Getting my candle mold machined is taking a little longer then I want, or expected. As I mentioned earlier I stopped by at my local CNC shop http://www.edjprecision.com/ to get a quote. For two small 100 mm x 100 mm x 10 mm plates I was looking at around 30 hours at around 75-100$ an hour. Wow I apparently should get into the CNC biz. So let’s take the conservative quote. $2250. So I was thinking of selling let’s say 15 WickBricks for $20 a set. That’s gonna take quite a few, less COGS, before I break even. I am obviously looking for a less expensive approach. I would like to break even a lot sooner. So my next route is to get an online quote. These places tend to work off of .STL files. So I needed something (preferably free) that could create .STL files. When I was working on the WickBrick patent I did my drawings using Googles free version of sketchUp, a very nifty 3D program but I didn’t have the budget for the full version with exporters. (After looking there is a free STL exporter for google sketchup for non commercial user, I tried it and it sort of worked. I didn’t have IE 7 installed so maybe it wasn’t a fair test but here is the site http://www.cadspan.com/tools ) they also had a link here http://www.rapidarch.com/rapidarch-pricing/ which is very cool! But once again very expensive. So first I spent some time with Alibre Express but they don’t offer boolean operations with the express version so I dropped it. So then I spent a lot of time trying to learn Blender it’s a good thing I’m a fairly quick software study. But man Blender is complex, it took a lot of time to get used to the right click selection and its quirks but I actually started to like it. But, I started to run into serious difficulties with boolean operations. I was probably going about my model building all wrong. So then I ran into this page http://www.freebyte.com/cad/cad.htm and I said ah ha there has to be something I can use on that huge list. So from the list I downloaded Free – CoCreate Modeling Personal Edition
This software is cool, but once again I had a steep learning curve. My brain hurt after learning some google SU -> Alibre -> Blender -> CoCreate. Each one having its own quirks. For some reason I wasn’t wrapping my brain around CoCreate. I couldn’t move objects like I wanted. BUT, I did know that the boolean operations actually worked, and it exported .STL files.
So after watching some tutorials and much trial and error I was able to create my negative space candle mold. So now I have been sending out my feelers for price. I emailed www.QuickParts.com for a CNC quote. I’m thinking I want the candle mold made from Aluminum. They emailed me back quickly and said they would get back to me in one day, very nice customer service.
In the meantime I started submitting my .STL files to online places to see what their instant quotes would come out as. https://www.zoomrp.com which creates a prototype in HRP (High Resolution PolyJet) White plastic. Their specs for the HRP are
The product will be produced from a high resolution process with a print resolution of 600 DPI (42 microns; 0.0017”) in the X/Y axis and a layer thickness of 847 DPI (30 microns; 0.0012”). Features include:
- Excellent impact strength.
- High flexural modulus.
- Proven to withstand functional testing at 212ºF without breakdown.
- Elongation to break is up to 25%, making it an excellent material for snap fit applications.
- Rigid and suitable for functional model
So for my two parts (Ship tommorow lowers it by almost 100$) it comes out to $436. My parts are 150 x 100 x 10 mm with 10 fairly complex cavities.
Next up I went to try out QuickParts rapid quote system. I think I am comparing a similar material. They offer a polyjet and quite a few varieties. High Res Rigid Translucent, Rigid VeroWhite, Elastomer TangoGray, Rigid VeroBlack, Rigid VeroBlue, Elastomer TangoBlack, TangoPlus. It looks like the Hi Res Rigid VeroWhite, VeroBlack, and VeroBlue have the Highest Heat Deflection Temp of 113-120°F. Hmm that makes me wonder if this is a good material for a candle mold. A rough Internet search show a wax melting point of around 148°F. What is interesting is that ZoomRP says their HRP is proven to withstand functional testing at 212ºF without breakdown.
But WOW, way to go QuickParts. My two parts come out to $180! Might be worth the risk of melting the molds for that price 🙂
Let me say I am really impressed with the QuickParts site. When doing an SLA quote you are able to specify your lead time. Same two parts created with SLA with the economy lead (two weeks out) comes to $281.
So my head is going round and round with the different types of materials that are available. Just for grins I will probably get a PolyJet form made just to experiment.
Ok, in my continuing quest for a cheaper deal I decided to check out www.redeyeondemand.com Their site is possibly the best so far. With a cool activeX control that lets you look at your uploaded .STL files. That is just cool for coolness sake. So how does the price compare?
RedeyeOnDemand comes out at $180, if I do it in VeroBlue PolyJet I can get a free overnight build which is cool! Wow I’m amazed that their pricing engines are that close to each other.
My next victim www.dpt-fast.com They also use a STL activeX control, which crashed my browser 😦 I don’t know if it was their fault though could just be IE. BTW using IE appears to be recommended when doing business with any of these online quick prototypers. Ok, well it has crashed on me twice now. Ok, well goodbye dpt-fast.com third time you crash my computer (a different system just to be sure) and we are through.
Hmm so as far as I can tell it appears that QuickParts and RedeyeOnDemand are about the same. Redeye is a little bit slicker, and offers a free overnight build so I am going to give them a try.