Making moulds to make moulds.

[blind pig]

Had a thought whilst waiting for the Tequila to kick in and I go to sleep.

Has anyone ever thought of making a mould, to make moulds?

Stay with me here.....

If you are a company (Lets say FW) that has a product with a high turn-over rate (say orc trucks) and you're only getting 50 castings before the mould breaks-down and you need to remake the mould, can you make a mould that would actually make the moulds to cast your product?

EG. 1. Ultrasil mould of an orc trukk wheel (might be lucky to get 100 castings)
2. Pinkysil mould made of the mould to make Trukk wheel.
3. Ultrasil mould is cactus after 60-100 castings.
4. Poor Ultrasil into Pinkysil mould (after liberal spray of Rocket Release), six hours later have
mould of wheel again.
5. make wheels in new Ultrasil mould.

The Ultrasil and Pinkysil are two different types of addition cured and condensation cured silicones, and a good coating of Releasing agent should stop them sticking.

I know from experience that Pinky and Ultrasil will not stick together when curing......

Anyhoo ramblings of a tired mad woman over
Night
Bec

Ps. Hello, as this is my first post in the Forum.

[mangozac]

Hey Bec I wondered how long it would take for you to join in

I have had similar (although less thought through) ideas in the past. The problem is that on anything other than my simpler moulds I still have trouble getting perfect casts, so I worry about having the same problem doing silicone mould moulds?

Certainly for simple, high volume parts such as trukk wheels it would work well though. Got any plans to give it a try?

[blind pig]

I've been lurking.

I make a lot of barricades for my 40K scenery, I was thinking of giving one of those a go, as I use them so much and the old moulds have now broken-down.

Being able to just pour some resin into moulds and have complete scenery (minus the painting) in under an hour is very handy.

The mould for a mould would look rather like the final product in Pinkysil (ie. a positive copy of the original), just with sides and a bottom made of Pinky to form the sided, instead of lego or card.

Perhaps companies like FW have their moulds for moulds out of metal?

[mangozac]

You could theoretically pour the mould mould (we need a better name for this) with white metal, although I do wonder about its longevity. Such low melt alloys bend and fracture a bit easily. But if you're going to have a rigid mould mould, why not use resin?

It's funny - every time we discuss production techniques there always reaches a point where we ask "How does FW do it?". If only we had a mole on the inside!

[blind pig]

[slaps forehead]

Yup, making a mould mould out of resin would work too......

As for FW, I was good enough to have a quick tour when I was there three years ago (buying lots of FW stuff and having big tits helps) . They mainly showed me the sculpting and future releases, but I did have a look at their casting section.

It was mainly one piece split moulds. This can be seen on many of their pieces. Sadly, photos of production areas were not allowed.

When I next go back for a FW Open Day (Not this year unfortunately), I'll see if I can get another behind the scenes look and carry a sneaky spy camera,

Bec (Who's now going to do a resin cast of a mould and give it a go)

[mangozac]

I was looking at some moulds today thinking about this. If you think about it with a split mould, a standard resin cast is going to be very similar to the actual mould master. It just doesn't have the outer walls which will hold the silicone being poured in.

With two part moulds I think the resin mould mould would work especially well.

That's cool getting to have a tour of FW. Did you manage to see how they mix the resin? I'm expecting they have connected to tanks of the two resin parts. Measuring out and mixing the two parts by weight in cups takes way too much time!

I have a mixed feeling with the split moulds. I'm thinking I may use them more on the next kit, as I now have a better understanding of how to chop up the model best for casting and especially with split moulds in mind.

Don't forget to share your mould mould results

[blind pig]

The tour of FW was done with a few phonecalls (and quite a few thousand Pounds spent with them)

From what they would show me, they were using mixing cups for the small stuff, and a hand-held mixing unit with two tubes going into a thing which looked like a spray gun.

Pressure pots were in use, as there was a compresor running.

It was humid and raining today, so no casting I will post photos of a barrel mould that I use frequently.

[paulson games]

Provide you have a container that'd reassemble on the same size/dimesions (like legos) you could do resin masters of each half that way all you need to box it back up and pour silicon to make any number of molds off of that master.

The other option is to do a 2 part mold like normal, once side A is properly molded you do side B. Once side B is finished you peel it off but leave the master part and side A alone and make more copies of side B. Once you've molded as many B sides as you'd need you take the part out fit it into side B and repeat the process for side A. That way you don't need to mess around with clay or cutting parts free from a single piece mold.

Depending on the quality and rigidness of the silicon the master part may not seat in back in the silicon. However the platinum cure silicon I've been using from Tap plastics is pretty dang flexible and I've had almost no issues with putting parts back into place even with a lot of intricate fur detail it pairs right back into place without any gaps and I haven't gotten silicon leakage, so it's allowed me to duplicate some of my molds without too much work. Simple shapes are a snap to seat back into place and complex stuff like fur and high details just takes a bit paitience and carefully flexing the mold till it fits right.


If you can get any insider info on what FW does for their process I'd love to know. Even with using a vacuum and pressure system I'm still getting bubbles at times and it's driving me nuts. I'll get a 97% bubble free cast but I still get a large bubble here and there which I just can't seem to eliminate. I'm suspecting that maybe my vacuum isn't vacating the chamber quick enough or maybe my resin working life is too short. Might try a few casts with a smaller amount of catalyst to see if that increases the working life enough to get the bubbles out.

[blind pig]

[mangozac]

[blind pig]

[blind pig]

happened to have a patient today whos' brother worked at a Sydney Rapid Prototyping firm (I'll try and find their website and post it later) and was visiting her.

I got talking to him about their 3D printers (I really want one) and resin casting techniques.

He said that for some polyurethane resin moulds that are casting thin objects , they use upto 15000Psi - yes 15,000 Psi - to force the sesin in and leave no bubbles.

I nearly pooped myself thinking of that!!!!

[mangozac]

It just goes to show the massive difference between hobby and professional/industrial techniques. I imagine they would be making extremely high quality, precise components?

It seems that there are many benefits to keeping your resin cool but unfortunately I don't have a fridge in which I can keep it. Perhaps I'll make a little peltier cooler box to keep the resin bottles that I'm currently using in.

It seems to me that a 3D printer with good enough resolution for our kind of models is extremely expensive. IMO there's nothing worse than that grainy finish of printed parts without enough resolution.

Over the last 6 months I've been collecting parts with which to make a tabletop CNC 3-axis router that can be used for machining model parts. The idea is to use it to create parts of the model and then use those parts the traditional way.

[blind pig]

I've been thinking of getting myself a CNC router to play with; one of the Blackfoot ones below (it can also be fitted with a 200W laser)

There is a CNC Group that meets here in Brisbane once a month, their aim is to put heads together and help each-other build their machines. I'll let you know when the next one is on.

As to the 3D printers, well, you get what you pay for and unless I win the lottery, I will never be able to afford the 100K plus for a good one. My work (PA Hospital) uses the UV laser and liquid resin type, to build models from MRI scans to make replicas of parts of the skeleton that the surgeons are interested in (usually because they have a wopping tumour near a joint). I have coveted that machine, but no amount of beer-slab bribes to play with it have been successful.

http://www.cnczone.com/

http://buildyourcnc.com/default.aspx