A34 Comet Mk I Type A - New Build

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Stephen White
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Re: A34 Comet Mk I Type A - New Build

Post by Stephen White » Mon Aug 06, 2012 10:44 am

Thanks Adrian and Steve. The early pattern idlers are 85mm in external diameter and the tyre rim is 21mm wide. Probably a very bespoke size for any commercially available tyres? I did think of moulding but it would be a lot of effort for four off and I'm not familiar with the materials. I did think that the pressure of the track would tend to retain the tyre on the rim but any lateral forces could be a problem. That's why I chose to replicate the inner rims as per the real thing. They weren't difficult to turn, at least not in comparision to the internal shapes. Thanks for the interest Stephen

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Re: A34 Comet Mk I Type A - New Build

Post by Simon Peck » Mon Aug 06, 2012 2:44 pm

Hi Stephen.
Very interesting work you are doing! Just a thought, I don't know if it would work, but could you make the 'tyres' from round black nylon rod? You could turn it to the exact size on your lathe. I know it's not rubber, but it would be durable.
Cheers,
Simon

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Re: A34 Comet Mk I Type A - New Build

Post by Paul Morris » Mon Aug 06, 2012 3:04 pm

Hi Stephen.

Just a thought what if you could get hold of a "sample" of black rubber hose / airline or hydraulic pipe that was just about the right size and force it over a mandril and then turn the tyres on your lathe? I know it would be pot luck to find nearly the right size but might be worth 20 mins looking :idea:
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Re: A34 Comet Mk I Type A - New Build

Post by simon_manning » Mon Aug 06, 2012 6:53 pm

inspirational comet building, great to follow even though i do not own one, but would like to, keep the progress coming stephen, regards simon.

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Re: A34 Comet Mk I Type A - New Build

Post by Stephen White » Mon Aug 27, 2012 8:33 pm

Thanks guys for the interest and kind comments.

Last pics of the finished replacement idlers with hub caps detailed:

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Now for the hull outer side plates which have a lot of detail to add. Firstly the side plates were made up from five seperate pieces so the joins were milled out. Then shape of the cut outs which allow the suspension to travel were corrected. The real ones were deeper with rounded corners. There are something like 150 hex head bolts on the sides, so the fastner suppliers are in for a bonanza:

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Stephen

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Re: A34 Comet Mk I Type A - New Build

Post by Stephen White » Sun Sep 02, 2012 9:23 pm

A large bag of 7BA hex head set screws has arrived so no excuses.......

Marking, centering, drilling, they certainly didn't design the Comet for ease of production. Firstly the surface prep - several coats of UPol High Build Primer in a random pattern followed by some work with the miiling burr.I've decided to do a section at a time, for variety. So here is the first, with the distinctive bolt patterns:

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Stephen

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Re: A34 Comet Mk I Type A - New Build

Post by Steve Stuart » Sun Sep 02, 2012 10:43 pm

A week of rain has helped you drill how many holes?!
And for interest, what size of bolts are you using?
All the best, Steve

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Re: A34 Comet Mk I Type A - New Build

Post by simon_manning » Mon Sep 03, 2012 12:05 am

perhaps the chief designer of the comet had shares in a nut and bolt company, exacting work stephen and well done, regards simon.

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Re: A34 Comet Mk I Type A - New Build

Post by Stephen White » Tue Sep 04, 2012 4:48 pm

Thanks both. I keep thinking of the aircraft workers you see in wartime films rivetting up structures or the ship builders doing the same with bigger rivet guns. I suppose you get into a rhythm.

Steve - 253 to be precise and I've used 7BA hex heads. They are within a couple of tenths of a millimeter of the real scale size, closer than 8BA which do look too small.

All the best.

Stephen

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Re: A34 Comet Mk I Type A - New Build

Post by Steve Stuart » Tue Sep 04, 2012 11:47 pm

253 is a bit daunting, however 7BA fits in with what I have used elsewhere, so that is good confirmation! On another note, one of the Isle of Wight Tank Museum Comet hulls some of the 'bolts' are countersunk, is this a later adaption? In other words a B variation.
Steve
P4110798.JPG
Comet Hull Side Plate

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Re: A34 Comet Mk I Type A - New Build

Post by Stephen White » Sun Sep 30, 2012 10:31 pm

Some work on the side panels - different textures to highlight the individual panels, all trying to simulate rolled armour plate:

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The axle covers were slightly recessed as here:

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So some milled rebates:

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Stephen

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Re: A34 Comet Mk I Type A - New Build

Post by simon_manning » Sat Oct 13, 2012 7:26 pm

coming on a treat stephen, always interesting, regards simon manning,

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Re: A34 Comet Mk I Type A - New Build

Post by Stephen White » Sun Oct 14, 2012 9:57 pm

Simon, good to know you're out there. Your JP is looking quite stunning.

More random work on the outer hull sides. Photos from Fabrice of the Isle of Wight Comets made me realise that the cutouts for the suspension travel have a small chamfer cut out - it's not on the original wartime drawing:

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So revised shape:

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The more I use UPOL High Build Primer, the better it gets for re-creating rough rolled armour plate and castings. I spray several random layers and then use the Proxxon and different milling cutters:

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Completed adding the external bolts and assembled the return roller housings. The end of the shafts should have a central hole and two chamfers:

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A few minutes with the milling machine:

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Some general views of the outer hull side, loose fitted to the inner:

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Regards

Stephen

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Re: A34 Comet Mk I Type A - New Build

Post by simon_manning » Sun Oct 14, 2012 10:36 pm

my jp is like skipping over the surface of building, this is nuts and plenty of them, i did'nt realise the comet level of detail, superb! regards simon,

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Re: A34 Comet Mk I Type A - New Build

Post by Dennis Jones » Mon Oct 15, 2012 11:11 am

Brilliant work Stephen. Just starting my Tiger but it won't have that amount of detail but I am hoping to get a lot of working extras on this one as plenty of room in the hull, recoil and muzzle flash, m/c gun flash, opening hatches under r/c, moving figures and smoke of some sort. Keeps the public happy cos as you are aware I am a demo man.

Dennis.

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