eldrick

I'm trying to cool the PTFE barrel better, not the heatsink. Note that I left a slot at the bottom of the alum deflector, to allow some useful air to flow over the lower heatsink. The air that is deflected toward the barrel wasn't cooling the heatsink anyway - it was moving on past it one cm above it, and providing no cooling to the heatsink whatsoever. Since there is no dual extrusion, and won't ever be, with this head design, there is no reason to waste the cooling that can extend the life of the isolator indefinitely.

http://www.2engineers.com/shop/ceramic-hotend-chess-for-1-75mm-fillament/ Note: it needs a PTFE liner for PLA, as Daid points out. Also, "When using the hotend with PLA please use a small fan for cooling the barrel." Bottom line on the tweak: can't hurt, costs nothing but a few minutes, apparently extends the life of the plastic collar indefinitely - mine now has over 2000 hours on it without replacement.

It still cools the heatsink, just not as much on the cooler part of the heatsink at the right. That's why I left a gap at the top and bottom of the deflector. Cooling the parts near where the heat is generated is more effective than cooling the heatsink an inch away. If this was an issue, dual extruders would be problematical. The tweak just uses some of the airflow that could otherwise cool a second extruder. The deflector is about 1mm thick, and is held in place by the two screws that attach the top and bottom plates to the slotted vertical plate. The tips of the screws intrude into the second slot, and wedge/clamp the deflector plate in place quite firmly.

I've seen exactly what Robert describes, and thought at the time that it was a bug. It is, AFAIC, and one that negatively affects print quality.

Oops - actually I'm using Simon's code with patches, but the net is the same. On my machine with the patched 14.06etc., it doesn't actually start extruding until several inches of skirt have been traced, whether it is after an Abort or successful completion. The manual prime method Always works, so I'll continue to do it...

I agree. I'm using 14.06RC6 on Mac. I've finally become used to manually priming before every print, whether the previous one was aborted or completed: I extrude until filament comes out (usually around 20mm) and then retract 8mm or so. That seems to produce a decent start on the skirt without creating a blob. The standard retraction after and extrusion before a print simply cannot be trusted to start a print cleanly. Still.

I've now got evidence that too-high PLA temperatures cause clogs. When extrusion slowed down on my UM2, I had been printing a part with White DiamondAge PLA at 220C (while the nozzle had a buildup of brown crud in it). After removing and cleaning the nozzle thoroughly, I resumed printing, but dropped the temperature to 215C. It printed fine, but I started checking the nozzle by the heat/cool/pull method after each print. Sure enough, after each 8-hour print, I found brown crud on the filament after pulling it out, so I started dropping the temperature back toward what I had always used in my TrinityLabs printer. At 210C, brown junk in the nozzle again, and the same at 208C. So I dropped back to 201C which is what I had always used with this filament, and I'm now getting a completely clean end when I heat/cool/pull the filament after each print. No problems at all with extrusion at this 201C, as it is above the melt temperature of this filament. DiamondAge PLA is known to print a bit cooler than others - I've used it down as low as 185C with no issues, but I conclude that as expected, overheating PLA carmelizes it, and causes clogging over time, to the point where high-friction in the nozzle causes high pressure, slow extrusion, and increasingly poor performance as it deposits more and more brown hard stuff in the nozzle. If you have a known-clean nozzle, I'd strongly suggest paying attention to the manufacturers recommendations on temperatures. PLA is known to cook and harden, causing clogs. If you have to go more than a couple degrees above the recommendation, you've probably already got the problem, and are making it worse as you jack up the temps to compensate.

Print a plastic fan shroud to replace the OEM metal one - it resonates and amplifies the fan noise.

If you put the spool on the floor, be sure to arrange for something to remove dust and specks of plastic from the filament before it enters the extruder, to prevent nozzle clogs - floors are where the dirt goes...

I'm not sure if there is any clearance at the back of the moving head when in Home position, but it occurs to me that a partial fan duct for the 25mm fan could perhaps draw more air from above, rather than sucking in air from directly above the heated bed and hot-end. Anyone?

Since the above note, I rec'd a note from the Managing Director at DiamondAge: "We have, in fact, decided to withdraw from the US retailer market. Dealing with US companies has not proved profitable or reliable." "Others are welcome to resell, but there will be no more specific distributorship deals." Their filament is best-available as far as I am concerned, but shipping direct from N.Z. makes it prohibitively costly. On the U.S. west coast, ProtoParadigm is the best pick.

I suspect that JohnA has it right. I have also had to raise the temps to print material on UM2 that printed at lower indicated temps on another RepRap printer.

Google "3d printing pla temperature" and tell me what you see. Almost every manufacturer recommends printing at 180-210C, and my results back that up.

Since my previous post, I've rec'd correspondence from a Director of DiamondAge, that "We have, in fact, decided to withdraw from the US retailer market. Dealing with US companies has not proved profitable or reliable." "US Companies" being printbl.com...

Funny - that's not what any manufacturer recommends for their PLA. Have a look at the ProtoParadigm page. I've run DiamondAge at 190 or so, Protoparadigm at 205C, and BTW, note that Ultimaker recommends 203C for their PLA, as set in the Robot test print. Ultimachine states: "This is Natureworks PLA4042D extruded into 3mm filament. Samples have been tested by various RepRap members and it is a wonderful build material. It prints at temperatures around 170C and has minimal warp when cooling." YMMV, but I'd suspect a bad temp. sensor or high-friction nozzle if you have to print PLA at 230C. I personally find that running DiamondAge PLA over 210C leaves brown crap in the nozzle (revealed by the nuclear method) every time, after a few hours of printing. BTW, the "testing I did" link seems to be busted.

I strongly suspect that half the extrusion problems reported are simply due to people using much too high a temperature with PLA. PLA is intended to print at 180-205C, and if you go much higher, you will carmelize/carbonize the stuff and leave high-friction brown crud (think burnt sugar) all over the inside of the nozzle. Even 215C can cook PLA when the printer temperature overshoots higher while heating. This brown stuff is Very difficult to get out without removing the nozzle for a thorough cleaning. Even the Nuclear cleaning option rarely gets it all out. Here is an excellent reference to material selection and printing techniques: http://www.protoparadigm.com/blog/2012/06/3d-printer-filament-buyers-guide/

(Duplicate post) While I like the DiamondAge PLA, which is monochiral and very hard, I've recently had serious problems due to dirt on the filament in the sealed bags in which I received me coils of white from the US distributor (printbl.com). I've had a series of clogs on my UM2 that are definitely caused by the black specks visible on the white filament inside the sealed bags. (It's not from the extruder - I'm using Robert's, printed in white.) Further, their US distributor, printbl.com, is offal (sic). They sell PLA only, and typically, currently have only five colors in stock of the 19 listed. They offer white and ivory only in coils, although DiamondAge manufactures several sizes of spool (and also offers ABS). To top it off, the printbl.com web site hasn't changed a word in almost two years, and the site has been off the air frequently. It is difficult to tell whether they are really still in business. Bottom line is that unless and until DiamondAge finds a new U.S. distributor, I cannot recommend the DiamondAge filament, unless you want to pay double to cover International shipping direct from New Zealand. As supplier of both ABS and PLA, I can enthusiastically recommend Protoparadigm.com. Good service, good prices, and I've never had an issue with their filament. Ultimachine.com also offers good filament in ABS and PLA, and good service, and has truly White PLA, which Protoparadigm doesn't sell for some reason. printbl is off my list for good.

(Duplicate post) While I like the DiamondAge PLA, which is monochiral and very hard, I've recently had serious problems due to dirt on the filament in the sealed bags in which I received me coils of white from the US distributor (printbl.com). I've had a series of clogs on my UM2 that are definitely caused by the black specks visible on the white filament inside the sealed bags. (It's not from the extruder - I'm using Robert's, printed in white.) Further, their US distributor, printbl.com, is offal (sic). They sell PLA only, and typically, currently have only five colors in stock of the 19 listed. They offer white and ivory only in coils, although DiamondAge manufactures several sizes of spool (and also offers ABS). To top it off, the printbl.com web site hasn't changed a word in almost two years, and the site has been off the air frequently. It is difficult to tell whether they are really still in business. Bottom line is that unless and until DiamondAge finds a new U.S. distributor, I cannot recommend the DiamondAge filament, unless you want to pay double to cover International shipping direct from New Zealand. As supplier of both ABS and PLA, I can enthusiastically recommend Protoparadigm.com. Good service, good prices, and I've never had an issue with their filament. Ultimachine.com also offers good filament in ABS and PLA, and good service, and has truly White PLA, which Protoparadigm doesn't sell for some reason. printbl is off my list for good.

(Duplicate post) While I like the DiamondAge PLA, which is monochiral and very hard, I've recently had serious problems due to dirt on the filament in the sealed bags in which I received me coils of white from the US distributor (printbl.com). I've had a series of clogs on my UM2 that are definitely caused by the black specks visible on the white filament inside the sealed bags. (It's not from the extruder - I'm using Robert's, printed in white.) Further, their US distributor, printbl.com, is offal (sic). They sell PLA only, and typically, currently have only five colors in stock of the 19 listed. They offer white and ivory only in coils, although DiamondAge offers several sizes of spool in White/Ivory (and also offers ABS). To top it off, the printbl.com web site hasn't changed a word in almost two years, and the site has been off the air frequently. It is difficult to tell whether they are really still in business. Bottom line is that unless and until DiamondAge finds a new U.S. distributor, I cannot recommend the DiamondAge filament, unless you want to pay double to cover International shipping direct from New Zealand. As supplier of both ABS and PLA, I can enthusiastically recommend Protoparadigm.com. Good service, good prices, and I've never had an issue with their filament. I've also had good experience with ABS from Ultimachine.com - haven't tried their PLA yet. printbl is off my list for good.

While I like the DiamondAge PLA, which is monochiral and very hard, I've recently had serious problems due to dirt on the filament in the sealed bags in which I received me coils of white from the US distributor (printbl.com). I've had a series of clogs on my UM2 that are definitely caused by the black specks visible on the white filament inside the sealed bags. (It's not from the extruder - I'm using Robert's, printed in white.) Further, their US distributor, printbl.com, is offal (sic). They sell PLA only, and typically, currently have only five colors in stock of the 19 listed. They offer white and ivory only in coils, although DiamondAge manufactures several sizes of spool (and also offers ABS). To top it off, the printbl.com web site hasn't changed a word in almost two years, and the site has been off the air frequently. It is difficult to tell whether they are actually still in business. Bottom line is that unless and until DiamondAge finds a new U.S. distributor, I cannot recommend the DiamondAge filament, unless you want to pay double to cover International shipping direct from New Zealand. As a supplier of both ABS and PLA, I can enthusiastically recommend Protoparadigm.com. Good service, good prices, and I've never had an issue with their filament. I've also had good experience with ABS from Ultimaker.com - haven't tried thjeir PLA yet. printbl is off my list.

Have you raised the temp. or changed the fan speed?

My experiment: http://umforum.ultimaker.com/index.php?/topic/6084-um2-bowden-block-cooling-improvement/

Sorry, but Youmagine is still slow as worms.

I can't think of any reasonably easy way to measure the net effect. I have an IR pyrometer, but the teflon block is small and well-hidden behind the fan shroud. However, if UM chose to put a fan there, it's probably necessary for cooling the cold side of the hotend, and more airflow on the block is going to be better than less. How much better, I have no idea.

Or try this to improve airflow to the Bowden block: http://umforum.ultimaker.com/index.php?/topic/6084-um2-bowden-block-cooling-improvement/