see the details, I also like to see the models used like tanks rather than shelf queens. The movement and capability of these 1/6 metal models is for me their USP and my main reason for getting involved. Inevitably accidents will happen, whether it's a careless slip of the controls in the tank park or misjudging the terrain out on the range.

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At a recent show my Comet managed something akin to laying a fascine... but in reverse - it picked up a sand bag with the tracks and draped it over the glacis and turret side, bending all my extra details. fortunately because of Chieftain I hadn't got around to adding all the nice Armorpax white metal parts otherwise there would have been real carnage - the driver still doesn't look best pleased !

David

[John Clarke]

Great pictures David,
(Chieftain 1, building 0, Ditch 1, Chieftain 0)

At first I was considering you were worried about FPV drones, But when Marco wrote:

Little children standing in the way.

It took me back to a time when the only 1/6 scale MTB model that could be brought was fibre glass hulled, where on one day out and about I took the deck off to do something to the models control gear. While my back was turned and bent down, a I child had stepped up and stood on the deck trying to look over my shoulder. His guardian standing close by, allowed the child to do this. While I was impressed with the strength of the deck and I was of course concerned for the child's welfare and I did muttered something colourful to the guardian!

General public

So, expect the unexpected!

[David Battson]

Next up is the basic build and initial fitting of the mudguards.

Starting at the front, the first problem is fitting them to the hull side. Not an issue for the kit, but a self inflicted problem for me and due, rather ironically, to the presence of the mudguard fixing rail detail I added as part of the work to the glacis. The rail protrudes out from the side of the glacis and on the real thing, the mudguard is fixed to the underside of the rail by a row of small bolts which look to be an absolute maintenance nightmare.

Options to make them fit are either cut away the inner edge of the mudguard or move them outward so that they fit flush with the rail. To save some work and avoid loosing the inherent strength of the kit pressing, I went for the second option and added spacers between the mudguard and the hull side.

With the mudguards fixed in position, I then had the required dimensions needed for new first and second mudguard support arms to fit the revised glacis profile. The basic shapes were machined up from solid aluminium. Details added to the first arm included a side light and wing mirror support arm. The side light housing is designed to take a 10mm LED which is the perfect size and shape. This is however likely to need some electronic trickery to reduce current/voltage to ensure that the sidelights don't out-shine the headlights which are much smaller LEDs.
The wing mirror support housing was made from a 'T' shaped piece sandwiched between two cones and filed down to shape. Details of the contemporary early 70's mirror are rather hard to find as they seem to be seldom used. Can anyone in the know advise if there was a time when a driver was required to have mirrors, maybe such as driving on public roads ?

Although derived from different refence measurements, the distance between the front support arm and the first bend for the upper rollover section was absolutely spot-on to scale. The forward length of the upper section was however 5mm shorter than scale, not an issue for the kit, but another self inflicted problem for me. Moving the idler forward by 5mm as part of the work to the toe plate has now compromising the track clearance to the mudguard. To provide the required clearance, a 5mm strip was let into the upper panel. Since this required rebuilding the front, other mods were made including lengthening the front panel, extending the tie-in on the side panel to just before the support arm and adding an angle fillet to the inside edge. The latter being required, because the upper edges should be parallel rather than tapered like the kit.
The new shape was held together using rivets and fish plates. Maybe not the prettiest of solutions, but it is robust and hopefully wont break apart the fist time long grass and small branches get dragged around in the track.

To finish off for now the inner triangular bracing panels were added. The final details and finishing will come much later on after the larger ticket items like the panniers and storage bins are sorted.

[John Clarke]

Beautiful job as always David, A few dings on the mud guards won't hurt, more realistic, that and the slight droop at the front.

[David Battson]

Next up is the rear mudguards

First job is to reduce the mudguard overhang over the sprocket. Whilst the sprocket is in the original kit position, the rear plate has been moved forward and it's angle to the vertical reduced as part of my work to the final drives. This has left the mudguards sticking out from the rear plate by 15mm more than they should based on scale measurements from the real thing. To solve the problem, rather than rebuild the overhang, I cut a corresponding amount off the other end and slid the whole assembly forward by 15mm.

Moving to the inside edge of the rear mudguard, being a Mk5, the kit reflects a modification made during the MK3 run in which a chamfer was cut from the outside corner to provide clearance to an upgraded exhaust casting. Whereas the early exhaust castings ran close to the side of the exhaust box, the upgraded casting came out on a larger radius, improving the flow of exhaust gasses and cooling.

Early casting

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late casting

To roll back this modification, the inner edge was cut away and an earlier profile grafted on. As with the front, everything was rivetted together. The inner edge also bolts to a bracket added to the end of the hull plate. The oval hole provides clearance to one of the modified final drive fixings. Whilst it's a bit early stages for the finer details, I couldn't resist adding the two jewel like rear reflectors from Steve Winstone.

[John Clarke]

Nice Job David I seem to be in a similar boat, not 5 star like this, more like steerage , but do one job and another presents itself.

[David Battson]

Hi John,

Yes you are absolutely right, every action has consequences - unfortunately not all of them are obvious at the time. It's only until you go to do the next quick job and then realise things don't fit because you changed stuff earlier up the line. Though to be fair, of all the work done so far, these rear mudguards are the first self inflicted mod arising from the decision to stray from the kit Mk5 and make an early Mk3 so it was always on the cards.

I see you are using the book 'Chieftain Down range' - it's a fantastic reference, really good for showing how the tank was put together or should that be comes apart ! Sad to see all those Chieftains destroyed, but it makes me feel better that whatever stage my build is, there's a real one out there in worse condition - so if ever I decide to give up I just need to get the rust coloured paint out and job done, a finished model.

David

[David Battson]

Additional Support
Looking ahead, the rear half of the turret turn bearing is only fully supported when the engine deck is properly bolted in place. This is not an issue if the instructions are followed exactly, but could be a problem for anyone planning to modify the engine deck or leave it loose in order to provide easy access to the batteries, motors and electronics. In response, a piece of 38mmx25mm box section was bolted transversely across the hull sides. The box section was positioned as far forward as was possible without impacting on the rotational space inside the turret ring any more than the side arms of the glacis casting. This modification serves three purposes

1 -Additional support to the turret bearing , independent of the engine deck fitment.

Turret bearing support

2 - An additional joining point for the front and rear mudguard sections, as well as helping to ensure they project out horizontally from the hull sides.

Mudguard join

3 - Acting as a partial central bulkhead to help resist twisting of the long and slender hull in an area where there there are joints in the mudguards and between the pannier sides and glacis. To achieve this, triangular bracing webs were added, whilst being careful not to compromise usable internal space.

Partial bulkhead

[Vince Cutajar]

Wow

[David Battson]

Next up on the build are the rear panniers, starting with the pannier side plates.

The kit side plate runs from the inside face of the rear plate to tie in directly with the glacis casting. The lower edge tapers inwards such that the height of the side plate reduces towards the front. However this taper is matched by the rise in height of the mudguard as it slopes up towards the the front of the tank. As a result on the kit, the top edge of the pannier side plate and hence the engine deck which springs from it, is horizontal when viewed relative to the longitudinal axis.

kit pannier

kit pannier

Looking at the real thing, the side plate slightly overruns the rear plate and stops 80mm short [in scale terms] of the glacis casting. The shape of the side plate is, for the most part, rectangular which means that on the real thing the top edge of the pannier side plate and hence the engine deck, rises up with the slope of the mudguard towards the front of the tank or put another way, the engine deck slopes down to the rear of the tank. This could help explain Chieftain's capacity to store water and spilt diesel on the engine deck against the wade rail, ready to pour onto the driver should the tank stop suddenly or set off down hill.

New rectangular side plates were made up with the top edge chamfered to match the slope of the pannier top plates. The gap between the side plate and glacis casting is filled with a transition casting which makes up the difference in profile between the 30degree slope of the side plate and the undercut bowl shape of the glacis. This was made up from a block of aluminium faced up with car body filler to make the sculpting process a little easier.

new rectangular pannier

transition piece

panier plate comparison

pannier plate comparison

Despite the pannier changes so far, it still looks possible to graft on the kit engine deck, although the section nearest the turret is likely to need a bit of fettling to get the required clearance under the turret bustle.

David

kit engine deck added

kit engine deck added

[John Clarke]

As always, your attention to detail is remarkable, it's almost like another model compared to the Armortek original.
These pictures showing the hull "naked" as you say, wouldn't look out of place down range
Looking forward to the next installment.

[David Battson]

Finishing off the rear panniers,

Looking at the real thing, the inner sides of the panniers are a vertical extension of the hull side plates. To replicate this, new rectangular internal plates were made up and bolted in place at either end. Since the pannier plates are relatively slender, some internal spacers were also made up to add a bit of rigidity and hold everything in place to the required angles.

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The pannier tops on the kit engine deck overhang the new inner side plates by about 14mm on either side, so as an alternative two new narrower top plates were made up. Planning ahead, slots were milled into the top plates for the hinges, making the hinges sit a little lower and ensuring they stay at right angles to the engine bay opening and properly aligned for the engine hatches.

The width of the new engine bay opening finished up be very close to scale. Despite the overall size of the Chieftain kit, the hull is relatively slender and internal space is limited. So whilst the enclosed panniers look more like the real thing, they also block out a lot of valuable space meaning things may have to change when I get around to planning the internal layout.

[John Clarke]

You've changed so much (all) of the supplied rear deck making it look so much better. The pannier angles now look so much sharper, just better, the supplied rear deck had faint bends in it, mine were in the wrong place too.

To the casual viewer it doesn't look as if there much of a change, but to me it's a complete redo.
I'm looking forward to seeing how you get on with the deck grills, I'm guessing you won't be using the supplied parts as they are not the correct sizes to the original anyway, a major gripe of mine, though you may be planning the earlier Mk 3 layout anyway.

Your right about space, The panniers did supply some useful space for the modules. The motor gearboxes gobble up a lot of space, the twin smokers (the bigger the better) and there's not much space under the turret either, even for smaller batteries if you want a reasonable amount of elevation from the main gun with its counter balance weight. Then there's the speakers if you upgrade, even less space.
I will be putting my recoil module in the turret along with a second receiver which seems to have an abundance of space.

Yours is a most fantastic build, can't wait for the next installment