Black Prince Scratch Build

43rdRecceReg · Post by **43rdRecceReg** » Mon Jan 11, 2021 4:41 pm

Your soldering, (or is it almost brazing?), is as exemplary as every other feature of this project, Peter.
I can just about solder wires and terminals; but couldn't begin to patch panels and parts together in the way you do,

Looks almost as if you have a skilled Lilliputian team of welders helping you out there

quitcherbitchen · Post by **quitcherbitchen** » Mon Jan 11, 2021 7:36 pm

Very impressive. What kind (type) of soldering kit did you rely on? With my shaky hands I am better at welding LOL.

enginepeter · Post by **enginepeter** » Mon Jan 11, 2021 8:05 pm

Hello Roy and quitcherbitchen

This was mainly soft soldering, very occasionally silver soldering if I wanted a higher melting point solder for complex pieces. As I think I said earlier, a file and emery cloth can work wonders in tidying up after soldering. I tend to pile it on and then sort it out.

Welding - thats another story. I have to use an angle grinder and disks to clean up my work - it was not good enough to leave with all the peaks and troughs! With some of my engines I had to bend/cut steel bar and angle iron then weld it so that when painted (or heavily rusted) it looked like original cast iron. Fortunately I had acquired a large number of abrasive disks so it was not a problem to use them up. However, the workshop window by my vice now has a frosted look from when it was bombarded over the years by the sparks from the grinder!

I no longer work on engines - it is far better to sit in the warm and use a soldering iron. I have to say I have 3 of differing sizes and wattages - I use to use the big one to soft solder fuel tanks.

Peter

EAO · Post by **EAO** » Tue Jan 12, 2021 6:54 pm

Ah yes, the Economy gas engine.

My Father had several, a 1 1/2 H.P., and a huge 5 H.P. engine. Always amazes me how these things got across the "Big Pond".

Still amazed by your tank and skills, watching eagerly for new updates!

Cheers,
Eric.

enginepeter · Post by **enginepeter** » Tue Jan 12, 2021 7:47 pm

Thanks Eric. Full sized engines are a bit too heavy to lug about and work on now. A 5hp flywheel can weigh quite a bit. Having said that I have to be careful lifting the Black Prince so I don't do my back in!

Peter

enginepeter · Post by **enginepeter** » Wed Jan 13, 2021 11:10 am

Once the mudguards were fitted the painting stage was reached. Before doing this, with everything was assembled and it was given a test workout to identify and solve any issues. It was then stripped to basic sections for painting.

The first items to be tackled were the tracks. The outer edges had already been ground off so the track would fit. Each link was now subjected to the drilling of holes in the centre to appear like the original and filling off the grips. A miniature grinder was used to cut ridges in the front of the track bar with the track being held by the vice in yet another jig.

To prepare the tracks for painting/weathering the original painted finish was stripped off by first soaking in vinegar then using a stiff brush. I had some metal bluing liquid so the tracks were treated with this. After following the recommended bluing process the tracks were washed in water to arrest the process before thoroughly drying out.

Then a combination of various washes and mud were added before spraying with varnish to seal it.

enginepeter · Post by **enginepeter** » Thu Jan 14, 2021 2:38 pm

Having extensively used alloy sheet for the build I had a very smooth surface apart from a few scratches and knocks. To give a finish closer to cast steel I stippled several layers of Milliput putty. This was first turned into a creamy paste by soaking in water and spending some time stirring and pressing it to break it up. I used this mixture as I thought that it would stick well to the alloy.

Once these coats had dried the entire tank was sprayed with two coats of an etch primer before covering it by spraying several coats of paint mixed to SCC15. The 'No 4' was painted on the front then the whole tank was given a coat of matt varnish. It was then re-assembled.

As part of this process the electrics were connected. The on-off switch was accessed through the RH side hatch and the volume the LH side hatch. The speaker and other parts were fitted along with the battery recharging point, accessible through a front hatch.

Most of the Black Prince photos were taken during the trials when they were "muddied up'. I next decided to dirty the tank rather than have a pristine one. So various washes and muds were next applied.

enginepeter · Post by **enginepeter** » Sat Jan 16, 2021 10:07 am

During the trials in 1944 all the tanks had a full complement of tools, camouflage nets etc so these were added after painting.

Two shovels, sledge and pick axe handle were added at the front.

Oak strip was cut into narrow strips then filed/sanded to shape, before being varnished then weathered. The heads of the shovels were cut from brass sheet, soldered to bent brass tube.

The pry bar was simply made from brass rod, filed at the ends.

Clamping clips were cut from sheet brass. The butterfly nuts were a challenge. The ones available looked too small so I had to make them. Thin brass was soldered to 16 BA nuts and then filed to shape. These were fitted to threaded rod cut from long 16 BA bolts.

At the rear there were mounts for petrol/jerry cans. These mounts were made from brass soldered to the mudguard before painting. The cans themselves were 3D printed.

The camouflage net and tarpaulin were made from kitchen towel, painted in water/PVA before being folded. The ‘leather straps’ were 3D printed and after inserting in the mounting lugs on the side of the turret, glued in place.

Tow ropes were made using thin copper wire twisted together. The shackles were made in two parts, using 2mm solid brass rod, shaped in another jig, soldered to some 1/8th inch brass tube.

To get some realistic sounds I looked for Churchill ones as they had the same engine and similar tracks/running gear. I found the most useful to be some U-Tube videos made by the Churchill Trust of a MK IV. I managed to extract from these engine and track sounds. Not perfect but better than nothing.