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 » Tue Jun 04, 2019 12:39 am

Thanks, Adam, Herman and Tom. All points duly noted. :thumbup: I think I've rigged the suspension so that if anything breaks, it shouldn't provoke a massive shouting session. :|

Now, getting the return rollers fitted, so that that they can also be 'maintenance-friendly,' is still an even knottier problem to solve. I think I have the solution; but am waiting on Pz 111 rollers rolling in from Rctank. I don't think it matters that much if the roller mountings are bonded in place, so long as the axles and rollers can be withdrawn.
Meantime I'm making the front mudguards, and planning to fit the (working) headlights and light guards to the front glacis panel. More on those things later.. :wave:
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Postby 43rdRecceReg » Thu Jun 06, 2019 8:34 pm

Assembling the front mudguards involves bending a plate, and can be pretty tricky. The outermost joint between plate and triangular side has a curved fillet to act as a former, and to reinforce the joint. The inner panel doesn't have a fillet supplied- so, I made one. The shape was already there in the discarded sprue/ styrene plate. :|
Comet build-lower hull-pic 33- mudguard fillet.jpeg
Former and fillet for front mudguard

Now, both the inner and outer wings have a curved former to help shape the curved part.
Comet build-lower hull-pic 34- fillets fitted.jpeg
Mudguard curved reinforcing fillets.

I may not bond the mudguards on just yet. Access to the front idler is easier during setup, without the wing of the mudguard in the way. I discovered that with the Cromwell build.
Now, it's time to fit the headlamps. This will then allow me to bond the glacis plate in place.
These bits are what I have available for the job:
Image
The headlights are from HL's Crusader model (an extra); but the same headlamps were fitted to the Churchill, Cromwell, and Comet as well. The donor lamps (for the wired LEDs) are from the Taigen T34. I bought several from Forgebear, intending to use them for the auxiliary lamps often fitted to the turrets of the Cromwell and Comet.
The Comet kit includes styrene lamp protectors, as seen below, but I preferred to buy the Crusader metal versions. They take a bit of shaping, and the crosspieces have to be cut out, but they're ideal for bolting- instead of cementing- in place :thumbup:
Image
Comet build-Lower Hull-pic 37-bulb transplant.jpeg
This was part of the bulb transplant from T34 to Comet

I'm aiming to copy the light arrangement on the Polish Comet.


Image
It ought to be fairly straightforward... :)
Ahh.. but with builds such as these, it's wise to expect the unexpected. >:<
On these two blueprints (necessary when ye have nae other sources :problem: ) the lights and protectors are symmetrical, as are the curved retainers that hold the two ropes.
Blueprint Comet overhead- Version A-symmetry.jpeg
Blueprint A- Comet front lamps

Blueprint-Comet A34-version B-symmetry.jpeg
Blueprint B- front lamp assembly
Blueprint-Comet A34-version B-symmetry.jpeg (94.89 KiB) Viewed 247 times


Sooo...I began drilling holes for the lamps on the glacis plate, having used a ruler to ensure the holes were the same distance from the edge. After I'd drilled the holes, and begun to fit the lights- I noticed something amiss. There was an odd lack of symmetry. Then, I twigged that the curved two rope holders are not symmetrical on the model. They're out. In fact, by a shade one is 22mm from the edge, and the other slightly over 25mm. :think:
Comet build-Lower Hull-pic 39-asymmetry.jpeg
Glacis component asymmetry
Hmm..that got the inner detail (semi) obsessive wondering what was going on. Did CL know something about the design that had eluded me, or could he have made a mistake? 8O
Last edited by 43rdRecceReg on Fri Jun 07, 2019 11:18 pm, edited 1 time in total.
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Postby PainlessWolf » Thu Jun 06, 2019 8:55 pm

Good afternoon, Roy!
Great work and a keen eye for noticing the non symmetrical tow rope holders.
regards,
Painless
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Postby 43rdRecceReg » Thu Jun 06, 2019 9:00 pm

No matter what the actual answer to this conundrum might be, I still have to carry on with the fitment. However, I don't want to keep drilling holes, and so I resolved to have the lamps and their protectors appearing symmetrical, whilst there's not much I can do about the two holders. They're fitted in precut grooves.
Well, here's what the lamps look like with defenders in place. The LH lamp has 'glass fitted, whereas the RH one will have a hood or shroud fitted, as per the setup on the Polish Comet. I'll have to make that myself.
Image
Incidentally, I've just found some interesting pics of a Comet rebuild on a Czech Museum website. https://tankysmrzovka.cz
For anyone wondering what the Cromwell and Comet suspension looks like with the skirts pulled up, so to speak, these pics of a stripped down Comet should prove interesting:
Comet-Czech rebuild-6-shock absorbers.jpeg
Czech Comet suspension bared

Image
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Postby 43rdRecceReg » Fri Jun 07, 2019 11:29 pm

PainlessWolf wrote:Good afternoon, Roy!
Great work and a keen eye for noticing the non symmetrical tow rope holders.
regards,
Painless


Thanks, Painless. Beyond the somewhat spartan guidelines in the build Pdf, much of the construction process is unknown territory; and I guess that's what makes it so compelling in many ways...once you get the bug, that is :D
Then again, there's always another conundrum requiring the Midnight Oil to be lit. :think: :S
The next one concerns the Henntec unit, and how to fit a Pz 111 idler to it. The standard axle and locking rings (collars with locking grub screws) supplied with the kit are too large to go through the metal idler
(with idler bearing fitted). The plastic idler version has what looks a captive self-tapping screw functioning as an axle. This, is too small for the Henntec arm. More on this later, with pics.
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Postby 43rdRecceReg » Sat Jun 08, 2019 12:18 am

Before I get back to the knotty drive train issues, I thought I might mention the difference between the Cromwell styled storage boxes supplied with the kit, and the actual appearance of Comet units.
The Comet units have plain surfaces (without the embossed stiffening ribs), and the lids have lipped edges so:
Click to ENLARGE these pics, by the way. :thumbup:
They're not pasted in from Imgur.
9.Comet-l.h.storage bin.JPG
Comet L.H. storage bin

Here's shot of the bins on a Cromwell blueprint. The raised ribs are apparent of the top of the unit and the lid, The lid itself is flat, and has no lipped edges. This is what you will get with the Comet kit,, and it's wrong, I'm afraid. Still, all that needs to be done is to fit the panels with grooves for the ribs facing inward, so that the plain surface is the visible one.
Cruiser Tank Mk.VIII Cromwell copy.jpg
Cromwell overhead blueprint shot of storage bins

First, I had to remove the raised edge of the bin's sides. On the Cromwell, the lif sits flush inside this raised edge. On the Comet, the lid extends right to the side's edge, and then hangs over it in the form of a short lipped edge. I seem to be making the terminology up as I go along; but I hope you're getting the drift. :lolno: Finding the actual engineering terms used by the designers, is a major task in its own right. :think:
Comet build-Storage box mod pic A.jpeg
Comet storage box mod pic A

I actually had to replace the supplied styrene lid, as it was too short to reach the edges of the box. Then, I used some split 2x2mm angles styrene to create the edges. I might trim a bit off yet, for scale purposes.
I also added a 1mm styrene tube (bar) to simulate the type of hinge used on the box, that runs the length of it.
Comet build-storage box mod-pic B.jpeg
Comet build-Storage box lid modification.

Still more to do to get the right look, but it's 90% there, I think.
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Postby BarryC » Sat Jun 08, 2019 12:24 pm

Roy,

You've doing a fantastic job. :clap:
No RTR or "Shake the Box" build happening here! :thumbup: :thumbup:

Barry
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Postby PainlessWolf » Sat Jun 08, 2019 4:13 pm

Good morning, Roy!
You are doing a great job keeping the details in mind and making available parts work with some neat scratch building and modding. I'm looking forward to seeing this one finished and running. Barry! I hear your Alien Overlords and your Machine Shop calling. Get back to work!
regards,
Painless
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Postby Son of a gun-ner » Sat Jun 08, 2019 4:15 pm

BarryC wrote:No RTR or "Shake the Box" build happening here! :thumbup: :thumbup:

Barry

Do you mean like your builds Barry :P
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Postby 43rdRecceReg » Sun Jun 09, 2019 12:23 am

BarryC wrote:Roy,

You've doing a fantastic job. :clap:
No RTR or "Shake the Box" build happening here! :thumbup: :thumbup:

Barry


Many thanks, Barry! After years following your meticulous metalworking miracles, I'm afraid I can only offer this modest contribution in plastic (mostly :D )
RTR? :haha: More like 'Road To Ruin' especially with these flatpack builds, as the cost keeps mounting.
I just discovered that the Heng Long Stug motors (StuG gearboxes were recommended) simply won't fit. Even a contortionist, with Houdini's abilities, couldn't have figured a way in for these boxes. I've ordered some Taigen StuG motors, they look as if they can be levered into place. Fingers crossed.
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Postby 43rdRecceReg » Sun Jun 09, 2019 12:33 am

PainlessWolf wrote:Good morning, Roy!
You are doing a great job keeping the details in mind and making available parts work with some neat scratch building and modding. I'm looking forward to seeing this one finished and running. Barry! I hear your Alien Overlords and your Machine Shop calling. Get back to work!
regards,
Painless


Thanks for the encouraging words, Painless. Scratch building, or even improvising parts, can be very satisfying when the results are good. However, working on static components (the Tank furniture) is generally easier
than fitting an effective drivetrain, an electronic heart, and an electro-mechanical means of getting the turret and other parts to move- especially where none had existed before. Upgrading RTR models has the advantage of having ready-made screw holes, plastic lugs, working motors, and other means of attachment for the builder to be guided by. Here, there's nothing. :| :problem:
So, you make it up as you go along.
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Postby 43rdRecceReg » Sun Jun 09, 2019 12:53 am

This sprocket has been beautifully formed by CNC tech, but that doesn't prevent it being a pain to assemble. It's not just all those wee bolts that have to be screwed in place (click to ENLARGE these images):
Comet build-drivetain-sprocket.jpeg
Comet build-drivetrain-sprocket assembly

The two gear wheels on each sprocket will only align properly, when the pre-drilled holes match those the in the wheels. It's possible to spend ages twirling them until they appear to be synchronised (a bit like 'cracking' a safe, I image- though I've never tried it).
When provisionally aligned, I use a straight edge to judge whether the gear teeth match, and whether they're also in line (parallel) with the hub.
Comet build-drivetrain-sprocket B.jpeg
Comet sprocket alignment

When they do look OK, a final check with a portion of track is a sensible next move. Prevention is better than cure in medicine, just as getting things right here at this stage is better than having to fix them later. :thumbup:
Comet build-drivetrain-sprocket C.jpeg
Comet sprocket test fitting to track

The track used here is the plastic Pz 111/IV type. I may even use it on the finished model, as it's fairly hard wearing.
Getting the drivetrain properly aligned is absolutely crucial in the build. Any excessive slackness, or toe-in/toe-out in the wheel mountings, return rollers, idlers and sprockets can add so much rolling resistance
to the drivetrain that it stalls the motors. :eh: >:< We all know what the consequences of stalled motors can be (they're often written in £s $s and Euros).
As the StuG motors I bought for the project simply won't fit in the precut orifices in the kit, and I don't want to force them in, I've ordered some premium Taigen StuG motors that look like the should be a better fit.
Right now, then, fitting the sprockets has stalled. Life's little ironies, eh?
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Postby HERMAN BIX » Sun Jun 09, 2019 1:12 am

Such microscopic details, just to get the sprockets to work!
I had a Matchbox Comet back in the day in 76th scale, liked it then, love yours now.
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Postby 43rdRecceReg » Sun Jun 09, 2019 1:23 am

So...it's back to the idler issue. Yes, the idlers are not an easy fit either. I have no kind of axle (whether from HL or Taigen) that will pass through the metal idler bearing and the suspension arm of the Henntec unit. I have a brass screw that's a good fit for the bearing in the metal idler, but is almost 2mm too small in diameter to fit in the Henntec unit. Then there's the cheapo plastic idler with it's incorporated self-tapping screw. It almost Fits in the Henntec. With a bit of filing, and judicious use of the Henntec arm's grub screw, it could be made to fit. But... I really wanted to use the metal idlers, with their superior built-in bearings (The plastic Pz 111 unit only has a bronze bush...). :problem:
Comet build-drivetrain-idler options.jpeg
Comet build-drivetrain-idler options

This is the plastic option. The screw almost passes thought the Henntec suspension arm. With filing, it would.
Comet build-drivetrain-idlers-option 2.jpeg
Comet idler- metal option 1

here the brass screw that fits the metal idler's bearing perfectly has been threaded into a tapped brass bush. Unfortunately, the bush is over 4mm in diameter, and the hole in the Henntec arm some 3.6mm.
With a lathe I could reduce the bush in size; but I haven't got one. Alternatively, I could drill the Henntec arm so that the bush would fit- but I really don't want to do that.
The third option is where I retain the metal idlers with brass screws, but make a sleeve out of brass tubing to make fit in the Henntec unit a tight one, when the grub screw is tightened. The brass collar could be sawn along its length to allow it to compress (a) around the brass screw; and (b) to slide tight inside the Henntec arm. The grub screw would prevent it from coming adrift. Well, that's the theory. The best laid plans o' mice and men, eh?
Here's the screw passing through the Henntec arm. Given that the Henntec's grub screw can take up play on one side, it might not even be necessary to have an insert sleeve that goes all the way around the screw.

Don't imagine for one moment, future builders, that progress will be smooth with builds like these. There are more hurdles here than in the Grand National. :problem: :lolno:
Attachments
Comet build-drivetrain-idlers-option 3.jpeg
Comet idlers- plastic option
Comet build-drivetrain-idlers-option 1.jpeg
Comet metal idler. Brass screw needing a sleeve
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Postby 43rdRecceReg » Sun Jun 09, 2019 1:30 am

Before I go off for my much needed ugly-sleep, I thought I'd post this pic from the Czech museum I mentioned earlier. This one has some useful details of the return rollers, and suspension, on the Comet; but is also fronted, rather charmingly, by what must be a sort of Czech harvest festival lunch. I bet that's a nice tasty Budvar beer in the jug, as well. :thumbup:
Hmm..looking harder, is that some sort of whip in the foreground?
Image
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Postby PainlessWolf » Sun Jun 09, 2019 2:23 am

Good afternoon!
Tanks, particularly, British ones, go well with any sort of regional specialty. Whips...Hmmmm. I don't know....
regards,
Painless
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Postby 43rdRecceReg » Sun Jun 09, 2019 6:35 pm

PainlessWolf wrote:Good afternoon!
Tanks, particularly, British ones, go well with any sort of regional specialty. Whips...Hmmmm. I don't know....
regards,
Painless


:D
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Postby 43rdRecceReg » Sun Jun 09, 2019 7:01 pm

Well, I looked at the idler options (..and no, I don't mean the Life of Leisure ones :lolno: ). The plastic one was just about workable; but the assembly is wobbly and wonky. Then again, the plastic idlers for the Pz 111
are fairly cheap.
The option to make shims out of 5mm brass tubing had promise; but didn't deliver. It looked, and felt, messy.
Thus- it was down to the milling of the tapped brass sleeve option. These brass tubes are left over from a Tiger 1 suspension upgrade idea. They were originally fitted to a bar that stiffened the hull sides, whilst providing
anchor points for the swings arms. Chris Ludwig also sells a similar bar for the Cromwell:
DSC01720.jpeg
Alloy support bar for suspension arms
DSC01720.jpeg (55.85 KiB) Viewed 151 times

Anyway, by a stroke of good luck, I had some brass screws that were a perfect fit for these threaded studs/standoffs
Out came the trusty Dremel, as I don't have a lathe or hobby milling machine in my ever-burgeoning collection of specialist tools. As it happens, there's scarcely any room for additional hardware these days... :problem:
Comet build-drivetrain-idlers-A.jpeg
Comet build-axle sleeve for idler

Sorry about the grainy quality of the image. It was taken in low light conditions.
Then I used a captive metal file as the cutting edge of the improvised 'lathe'.
Comet build-drivetrain-idlers-B.jpeg
Milling idler sleeve to fit Henntec suspension arm

Comet build-drivetrain-idlers-C.jpeg
Idler sleeves for Henntec stub axles.
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Postby 43rdRecceReg » Sun Jun 09, 2019 7:11 pm

It's looking good. I added some washers either side of the metal idlers in order to support the axle bearings. Then, took a provisional measurement from the centre line of idler halves (where the track horns pass through)
to the sidewall of the tank. The gap was just around the 18mm mark. This means that when the Pz 111 return roller mountings are fitted, the 18mm alignment target for the complete drivetrain looks doable.
Image
Now that the idlers look ok, I should be able to fit the glacis plate as well as the front mudguards. :thumbup: (Barring any other unforeseen hitches :/ ...but, it seems, they can never be discounted.)
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Postby PainlessWolf » Mon Jun 10, 2019 1:37 pm

Good morning, Roy,
Now that is building with hand tools. ;o) Clean work and durable. All that can be asked for.
regards,
Painless
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