There are several teams in the reprap and makerbot communities working on granule extruders... There are a few more challenges than you would expect. (and as you pointed out, they are fairly big and heavy (compared to the current filament extruder designs), meaning the print head may need to be stationary). <div>
<br></div><div>Many of the current projects focus on extruding granules into usable 3mm filament, that way the existing 3d printer designs can make use of it, and you have a simple standalone extruder for processing granules into usable filament as you need it. (would also let you mix dye into your filament for custom plastic colors and so on in small batches).</div>
<div><br></div><div>Another added benefit of a granule extruder is that you could then throw your botched/sample/test parts and purge extrusions, and any other "waste" plastic into a blender, chop it up into small granules, and recycle it back into usable filament again. Which would be very useful indeed.</div>
<div><br></div><div>Several of the current designs use a large (3/4" or larger) auger drill bit, (normally quite long like 12") and a matching pipe of appropriate diameter (to fit snugly around the bit). This design creates a plastic pump which can accept granules, and they melt in the heated pipe until they are able to be extruded out the other end.</div>
<div><br></div><div>Currently many of the existing challenges are around isolating the heat to one end of the pipe. It tends to work it's way back during operation (the bit is metal and so conducts heat well) causing the granule feed to eventually clog, because granules get sticky and plug up the works...</div>
<div><br></div><div>Another problem is stop/start... Once you stop the unit, the plastic hardens, sealing the whole thing shut quite nicely... Requiring a fair bit of heat to re-melt it and allow the auger to start turning again...</div>
<div><br></div><div>Definitely not insurmountable problems, obviously it's done in industry, but I think the challenge is doing it fairly small, cheap, and usable for the hobbiest...</div><div><br></div><div>I have WAY too many projects on the go at the moment, but very soon on the list is getting a granule extruder working (to this end I've been saving all my scrap plastic since I started with my Mendel, and I currently have about 2lb of scrap, ready for recycling). </div>
<div><br></div><div>Anyway, if anyone decides to endeavor down this route, I would definitely be interested.</div><div><br></div><div>- Paul<br><br><div class="gmail_quote">On Sat, Feb 5, 2011 at 7:58 AM, Darcy Whyte <span dir="ltr"><<a href="mailto:darcy@siteware.com">darcy@siteware.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><br clear="all">If plastic comes in granules, then why not make an extruder that accepts granules?<div><br></div><div>
Perhaps some sort of a bin and a heater. Especially if you had a moving platform rather than a gantry.</div>
<div><br></div><div>I'm planning on making adhoc stuff rather than production with my extruder (when it arrives). So I'll probably live with whatever suppliers the community is using for makerbots and stuff.</div>
<div><br></div><div>But on another project I am planning on manufacturing some propellers. I haven't figured out how to do that yet but I might need to figure out where to buy bulk plastic for that. </div><div><div></div>
<div class="h5"><div><br></div>
<div><br></div><div>
<br><br><div class="gmail_quote">On Fri, Feb 4, 2011 at 1:19 PM, Paul (Maker Engineering) <span dir="ltr"><<a href="mailto:paul@makerengineering.com" target="_blank">paul@makerengineering.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Makergear is in the USA, as are all the other 3DP suppliers I've been able to find.<div><br></div><div>I order mine from Ultimachine (I use PLA) and pay a fair bit of shipping to get it here.</div><div><br></div><div>
One of the problems with PLA is that there is only one manufacturer in all of north america that I know of producing it, which is NatureWorks. In addition there is another in the Netherlands. So if you order straight from them in very large quantities it gets fairly cheap.</div>
<div><br></div><div>ABS is easier to source because there are manufacturers all over the place.</div><div><br></div><div>NatureWorks doesn't normally sell it in 3mm filament either, but they do sell it in granules (as most suppliers sell). But most manufacturers will sell filament as well for an additional cost (basically because they have to take the granules and extrude them into filament for you). This is why granules are cheaper, and why so many are working on building granule extruders to be able to extrude our own filament.</div>
<div><br></div><div>Many suppliers and distributers also have the ability to extrude 3mm filament because it can be used in plastic welding. But is normally cut into short lengths, so with a special request you can likely get spools of continuous 3mm filament in Ontario (specifically in the GTA) quite easily... I believe several of the <a href="http://hacklab.to" target="_blank">hacklab.to</a> guys were mentioning they had a supplier in the toronto area that was able to provide them with very large quantities of 3mm abs filament for a reasonable price.</div>
<div><br></div><div>Hope that helps!</div><div><br></div><div>- Paul</div><div><br><div class="gmail_quote"><div><div></div><div>On Fri, Feb 4, 2011 at 12:14 PM, Darcy Whyte <span dir="ltr"><<a href="mailto:darcy@siteware.com" target="_blank">darcy@siteware.com</a>></span> wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div></div><div><span style="font-family:arial, sans-serif;font-size:13px;border-collapse:collapse"><div>
<span style="font-family:arial, sans-serif;font-size:13px;border-collapse:collapse">I ordered a small amount to get started at: </span></div>
<div><span style="font-family:arial, sans-serif;font-size:13px;border-collapse:collapse"><a href="http://www.makergear.com/" target="_blank">http://www.makergear.com/</a></span></div><div><br></div><div>Not sure where they are from their web site.</div>
<div><br></div><div><br></div><div><br></div><div><br></div>Date: Thu, 3 Feb 2011 20:11:32 +0000<br>From: <a href="mailto:emteeoh@gmail.com" style="color:rgb(28, 81, 168)" target="_blank">emteeoh@gmail.com</a><br>Subject: [Lab] Plastic for makerbots<br>
To: <a href="mailto:lab@artengine.ca" style="color:rgb(28, 81, 168)" target="_blank">lab@artengine.ca</a><br>Message-ID:<br> <872190262-1296763893-cardhu_decombobulator_blackberry.rim.net-2144851823-@bda256.bisx.prod.on.blackberry><br>
<br>Content-Type: text/plain<br><br>Hi!<br>I've got a quick question: I'm wondering if you can tell me where you're buying plastic for your makerbot? I'm assuming there has got to be a better way to get it than importing it from new york, but none of the plastics suppliers I can find in toronto seem to sell 3mm filament.<br>
<br>Thanks!<br>Sent on the TELUS Mobility network with BlackBerry</span>
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