Armortek

Stephen,

How frustrating, but kudos for kicking it into touch. Out of interest just how much additional range did the tank provide under combat conditions?

As for the coupling, I would break it down into primitives, simple shapes, eg just get some rod and then drill out whatever spare hex head bolts to hand and slip them, plus some short pipe off-cuts, over it. The only bit needing turning is the conical brass union a third of the way along. Once you have the hex sections looking proportionally right, you can soft solder or glue them to the rod and then bend the two ends to match the fittings. Just scribe the short length of expose thread, if you must!

I recall the feed end was just two unarmoured pipes going up under the hull rear plate into the engine bay. Or was this a pre-restoration lash up on Paul's vehicle?

Looking at my reference photos again, one small detail of the folding door that covers the recess caught my eye, the front edge extends across the gap between the LR tank and the rear plate of the engine bay. So you might wait until you have mounted the LR tank to the hull before settling on a final dimension for the said door.

Great stuff!
Fabrice

Stephen,
Herewith photo showing protruding door lip. It must be one of your's, so thanks for sharing! cheers, Fabrice

Thanks Fabrice and noted re the hatch cover size. Your question re extended range elicited an interesting answer from Bruce Cameron in Australia, who was a troop leader on the last RAAC rotation in Vietnam and who has written the definitive account of the RAAC in that campaign (Canister, On, Fire). I quote:

Fabrice asks on your Armortek site, what additional range the LR fuel provided on operations. This is a good question.

In answering, firstly may I say that we didn't refer to it as a 'LR fuel tank', but a '100 gal fuel tank'.

This is relevant because we didn't consider the extra fuel in terms of miles or kilometres. Vietnam was not like NW Europe, we weren't speeding from one place to another to engage the enemy. Such redeployment happened from time to time, but mostly we were grinding our way through jungle and thick vegetation (offense) or were relatively static (defence). Fuel capacity was relevant more in terms of endurance, than 'range'. The 100 gal fuel tank almost doubled the capacity of the LH and RH internal tanks, therefore, you could say it extended the Cents' endurance by the same margin.


Onwards with the tow rope mount:





It looked quite simple and with excellent drawings from Allan Bowers, the parts were straightforward. I used a swage block to shape the central piece:







The assembly though was tricky to align. This is a trial fit and I'm not sure the angle to the back plate is quite right:







Regards

Stephen

More details. Corrected the angle between the tow rope support and the rear face of the tank:




Mounted the outer tow rope supports:







Installed, drilled and reamed the tank mounting distance pieces:




And made a start on the two fuel drainers:








Regards

Stephen

Stephen,

Quick question on swaging small brass parts. Do you anneal the pieces during the process or just cold work the parts into smaller diameter grooves until you arrive at the radius required?

I only ask because in your photo you show a swaging rod far smaller than the groove under it.

Smashing details.

cheers, Fabrice

Fabrice

Yes, I did anneal before working. if I were doing a simple curve, brass is fine when annealed. For more complex shapes, if using the dapping block for example, to make a domed sharpe, I'd try copper.

As you say, I start with an oversized swaging groove and work downwards in size to achieve the desired radius.

I've learnt most of my brass work from the book you recommended:

http://www.amazon.co.uk/Model-Building- ... 0764340042

It's strange though that although the author mentions dapping, he doesn't mention swaging. There are plenty of vids though on the Toob.

All the best.

Stephen

Completed the fuel drains. I couldn't resist adding the lock wiring, although chances are that with the drains located under the tank, they'll never really be seen:







Next the inspection panel.

Regards

Stephen

Hi Stephen.


this mission of yours just keeps making me smile you have put so much into it and its all great stuff, looking forward to seeing it in October.
Cheers Paul.

Bonza idea!
That'll stop those commie VC mice stealing your imaginary fuel..
Very nice finish BTW, looks like stainless. Almost a shame to paint them, almost.
cheers, Fabrice

Stephen

Excellent job on the fuel drains, I did not fully understand the design when I built mine. Thanks for showing so much detail I am learning all the time.

Regards

David

Thanks Paul, Fabrice and David.

Completed the inspection plate:





When Paul Scott took his tank back to bare metal, these markings on the surface of the armour plate came to light:










They are all over the vehicle, here on the turret:



Once you see them, they're quite prominent and very easy to replicate:







We believe they're the result of Brinell hardness testing of the armour plate during manufacture.

Regards

Stephen

Or trying to look busy with the grinder when the Supervisor walks past....

But given how very extensive the marks are across the top surface of the 100 Gal Tank, could they be a crude anti-slip treatment too? Just a hunch.

Lovely details.
Fabrice

I thought when hardness testing a ball bearing type affair was banged into the metal? .Never seen marks like that

Chris, Stephen

This whole grinding marks conundrum is of interest. Clearly dozens of small nicks across the top surface does not sit well with the concept of a supervised one-off Quality Assurance type test. It is just too random and too time consuming.

I have suggested the top surface marks could have been cut to add grip, because form follows function, and they are there for a reason. So what else could be achieved from superficial grinding of the other, not horizontal, surfaces? I will run this past grizzled old engineers of my acquaintance too, but here are two thoughts off the top of my head..

a) the plume of sparks would have a specific colour and combustion pattern. This is a classic way of identifying the composition of an unknown piece of metal. Yet the manufacturers knew exactly the composition of the plates (and their hardness) before they entered the production line. This was the 1950's, not 1917, after all.

b) could the application of the grinding wheel to the hardened armour plate have served to "dress" the grinding wheel, and safely test it for concentricity/cracking prior to extended grinding work along the edges as part of the pre-welding preparation? We are assuming that these marks were made *after* the assembly of the 100 Gal tank. They could have been made before, when considerable weld-prep grinding work was taking place.

Is there any record of similar marks being found on other vehicles? Any accounts of this dressing technique being used in other industries, eg ship-building, boiler making or locomotive construction? I will make my own enquiries, but any evidence is would be useful.

Looking at Paul's photos, I am no longer convinced by the "hardness testing" explanation. It does not match the evidence, so there must be a better explanation.

Fortunately, whatever we discover about the reasons for the marks, they are there on the full-size vehicle and should remain faithfully reproduced on the model! Phew!

cheers,
Fabrice

If they are grinding marks,there's a very good chance it's the welder just stopping the wheel in his grinder before putting it down.
Chris