Stage 4: Tracks

"Keep on Trackin'..."

Stage 4 consists of just Pack 15 to build the pair of tracks.

Another (thankfully short) cold spell, followed by the Christmas period has meant relatively slow progress of late. However, since Stage 4 is basically one pack, I'll present it here complete and in one hit...

Pack 15

	On the face of it, Stage 4 is simple, and an out-of-the-box build shouldn't take more than a couple of hours or so. There is a single cardboard box containing all the bits for Pack 15, which consists of only three different parts - the track links (bagged in 5's), track pins and 'washers'. The latter aren't plain washers, but washers on steroids! They have teeth, and are a very tight fit over the end of the track pins, so holding the links together. Each left & right track is built from 54 links, pins and washers, though the manual notes that after some use when the tracks have worn a little and bedded in, one link may have to be removed, thereafter "giving years of trouble-free life". As the model hasn't been out long enough to validate that claim, maybe Armortek are hedging their bets by providing spare track links (12) and pins (4), and are also generous with the washers. The track links are pretty solid jobs, and are close (but not fully identical) to the prototype early series Sd.Kfz.7 tracks. It looks as if they've been chemically etched to give a darker patina, and (if desired) need no preparation to make up the complete tracks, perhaps apart from the top 'cushion' being painted matt black to represent the rubber pads of the original.
The above photo shows stages in the track construction. Starting from the bottom, we have: the individual parts (see later what the pins at the very bottom are for) a length of 10 links (I found this to be a comfortable length to handle) the underside of the track cut rubber pads and pads attached (see later) 'rusted' track. This was achieved by a weak paint wash, roughly 1 part Humbrol #82 (matt orange lining), darkened down with 1 part #73 (matt wine) and 8 parts white spirit, which naturally draws the pigment into the nooks and crannies, leaving only a thin dusting over flatter surfaces.
	The manual suggests the pinning is easier with two people, but I didn't have that luxury, so I made do by making a small 'anvil'. This was just a bolt of the same diameter as the washers, with the head cut off and a 3.5mm hole drilled coaxially. This was securely held in a vice. A washer is placed on the top, over the hole (see photo), and a pin inserted between two track links and the assembly positioned over the washer. A few taps on the head of the pin with a small hammer is enough to drive the washer home.

Deviations from the Plan

While the tracks can be built 'out-of-the-box' as described above, I made a couple of deviations from the manual-specified build. All in all, this probably tripled (or more) the total build time for Stage 4. Because it's worth it.

1) Belt & Braces

Armortek use the same method for fixing their big tank track links as for the half-track - only there are twice as many links to do! But it's known that the washers can come off the link pins with the strain of track-steering. The Sd.Kfz.7 of course can be steered by the front wheels, but track-steering is still needed for tight turns. So one might expect to pop a washer from time to time.

To prevent this, the tankers drill'n'pin their link pins. I set up a bench vice on a (very old B&D) drill stand and bolted all down so that I could consistently drill in the same place. Initially, I did one pin at a time and fine-tuned the position. I used a 0.9mm drill bit for most pins, having started with 0.8mm and then 0.85mm. Not that these were too small, just too fragile...

The link pins aren't of hardened steel, so the washer teeth do dig in a little, so may well resist slipping and so the following may be a complete waste of time...

Anyway, to ensure the washer isn't going anywhere, a pin is inserted through the drilled hole after fixing the washer in place. I used ordinary common-or-garden sewing pins. 'Borrow' some (at least 108) from the sewing basket if you dare, but as they're hardly going to break the bank, I bought my own packet.

If you've got the hole just right, the pin head can be snapped in place under the lip of the washer with needle-nosed pliers, and the excess shank snapped off flush with the underside of the link pin by bending back and forth with said pliers leaving an almost invisible job - see photo. If the pin head isn't well trapped, leave 2-3mm of shank and bend it round the link pin.

2) Rubber Soul

The prototype had rubber pads on the tracks to prevent destroying any hard road surface it might run on (e.g. Sd.Kfz.7 book pages 48-52). The model has lumps moulded into the top of the track links (see 'pin' photo above) to represent these pads, and these can simply be painted matt black. However, I think any paint would wear through very quickly, especially if run on hard surfaces or using track-steering. The treated metal surface would also wear, leaving bright metal - hardly authentic.

So I've added rubber pads, which will be much more realistic, and which can be replaced should they come off or be worn down. The source of this material is a cheap (and I mean cheap - £3.49) set of rubber car mats. These were ribbed with thin (about 1mm) and slightly less thin sections 1.5 -3mm wide. From the thin sections, I cut 1cm wide strips and from those, 3cm lengths - as per this photo.

In addition to the required 108 pads, I cut another 50 or so as spares. Still a whole mat left over if more are needed...

Having roughened the rubber and track links with sandpaper (1), the pads were superglued on, holding down until set (count to 60) with a piece of rubber off-cut so as apply even pressure over the curved surface and edges and (more importantly) not to leave skin on the work (2). When completely set, the pads were then trimmed as necessary, corners were sanded round and a fillet of glue applied so as not to leave any chance of the rubber lifting off (3). After leaving overnight, the metal ''pad' and rubber edges were painted with matt black (2 coats) (4).

I'm not fussed that the illustrated pad has a nick in it. The real ones got pretty chewed up, and after painting, it doesn't really show up anyway. And, this isn't a show-piece with judges going over it with a microscope.

Finishing tracks

To finish off, the tracks were given a wash of 'rust' (see above) and the short working lengths of 10 links all joined together. The track could then be fitted to the model and the ends joined with a last link pin, temporarily secured just with a (sewing) pin. I suspect that it may be easier to work on the body (Stage 5), especially when fitting the mudguards, with the tracks removed.

The second track was assembled in exactly the same way, except that the track pins are inserted from the opposite side so as to give a right- and left-handed pair.

The idler adjustment screws can then be tightened to take up any slack. Judging from the examples in the Sd.Kfz.7 book, the track lightly rests on the top of the road wheels - it shouldn't be tensioned too tightly as this will result in too much strain for the motors and excessive wear on the idler wheel bearings. Too loose, and the track will flap about and maybe cause some damage.

Motors

Before the bodywork starts to be fitted, it's easier at this point to mount the two drive motors from OP1. This is a simple matter of sliding the gears into the drive gearbox through the holes in the chassis and bolting the motors to the mounting plate that comes with them. As for the winch motor and servo from OP1, the motors where painted with the drive shaft/gear and wiring masked off.

When there's somewhere to temporarily mount the electronic components, I'll test the drive under it's own power, and report on that in the next part of the build.

And so we end our Stage 4 tracks.

Total elapsed time from the boxes arriving: 23 weeks

Total model attention time: approx 70 hours

Total build time: approx 45 hours

Page last updated: