Cromwell Mk 4 1:16 scratch build Ludwig kit

[43rdRecceReg]

Grateful for the supportive observations, B-Man, Alwyn (scratch maestro!), and Herman. Finding solutions to unforeseen problems seems to involve walking around in a daze; misplacing things (I found the soap in the Fridge ); ignoring the dog's need for a walk..or even dinner ; and bumping the old head on cupboard doors. Yeah, Turret rotation would seem to be child's play; and it is when everything is already moulded in place by some precision factory process- and you have the right screws for the job. I say that, because most of the screws I used for building computers, and general D-I-Y, are totally unsuitable for RC tanks. It would be handy if mixed multipacks of HL/Tamiya compatible screws and bolts were available in bulk, instead of lurking in the occasional tiny plastic packet that may (or may not) accompany the component.
Part of the reason I started a thread on alternatives to the standard HL/Taigen turret motor, was because the cramped interior of the Cromwell upper hull meant nothing fitted as it should, and options for placement (motor) limited to only one position...and then only just. I wanted something more compact. The same applies to the turret elevation recoil systems: simple and uncluttered gets my vote.. The Asiatam I'm trying to fit is very annoying.
Here, by the way, is Imex-Erik's take on a more compact turret motor option- for those who are still awake!. Once again, attaching it to the standoff-challenged styrene hull would be another matter. You really don't want
screw heads appearing through the nicely painted hull plates like some sort of metal mole, or tropical grub...

phpBB [video]

[AlwynTurner]

Hi re the screws if you look on eBay for a2 posi flange self tappers they come in a variety of sizes and lengths, are quite cheap, and delivered pretty quickly (look under supplier massiveattack007).
http://www.ebay.co.uk/itm/361075058894? ... EBIDX%3AIT
I try to keep a selection in a multi pack box. Also do not discard faulty electrical or electronic equipment without stripping it for useful bits such as screws, nuts, bolts, nylon pieces, odd bits of plastic, wire, connectors; when scratch building you will be amazed how many of these bits come in useful.

Alwyn

[tomhugill]

My solution was to bond the rotation unit directly on to the upper hull, this allows use of the standard ring. The drawback is you have to snap the rotation unit off if it fails. But I've found they rarely do so the trade off for me was worth it.

I do really get a kick out of seeing how different builders attack a problem, it's been great to see this build and wibblys comet build run together. Gives me ideas to take away for my build (I promise I'll get it done soon!)

Regarding your recoil unit, if there's any way you can detach the turret roof I would do it. I've had to work on pretty much all the bits in my turret since it was installed for one reason or another and having the whole roof come off has been a real boon.

[OnTrack]

miniature screws, hinges etc.,as well as bits from our Teutonic tech maestro (Chris..)

RR, this is an outstanding thread. Somehow I missed it earlier but am glad to have found it now. Can you say more about these hinges, screws, bits, etc.. ?

Also, thank you for sharing such detailed pictures of the kit, tools and your techniques. I'm aspiring to go to RC with some of my static kits and this thread is extremely helpful. I've also wanted to see what a Ludwig kit looked like up close and now I know!

[Raminator]

An elegant solution Roy, glad you got it sorted. Got to be getting close to the home stretch now, right?

I say that, because most of the screws I used for building computers, and general D-I-Y, are totally unsuitable for RC tanks. It would be handy if mixed multipacks of HL/Tamiya compatible screws and bolts were available in bulk, instead of lurking in the occasional tiny plastic packet that may (or may not) accompany the component.

I've taken the opposite approach and re-engineered things so that they'll take standard M3 bolts instead of the random assortment of crappy self-tappers you find in these things. You can buy them by the hundred for peanuts and they come in so many lengths and heads you'll always get one to fit.

My solution was to bond the rotation unit directly on to the upper hull, this allows use of the standard ring. The drawback is you have to snap the rotation unit off if it fails. But I've found they rarely do so the trade off for me was worth it.

For my T-34/76 I superglued some M3 nuts to the hull roof and drilled out the rotation motor so they'd be embedded inside the mounting holes. It let me mount it flush to the hull roof without having to be brave enough to glue it in place.

[43rdRecceReg]

Again, many thanks for the input Alwyn, Tom, OnTrack, and Ram. Food for thought there- in fact, a four course meal I agree that it's fascinating to discover how folk look at, and tackle, problems or puzzles from different angles.That's surely why Boards such as this one have so much to offer (besides the laughs and topical stuff..) As for retaining bits 'that might come in useful', well, I do that; but M1 to M3 sizes have not figured much in my
D-I-Y world until now. Then, Alwyn, there's always the issue of mission creep clutter to consider
Incidentally, I've been trying out different adhesives on this job, and for ABS and Nylon to Styrene I found 'Plastic Fusion' epoxy 'super glue' to work quite well. Certainly found it easier to spread than Gorilla Epoxy.
Despite its name, Plastic Fusion also bonds aside range of materials to a wide range of materials. CA superglues (even Loctite gel) set too fast, and were brittle when non-styrene materials were bonded to styrene surfaces.
While I'm waiting for the electronic heart to appear in the post (Clark TK60), I thought i'd tackle the Headlamp Guards that are present on most of the Cromwell variants (not the Comet- mostly).
I wanted then to look a little irregular, as they often appear on surviving examples of the Tank, like this one at Bovington:

MK IV Headlight Guards

I started by cutting up some 1mm copper wire from some old two- core and earth domestic wiring cable. Then I drilled some holes in the glacis plate for the back legs of the guards, just behind the small crossmember. Next, I beat the front sections flat (as per the real thing). I had intended to to drill them- and fit tiny bolts, but that was a task too far. So I bonded them, and added bolt heads instead. The spacing at the front is not uniform, but I liked it that way. When they're sanded and painted, as with glue trails and marks, they should look ok.

Old copper wiring

Cut to shape with flattened tab at the front

Bonding rear legs with epoxy

Tabs and bolt heads bonded to Front armour plate

Still the detailing on the engine deck to do; but it's impossible to find decent photos of the Cromwell's deck. Where the 1/35 miniature specialists get their details form I don't know. For now, i'm using my Tamiya 1/35 as a rough guide, as well as some blueprints from: https://www.the-blueprints.com/blueprin ... /cromwell/
There are quite a few blueprints for the Cromwell, in a variety of sizes, but the drawings all seem to have been supplied by one person, a Dr Saranga; so how accurate they are, I don't know. Personally, i'd like full access to the Bovvy Cromwell, with a tape measure and my trusty Canon D600... You can but dream

[PainlessWolf]

Good morning, Doc,
It's looking Grand! Just the right amount of detailing and a solid mount on those guards. Any running through the rough that you do, you've got them set up strongly to take the abuse. If and only if, you feel like doing any more tinkering with the front, you can put a drop of Debonder on those headlight covers and remove them ( odd for me to say that I know ) and put on the semi circular style that the Bovington unit has mounted. Following along!
regards,
Painless

[43rdRecceReg]

Good morning, Doc,
It's looking Grand! Just the right amount of detailing and a solid mount on those guards. Any running through the rough that you do, you've got them set up strongly to take the abuse. If and only if, you feel like doing any more tinkering with the front, you can put a drop of Debonder on those headlight covers and remove them ( odd for me to say that I know ) and put on the semi circular style that the Bovington unit has mounted. Following along!
regards,
Painless

Hi, Painless. Yes, I have mulled over that particular visual discrepancy at length..(hmm... 'mulled', in this, and in a growing number other instances is more like 'fermented' ). These things certainly occupy a lot of time and thought. My brain begins to fizz with it all, now and then. I have some styrene tubing with about the right diameter to make the shroud for the lights, but debonding the cover would be a good first step, and It's on my ever expanding list of 'to- dos'. As with your Tiger project, I want this to look authentic and perform well out of doors, without falling to pieces. With robustness as my watchword, I'm taking my time to make
the Cromwell as solid as such a project kit can be. Gary's (Max U52's) Vacuum cleaner and panty hose trick, won't be much use for finding wayward tank parts in my wee Highland domain!

[Raminator]

Still the detailing on the engine deck to do; but it's impossible to find decent photos of the Cromwell's deck. Where the 1/35 miniature specialists get their details form I don't know. For now, i'm using my Tamiya 1/35 as a rough guide, as well as some blueprints from: https://www.the-blueprints.com/blueprin ... /cromwell/
There are quite a few blueprints for the Cromwell, in a variety of sizes, but the drawings all seem to have been supplied by one person, a Dr Saranga; so how accurate they are, I don't know. Personally, i'd like full access to the Bovvy Cromwell, with a tape measure and my trusty Canon D600... You can but dream

I've got a bunch of photos of the Bovington Cromwell from my trip last year, I think this is the clearest shot I have of the engine deck:

• 

Resized to fit the forum, but if you'd like the full-size version (or photos of anything else) let me know and I'll find somewhere to host them for you.

[43rdRecceReg]

Many thanks for that, Ram I found a photographic 'walkaround' on Youtube with useful info, but images look vague after a screen grab. Your image is nice and clear. I'm having surgery on my foot on Wednesday, and my dog's been unwell, so the Cromwell project ground to a temporary halt. Even obsessions can be overridden by changed circumstances....
However....
Having managed to shoehorn the Asiatam/Taigen Recoil and Elevation unit into the cramped Cromwell Turret, as a trial fitting, I thought I'd connect it up a a spare Taigen MFU and test it's functionality. Critically, I needed
to work out where to fit the unit in the turret, in such a way that the barrel can rejoice fully, and have a reasonable amount of elevation. Given the absence of any fixed fittings: captive nuts, lugs, moulded- in- standoffs
etc..the space inside is totally unmapped, so to speak.
Something to note here, for future Cromwell builders, the Cromwell tank was unusual in having an internal gun mantlet (like the Churchill, which also had a cramped turret). Most WW2 tanks had external mantlets.
Given that the turret is already fairly cramped, accommodating an internal mantlet was not the best strategy. Because of this, the 1/16 scale Cromwell inevitably reflects the same design flaws and limitations of the real thing. While the Pz 111 also has a smallish turret, with about the same amount of space available, the attached Panzer storage bin can permit a standard HL/Taigen elevation unit to be incorporated, as well as an airsoft unit if required. This space is absent in the Cromwell, but present in the Comet. In other words, gun options are very limited in the Cromwell model, but not in it's offspring: the Comet. Ludwig's Comet Turret should take an airsoft unit and HL elevation unit with ease, although retention/fixing devices still have to be designed and fabricated by the builder.
So.....
I removed the Asiatam unit by a feat of prestidigitation. (Note again to prospective builder: leave the entire turret roof off when assembling the turret. Chris Ludwig's approach was to glue the rear portion in place. This is what I did; being none the wiser. Being glue-happy at the time, I'd made sure that the back section would never come adrift, even in the event of some major conflict. Removing it now would wreck the Turret..)
I needed to find just how far the Asiatam recoil travels in one full rotation.

Marking barrel travel start

Barrel travel marked with black pen...

Travel was something in the order of 19mm. Now for the elevation, but for that I needed to wire the whole thing up and cycle the movements. I got a flash, a bang (speaker), but no wallop! The elevation unit worked.. but it's horribly noisy, but the recoil motor seems to be dud. I ran various tests..including using my trusty continuity tester, and 6vdc battery pack (simple testing DC motors).

Recoil motor dead as a DC Dodo..

No joy. Even if the capacitor was a dud, and the soldered connectors dodgy, the motor should still spin when connected to a dc source.The recoil motor is actually +/- sensitive, unlike most DC motors, but in the event not even Lazurus could get any life into this crappy thing
I've sent off for another motor, and I'll probably rewire the unit along the lines of Open Panzer's simplified arrangement, (same as Aussie kev's); but for the moment, it's bye bye Asiatam , and Hello Clark Universal Recoil and Elevation servo unit