Monday, 31 August 2015

HBK Moulds design, casting and such

So as per last weeks post I decided to keep everything in house.

Back when I was learning to cast 6 years ago the main assumption was you made 2 part moulds casting. The people started to use split moulds because it was far quicker and you could get really close to a perfect cast since the parting seam was only partway around. The technique was new to most people there wasn't much in the way of info and after reading up about it that's how I set out to make my moulds. There were a lot of blanks left to fill in and my technical skill and tool box were basic.

I started with plastic card mould boxes sealed with plasticine but they were iffy and often leaked, so I switched to Plastic cups they were pretty good and fast to make moulds. I also got lazy when it came to adding proper venting to allow air bubbles out because I had vacuum pump I could degas the resin before pressure casting it. And that worked well for the more simple MW4 models they were blocky with surface detail. But I found more and more the MWO models had more detail, undercuts and fins etc that technique was becoming inadequate.

One good thing that came from trying to source a caster. One of the companies I spoke to (a well regarded judging by the list of commercial companies that use their services) came straight out and said he be to expensive to do the work.  But he was happy give some advice so told him some of the problems I had, he walked me through how he'd do it. There was no magic trick on how time consuming it would be to cast but there were lots of ways I could improve my moulds. I then spent a fair bit of time researching what he had told me.

  • No more being a slacker I had to add venting, make sure there's no big spots where bubbles can sit. Time spent here pays dividends over fickle casting later on.
  • Second I had to make square moulds because they align better. Since my earlier attempts I had bought a glue gun and this it a perfect way to quickly seal cardboard mould boxes but does take allot more time than just dropping stuff in a cup.
  • Then I had to thicken my mould walls much more than I had been doing before plus extra thickness on the side to be cut
  • Draw a straight parting line then with the help of someone holding the rubber taught (I always did it by my self) and a fresh thin scalpel blade make a cut waving back and fourth across the line
  • One of the guides I found on line recommended cutting as little as possible at first and using a mould release to help the master out. Then its a case of easing the parting line down till you get a happy balance.
  • Lastly he recommended going with a clear RTV(rubber) so you can land you parting line perfectly around any details. 6 years ago it wasn't that common to hear people talk about clear rubber. I started with the blue stuff like most and stuck with what I knew worked. I did some research into the clear RTV. It's not as easy to work with its allot harder and it can react badly to certain substances such as super glue. I ordered some samples of which one company never got back to me and the other one will send me something but unfortunately the guy (apparently there is only one) who decants the rtv is away on holiday till Tuesday. bummer
Any way I had some blue RTV and I decide to mould the masters that had simpler parting lines. So I followed all the above advice and waited for the moulds too cure. I had to wait 2 days for the kids to be out and the wife to be in a helpful mood to cut open the moulds. The resin also has to be cast on a dry day but we had 3 days of torrential down pours to wait out.

HBK foot mould

Any way the wait was worth it, the parts came out pretty much exactly how the masters went in, a few some small bubbles but you can't vent everything, the parting lines were really tight you couldn't even where tell there were but for some thin flashing that just brushed off, I'm so happy how they came out. Since I've used mould release the parts went into the sonic cleaner with some organic degreaser, they'll get a soap bath and a rinse after that (you don't want some grease spoiling a nice paint job).

As soon as I can get some more RTV I can finish of the rest of the moulds and get a whole model cast.

Saturday, 22 August 2015

Making mould preparations

I've not forgotten you guys or the HBK. I was just chasing my tail for 2 weeks.

I was looking to outsource making the moulds HBK as some of you might remember I hurt my thumb and it was a little more serious than I joked I worried I wasn't fit enough to make moulds/casts.

I know from went I first started that good and well price mould makers are mythical, the truth is there's very little profit in mould making since its so labour intensive and that's why I originally started casting myself. Needless to say looking for quotes resulted in having to make a 3hr trip to this 'professional' workshop where I had to wait 30mins for someone leave before I enter and receive my model. It was totally avoidable and cost me 2weeks.

Anyway it just reaffirmed that everything is best done in house where I have total control. The other good news is after going to my GP x3 and getting no where, I went privately to see a dermatologist and she fixed me up. Apparently I touched something that cause an acute allergic reaction (like a heavy metal) some cream and a few days my thumbs much better.

So I've start the process of making pour spouts for everything. Its fiddly task but I'm going to take it slow and really go for making good moulds that cast well. On the centurion I regretted not making better moulds it made for tricky casting so spend a penny here save a pound (in time) later on. So lots of vents/big chunky moulds/tape bridging are the order of the day.

Friday, 14 August 2015

Forward planning - multi tasking leopard

Currently the CNC machine is sitting idle which is no good. It might as well do something with it so with that in mind last year I had the Leopard dropship printed but I was never happy with how it came out (its what prompted me to got to CNC) so I decided to abandon it. But I still have this great Leopard dropship 3D model ready other and sub dividing for CNC.

Before I invest a small amount of time in it I want to know the level of interest in a table top scale Drop ship. If there's not enough hands up then I'll probably just make it a personal project. As there no patron the price would probably be £200 which given its bigger than a thunderhawk from forgeworld (£410) and I'm not a professional shop I feel that's fair. That price didn't come out of thin air either the leopard is scaled bigger than any 1/60 scale assault mech plus it has an interior which just increases the amount of work but it'll be the first Battletech dropship to have a working bay that doesn't look like a soap bar or a football.

And for those who havent seen it together;

If you want one contact me on the address below. I'll keep a list and if I get enough people interested then it'll be a go I'll CNC it. A deposit of 25% before making moulds and the balance upon dispatch. I expect that it'll be ready to ship around new year if not earlier assuming there's brisk interest.

Feel free to share this post if you wish to drum up interest

Thursday, 13 August 2015

Samples made for Roland

So just a breif update while I take care of some stuff a semi model related post.

Roland the company that supplied my CNC machine ask if I would provide them with technical samples (recognisable part) that can be produced. So I whipped a few of these up and they'll be displayed in their technical departments in UK, Germany and Japan.

They look interesting to me and thought you guys might like to see;

It's the lower arm meshes grouped as machined just from 1 side.

Wednesday, 5 August 2015

Must be Humpday - MWO hunchback

I've been promising updates for a while this ones going to be a whopper.

What we have above is the break down of the model into its component parts about 30 in all. Below is the model held together with pins and double sided tape (it can't be glue but it still needs to be cast) hence why its a bit droopy. It also has a black painted resin lower leg because those are mirrored parts.

Then we have the 4 variants top left to bottom right 4G/4P/4SP and the 4J

And finally we have a 360 of the sway back.

The model is approx 16.5cm tall to central mass.
- Static articulation (glued joints);
  • ankles
  • knees
  • hips 
- Free articulation;
  • waist
  • shoulders
  • upper elbow
  • lower* elbow (if you remove the tab). 
- Swappable parts
  • The AC20 (hot swap)
  • Laser (hot swap)
  • LRM humps (hot swap)
  • Right SRM (hot swap)
  • Left SRM requires the the rear barrel be left off and removal of this section of the torso;

In all it took 4months of machining to design and make the model at quite a hard pace. I have a few cockups along the way including having to machine the front torso twice (particularly painful given its 4day machining time) the laser hump had to be redone restarted because the block was off centre by a few mm. Tiredness lead to 3 broken bits which was frustrating but I've learn not to allow my self to be rushed or work tired.

I feel this is another big step up in terms of finish and design. More telling is I feel satisfaction with the process used to make the model. The Roland MDX-40a performs excellently in its task. I think I will change software, but its a case if doing some research before learning yet another program. I think I will also treat myself to a set of custom Mill ends (bits) to make my life easier all 25mm in reach so I'll only have to calculate depth once while writing out tool paths.

Anyone wishing to ask a question or get in touch about the models I make feel free to drop me an email on;


Oh and hey looks whose 'Wang is popping up all over MWO website and 'Dev Vlogs'