Misc: Moulding & Casting, cont.

My erdpfahl. Far from perfect, but passable... I hope?

I'm kind of getting ahead of myself here, starting with the above image of numerous erdpfahl, or stakes, and other bits and bobs. But they are the item I first had a yen to scratch-built and cast in resin, thereby launching this whole moulding and casting saga.

I did a lot of mould-making and quite a bit of casting after the episodes I've blogged already. And I'm not showing all of them. One thing I did was cut the big mould which contained ammo boxes and shells down into two smaller moulds. And in turn I then further cut these moulds in two, adding more pouring and venting channels. The improved results, pictured below, show that this was a better idea than simply chucking the mould out.

Much better results from modified moulds.

The largest group, at the top, are best.

In the image above, I've cleaned up the castings from the modified moulds, and 75% or thereabouts are great. There's one iffy one, and one outright dodgy/unusable one per item: spent shell, live round, and ammo box.

Next up I decided to revisit copying some wheels. But this time in sets of four, and with properly laid out pouring and venting channels. Would this extra effort produce better results? Indeed, would it yield usable items?

Sets of better prepared wheels, ready to be moulded.

Wheel moulds in progress, plus another single erdpfahl mould.

Once all the new moulds were made I get the whole lot ready for a potential complete casting session (not, alas, of the Hollywood starlet variety). And here they all are. A good little set, quantity wise, even if not quality wise. One issue however, is that the resin I'm using cures so quickly I can't really cast a whole set as big as this lot. If I try to, the resin is already going off before I've done all the pouring.

Lots of luvverly blue moulds...

Before I move on to the final chapter in this saga, for the time being at least. Here are a couple of pics of some of the multiple little gubbins that I made for the 88s, this time cast in several sub-sets, as opposed to the over-filled single mould attempt I made earlier on. As can be seen in the upper of the two images below, I usually try and do a few other little moulds as well, to use up all the resin I've mixed.

Casting the 'multiple gubbins' moulds.

The results of splitting stuff up speak for themselves, I think

As the lower pic above shows, pretty clearly, breaking the over-filled mould grouping into smaller sub-sets paid off. Air flows far more freely through the admittedly still tiny passages, and the items are, as a result, far more likely to cast properly. The wheel on its own and a tiny erdpfahl, nigh on invisible below the wheel, were the only successes out of the several other smaller moulds in the upper of the two pics above.

After the steps shown just above, I moved on to a more mass production casting stage, and the results are shown immediately below. Including one set each of the new tyre casts. The latter aren't perfect. But I think they are usable. I'll be doing this with a few wheel sets. Primarily on account of Chester, our new cat/kitten, waging a pretty successful war on my mini-Wehrmacht forces. I have artillery, cars, trucks and even tanks needing various bits - mostly wheels - replacing. I had to move my whole modelling workspace upstairs out of the lounge on his account. The little devil! 

Once I got a stockpile going, I started to feel reasonably pleased.

Bagged up, sorted into groups for specific jobs.

And so it finally came time to add some of this stuff to a few of the models for which they've been produced. The moment of truth, I suppose! I started with the Hasegawa 88s, both of which needed erdpfahl, linkages, and handles. I've done one as if just deployed, before being staked, and the other with the stakes going through the arms/legs, whatever they are, ready to fire.

A Hasegawa 88with added stakes (stowed), linkages and handles.

Stakes deployed, and ammo and boxes added to the scene.

This is the Airfix 88, with stakes deployed, linkages, and (not visible) handles.

Another view of an Hasegawa 88, with stowed stakes, plus ammo stuff.

I've gone to great effort, considerable expense, and produced some not too great parts, that most folk probably won't even notice. Yay! That's the life for me. And, I think, quite typical model-making behavious, from what I see elsewhere. But I've had a lot of fun, and learned a fair bit. I think for my next attempts at mechanical reproduction, I'll try another and much cheaper technique. But before I get to that point, I think I need to paint these 88mm guns. And perhaps even base them?

Misc: The Saga Slows Down...

Newly arranged sub groupings start to take shape.

Ok, so here I am, on Tuesday, having separated all the 88mm stuff into four groups last night. And made three sprues up. I've endeavoured to make the casting and venting pipes, the ingress of resin and the air egress, bigger. Hopefully on my next casting session, the resin will reach all the nooks and crannies.

All four sub-groups, on their own sprues; larger casting and venting 'pipes'.

With all four groups 'sprued up', it was time to make the silicone pouring forms. I took a tip from some of the online videos I've seen, and made the foam-card forms two-part. As a one-part arrangement, previously, it was very tricky trying to work in such a tiny confined space. This method allows one to work on the bottom half first, embedding your objects and levelling your plasticene, etc. And then you put the top part on to pour the first silicone part of the mould.  

Working on creating two-part forms for moulding.

The final pic, below, shows all the lower halves, filled with plasticene, awaiting the trimming of the casting and venting sprues and the embedding of the parts. I did this around lunchtime today. And I'll probably come back and add to this post later, once I've got the objects embedded, and the other halves of the forms in place.

At that point, it'll be time to add mould release - I'll add more, and be more scrupulous about it - and mix and pour another batch of silicone. I desperately hope that this time I succeed! 

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Lubed up, forms built... ready for the pouring.

Some considerable time later the same day: I lubed the moulds with vaseline - and not mould release (that's for the second silicone pour, and not for using on the plasticene... I discovered!) - super-glued the top parts of the forms in place, and poured part one of each two-part mould. Those two steps looking as illustrated in the two pics, just above and below.

And there they are. Now comes the waiting...

I guess-timated the quantity of silicone I'd need, at half as much as I'd used on my previous attempt. And, somewhat miraculously, that proved to the perfect amount... phew!!!

Misc: Silicone Moulds & Resin Casting, the Saga Begins (Kind Of)

Ammo from the Hasegawa 88s I previously built.*

* The observant might notice I've drilled out the ends of the spent shells.

Things have gotten a bit asynchronous, if that's a word? What with techy issues plaguing me, from Apple iStuff that holds charge for 2 seconds to Blogger updates that pout the kibosh on the workflow, things aren't as smooth as they might be.

Anyway, the result is that this post ought to precede the last one, but I can't be arsed, faffing about any more than I already have. So here it is. These pics and the accompanying text document the run-up to the previous post, where I poured my first few silicone moulds...

My two main mould forms, ready for the first pour.

I used rice to calculate the approx' volume of silicone I'd need.

Not using the scales yet, but I've marked two lines...*

* The thicker lower line is actual volume required; the thinner higher line allows for a little extra, just to be safe.

As can be seen, I built forms using foam-card and, for the two-part mould for all the scratch-built 88mm gubbins, embedded the parts in plasticene, with the added channels for vents/sprues. The ammo is purely for an experimental test moulding: can I reproduce stuff in a one-piece mould and get it all out on long single beam style 'sprues'? The 88mm bits, on the other hand, I'm intending to produce in small quantities, to detail my models.

I mixed the silicone in a disposable cup, and... gulp, poured it.

About two hours later, it looked like this... i.e. much the same!

I spent a fair bit of time after pouring the silicone tapping the forms, and popping air bubbles as they rose to the surface. This was kind of satisfying in the same way that dealing with blackhead can be (overshare?). I now had to wait, between 8 and 24 hours, to de-mould. I'd then be ready to pour a test batch of the ammo. But the 88mm bits and bats would need the second half of the mould pouring first.

Misc: Silicone Moulds & Resin Casting, the Saga Continues...

Two extra last-minute moulds...

The above photo shows my first two silicone moulds to be, er... de-moulded? Is that the right term? At left is my first attempt at an 88mm erdpfahl, or stake. That mould is one-piece, with a slit cut along it longitudinally, on top. In the centre is a repro of a German truck wheel. That is a two-piece mould, but made by cutting a one piece silicone mould in two laterally, around the circumference.

Both of these are purely experimental tests, not for 'production'. The erdpfahl, 'cause it's too crappy, and the wheel, because it's a copy of a commercially available model piece. Anything that I might plan to reproduce for actual use will have to be original, so as to not infringe on copyrights. But in terms of testing out the mould-making process, it's helpful to try out a complex shape with fine detail. In addition, both pieces, the erdpfahl and the wheel, have holes that pass though the whole piece. And I wanted to see how moulding and casting such things worked out in practice.

These two moulds were actually afterthoughts, made with leftover silicone - which had already been left an hour or more - from pouring the two larger moulds I'm making. I really wasnt sure if the silicone was too far gone already. But they appear to be usable, from a brief visual inspection. These moulds have been opened up after about 8-10 hours curing time. I'm going to leave the other larger moulds for the full 24 hours (the product recommends between 8-24 hours).

Tiny ill-formed moulds, made with leftover silicone.

I'm putting this post together without access to my iPhone - battery dead/charging, elsewhere! - on which I have most of the photos of all this process. So I might return to and amend this post, to show more of what I did. But here's a brief summary: The erdpfahl stake is scratch-built from styrene, the wheel comes from a kit, they're both 1/72. I used foam card and plastic (styrene) card to make forms, or enclosures, to hold the silicone. And on these two instances, I rather messily slopped the partially cured silicone into one side of a rectangular or near square form. I then placed this on a small foam card substrate, popped the piece I'm moulding into the silicone, and then plonked more of the blue goop on top. 

The silicone and resin moulding and casting set came with wooden spatulas, like oversized lollipop sticks. I used these to press the silicone and mummified parts into the form. These were then left overnight to cure, and freed from their forms this morning. The moulds needed tidying up a fair bit, as I'd made them in a very messy ad hoc way... the were after all afterthoughts/experiments. And finally I had to to cut into the silicone moulds in order to retrieve the cast objects. One cut along the top of the mould, from the pouring sprue/vent, for the stake, which I popped out by deforming the mould, and an all round lateral circular cut for the wheel (I'll also need to cut a pouring and possibly also an air-release vent for the latter). 

I also had to do some fiddly cutting inside the moulds to release both pieces, on account of the through-holes they both feature. After all this stretching and butchery, will these moulds produce usable castings? I'll have to have a try, and see. In the meantime, I'll try and add more pics from my phone, once that's back to life, and exercise patience re the larger pair of moulds.

Misc: The Postman Sometimes Rings Twice...

Oooh... exciting!

I'd wanted to title this post 'The Postman Always Sometimes Rings Twice', but I couldn't find a way to get the crossed out text in the title of my post. Hey-ho, never mind. Sooo...

Phwoarrr!!!

A couple of days ago I ordered a few models from Hannants, all German WWII, all 1/72, and all of which, I guess, come under the soft-skin/rear-echelon banner: three trucks and a car. These arrived, very well-packaged, this morning.

Chester enjoys the empty box... bless him!

Chester, our new* and still very young kitten, was almost as excited about this as me. Only, rather like Eeyore, in that touching Winnie the Pooh tale, where he gets a burst ballon and an empty honey pot, Chester was more interested in the empty honey pot than the contents!

* Tigger, our super-fluffy moggins, and occasional star of a post or two online, perhaps even on here, alas, passed away earlier this year.

I'm looking for'ard to building these babies.

Whilst I won't be starting in on any of these new arrivals today, I will be continuing to work in detailing my 88s. I refined some of the parts today, sanding, filing, paring back, shaping, etc. I've also constructed a form for my first resin-casting silicone mould. Today I'm planning to pour the first half of said mould. 

Yesterday I used a hot glue gun for the first time, which was interesting. I think the big bag of glue-sticks I have are poss' meant for a different glue gun, as they seem too thin, and don't feed through the gun properly when I pull the trigger... which is annoying!

I bought some foam card from a shop in Peterborough.

And mixed some plasticene, to set the parts into.

The good, the bad and the ugly...

In the above photograph, the three items in the upper left are rejects: a malformed brass shell, ditto the crappy wobbly-holed erdpfahl, and an ammo box lid that melted into a near shapeless blob. The other bits have been improved, and, bar the wicker ammo box and lid - which need a little more detailing - are ready for moulding. 

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Ready for moulding? Hmmm... infamous last words. It's now several hours later, and I'm hardly much further on. I used a technique of mixing Milliput with water until it's so dilute you can paint with it. I then loaded the wire 'wicker' several times. The idea being that whereas before it was full of air, in the voids or interstices between wires, it should now still have the woven texture, but hopefully won't trap any silicone, when I pour the mould.

Re-shaped shell, detailed wicker ammo box and lid, etc.

I also decided, on referring to images of real 88mm ammo, that my live shell needed reworking. That was super-fiddly and took ages. I think I need a mini-lathe of some description, so I can make parts like this more easily. My original version took the Hasegawa ammo as it's starting point, which is much more 'stepped' than the real thing. A strap and buckle on the lid and wicker ammo box completes my pre-moulding prep.

I'm having a break now, and thinking about how on earth I'm going to embed and lay out these tiny ultra-delicate parts. Even though I'm getting next to nothing done, it's quite intense work! I feel drained... 

A bizarre looking little kit!?

And to finish this miscellany type post, the above image shows a strange looking little kit from a range of 1/72 kits I'm intrigued to try out. These kits are currently available very cheap at the Tank Museum's online shop (click here to have a look). It was whilst watching one of curator Davis Willey's back garden based Q&As that I was reminded of these oddities - I'd encountered them before online - as he had one on his table, amidst sundry stuff he's trying to help the museum shop flog.