Black Prince Scratch Build

[enginepeter]

The BESA cradle was fabricated from soldering various pieces of brass with the barrel and mg body turned from steel. The ball joint mount was also made of brass with smaller screws being dummies and miniature screws used to mount it to the front armour. The machine gun cradle was threaded for a lock ring to hold a spring in place so the mg could twist and turn in its mount.

The drivers port was again fabricated from brass with a bit of experimentation to get the hinges right so that the port would open correctly.

The front tow hitch was added. This was not present in the early photos taken at the time of the trial and was assumed to be a later addition.

The front headlamps were made to scale and then I struggled to fit the two LEDs. I tried fibre optic cable but was not satisfied with the amount of light thrown.

[enginepeter]

The rear of the tank presented numerous challenges. Just soldering the numerous strips making up the metal grill for the exhaust required numerous heat-sinks and care.

The surround at the top of the exhaust grill was made from machined to scale scale angle iron with extra filets added in the corners for strength and enable small mounting screws to be used. Extra fittings such as junction boxes and mounting points were then added to this surround to mirror the original.

The smoke boxes and telephone case were mainly made from single pieces of thin brass, cut then folded before being soldered. Threaded rod was soldered to the rear to fix them to the rear panel.

The addition of a tow hitch and tow lugs as well as the pick axe head completed the rear panel

[EAO]

Enginepeter,

That is one of the nicest "rear ends" I've ever seen! Beautiful work!

Regards,
Eric.

[enginepeter]

Thanks Eric - it doesn't look so good when covered in paint and mud!

Peter

[enginepeter]

The main problem with the turret was to get the mantlet/housing right. The majority of photos showed the mantlet with the canvas cover fitted, that was added during the trials. Fortunately, the Comet mantlet appeared similar so this was also used when deciding on the design.

To save the time and expense of machining metal, several prototypes were 3D printed and it was not until I got to Mk5 that I had a decent model. This was then converted into metal by machining, filing and drilling with a little epoxy metal added in a couple of places where I erred. A 3D printed template was used to check I had a profile that matched my drawing. Steel pins were used to hold the mantlet, secured by grub screws.

Another BESA mount and barrel were made to fit the mantlet.

There was no problem in machining the barrel as this was the 3rd 17 pounder I had made. It had a 4.5mm bore so a LED flasher could be fitted.

To make the turret itself, the floor plate was cut first. Slots filed for the roller bearings as well as clearance slot for the barrel elevation movement with housings then being made for the bearings. The side walls of the turret had all the appropriate angles machined to ensure a good fit and were tapered at the top to match the appearance of the original. The sides were screwed to the floor before being soldered together with the mantlet fitted and held in place by screws through the sides.

After cutting out the roof attention turned to the loaders and commanders’ hatches. The loaders hatch was fabricated in the same manner as the front hatches.

The commanders hatch took a bit of thought so as to end up with a scale size, revolving with an opening hatch. Templates were 3D printed before brass sheet was filed to size and then soldered together. The plastic for the prisms were added after painting. Fitting the miniature springs to the cupula latches proved interesting as they were lost forever when they pinged across the room.

[enginepeter]

The mount for the barrel/recoil was cut from aluminium and gears 3D printed for elevation and traverse, operated by servo motors.

To complete the turret the rear box was made as well as fittings such as the commander’s sight, fire extinguishers and aerial bases. The commander’s sight was again a miniature soldering job.

Holes were drilled in two of the turret walls, fitted with bent spring wire to act as the tie down points for tarpaulins etc.

[43rdRecceReg]

Fantastic looking turret, Peter. I could have done with one of those on my Comet I've noted outstanding work on the telephone box, and smoke dischargers. That's not, of course, to say that it's not all outstanding.- which it is. It's just that I made those components out of styrene- and they're only just about credible.
Yours, by contrast, are museum quality- and metal!
Just out of curiosity, how much do you think she'll weigh when fully kitted out?

[enginepeter]

Thanks Roy.

Solder can be used to cover a multitude of sins!

The trouble is I don't know what I can do to follow this! Its taken 18 months of solid work. I dread to think of the number of hours it has taken. Lockdown/social distancing has provided a perfect excuse to lock myself in the study and workshop!

Yes it is heavy - hence my earlier comments on the gearbox. Just weighed it - 8kg!

regards

Peter

[enginepeter]

The last major, and a difficult task, was to make the mudguards. This would have been easy if permanently installed, but I thought this would be a recipe for disaster if I had problems with the tracks or drive so they were designed to be held in place with the minimum of bolts.

The mudguards themselves would be made from sheet brass, 0.25mm thick. They would be made in six sections in a similar manner to the full-size tank. When completed some of the sections would be soldered together leaving two parts a side. The inner part of the mudguard would be held against the inner hull wall by a slotted strip of alloy screwed to the hull. The outer side of the mudguard would be bolted to the outer wall with seven bolts each side, four of which would be in original scale positions at the front and back.

The plan was to start at the front, moving to the back with the fifth. penultimate, panel made overlong so it could be trimmed in the final fit.

Starting with the front, brass angle was cut and bent first, before attaching the sides and then the top.

To fit the inner hull side brass angle was soldered to the sections of brass that would slide into the slots to make the inner wall. Holes were then drilled for dummy bolts the were soldered in place when the mudguard tops were soldered to the inner piece.

The main sections of the mudguards were made in two parts, the top and the outer wall to which some narrow strip was soldered at the bottom. Templates were 3D printed for the top to check the profile after bending in a metal clamp to scribed measurements. The sides were formed in the vice using a male and female mould that was 3D printed with the bottom strip added later, which were then drilled for the fitting of dummy bolts.

The rear sections proved a little troublesome with parts being frequently adjusted to cope with the changing angles before soldering. Quadrants were made to hold this in place against the hull.

[enginepeter]

The front part of the mudguard needed inside panels making to follow the slope of the glacis as well as adding a grab handle and tool mounting points to the left side. The outside at the front also required the cutting away of a curved section leaving the track visible.

Once the mudguards had been completed attention turned to the various channel sections. These were of differing sizes, used to cover the joins in the original sections with narrower ones used on the top to strengthen the panels. The first step was to cut some 50 strips of brass. These were cut slightly oversize using a guillotine and then filed to exact dimensions using a jig. These strips were then pressed to the required shape using a mould in a vice. The moulds were 3D printed and worked well with the thin 0.12mm thick brass.

These channels were then soldered to the mudguards with holes drilled and further dummy bolts fitted where required. I started with the channel over the joints, with several of the sections also being soldered together. Finally the strengthening channels were added. Handles were added over the side hatches.

After a bit of adjustment both mudguards were fitted using holes drilled in the outer wall for bolts to secure them. Testing showed the tracks running without any problem.