Sherman Crab (again!)

[Jakko]

One I started about two years ago for the Animal Antics group build:

Jakko’s 1:35 Sherman Crab Mk. I — seeing double?

It dawned on me a while ago that my Brewster 339 doesn’t really follow the spirit of this group build: yes, it’s known as a Buffalo, but only in British service, really. Mine will be an ML-KNIL (Military Aviation of the Royal Netherlands-Indian Army) machine, though, and pilots and crews knew...

www.scale-models.co.uk

This has sat around unfinished since then mainly because I couldn’t find a good way to do the flail chains, which I want to be of the specific pattern this particular Crab had. A few months ago, though, someone 3D-printed me parts to make them up, based on measurements he took from the Crab at the Overloon war museum:

And tonight, I finally got round to trying to assemble them … emphasis on trying, which it was As he had printed them with holes through the pieces to take connecting pins, I bought 0.4 mm brass rod to do that with, cut some lengths and assembled what I need. Here is what about 20 minutes of work got me:



The length on the right is a cut-down piece of Resicast flail chain, as “my” Crab’s flails started with some links of that before going on to clasps, oval links and rectangular plates before terminating in a ball.

I’m not sure this is going to work. Even if I assume assembly will get easier with some practice, I’d probably still be looking at ten minutes or so per chain, times about 40, which is far more effort than I want to be putting into this … I’m starting to think a better solution would be to print up the chain as a whole (with interlocking rings etc.), then bend it into shape with some heat from a hair dryer. But that means drawing that and getting someone to print it — luckily I have a (different) friend with a 3D printer who lives not too far away … I think I may have to give him a call soon.

 

[Jim R]

Hi Jakko
I remember this - I even remember the last post talking of Shapeways.
I wish you well with this. There must be a way
Jim

 

[Richard48]

Good lord Jakko.You must have some patience for this kind of work.Im surprised the kit hasnt appeared in styrene but it be a pig to do chains in plasic kits i guess.
More patience than i mate.
Richard

 

[Tim Marlow]

Might take a long time, but it does look rather good….could you just use these for the on view outside ones and use something a little less complicated for the internal one that are not as visible?

 

[Jakko]

I remember this - I even remember the last post talking of Shapeways.
I wish you well with this. There must be a way

Similar talk on another forum resulted (eventually) in me obtaining the 3D-printed links I wasn’t quite convinced when he sent them to me, and I’m even less so now, but I think I’ll try assembling a couple. Ore to see if it gets easier. If not, I’ll turn to plan B: one-piece printed ones that I’m sure my friend can make for me.

Good lord Jakko.You must have some patience for this kind of work.

I have patience with this to a certain level, but from what I’ve done so far, I think this is likely to over that by some degree.

Im surprised the kit hasnt appeared in styrene but it be a pig to do chains in plasic kits i guess.

A different type of chain would be doable quite well in plastic, I think, but it probably boils down to the same old song: “nobody wants British armour, especially specialist vehicles, in plastic …”

 

[Jakko]

Two improvements have made this chore semi-manageable:



The obvious one is using Blu-Tack to hold the rods onto which I thread the links. The other is to run an 0.5 mm drill through the holes in the links before trying to assemble them. When I was lying in my bed last night, I realised that a major part of the difficulty I had in assembling the chain was because the rod didn’t want to go through the holes, probably because of the deformation caused when I cut off these short bits from the metre-long rod I bought. Enlarging the holes slightly takes a lot less effort and is far less stressful than trying to force the pretty fragile links over the cut end of the rod.

Once it’s on all four rods, I put a dab of superglue on both sides of the link on each rod, using a sharpened cocktail stick, so it flows into the joint and hopefully makes the joint permanent. Should I accidentally glue together more than I should, that’s not really a problem, based on photos that show the chains of the real Crab this is a model of

I then trim the rod off with a pair of high-quality cutters that can cut right up against the link. With my normal cutters that I use for plastic parts too, it leaves a bevelled edge sticking out half a millimetre or so from the side of the link, which is very obvious. With these, though, I can cut the rod off almost flat against the link.

So far I’ve made three chains, and where the first one took twenty minutes, the others took about that same amount of time for both together (including the time it took to take a few new parts when some broke), so I seem to have halved construction time Still far from ideal, but doable, in a way. If I can make myself, anyway …

 

[Neil Merryweather]

they do look spectacular, Jakko- I hope you keep the faith!

 

[tr1ckey66]

Stick at it Jakko - the result will be worth the effort. I’ve built the Resicast Sherman Crab in the past and always felt the flails let it down, as they don’t really lie that naturally. With articulated chain links this should hang with more realism.
Great work
Paul

 

[Jakko]

they do look spectacular, Jakko- I hope you keep the faith!

So do I, and ideally I’d have them ready, painted and attached to the tank within about a week … This because of a temporary museum exhibition about the vehicles used in the landings on Walcheren, put together by yours truly, in which I also want to display models of them …

Stick at it Jakko - the result will be worth the effort.

For the model, certainly. For my nerves, I’m not so sure

I’ve built the Resicast Sherman Crab in the past and always felt the flails let it down, as they don’t really lie that naturally. With articulated chain links this should hang with more realism.

The Resicast parts aren’t too bad, and if my subject had had those chains, I would just have used them However … The fit shouldn’t be a problem: just apply some heat and bend them around the drum.

Also, I get the impression Resicast picked the type they included carefully, because it’s the only one you can properly mould in resin, even though it appears to have been much less common than the type I’m building here.

I need to use about half of each of the Resicast chains, as you can see in the photos. The chap who printed these for me originally made them including the “bicycle chain” upper half, but there’s no way in hell I’d assemble that section as well It would add another 15 printed parts and eight pins, the printed bits all smaller than anything I’m working with now …

 

[Jakko]

That’s 41 chains fully finished, other than painting and bending (some of them) to fit the tank.

As you can probably imagine, this was [sarcasm]a great, fun job I would happily repeat[/sarcasm] … It went reasonably well until the last of those four plates of parts, where something appears to have gone slightly wrong with the 3D printing, causing a lot of the openings in the parts to fill up. Drilling out the eyes on the D-clasps saw quite a few break, to the extent that there were parts for 48 chains, out of 41 I needed, and all I have left of the D-clasps now is enough for one chain. If you look closely at the photo, you can also see I had to make four rings from copper wire, due to the same problem: many of the printed rings having filled up to the point where trying to remove the excess material caused them to break. Luckily those rings are easy enough to fabricate — if I had run out of usable D-clasps I would just have hung a few less chains on the underside of the roller.

Of course, once all that was together, I still had to stick two etched parts from Resicast to each of the chains, for the attachment to the roller.

 

[Tim Marlow]

Fantastic. The finesse of the result will still be evident long after the pain of construction has faded into the ether…..

 

[scottie3158]

Very nicely done Jakko as Tim said they were well worth the time.

 

[Jakko]

Thanks, they do look good. I now have to find a way to paint them, though, which also will be tricky. After that, I need to bend some into a curve (you can see one I already did, as a test), to fit the roller.

 

[Jakko]

As if the flail chains wasn’t enough, I discovered over the past year or more that I had made a number of minor mistakes on the tank itself, so I had to go back and scrape off paint to correct them:



Crabs had a surround around the gun shield, for attaching a canvas cover to keep out the dust and dirt thrown up when flailing. The tube on the shield is for that as well, to allow the gunner’s telescope to be used. I had missed this because most pictures you see of Crabs have the canvas cover attached.

The periscope covers that Asuka provides are flat rectangles, and though this is correct for the majority of Shermans, this particular one had “roof-shaped” ones (as I think of them), which a mate with a 3D printer made for me after my own attempt to file them from plastic strip failed miserably.

I also had to replace one of the chain attachment points on the flail axle, because it had broken off at some point without me noticing. Luckily, Resicast provides plenty of spares as separate pieces (the normal ones are cast into the axle).

Also, I scraped off the division markings because I had used too large a decal for that on the front, while that on the back was in the wrong place — it turned out when a picture of the rear of the tank surfaced about a year ago. I still need to paint all of this over, of course, and also the red I put on the first-aid box on the hull rear. Again, that photo showed the arm of service marking wasn’t on the box, as I had assumed, but inboard of it.

Oh yeah, and I need to put the word CHERRY on the deep-wading chute on the back, as well as T148656 inside the stowage bin on the right, which will be fun …

 

[Airborne01]

Ouch! Good luck with that Jakko; when will your 19th Nervous Breakdown happen?

 

[rtfoe]

View attachment 436139

That’s 41 chains fully finished, other than painting and bending (some of them) to fit the tank.

As you can probably imagine, this was [sarcasm]a great, fun job I would happily repeat[/sarcasm] … It went reasonably well until the last of those four plates of parts, where something appears to have gone slightly wrong with the 3D printing, causing a lot of the openings in the parts to fill up. Drilling out the eyes on the D-clasps saw quite a few break, to the extent that there were parts for 48 chains, out of 41 I needed, and all I have left of the D-clasps now is enough for one chain. If you look closely at the photo, you can also see I had to make four rings from copper wire, due to the same problem: many of the printed rings having filled up to the point where trying to remove the excess material caused them to break. Luckily those rings are easy enough to fabricate — if I had run out of usable D-clasps I would just have hung a few less chains on the underside of the roller.

Of course, once all that was together, I still had to stick two etched parts from Resicast to each of the chains, for the attachment to the roller.

It's crazy Jakko but I like it. Hats off for the perseverance.

Cheers,
Richard

 

[Jakko]

when will your 19th Nervous Breakdown happen?

Luckily for me, I don’t get nervous breakdowns over building model. All kinds of other stuff, sure, though

It's crazy Jakko but I like it. Hats off for the perseverance.

You want to hear the even worse bit? I lost one of the chains

This afternoon, I went and sprayed them black, with primer from an aerosol can. I did this in the shed on a piece of old newspaper, carefully from a good distance so the spray wouldn’t blow the chains away. After I was done, I left the door of the shed open so the fumes from spraying would dissipate a bit; when I returned maybe ten minutes later, a gust of wind had blown the newspaper to the floor Luckily the tackiness of the paint had left most of the chains stuck to it, but a couple had come off. I found the others of the floor, but after counting I only had 40, not 41. After spending quite a long time searching, I still haven’t found the missing one

 

[Airborne01]

Luckily for me, I don’t get nervous breakdowns over building model. All kinds of other stuff, sure, though


You want to hear the even worse bit? I lost one of the chains

This afternoon, I went and sprayed them black, with primer from an aerosol can. I did this in the shed on a piece of old newspaper, carefully from a good distance so the spray wouldn’t blow the chains away. After I was done, I left the door of the shed open so the fumes from spraying would dissipate a bit; when I returned maybe ten minutes later, a gust of wind had blown the newspaper to the floor Luckily the tackiness of the paint had left most of the chains stuck to it, but a couple had come off. I found the others of the floor, but after counting I only had 40, not 41. After spending quite a long time searching, I still haven’t found the missing one

Real time structural failure mate!

 

[Jakko]

My own stupid mistake, of course. I should have kept the door closed until the paint had dried enough that I would take the parts inside, or put something heavy on the newspaper so it wouldn’t blow away. But it was a quiet day today, wind-wise, so the thought didn’t occur to me at all that this sort of thing might happen

 

[Jakko]

The real tank that this is a model of, is back where it belongs:



Since about 09:30 this morning