Mark IV No. 01 - "Kathleen"

[Adrian Harris]

Don't you just hate it when a bunch of fasteners turn up from Ebay and you can't remember what they were for

Still, the remaining M3 brass inserts have arrived so I can carry on with the female sponsons.

Adrian.

[Adrian Harris]

Female sponson ends have been fully kitted out with the new inserts, so once the Loctite has time to go off, I'll start building them up. Then I need to make out the missing rivets on the roof and add them, without clashing with the fasteners already installed

I've also stripped the paint from some of the internal panels, which I had painted white and now think should be in red oxide.

The billets arrived for my replacement rollers but this size of stainless steel is about the limit of what my CNC lathe can handle, so the surface finish is not good enough yet. I think I need to work on the speeds and feeds, which isn't a problem, but with each billet costing around a fiver, it's a bit daunting

Adrian.

[Adrian Harris]

Been getting a bit bored with all the painting so thought I'd have a crack at some detailing.

When you start to look, there's an awful lot more detail to a Mark IV than just the rivets. These armoured covers for instance:

The model parts are fixed on with M3x16 hex head bolts and nuts. I felt the M3 nuts were too thin, so decided to swap them out for 6BA brass nuts and bolts, with the nuts on the outside. A ring of holes has been provided on the kit part for the inner nuts, but no fasteners are supplied and, as they appear to be slightly smaller, I decided to use 7BA for the inner ring.

In order to fit them, I have ordered 7BA full brass nuts and 7BA x 1/2" CSK brass bolts.

The first step was to drill the existing holes all the way through the part, using a 2.5mm drill:

Next, I counter drilled from the rear with a 4.5mm drill, using the stop on the drill press so that all the holes were to the correct depth:

The last machining step was to mount the part in the lathe and drill a 3mm hole through the centre. This is for a short length of 1/6th brass square bar to add the final detail.

This is how the part looks prior to priming and installation:

Adrian.

[Adrian Harris]

Back to spraying the various armour panels this evening and something was bugging me.

Why are these rivets not lined up in pairs as on all the other armour plates ?

A quick look through my various other pictures and it turns out they should be lined up, and there should be a gap above the angled line of rivets.

Easy enough to drill new holes but filling in the other holes may prove to be a pain. I've done it before with silver solder but that means stripping all the paint off again. I could use an epoxy such as JB Weld but I wonder how much of a grip it will get in a 1mm thick panel. With the lack of any kind of suspension on these tanks, everything gets bounced around when driving about.

Adrian.

[Adrian Harris]

Time to tackle the dreaded track plates.

The centre detail screws were added a while ago, so today I gave them a quick flash of etch primer before the red oxide goes on.

Once that has dried it will be time to mount them to the chains and give them their final coats.

Adrian.

[Chris Hall]

Adrian -

You're certainly cracking on - any chance of bringing her to Tankfest ? Or are you still aiming for Amiens ?

I've now found some time to reply to your recent comments:

1. Gearbox cover plate (EK0324)

This does benefit from some attention. I bodged it on Liesel, and put in some short M3 hex bolts, which self-tapped. Good enough for stand-off, but not nearly as precise as you ! For Flaming Fire II I always intended to drill through so the nuts are on the outside, which is more correct. Incidentally, the vision flaps on the front cab (EK0618 and EK0620) would benefit from the same level of attention.

2. Rivet patterns

You're correct that all the pictures of Mark IV's show those rivets as level in pairs. However, Mark based the Armortek model on the original drawings, which can be seen in the rear inside cover of the Mark IV Haynes Guide. That had the rivet pattern as on our tanks. It's an example of the differences between design and production.

3. Making the tracks

I actually enjoyed bolting the track plates to the track chains ! It's one of the few jobs you can do on a production line basis with background music playing. It helps if you have a long enough table to do it in one stretch. A word of warning, though - don't get any skin pinched between those plates when you're picking the assembly up - it really hurts ..... As for painting the track plates, I didn't do it as I thought it would wear off very quickly. Instead I assembled both sets, and then gave the plates a coat of caustic patio cleaner. Overnight that created a nice patina - not rust, but definitely a used look, enhanced by running in mud.

Carry on the good work,

Chris

[Adrian Harris]

Definitely aiming for Amiens 100, doubtful she'll be a runner for TankFest but maybe static.

1) I've received the tiny square brass section for the centre detail on the gearbox covers, so they should be complete soon.

2) I'm going to get some new strips laser cut and will fill the old holes on the armour plates with soft solder - thanks Steve - and then drill new holes in the outer frame for the new positions.

3) I've sprayed up all the rear faces of the track plates but realised if I mount them and then try and spray the fronts, I'm not going to be able to get paint under the horns when laid out flat, so I may have to spray just the horns, then mount them, etch prime the fixing screws then flash over the whole lot with the top coat. Time will tell if it was the right thing to do. Hopefully running dust will cover any inadequacies in my execution

I'm surprised that the horns don't seem to wear shiny on any of the BoB tanks, that I've noticed anyway.

I've also made a start on my cunning plan for tensioning the drive chains without needing to remove the armour

Adrian.

[Adrian Harris]

Am I right in thinking the handed pair of EK0113 parts have been folded upside down , so the deflector holes face the wrong way

Adrian.

[Oliver Brüninghaus]

Hi Adrian,

lacking any answer from the pros I’ll show my solution.
I think this section needs to be corrected.

Regards
Oliver

left side

right side

[Adrian Harris]

Danke Oliver

I have drilled two new holes in line with the others and will fill the empty with screws as you have done.

I see you have changed the angle slightly so the end of the baffle meets the end of the hole. I may do that as well, otherwise the debris will be trapped in the corner. Not that it seems to have been an issue for the three BoB tanks.

Adrian.

[Kevin Hunter]

Hope I’m not about to embarrass myself with my ignorance but...... aren’t those deflector plates meant to channel muck out through the hole in the inner side frames? Given that the track moves from rear to front it seems that debris would accumulate against the outer frame where the holes are covered by the outer armour.
I’m sure this topic has cropped up before but I can’t find the previous references just now.
What am I missing, if anything?
Kevin

[Adrian Harris]

As supplied, the baffles do point the wrong way and trap debris against the outer plates, hence the need to drill new holes so that the baffles face inwards. Page 16 of the manual actually shows them facing the wrong way

Due to the way the holes are aligned in the sides of these pieces, it's not possible to simply switch them from side to side on the tank to get the correct orientation.

Adrian.

[Steve Stuart]

Yes, that's the way to do it. I was going to try and find a link to the posting where Chris and I talked about it, but thank you to Oliver, I am saved from doing so. I have to tidy the Garage and get on with working on my Comet mudguards instead!
Steve
PS The Bovington Amiens event is going to be a great opportunity for the Band of Brigands to show off!

[Chris Hall]

All -

The original discussion on this would have been around 3 years ago in my Liesel thread. The plates are indeed the wrong way round, and need to be put in as Oliver has shown. It only requires two new holes to be drilled - I blanked the old ones by gluing a spare rivet in.

Debris does indeed gather behind the plate - both Daniel and I showed pictures of it when we took our tracks off, describing it as the 'birds nest'. But it doesn't interfere with the track running.

It's a small, almost invisible, but historically correct change for the Mark IV. Confusingly, the Mark V has them the other way round, ie. the way shown on Page 16 of our instructions !

All the best,

Chris

[Adrian Harris]

> Confusingly, the Mark V has them the other way round, ie. the way shown on Page 16 of our instructions !

But it also has the chute through the outer skin, so the debris falls to the outside, rather than all over the back of the Mark IV, where it will presumably sit like tinder on the fuel tank

Adrian.