Whilst casting some 15mm building stock a few days ago something rather bizarre happened. What was supposed to be a large advanced building turned into a bit of a blob.
The resin comes in two parts (resin and hardener) which is mixed together in equal quantities. Normally everything goes according to plan but on this occasion once the resin was poured into the mould it started to expand in a style similar to fill and fix foam. It was also making a noise that would make a bowl of Rice Krispies proud. Since it was around midnight at this point I left it to calm down overnight.
We’ve been using the same type of resin for well over a decade and I’ve never had this happen before. I can only assume that the tub of resin had been contaminated in some way or was past its use by date. Certainly using the same tin of hardener with a new batch of resin has worked fine since.
The end result is far too good to simply bin. Around half of the building is now hollow and the surface has a variety of decent damage marks on it. So the plan now is to carefully cut off the lump of resin from the bottom and paint it up as a destroyed building.
So I’m off to get a new blade for my hacksaw and we’ll see how it goes.
Phil brought several new moulds to the workshop last week. One was the production mould for a new set of 2mm civic buildings, including a town hall, grammar school, hospital, library and large church. The mould looked good, the castings were excellent and we were really pleased…
Until we looked closely at the church tower. Unfortunately the sides were bowed in and concave on all four sides. We’re not sure if the master model has deformed under pressure or if the print was faulty and we didn’t notice, but it doesn’t really matter, it’s not up to scratch either way.
After some thought we’ve decided to release the set without the church rather than completely scrapping an expensive mould. We’ll get the church reprinted and make a new mould, which will also allow us to create several different variations of the tower. The church-less set will be available at the end of this week (I just need to paint some for photography) and the church later in the summer.
Its just me (and the cat) in the house the weekend. No children!!!! Just time for me to play catch-up in the final couple of weeks before Salute. And my god I’m going to need the time. The list of jobs seems endless.
We’re having two full days of casting at the end of this week and I have a stack of new moulds to sprue and vent before then.
We spent last night making the master castings for the new British spaceships. They all need checking, cleaning up and then popping into the vulcaniser. Then of course the moulds will go onto pile above and to wait their turn for venting.
Add to that trying to fit in making resin stock since we’ve pretty much got none left after our recent birthday celebrations, sticking heads on Belgian ladies (before popping them in a mould) and I also need to fit in a trip to the supermarket for my mother as well.
Having written a rambling piece about the new unit bases for Celtos, I mentioned that we were already in the process of making resin cast bases, but neglected to show any pictures.
As you can see in the picture above, there are five types of base
ten normal infantry figures on 25mm bases (this is the basic warband)
ten infantry figures, one of which is on a large (40mm) base (warband with large hero leader)
four 40mm bases (most cavalry or monsters on large bases)
three 40mm bases (Fomorian Blood Reavers)
plain base (for very large monsters, chariots etc)
The bases have been 3D modelled and printed so the slots for each base are precise and fit perfectly. In this next picture, the bases have been given a textured surface and then sprayed with primer – if we didn’t do this then the texture material would be pulled off by the mould.
The next task is making RTV (Room Temperature Vulcanising) rubber moulds for each base (multiple moulds of the more common bases). I make these three at a time, to avoid too much wastage of the rubber. The bases are lined up in mould formers (in this case, they are very cheap metal flan dishes from Asda !) ready to have the rubber poured over them. The scales and calculator are to work out the exact amount of rubber I need (it’s too expensive to mix too much and then throw it away), the calculations are scribbled somewhere on the newspaper !
Hopefully we should have some sample castings to show you soon.
One of the most tedious parts of getting a model into production is the unglamourous but very necessary job of cleaning up master castings (known as ‘tins’) ready for the production moulds. I find this part of the process extremely dull (I may have mentioned this before …) but it has to be done. These castings have to have any small vent sprues, flash or mould lines cleaned away and filed smooth – otherwise we’ll just reproduce these imperfections when we make the production mould. We always cast more items then we need for the production mould, because castings that might seem OK in the workshop on a cold evening may not always pass closer inspection when cleaning up. Any pitting or less than perfect detail will see the casting rejected.
I spent my evening yesterday with some of the tins for the Bizon production moulds. The Bizon in particular has a lot of pieces and will need a lot of moulds – some of these will be shared with other models (such as the track units, side-skirts and gatling turrets) whereas others are unique to this model (track-guards and turrets).
In this photo you can see a selection of bits – side-skirts and external stowage (bottom left) which are cleaned up and ready for the production mould, some turrets (top left), one with gun which is cleaned and ready and a batch of others waiting for a visit from clippers and file, and some raw track-guards (bottom right) which I’ve yet to tackle.
In other news … the prints for the three PacFed tanks have turned up, and they look superb. Unfortunately I’ve already dunked them in jar of cleaning fluid and forgot to take photos of the assembled pieces first (doh !) so you’ll have to make do with a photo of some undefinable pieces floating in some murky-looking gunk …
For the last year or so we’ve been experimenting with 3D printed models in various shapes and forms. We’ve been playing with different printing materials from different printing houses, different types of mould, different ways of preparing the models before moulding and so on. Some have been successful, such as the ranges of 6mm and 15mm SF desert buildings which have sold so well they’ve funded the experiments of other types of models. Others have been less successful, and have resulted in destruction of some rather expensive masters. Yet more have been previewed here on the blog and then disappeared from sight without further mention. And yes, we know that lots of other companies have pretty much mastered the process and there are mould-making and casting specialists out there that we could have turned to and got them to do everything for us. But we’re nothing if not stubborn, and we have been convinced that we could master the process ourselves and keep everything in-house.
We’ve switched to a new printing company for the high-detail models, and the first batch of prints arrived recently – a mix of 6mm and 15mm vehicles. The quality of the prints was better than we’d had previously, and more importantly the material looked to be much more robust. Last week we previewed some of them, a range of 6mm Indonesian Republic tanks for our Iron Cow range. We’re pretty pleased with these, but on very close inspection the castings are not quite right – some of the surfaces are rough or pitted and some of the detail is not as crisp as we would like, so they aren’t suitable for release quite yet. So we tweaked a few things, and tried another mould, this time of parts for the 15mm scale Neo-Soviet Bizon tank. And here’s the result:
Pleased ? That’s a bit of an understatement … I had a grin like a Cheshire cat all the way home ! On this close-up you can see nice smooth, crisp castings which fit together perfectly.
So we reckon we’re almost there now. This is obviously only a master mould, the parts need to go into production moulds and the hull, which will be made in resin, also needs moulding. But we might see 15mm Neo-Soviets and 6mm Indonesians released this side of Christmas with a bit of luck 🙂
I’m in the middle of cleaning up castings for 58 arms and 18 torsos to make the production moulds. After much debate, we’ve decided on a solution of torsos with cast-on left arms and separate weapon arms (as much as anything, because we don’t think cast on weapons arms would be possible in the poses we would like). The arms have already gone off for moulding, but the torsos are lying on my desk being filed and sanded to remove mould lines and casting sprues. And, by George, it is tedious work … ! I took a photo of the torsos lined up just as an excuse to take a break and write this post !
The filing and cleaning is all done, the next stage is to take dremel and superglue and attach the left arms. After that, the joins need to be filled with green stuff – only then can they go off to Phil to be moulded. It’s a race against time as I leave for a week in France on Saturday, and they need to be ready so Phil can mould them while I’m away !
UPDATE – the race against time was won, the torso tins have left for mould-making …
It has to be said that the frivolous Simpsons-related title of this post has absolutely nothing to do with the content, except for a very vague spider link … but hopefully it made you look !
The Brigade vulcaniser (big hydraulic press that turns raw silicon disks into finished moulds with application of lots of pressure and heat) lives in Phil’s garage. Like lots of garages it’s none-too-tidy, being used for storage of all sorts of domestic overflow that has nowhere else to live and playing host to various wildlife that likes the warm, dark corners – mice (don’t talk to us about mice), spiders and so on.
One spider decided to make its home between the plates of the vulcaniser while it was inactive for a few days. Not expecting there to be anything inside, when Phil came to make a new mould he didn’t exactly do a thorough sweep for foreign objects. Now spiders aren’t the most robust of creatures, and several tons of pressure at 80°C isn’t the best thing for their constitution, as this chap found out:
Phil assures me that the ‘Poo’ isn’t really that, it’s just dirt/dust/rust. I’m not convinced …