RC Model Reviews

Hi everyone,

I am quite new to RC but I am interested in the possibility of this. By trade I am a 3D CAD Designer rather than a machinist so I look for ways to automate tasks I know nothing about. One of the things I would like to build is a 3 axis CNC router. This router could most likely (I am not sure of why not) be used to create moulds out of wood.

From my really brief research I found that EPP (Expanded Polypropylene) is simple to mould (relative to what, I don't know ). Does anyone know if it is simple to use and mould and if it is both available to private users and affordable?

Thanks,

Kamu

I have not tried any computer based cutting systems, but YouTube has many videos of these machines cutting various types of foam.
Please see http://www.youtube.com/watch?v=vUo2muEUGJI&NR=1 for an example.
Thanks,
Bryan

pushinoldrc wrote:I have not tried any computer based cutting systems, but YouTube has many videos of these machines cutting various types of foam.
Please see http://www.youtube.com/watch?v=vUo2muEUGJI&NR=1 for an example.
Thanks,
Bryan

That seems to be a CNC router. What I had in mind was a bit different.. which involves mixing the foam chemicals together and putting them into a mould (which would be created from what that video shows). I was wondering if Bruce/RCModelReviews had any knowledge on this.

Apparently not, no matter. I have fired off an email to ARPRO and we'll see what they say, as well as in regards to price.

If I read this correctly you can make a mould then fill it with an expanding foam to any shape you desire. So the cost of making a foamie plane could be a lot lower than through a retailer perhaps? You could sell as a kit and offer replacement pieces .

jeffie8696 wrote:If I read this correctly you can make a mould then fill it with an expanding foam to any shape you desire. So the cost of making a foamie plane could be a lot lower than through a retailer perhaps? You could sell as a kit and offer replacement pieces .

Exactly right. The problem is I have no experience with moulding anything, let alone an advanced type of foam.

I did a bit more research and a search on RCGroups, every post either has no answer or scares them away by saying they need machinery that costs quarter of a million. This is true.... IF we were thinking of mass production. This is NOT mass production, our mould contains one piece! By trade I work in plant design and when you think of a alumina refinery as a whole it looks like a huge big complicated mystery. If you break down each stage of the process it is very simple and can be replicated small scale in a laboratory with simple equipment. If all those really expensive machines do is heat up and inject into the mould then a DIY rig could be made up to do a single cavity mould, in my opinion.

To not be limited by the prices of simple foam blocks (that you cut a lot of it away!) and the shapes you can only achieve by hot wire cutting you could easily clone your Easy Star or make experimental modifications to the shape of it, or create a whole new plane design that would look like it came from a manufacturer (in theory, maybe I am dreaming)!

"So the cost of making a foamie plane could be a lot lower than through a retailer perhaps?" Well... take into account economies of scale. Making 100 Foamies in one go is going to be far cheaper than 100 in a singular homebuilt rig. It would, how ever, be crazy cheap for small quantity runs (5 or so).

"You could sell as a kit and offer replacement pieces" <-- I think you have discovered my dream (at this current point in time).

Big surprise, the company ARPRO never bothered to get back to me.

I am following this thread intently as I would like to know more as well.

Hi Kamu

Any news on this?
I think we're quite a few following this thread.
Personally i have considered beginning contacting some Chinese manufacturers but i haven't gotten around to it.

Anyone else have any experience with this sort of thing?

Cheers
/Stig

sap1975 wrote:Hi Kamu

Any news on this?
I think we're quite a few following this thread.
Personally i have considered beginning contacting some Chinese manufacturers but i haven't gotten around to it.

Anyone else have any experience with this sort of thing?

Cheers
/Stig

Hiya sap,

No news unfortunately. I have no CNC rig to make moulds. At the moment I am occupied with learning to fly my damn EasyStar (after a horrific crash ).
Basically what needs to be done:

1. Finding supplier of EPP chemicals and pellets, find out the cost effectiveness of this
2. Finding out and understanding the process required to mould, find out if it is possible to do as a home rig
3. Build CNC machine to cut out mould
4. Design and build the apparatus for the mould
5. Mould some parts.

Please let us know how the correspondence with the Chinese manufacturers go if you do so. I fear they will charge a high tooling cost (the construction of the mould).

Kamu