Anders,
What thickness did you make your washers? I made mine 3mm thick and added dimples for airspace.
I have not installed the vespel yet, I am waiting for a 24 hour print to finish. No matter how much I stare at it, it doesn't seem to go any faster.
My Vespel washer is about 1mm thick i think.
Here is how it looked a few days ago:
The black stuff is burnt residues from extruded plastic, not the washer being burnt.
The teflon insulator is a glass filled one and was brand new when I started counting hours.
I am not sure exactly what grade of plastic the washer it is, but I think it is Vespel SP1 (it was made from a scrap piece found in the workshop).
The washers that might be available soon are probably going to be made from another grade with even better specifications than the SP1.
so.. my feedback after a while..
i have been running around 500 hours with a vespel washer. i had to widen the washer to 3.2mm but it worked. kinda.
although i was very enthousiastic in the beginning, it kept collecting "muck". it seems the vespel was more sticky than i expected. i also had some issues with printing PLA after printing XT.
although I understand the concept, my focus will be more around the replacing of the PTFE coupler than into combining with a washer.
Interesting, I suspected that would be an issue and that is why I went for a washer as thin as possible.
I just want it thick enough for the temperature to decrease enough to save the spacer, any thicker than that will most likely just cause problems with PLA. (The washer always has to be warm enough to really melt the PLA, not just make it rubbery)
If i remember correctly I made the hole in my washer 3.3 mm for it not to interfere with the filament.
It appears to work fine with ABS, which was my main concern since the printing temperatures for ABS is what kills my spacers. I am testing PLA right now, but I don't have enough hours yet to get to any conclusion.
So far it works just fine though with PLA, but it needs further testing.
Interesting, I suspected that would be an issue and that is why I went for a washer as thin as possible.
I just want it thick enough for the temperature to decrease enough to save the spacer, any thicker than that will most likely just cause problems with PLA. (The washer always has to be warm enough to really melt the PLA, not just make it rubbery)
If i remember correctly I made the hole in my washer 3.3 mm for it not to interfere with the filament.
It appears to work fine with ABS, which was my main concern since the printing temperatures for ABS is what kills my spacers. I am testing PLA right now, but I don't have enough hours yet to get to any conclusion.
So far it works just fine though with PLA, but it needs further testing.
yeah it worked for like 200 or 300 hours perfectly. at that point it went downhill.. XT would still work, ABS would still work, but after an hour of printing PLA would simply fail.. i believe the Teflon ring would become too hot and then started "scraping".
in my opinion, the ring would have the be the exact same inner diameter as the PTFE coupler and the hot end. if it is smaller or wider, the filament will scrape a very tiny bit during retraction. after a couple of retractions it would start to slowly burn.. if you look at my pictures, you can see that i had to clear out a lot of black muck.. i believe that is burned \ scraped filament, causing my issues to increase evermore..
So if you guys can are willing to quit whinging about this issue long enough to take actually 15 minutes and FIX it, have a look at this thread: http://umforum.ultimaker.com/index.php?/topic/6084-um2-bowden-block-cooling-improvement/]
I disassembled the whole print head of my UM2 today after 2000 hours of printing mostly ABS, and found Zero deformation and No discoloration of the PTFE spacer. All it needs is some additional cooling from the rear fan, which will cost you nothing to improve, and adds zero risk.
It works, and no need to putz around with exotic materials or multiple replacements of the OEM piece.
This "problem" is a completely dead issue, as far as I am concerned.
Just quit your bitching and fix your machines. Please.
So if you guys can are willing to quit whinging about this issue long enough to take actually 15 minutes and FIX it, have a look at this thread: http://umforum.ultimaker.com/index.php?/topic/6084-um2-bowden-block-cooling-improvement/]
I disassembled the whole print head of my UM2 today after 2000 hours of printing mostly ABS, and found Zero deformation and No discoloration of the PTFE spacer. All it needs is some additional cooling from the rear fan, which will cost you nothing to improve, and adds zero risk.
It works, and no need to putz around with exotic materials or multiple replacements of the OEM piece.
This "problem" is a completely dead issue, as far as I am concerned.
Just quit your bitching and fix your machines. Please.
I don't think anyone is "bitching" just discussing other materials besides PTFE which (imho) is pretty interesting. Glad you found a fix which works for you though ;-)
I have mostly printed ABS and never had any problem whatsoever with the teflon spacer, even though it has been badly fried a few times.
On the other hand, it seems to work fine with a metal spacer and ABS too.
My impression is that the cause of the deformation is a combination of temperature and printing PLA, which apparently causes way more friction inside the spacer. (Just compare feeding PLA and ABS by hand, retracting and feeding again)
I am curious about korneel's results, did the shorter teflon spacer also suffer from deformations, even though not running so hot thanks to the vespel washer?
I would also like to know more about glloq's Duratron spacer. Besides the cost and the machining properties, that material appears to have potential to be a final solution.
For my part, I rarely print PLA, but I don't want to invent something that does not work with PLA, since the teflon more or less do work for most things I do.
My main goal is to find something that reduces the temperature of the spacer closest to the heater block because:
1. I think it looks ugly when it is fried, and it might affect PLA printing, even thought ABS seems to not care about fried spacers.
2. I want to be able to print at temperatures up to 300 C, and then to go back to PLA, without having to rebuild the printer each time.
I have a hard time believing that EldRick's spacer would have no signs of being burnt at all after 2000 hours at 260 C with that little extra cooling.
The reason is that teflon has way much lower thermal conductivity than brass, so the temperature closest to the heater block should be more or less the same with or without the extra cooling. (Or did you print at temperatures considerably lower than 260 C?
Here is how a glass filled spacer looks after a few hundred hours of ABS at 255-260C in my printer:
I am not surprised at all that it kept working for 2000 hours with ABS though. As I said, my machine never had any feeding issues or needed any replacement parts as long as printed ABS only.
So if you guys can are willing to quit whinging about this issue long enough to take actually 15 minutes and FIX it, have a look at this thread: http://umforum.ultimaker.com/index.php?/topic/6084-um2-bowden-block-cooling-improvement/]
I disassembled the whole print head of my UM2 today after 2000 hours of printing mostly ABS, and found Zero deformation and No discoloration of the PTFE spacer. All it needs is some additional cooling from the rear fan, which will cost you nothing to improve, and adds zero risk.
It works, and no need to putz around with exotic materials or multiple replacements of the OEM piece.
This "problem" is a completely dead issue, as far as I am concerned.
Just quit your bitching and fix your machines. Please.
honestly, not a very constructive post.
this thread is not about bitching, is about trying to find a solution. the "solution " you have posted is nothing different from what other people have posted here but takes a different approach.
I've also experimented with additional cooling or redirected cooling glows, I've tested the vespel washer as you can see above, and other solutions. I'm pretty sure Ultimaker themselves have done these tests as well as you can see in this thread. I don't think your solution actually fixes anything.
providing additional cooling to the coupler is great, but will not cool the area that is actually under stress here. it's the area directly touching the copper hot-end. this will at the bare minimum show discoloration and could be under sufficient stress to start disforming. no additional cooling will prevent the discoloration, especially if you are not cooling in that specific area.
the additional cooling could and will also induce additional stress and temperature shifts in the filament during heavy retractions. lastly, ABS and XT like materials are not very affected by the deformation. it's really PLA or other low temp filaments that are much less slippery than ABS and XT like materials that will be affected. my vespel washer worked perfectly until i had to print a very precise PLA print with heavy retraction (3DHubs fairphone case) and i just could not get this done without stringing and misformed prints. this was very strange, because on non-heavy retraction prints this did not show at all, neither did this show on precise mechanical parts in ABS and XT.
so i'm absolutely not disputing that in your case, with your materials, your printer, and the prints you make, the additional cooling has helped you. good for you.
ik could say that I do doubt the 2000 hours claim which is 90 days of non-stop printing, assuming you could change the print in under 10 minutes and doing multiple 6 hours prints a day. i have now had my printer for half a year and am almost touching the 4000 hours mark. in my mind, i;'ve printed over 20K hours but reality is that it's only 4000. sometimes it feels like ages when waiting for a print to complete 
I could also say that i never saw any picture of an unburned coupler after 2000 hours but then again, it wouldn't be much proof. honestly, i don't need any proof since i don't dispute that your solution might work perfectly for you. just like multiple solutions as posted here work for multiple people.
i am stating that the solution you posted, when looking at a mechanical point of view, would not be a universal solution. the problem is not in cooling, the problem is the combination of pressure, temperature and the convergence of a very hot piece of copper touching a piece of material that can't handle that very well. when you look at solving this with cooling, you could solve it by cooling the hot-end. one little issue, you would not be able to print anymore.
personally, i do appreciate everyones input here. everyone is trying, posting solutions that worked for them and trying to help improve the machine. posting that everyone should "just quit bitching and fix it" using the solution you posted (which will not longer be applicable once you use dual extrusion) is not very helpful or respectful to the work and thoughts people are sharing and does not contribute to a sharing environment.
posting your thougsh and reasoning behind why you've done this and how you have actually tested it is..
I have mostly printed ABS and never had any problem whatsoever with the teflon spacer, even though it has been badly fried a few times.
On the other hand, it seems to work fine with a metal spacer and ABS too.
My impression is that the cause of the deformation is a combination of temperature and printing PLA, which apparently causes way more friction inside the spacer. (Just compare feeding PLA and ABS by hand, retracting and feeding again)
I am curious about korneel's results, did the shorter teflon spacer also suffer from deformations, even though not running so hot thanks to the vespel washer?
I would also like to know more about glloq's Duratron spacer. Besides the cost and the machining properties, that material appears to have potential to be a final solution.
For my part, I rarely print PLA, but I don't want to invent something that does not work with PLA, since the teflon more or less do work for most things I do.
My main goal is to find something that reduces the temperature of the spacer closest to the heater block because:
1. I think it looks ugly when it is fried, and it might affect PLA printing, even thought ABS seems to not care about fried spacers.
2. I want to be able to print at temperatures up to 300 C, and then to go back to PLA, without having to rebuild the printer each time.
I have a hard time believing that EldRick's spacer would have no signs of being burnt at all after 2000 hours at 260 C with that little extra cooling.
The reason is that teflon has way much lower thermal conductivity than brass, so the temperature closest to the heater block should be more or less the same with or without the extra cooling. (Or did you print at temperatures considerably lower than 260 C?
Here is how a glass filled spacer looks after a few hundred hours of ABS at 255-260C in my printer:
I am not surprised at all that it kept working for 2000 hours with ABS though. As I said, my machine never had any feeding issues or needed any replacement parts as long as printed ABS only.
see my post above about Eldricks solution 
as far as the spacer, neither the spacer nor the teflon part suffered from any deformation. the teflon part looked as good as new even after printing 100s of hours with both ABS as well as XT.
my issues started when i tried printing PLA. that just didn't work well with the spacer and the additional friction. that is also where i think Eldrick's solution is lacking. ABS and XT print just fine with a deformed teflon piece. sure, it might impact retraction a little, but with a good feeder you should not really notice it.. it's PLA that will suffer.
the hack that i've started to use with a slice of the pfa bowden tube as the gasket, with about 80-90 hours printing time, printing pla and xt (caveats out of the way), has worked so far. i think it will at least extend the life of the coupler and make the cost of the disposable piece/s much less. not a permanent solution as others are looking for here.
but, i don't think you will ever get away from the need to replace those pieces, your mileage will certainly vary. reducing cost and availability is it least an approach.
would be interested to hear the results from any others that decide to test.
Always assume people are smiling when they post. Always assume people are nice.
Just quit your bitching and fix your machines. Please.
I'm pretty sure Eldrick is a nice person and when I read this I laughed.
I'm pretty sure Eldrick is just teasing us. And trying to be helpful.
By the way, this theory that isolator works fine for lower temps and PLA and works fine for higher temps and ABS but if you switch to PLA after 100 hours of higher temp printing the PLA gets stuck - that's devious! That's a devious theory. That might explain a lot!
Haha..! This is one funny thread!
Wiki says: The [29]
While PTFE is stable and nontoxic at lower temperatures, it begins to deteriorate after the temperature of cookware reaches about 260 °C (500 °F).
"Everything is true and legal, only the timing is sometimes off.."
Hmm. I'd say that being in a pan heated beyond 163°C is a pretty untenable place for a bird to be, and is quite likely to lead to bird deaths. If the bird isn't in the pan then I find it unlikely that it would be close enough for any PTFE vapours from cookware to trouble it. So, I'd say that "unconfirmed" is probably putting it lightly. My suspicions would tend more towards "totally made up".
Hmm. I'd say that being in a pan heated beyond 163°C is a pretty untenable place for a bird to be, and is quite likely to lead to bird deaths. If the bird isn't in the pan then I find it unlikely that it would be close enough for any PTFE vapours from cookware to trouble it. So, I'd say that "unconfirmed" is probably putting it lightly. My suspicions would tend more towards "totally made up".
no, it really seems to be a thing. bird owners actually talk about it ... i read it so it must be true. doesn't matter, i got flu symptoms so decided this must be the cause and i'm selling my printer. takers?
jokes to the side, all use a bit of caution. ventilated room is not a bad idea, don't print next to your work space if it's being used 24/7, watch temperatures ...
--Gentlemen ! You are all correct.
What we can focus on in addition, is that when the PTFE starts to emit fumes (the bird killing ones), it means that it starts to decompose.
When it starts to decompose, it begins losing its properties.
When loosing its properties it does not get any better, (if that
was the case, it would already be pre-cooked when we buy the thing),
no- on the contrary it starts to decompose more quickly, losing even more... etc..
As several of the oldtimers in here have pointed out, the PTFE decomposes
much quicker at ca 250 than at ca 220. I am not mentioning 260+.
Then, after an amount of hours at 260C it starts to soften up permanently, losing mass, etc..
Maybe shimming with teflon is a cure, if one in need of servicing!
Time for an update :smile:
I have printed about 200 hours now (the log says 182 hours but I know I forgot to log a few prints).
When printing torque wrenches I changed back and forth between PLA and ABS numerous times and I had zero problems so far.
The spacer still looks okay on the outside (looks a bit ugly at this photo though):
But there is a small deformation on the inside now which was not there at ~110h:
The deformation does not stretch all the way around the inside of the spacer for some reason, only about half way.
I haven't done anything obvious cause the deformation, I think. I did notice some black burnt stuff coming out of the nozzle a few days ago though, and I had an incident printing when the nozzle was not fully heated today.
If anyone else is about to try a Vespel washer, I think it might be worth trying a slightly thicker one, like 1.5 mm or so.
I was feeding both ABS and PLA by hand just a few hours ago and both appeared to feed perfectly fine, so as far as I can see up until now the Vespel is not causing any excessive friction.
Hmm, time to join in on the fun. Never really had trouble with extruding other than for things that probably have different reasons. During my UMO maintenance round I opened up my hotend to find this:
Left=used spare that has a little deformation on the other side
Right=current teflon. The hole is now 3,5-5mm conic hole instead of 3-3.2mm.
I can't really find any deformations and I'm not sure to what extend this would cause trouble on a UMO. I've been printing PLA only and quite a lot of Glowfill from Colorfabb
I am relatively new here and I am still catching up on knowledge scattered all over the forums but let me see if I got this right:
It may be a stupid question but here it goes anyway: Why not utilise the 2nd head space for ABS/XT and keep PLA on the existing place? The dual extruder is not happening in this form anyway.
My first PTFE spacer is likely gone and I am looking at alternatives. There does not seem to be a perfect solution, at least not at this stage. I do need to print PLA, XT and ABS.
Smart, and potential trouble:
You would need to lift the nozzle not in use by 1mm to avoid
head crash, alternatively buy a hotend with interchangeable
nozzle (removable). You could then remove the nozzle not in use in 5 secs.
Hey oldies: what about the software adjustment?
thanks
when you install two hotends, they need to be aligned at same height.
Ok, you have accomplished that.
Then when you start printing, the cold head will move into your existing
new layers and corrupt them.
Fix: lift or remove the other nozzle.
It seems this is one of two important show-stoppers for the
Um2-Dual extrusion project.
You cannot avoid running into the same problem without
lifting or removing the alternating hot end.
Edit: If your question is will this software help avoiding head collition, I am not sure, but it will fix "the dimensions and positiions" on the build plate, since the nozzles are not in the same
position
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I'd also be interested in testing one as well :-)
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