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destroyer2012

next UM nozzle ? Wish List

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This forum is sorely lacking a "wishlist" section where we can post what we would like improved in the next ultimaker iteration. This is why I have decided to make this post.

After endless struggles with the nozzle/ bowden tube interaction and other features of the UM nozzle I would like to voice my opinion on what I think the next UM nozzle should be.

1) Screw the bowden tube directly into the nozzle assembly. Pretty much everyone is having the "plug" problem, and there are way too many opportunities for that tube to slip upwards and allow the plug to form. Screwing it in solves that problem entirely, since the tube is no longer held by friction but by leverage (threads), which is much stronger.

2) Smaller hot zone. One of the primary reasons why ooze is so hard to get rid of is the fact that the UM hot zone is too long. Molten plastic stays in the nozzle even after retraction and results in dripping. A shorter hot zone allows the retraction of filament to have more effect on the pressure at the nozzle tip.

3) One-piece nozzle. The major reason for leaks is the fact that the nozzle itself is screwed into a brass tube which is screwed into a PEEK insulator, not to mention the bowden tube held on by sheer luck at the top. Too many joints result in too much leakage potential, so go with the J-head styled design and make the metal parts of the nozzle all one part.

4) Thin-walled heat isolator. The arcol hot end has this. Basically, a portion of the heater barrel is turned down so the metal is very thin. This forms a bottleneck for the heat and prevents heat from spreading upwards towards the PEEK insulator. Yes it does make the nozzle a bit more fragile but I think controlling heat is very important. This also helps to make the hot zone smaller and thus makes retraction a bit more effective.

5)Easily removable. I think it would be cool to be able to switch nozzles in and out. With a screw-on bowden tube this would not be hard. Just screw a short length of tube into the nozzle itself. A part at the top of the head assembly accepts this short tube and acts as a junction between the short tube and the long one coming from the filament feed. Since the junction is far away from the hot end no plugs can form there, and since the short tube is screwed into the nozzle, no plugs can form at that interface too even though no compression is applied to the short tube going into the nozzle. There's a gap between the short and long tubes (within the 'junction' part up top) which allows a tolerance in the length of short tube attached to the nozzle. The aluminum plate has U-shaped holes and fixing screws to allow the nozzle to be slid in sideways, etc.

The nozzle and filament feed are two of the major areas where ultimaker needs to improve, so let's make sure this happens.

What does everyone else think?

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that wasn't a very useful post Daid ;)

destroyer - I am so totally with you there, especially #5. I think it's a shame that the UM team don't take advantage of the fact that so many of the people who have bought their machines have an engineering or programming background and could be freely helping them improve the product. I was discussing ways to improve the hot end and extruder only this morning with some engineers here and several good ideas came from it. of course it doesn't help that discussion seems to be split across this and the google forum, further diluting efforts.

In particular, I'm aware that similar products are now appearing on the market at 1/3 the price of UM - it was bound to happen sooner or later of course. and the resin printer boys are making excellent progress - they can now cure a 6" square resin at 0.1mm thick in under 20 seconds, making total build time 20*(model height/0.1mm layers) seconds. the cost of resin in the US has now fallen to about the same as PLA, but alas no suppliers in the UK yet.

this is a really fast moving area - I invested a lot of money to buy an UM. I'd love to see improvements (and help work towards those improvements) in accuracy and speed before my investment turns into a very expensive XYZ table.

so if anyone wants to have a serious engineering discussion about the extruder or hotend, I'm happy to be involved and I think destroyer's points are an excellent starting point.

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Oh I know Daid which is why I wasn't too condescending, but what we don't know - is it cooking.. or just simmering? if something's going to happen in the next month then I'll hold tight, but if it's 12 months away..

that's an interesting kickstart project, tho it looks to be unsuited to UM since it's 'big heavy extruder on the head' design is it not? it looks almost identical to the makerbot design too.. amazing what people will part with their money for these days

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that's an interesting kickstart project, tho it looks to be unsuited to UM since it's 'big heavy extruder on the head' design is it not? it looks almost identical to the makerbot design too.. amazing what people will part with their money for these days

yes, "interesting" is the proper word for it, as it seems to have no genuine improvement over existing designs, but is just a straight copy of whats out there. which only substantiates what I think about kickstarter: http://gizmodo.com/5921391/yep-kickstarter-is-pretty-much-a-scam-for-useless-crap (for those not familiar with "the onion", their sarcasm is usually so blatantly seeping through that it is impossible to miss. in this piece on the other hand, they are almost dead serious, and very low on sarcasm).

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But at least you know something is cooking somewhere.

Well Ultimaker better hurry up because they are being left in the dust... Lack of updates on ultimaker blog is very offputting.

 

it doesn't help that discussion seems to be split across this and the google forum, further diluting efforts.

I severely dislike the google group so I will continue to post here in hopes that eventually people will migrate. Maybe starting a "hardware development" section of the forum would be a good start. Ultimaker claims to be open source? Then let's start developing it like that instead of this secrecy. Together we are stronger. Consider how much faster the development could be made if we were all working together on improving the nozzle design.

It's really a shame that buying stuff from the UM shop is so expensive for me (shipping to USA! Also everything seems overpriced). Thus I'm probably not going to wait for UM, and in any case the whole reason I spent so much money on this kit is so I could mess around with it.

You guys should all read this thread

http://forums.reprap.org/read.php?1,139866

 

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I doubt you're the only one who decided to put their hard earned money on UM so they could mess around with it, I can add a 'me too' straight away'. ;)

took me a while to read all that post, but the information is valuable. more important, it includes real numbers, real experiments and real engineering. so I agree, let's start developing something!

For those that read all the way to the end of that thread, the reprap boys make an important point (actually a few) that the extruder is the first weak point that has to be addressed - the head is fully capable of travelling at high speeds, but the material being pushed through has to match that or the print fails.

out of interest I tried printing the thin wall box they used - and it comes out perfect on UM at 100mm/s and at 200mm/s and at 400mm/s and at 2990348734mm/s ;)

took me a moment to notice it always printed in 4 minutes. the minimum layer time was overriding the print speed setting so they were all coming out at <100mm/s.

just goes to show how selecting a suitable test print is uber important.

I know you started this thread on nozzles destroyer, but can I suggest we discuss extruders (on another thread if you want) since improving the extruder has an immediate impact and benefit without having to change any other piece of hardware which makes it easier for everyone to get involved and try. the nozzle is going to be a bit bespoke and not everyone has access to the tools necessary to pitch in and help.

I could start such a thread by summarizing a discussion I had yesterday with some engineers about extruder methods. Having explained how the UM system worked they immediately said 'put the extruder on top of the head' so then I outlined the reason for NOT doing that. after which they thought it was quite smart but 'why don't you use a pinch and push system?' they asked

apparently this involves 2 barrel grippers that tighten (electromagnetic) when current is applied. as they tighten they are slightly cone shaped inside (a bit like Owen's clamp?) and so push the material running through the middle of the barrel forward. think climbing up a rope - you tighten one while the other is released, then use the other to tighten and push as the first releases.

I'm not sure if I explained that well enough, maybe it needs a picture, but it seemed a good idea.

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In particular, I'm aware that similar products are now appearing on the market at 1/3 the price of UM - it was bound to happen sooner or later of course

Can you name any?

About interchangable nozzles: does it make sense to put a smaller nozzle on for highly detailed small pieces? Can the Z resolution be made smaller then too, or are we at the limits there regardless the nozzle diameter?

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I fully agree it is a complete nuisance to have two forums. My preference goes to this one as well, as i am not a fan of google and how they treat private data.

Second on my wishlist would be much more openness from the ultimaker team as well. If they are developing something new then please tell us.(my guess would be a second extruder). For example i am thinking about a heated bed and if this is something they are developing then this would be good to know.

Third, They do not show much of a sign that they read this forum. Some more responses from their side would be good.

Enough of this winching, as in summary i am really happy with my ultimaker

And i have to start another print...

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I think the reason for them not telling what they are developing right now is so people don't get their hopes up and start to inquire about it all the time. When the first signs of the UltiController where shown it took quite a while to get from prototype to production. During this time people where like "Why I can't I buy it yet? I've seen it!". It's hard to see for people that going from "finished production data" to "products on the shelve" can take months.

And Ultimaking is doing research and development, and not everything during research will make it into products. We've seen prototypes of a heated bed at the first Ultimaker evening. But those prototypes where not active and where used as normal cold beds. So I'm guessing that had some troubles with those prototypes.

I've had an UltiController, ready and working, straight from the UM HQ, from a production run (as far as I can tell), more then a month before it was released in the shop. (FYI: With no wooden enclosure, and the wrong type of SD card)

I've seen, at UM HQ, some kind of prototype hotend they where experimenting with. This was the same day that I got my UltiController. No idea what the experiment was about, no idea if it will ever make it into the product. No idea if they are still experimenting with it.

I have, thanks for UM, dual extrusion in my machine. But I could make a long list of troubles with it, starting with just assembly problems. Don't expect a dual extrusion kit very soon I think.

They have (thanks to my evil twin) upgraded ReplicatorG to version 34.

So what are they working on? A lot. What will be finished and when? No idea.

I do have something new. But I'm not allowed to talk about that yet. When will I be allowed to talk about it? No idea. Do I have a blog post ready for when I do? You bet ya.

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Hy daid

Thans a lot for your explanations. Really appreciated. I understand that it is a very difficult balance between overexitement and discouragement, though once it is for sure in some cases they could be a bit more open.

And i really believe that they could put some effort and try to unify the discussion groups and steer it a bit.

As well their blog was updated more thana month ago so people have no idea what is going on.

So let's wait and see

Cheers

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nothing says we can't steer it ourselves a little in their absence. the extruder and heated bed are both areas we could (and should) be looking at. Bertho has an interesting development on the extruder front in a different thread - help him perfect this design further. and heated beds - I've seen several ideas here but none seem to have been overly successful yet, printing in ABS is an important step forward. personally I'm looking at different fan designs and lowering the minimum layer time whilst measuring print speed vs quality to try to get good prints faster. others have been looking at retraction lately which is another important area.

and ultifay> yes I could, but I don't think it's appropriate to do so in this forum. however, I will say one of them is American, it costs the equivalent of £410 (UM is about £1500), the spec. is only very slightly less than UM in terms of build size and precision (6" cube) and it prints ABS by default with a printed bed that comes with it.

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1) Screw the bowden tube directly into the nozzle assembly. Pretty much everyone is having the "plug" problem, and there are way too many opportunities for that tube to slip upwards and allow the plug to form. Screwing it in solves that problem entirely, since the tube is no longer held by friction but by leverage (threads), which is much stronger.

 

Yes, that might work. But when you have a good clog and your feeder is capable of a good push, then you might strip the threads. Then there is nothing left that you can do. Now after damaging the end of the bowden tube, we can cut off a short piece and try to continue to print.

How about widening the bowden tube to 4mm at the end, and have a 4.5-3.8mm tapered end sticking out of the brass tube. Now screw a clamp down onto the tube. You won't compress the tube ID because of the brass inside, and you get a perfect grip.

 

2) Smaller hot zone. One of the primary reasons why ooze is so hard to get rid of is the fact that the UM hot zone is too long. Molten plastic stays in the nozzle even after retraction and results in dripping. A shorter hot zone allows the retraction of filament to have more effect on the pressure at the nozzle tip.

 

I agree that the large hot zone causes problems. But there is also the problem that you need some time to get the plastic to melt. So will the smaller hot-zone be capable enough to melt large amounts of plastic for fast prints?

I think the quality issues we're seeing with fast prints are mostly due to the arduino not being fast enough to do things perfectly at the higher speeds. If I have time, I'll try to see what happens if I hook it onto an FPGA....

 

4) Thin-walled heat isolator. The arcol hot end has this. Basically, a portion of the heater barrel is turned down so the metal is very thin. This forms a bottleneck for the heat and prevents heat from spreading upwards towards the PEEK insulator. Yes it does make the nozzle a bit more fragile but I think controlling heat is very important. This also helps to make the hot zone smaller and thus makes retraction a bit more effective.

 

Sometimes a blob from the test-extrusion at the beginning gets caught somewhere inside the buildarea. Sometimes the object curls up during printing. This causes the extruder head to bump into the object. If that causes me to loose an extruder head, that'd be very expensive.

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and ultifay> yes I could, but I don't think it's appropriate to do so in this forum. however, I will say one of them is American, it costs the equivalent of £410 (UM is about £1500), the spec. is only very slightly less than UM in terms of build size and precision (6" cube) and it prints ABS by default with a printed bed that comes with it.

Sounds like you're talking about the PrintrBot, we'll see how that one holds up against an UM. Ultimaking just receiver a PrintrBot (inside information is fun sometimes). And a friend of mine hopes to receive his PrintrBot soon, but he is around position 1600 on the list.

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I think the main reason why people want to get things as soon as they are announced is they still associate ultimaker with an experimental open source project, and "ultimaker quality" means nothing to them. So maybe ultimaker needs to do something about that image. I suggest more blog posts as the answer, as well as selling completed fully functional kits. Until you guys release 'no fuss' printers, ultmaker will keep being understood as experimental and open source and will never be as successful as makerbot.

 

Yes, [screwing the bowden tube into the PEEK] might work. But when you have a good clog and your feeder is capable of a good push, then you might strip the threads. Then there is nothing left that you can do. Now after damaging the end of the bowden tube, we can cut off a short piece and try to continue to print.

Ideally, the system would be designed so that in the case of a clog the filament drive gear is what would fail first i.e. scrape a big gouge in the filament and stop pushing. I don't think the nozzle design should be intended to be taken apart and re-adjusted after every print as you suggest. Cutting off the tube is a very poor solution and the most it ever does is band-aids the problem.

 

How about widening the bowden tube to 4mm at the end, and have a 4.5-3.8mm tapered end sticking out of the brass tube. Now screw a clamp down onto the tube. You won't compress the tube ID because of the brass inside, and you get a perfect grip.

I'm not convinced that having a wider tube is better because I now have a 4mm ID bowden tube and while the friction is gone, the filament shifts around inside the tube and causes retraction to need to go farther, which is hard since our filament feeder is limited to ~40mm/s max speed. I ended up having to attach a short piece of 1/8" ID tube to the nozzle itself so the plastic doesn't melt upwards and cause a plug inside the bowden tube, but this still increases the friction on my slightly oversized plastic (ABS) a whole lot just as it enters the nozzle. The real solution is get better plastic that is exactly 2.8mm or so, then use 3mm ID tubing.

 

I agree that the large hot zone causes problems. But there is also the problem that you need some time to get the plastic to melt. So will the smaller hot-zone be capable enough to melt large amounts of plastic for fast prints?

Well I mean, the hot zone needs to be optimized is all I'm saying. Perhaps we need some data from a bunch of different nozzles to see which length of hot zone performs best. So what we need to figure out is how much molten plastic you actually need to do fast prints. How fast are we talking? I'm not convinced anyone has measured the max cm^3/sec of our current nozzle (which I imagine is huge based on me manually turning the feed gear really fast), and whether the machine can actually move fast enough to take advantage of that. Another important parameter is cm^3/s^2, aka the acceleration of extrusion. How fast can our nozzle lose pressure? Probably a function of hot zone length and plastic material properties.

You know, UM, if you guys published this information that would be really awesome. You are starting to phase out the current nozzle right? So if you've done this research tell us about it to at least contribute to reprap development. Really I can't see why sharing it would compromise anything as ultimaker's nozzle is NOTHING NEW.

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1) Screw the bowden tube directly into the nozzle assembly. Pretty much everyone is having the "plug" problem, and there are way too many opportunities for that tube to slip upwards and allow the plug to form. Screwing it in solves that problem entirely, since the tube is no longer held by friction but by leverage (threads), which is much stronger.

 

Yes, that might work. But when you have a good clog and your feeder is capable of a good push, then you might strip the threads. Then there is nothing left that you can do. Now after damaging the end of the bowden tube, we can cut off a short piece and try to continue to print.

Speaking from first hand experience, threading the bowden works. I haven't had a plug mid-print since I turned the end to 6mm, threaded it M6, and threaded it into the PEEK part. The only reason it's not more popular is because it requires more than hardware store tooling. You can't really thread it M6 without turning it down first.

The bowden does still plug, but only at the end of a print when the hot end cools down to ambient. If I start a second print without manually turning the extruder gear the filament will grind and fail during the first layer, and that's with a mk6 extruder gear (tlalexander extruder), which has much better bite than either the v3 or the stock hobbed bolt. Pretty easy to avoid once you know about it.

Back to the quote, you won't strip the threads off the bowden tube. The filament strips first. Threading the bowden completely fixes the hot end. Is there room for improvement? sure, but it works now, and I don't think about it. I've taken the nozzle off once (last week) to clean it in the last three months.

I've been working towards improving the reliability of the system rather than the speed. (The parts I want to print are big.) I've tried all of the available extruder options and the best results so far have been with a threaded bowden and the tlalexander greg's wade's type extruder with the mk6 gear. My current profile is 100mm print, 150mm rapids, and 3.5mm retraction and my parts look great. I haven't tried to go any faster. I'm OK with it being _only_ twice as fast as a makerbot .

So my recommendation: thread your bowden tube, print yourself a tlalexander extruder, maybe add a grooved bearing, get a spool of good quality filament and _then_ start testing your max speed. I can't wait to see how fast you can make it go.

Speed means nothing if your mean time before failure (MTBF) is less than your print time. You'll just make scrap faster.

Kyle

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Pretty much everyone is having the "plug" problem
That's not true. It is one of the major problems with the current design, but it does not happen for everyone. My stock setup never had a plug. Only when I added a 2nd extruder that 2nd extruder plugged, but the primary never plugged.

I finally added 2 sets of clips at the top and bottom, which solved all my plugging problems.

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it is important, but the title now opens it for all wishes - is that what you intended?

cos I have a huge list of them here..

Kyle > I thought your comments were very interesting and especially agree with the making scrap faster one. But I think it would be very interesting to see the quality of some of the prints from people who've modded their UM's.

I am printing at 100mm/s with as many software tweaks as possible and a Bertho extruder mod but still notice occasional failings on perimeters, alignment of layer problems (also seen on Ian's prints) and top surface imperfections.

before deciding that the solution is a tlalexander extruder I'd love to see what it can do - I've seen far too many 'upgrades' for UM that turn out to be downgrades or sidegrades and are only 'better' because that person designed them or spent so long building it they convinced themselves it was better.

one of destroyer's early comments regarded 'proof' by way of numbers, measurements or photos - there's a lot of rumor in the 3D printing world but we all (me included) need to demonstrate improvements are real and not perceived so we can concentrate efforts on further improving the best ideas.

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Yeah I don't think it's a good idea to cram everything into one thread. There's a nice discussion going on here for one part of the machine, no need to mix it up with other random stuff as well.

(feel free to delete this post if you disagree)

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Hi. Have anyone made calculations on how much heat you have to supply on at a given speed? I just wonder if the truble we get with the extruder and the hotends is caused by unmolten filament beeing jamed down into the nozzle? If the 3mm filament hasn't melted in the core, it will actualy block the nozzle. If the nozzle had been a little bit offset from the filament input, this would be solved.

Johan

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