Comet A34- Ludwig kit

This section is for builds that are not strictly Tamiya or Heng Long. For instance, replacing the electronics from a WSN or Matorro, or even a scratch-build.

Postby 43rdRecceReg » Fri May 17, 2019 8:59 pm

This air intake is built a bit like a sandwich. But it's certainly no BLT. Here the sandwich is completed by the panel that contains the access hatch.
Looking from underneath (deck side), it's possible to check that the bits align properly. :) Whoopee....they do!
Now, for the four homemade sides:
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After a bit of trimming to fit, the next order of business is filling and shaping.
For this, I used Plasto (made by Revell). It dries very rapidly so it's necessary to work quickly. I used it here, though, as it fills fine gaps more easily than Milliput. :thumbup:
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Ok, it looks pretty grim right now, but I just wanted to ensure that all gaps were filled, and dips levelled. After drying, it was time for coarse, then very fine grade sanding sheets.
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Getting there...
I'm happy with the shape.
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Then I put a bit of early primer on it, and bonded in place on the deck (and early temporary coat primer often shows up defects to be sanded out later, at the customising and finishing stage.
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Postby 43rdRecceReg » Fri May 17, 2019 9:02 pm

...and the primer helps to identify defects for later rectification...
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Postby 43rdRecceReg » Fri May 17, 2019 9:26 pm

Just realised that an intermediate pic of the 'sandwich' is missing. Looks like I forgot to add it to the text :/
Anyway, this is what the initial sandwich looked like:
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Now the arrangement should make more sense.
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Postby PainlessWolf » Fri May 17, 2019 9:48 pm

Roy!
It's coming along quickly and neatly. What you are doing is much more difficult ( IMHO ) than modding a RTR tank. Kudos, Sir.
regards,
Painless
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Postby 43rdRecceReg » Sat May 18, 2019 11:24 pm

PainlessWolf wrote:Roy!
It's coming along quickly and neatly. What you are doing is much more difficult ( IMHO ) than modding a RTR tank. Kudos, Sir.
regards,
Painless


Many thanks for the support, Painless. Some RTR mods require consummate skills, an eye for detail, and -as with semi-scratch builds (such as this one), can also require some real inventiveness.
With RTR, though, there's a good chance that there'll quite a few examples of how fellow modellers have tackled a mod, that one can refer to. Bespoke parts may also have used, and accompanied with useful installation instructions.
Here..the instructions run out, and the void has to be filled with homemade parts, often conceived by lateral thinking. It can really tax the old grey matter.... :shh: :)
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Postby 43rdRecceReg » Sat May 18, 2019 11:40 pm

One feature included in the kit (and a prominent one on the real Comet), is the gun lock/cannon clamp used to secure the 17-pounder when travelling.
Again, not all of the parts needed have arrived. But I decided to fashion the missing ones myself.
These are the main parts (note, they need trimming later to remove residue from the moulding/printing process). They may look a wee bit ragged, but all parts will be sanded with fine grade later and treated with surfacer if needed. :)
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One part, the tiny latch, is not shown here- but did come with the kit. The feet/swivels that fit on the arms of the lock bracket are not here yet, so I'll have to make them, as well as the two pivots they are bolted to.
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Here, the first component has been bonded in place.
and the second piece here. The drills really help to keep parts aligned properly during bonding.
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Then the three parts the locking arm consists of are glued together. I left the little bits of sprue in place, to add rigidity during the bonding process
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Postby 43rdRecceReg » Sat May 18, 2019 11:44 pm

Put together with M1.6 hex bolts (8mm) it looks a bit like this:
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The little latch with the drill bit through it actually moves..., as does the arm itself. Ok, it's not brass, but it came with the kit and it's worth the effort.
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Postby 43rdRecceReg » Sun May 19, 2019 12:01 am

But...the two feet that form a swivel on the arms of the lock bracket, as well as the pivots they engage with were also in a 3mm sprue I'm still awaiting.. :|
This is how I made them. Do ignore the roughness of the imked outlines. I really did know what shape I was aiming for, and had the old Cromwell sprue to act as a template for the pivots (that bolt to the engine deck).
The swivelling feet I had to invent.
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Tools I used to fabricate the pivots and swivels/hinges. (+ some fine grade emery paper)
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Checking the fit against the rough sprue template:
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and a second one:
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I used a number '2' circle to approximate the size of swivel casing the pivots would suggest...and roughed out the shape of the two feet needed, as well as the slots the arms of the lock mechanism would be fitted into.
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Here, I've cut the swivels out and bonded them onto the lock bracket. The two pivots are in the foreground on a drillbit.
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Finally, the components are assembled and cemented to the engine deck. Amazingly, it all works and looks (pretty much) as it was intended to. But says nothing about the amount of time spent on it... :problem:
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Time for a slurp, I think.
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Postby c.rainford73 » Sun May 19, 2019 1:21 am

Absolutely beautiful work :thumbup: Really well done
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Postby 43rdRecceReg » Sun May 19, 2019 11:11 pm

c.rainford73 wrote:Absolutely beautiful work :thumbup: Really well done

Thanks a million, Carl. :thumbup: It's going to be a long, long journey before this model gets its tracks into Highland heather. Partly, because I want to get everything right first time, but also because time is limited by other demands (keeping an eye on an ailing dog, for example)
I made (and rectified) lots of mistakes with the Cromwell build. Luckily, none were fatal.
The lessons I learned there, are proving really useful here. :thumbup:

I had a stroke of luck today. A 5/8in aluminium tube turned up today, via Ebay. Its internal diameter is 12.6mm... a nearly exact fit for the gun. :) This means I can use it as the sleeve for the gun barrel to slide in.
It's a good start, given that the sleeve/trunnion part seems to be unavailable from Christian :problem:, and an alternative is needed.
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Postby 43rdRecceReg » Sun May 19, 2019 11:44 pm

The Commander's Cupola is one of the more detailed parts in this basic kit, and really adds to the authentic look. To enhance the cupola, I decided to make some vision blocks for it that would reflect light, in certain conditions. The transparent protective disc, that comes with packs of stacks of bland DVDs, seemed a good potential donor...
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The vision blocks should be roughly 4mm (H) by 10mm (L). I scored the appropriate lines on the disc with my indispensable Tamiya cutting tool..
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I produced four, to begin with. I needed to see whether they would look the part (They did!), but now I need to adjust the size to 5mm X 10mm, find a suitable colour to paint behind them. Vision blocks ought to
show the interior of the turret, to some extent (unlike periscopes).
I took this pic from the inside of a Swiss AFV, looking out through a vision block. I guess, the bronze tinge is designed to protect against dazzling light, or bright Sun.- much as reactolite specs do. But,
the pic makes it clear that a black image behind the glass would only be correct, if the interior of the cupola had been painted black... Thoughts needed on that one. :problem: :)
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Postby 43rdRecceReg » Sat May 25, 2019 4:07 pm

Lots to do on the Turret, Mantlet assembly, and more bling bits on the Upper Hull needed (handles, hinges etc..); but I want to get cracking on the Lower Hull.
Hitherto, I've been referring to the sheets the parts appear in as 'sprues'. Tamiya and Airfix sprues are mostly like plastic tree branches, with the parts as fruit. After the parts are cut free, the sprues are only fit for the bin. Ludwig kits, however, are (Computer) cut, or formed, in large sheets of styrene of various thicknesses. I suppose I should call them 'plates'. Anyway, whatever the appropriate term, the residual bits are extremely useful.
Here's the plate the sides appear in:
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The slots in the side wall are just waiting to be filled by the bulkhead bits here:
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Make sure you fit them in the side that has location dots in the rear section. :problem:
You can see them in this pic. I could put red arrows in, but time is at a premium.
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I made sure there were no residual tiny plastic stubs left over from where the panel was attached to the sprue. It's important to get as tight a fit as possible, and the little stubs can get in the way. :|
At this point in the build, Christian's Pdf instructions show the fitment of plastic Tiger 1 suspension arms (swing arms):
Comet build-Lower Hull-CL-pic 1.jpeg
CL- Comet manual- assembling the sides

and with an adaptation...
Comet build-Lower Hull-CL-pic 2.jpeg
CL-Comet manual-suspension arms

Comet build-Lower Hull-CL-pic 4.jpeg
CL- Comet suspension- pic 4


Comet Build-Lower Hull-CL-pic 3.jpeg
CL-Comet manual-metal suspension arms

Then, there are little press in metal grommets which are threaded internally to retain the roadwheel axles. Again, no mention of the means by which the 'swing arms' will pivot within the hull sides. :|


Here, however, there's no mention of how the arms are actually secured between the sandwich of plates we're about to make. By 'secured', I mean the axle or pivot the arm rotates around. On his website, he shows
a metal bar with brass bushings as an option. The bushings pass through the sides and the arm and are secured, on the outside by a screw and washer. This is similar to the arrangement found on the Tiger 1 (HL).
But it's not shown here. :problem:
Later, we see an alternative arrangement, where alloy swing arms are used in conjunction with a spring, to simulated the Christie suspension.
I've found ( during the Cromwell build) that if you assemble the arms in place fully, with springs under tension (as per pics), it's hard then to bond the side to the floor plate. IMO, it's easier to fit the arms later..but it can be fiddly.
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Postby 43rdRecceReg » Sat May 25, 2019 4:25 pm

The metal swing arms come in two halves (split down the middle). It's necessary to bond them together. For this, I used JB Weld (metal )_ two part epoxy. I've used other brands before, but this one- I discovered- is remarkably free of the brain-spinning odours I've encountered before. It's also very easy to work and promises incredible strength (bit like the little blue pill :haha: ).
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Two brass rods were supplied with the kit. One- tubular, and around 5mm o.d., and the other is solid, and slightly over 3mm. The solid rod is a perfect fit inside the tube, and so I surmised that the tube would make a good bushing inside the swingarm pivot hole, and the rod would then pass through it, and the (sandwich) walls of the hull sides, to act as a bearing/pivot. It can be secured on the inside by the extra styrene strip intended to reinforce the joint between the inner wall of the side, and the hull floor. On the outside, it can be cemented in place with plasto or Milliput. More later.
The easiest way to bond the halves of arms was to fit them together onto the 5mm brass tube, Then, when dry, I simply sawed the arm off neatly leaving a 5mm bushing inside the arm.
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Here you can see the general arrangement.
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Postby 43rdRecceReg » Sat May 25, 2019 4:47 pm

I then sawed ten lengths of 3mm brass rod off. These will act as pivots within the arm bushings.
Here, I've fitted the arm on the outside of the side plate, to get an idea of the length and size of spring I'll need to achieve the right ride height. This time around, I wasn't able to get the springs supplied with the Cromwell kit, and it was a real pain trying to find an equivalent online. The smaller of the two in this pic is closer to the type Christian uses. It stretches to 30mm, and that should be ample.
But this raises the issue of choosing the right components to get not only a credible looking suspension, but also an effective one. Too long a spring would create a risk of the tracks fouling the track plate, too short would make it look like it was wearing elevator shoes (a la Elton John in the 70s). Then there's the knotty question of where to drill the hole for the spring retaining bolt. The location also has a direct impact on the amount of tension (and therefore suspension) the arms will have, and of course, will influence the overall look and feel of the suspension.
So...that's why I decided to test the spring externally.
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Jumping forward a stage or two, this is where I decided the spring retaining bolt should go. I used a compass and pencil to ensure that all holes would be drilled in the same place.
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Making the sandwich (bonding the outer side to the bulkheads on the inner wall) I used set squares and drill bits to ensure that the two halves were aligned properly.
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I also used weights to ensure to apply force to the bond, and also to negate any possibility of the plastic curling. :wtf:
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Postby 43rdRecceReg » Sat May 25, 2019 5:03 pm

Here's a quick look at the main components of the suspension. The little stub axle in the swing arm (the roadwheel axle's retainer) is now a rivnut, or threaded and splined nut insert. It's an improvement on the previous stub; but is not shown in the instruction pdf.
It looks like this:
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...and the general assembly. Note, I've already given the wheels a coat of primer and Olive Drab (this will be enhanced later) and the wee brass pivots I've cut are in the bag with the springs.
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But, before I get round to assembling the suspension in situ...
It's time to begin fitting the sides to the Hull floor. Again, it's vital to ensure parts fit together tightly (no intrusive wee plastic stubs., etc.,). Set squares are a must.
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But before all that, I added a strip of angled styrene to reinforce the joint between the Hull sides and the track plate that sits on it. It's not suggested in the pdf., but I think it's a good idea to strengthen joints where possible, so long as bolstering bits are concealed. :thumbup:
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Postby 43rdRecceReg » Sat May 25, 2019 5:07 pm

Oh, yes. I forgot to mention that I'm still awaiting the arrival of one half of a swing arm. Unfortunately, a bit was missing from the kit, along with several other parts. :| Nae bother, all will be sorted eventually. :D
...
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Postby Son of a gun-ner » Sat May 25, 2019 5:42 pm

Oooh, absolutely spiffing old boy, looks like you're getting along fine :thumbup:

That's the difference with different vendors, some you know you'll get top notch after sales service if you find a problem, and others it's always a worry whether everything is included first go.

Keep up the good work Roy.
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Postby Ad Lav » Sat May 25, 2019 7:09 pm

Good progress Roy!

A nice challenge :)
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Postby c.rainford73 » Sat May 25, 2019 9:23 pm

Roy this is really a joy to watch! Maybe not all joy on your behalf with all the little fiddly bits from time to time but it's really coming along great. Nice job
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Postby 43rdRecceReg » Sat May 25, 2019 11:02 pm

Many thanks, lads. :thumbup: As frustrating as (semi) scratch building can be, it certainly works the brain and fingers harder- and that can't be a bad thing.
Pacing the floor at night, for solutions, certainly helps with the 5,000 steps per day. :lolno:
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