BTW, what is to stop us from creating light envelopes of CAPA filled with support material? We might well be able to reduce the mass of CAPA in some printed artifacts even more that way. :-)
sorry about that... :-0
That would certainly be easy to do. It wouldn't save time, but it might save money. The other scheme is to build a solid CAPA shell for the outer few mm of the object, then infill the bigger volumes with honeycomb.
***The other scheme is to build a solid CAPA shell for the outer few mm of the object, then infill the bigger volumes with honeycomb.***
That's rather what I had in mind, except that you wouldn't bother trying to wash out the support material.
Just got a call from Image Plastics. They're running an extra shift this Saturday and hope to be able to process our CAPA then and ship it to me on Monday.
Here is what I am going to propose. I think that Vik for sure and Adrian probably have operational MkII's on some sort of positioning stages. I'm going to air mail them several metres each so that they can run it through their Mk II's and see if we have any problems using Image Plastic's filament.
If they don't I suggest that we make arrangements as Sebastien said to immediately buy another sack or two of CAPA and have it/them processed. The reason for this is that Solvay is quoting a 6 weeks delivery delay due to the overload on their capacity, so if we wait around until we actually need it we could find ourselves with a problem in having our repraps experiencing a lot of down time for lack of feed stock filament.
I still plan to divide up what I've had processed for the people who are ready to make use of it and save several metres each of those who are not so ready to test out their Mk II's when they get them built. Don't worry about that part. I think Vik especially is going to advance the project the most if he has an adequate supply of filament at this point.
While Adrian has generously offered to pay for a sack of CAPA and processing, I think that for substantial amounts we're going to need to be paying our own way pretty soon. Perhaps for those with smaller pocketbooks we can club to where individuals can buy as little as a kilogram or two out of a sack.
Does that work for everybody?
We got filament.
I just got a call from Leslie at Image Plastics. They processed the CAPA on Saturday and will ship it in the morning. The yield was 6.5 lbs of 3 mm filament. I don't quite know whether Sebastien just eyeballed the amount that he sent or whether we're going to lose maybe 5 lbs to waste when we run CAPA through a filament maker. I'm guessing that second option is what's happening if they're using a big extruder machine. It also may have been that they had to do several startups before they understood which settings they should be using. CAPA isn't your run-of-the-mill resin, after all.
In any case, we got about 350 metres of filament. The plant manager said that CAPA was "gooey" as he put it, but that it ran fine and was easy to process.
I'll say more as soon as I have it in hand.
Got one part wrong, they shipped it ground this morning. It should be here either late Friday or early Monday. :-)
I had a brief chat with Jim and put the speculation about missing CAPA to rest very quickly. Here are the results.
Sebastian's scales are fine.
He lost a few ounces figuring out the extruder settings for 3 mm CAPA. Those are all written down so no more losses of that sort need be expected.
Startup, stabilisation and shutdown of the extruder rig will lose you about 4-5 lbs regardless of the size lot you have processed.
He likes CAPA. He said that aside from the melt being a bit gooey (sticky... we've noticed that as well) it processes cleanly and efficiently in his extrusion rig.
What all this means is that if we have a 20 kg bag processed we can expect to lose roughly 10% of the weight of the CAPA to system startup, stabilisation and shutdown losses.
The filament arrived! It looks beautiful! This batch came out 2.8 +/- 0.009 mm. Vik tells me that the Mk II will eat 2.7 - 3.0 mm with no problem.
I blogged a pic of the filament on the developers' blog.
It looks like we can concentrate on the RepRap machines and forget about making a filament extruder for a little while. :-)
That does look very good. Sorry I have been a bit quiet - a combination of the start of term and preparing for my US trip. Forrest - let me know the costs of all this (including the distribution) and I'll sort out the money from PayPal when I get back.
Adrian - when I have all the numbers for shipping and such not I'll certainly pass them over to you. Shipping is going to be the biggest part of the whole thing. Making the filament was only about US$40 and getting it here.
I had an interesting discussion with Jim Waring this morning. He deliberately made the filament 2.8 after we specified 3.0 because of his experience with plastic welders, which, he said, specify a nominal diameter for the welding filament which is the maximum that the welder will handle rather than the average. He always backs off a bit on the diameter so that the filament won't jam the welding gun.
I've noticed that CAPA goes a little pink if you run it a little hot in the extruder. Jim now has a note to see if he can run it slightly cooler so that we don't get that pink effect.
BTW, Jim said that he can deliver filament including CAPA in something like 50 standard colours and can match colour chips sent to him as well for a rather low, one-time set-up charge.
Vik expressed an interest in getting some filament made from PLA. Jim said that he was happy to do that but to remember that the sample has to be big enough to overcome for the 4-5 lb loss that running it through his extruder causes.
He is also happy to supply us filament in more common polymers like HDPE and polypropylene at a fraction of the cost that we are paying for CAPA.