Awesome nozzle mod! Now if only I had a machine shop in my garage...
How hot does it get at the top of the PEEK section? It seems like the aluminum block is closer/more thermally connected to the PEEK insulator. What's the longest print you have done with this setup?
How long is your hot zone and how does the oozing compare to stock?
How long is the nozzle orifice?
With this design all you need is a quick release clip at the top of the PEEK and there we go, modular low profile nozzles!
How about not redesigning everything, but just put a connector piece of Teflon on top of the current PEEK? Plugs will happen in the Teflon (which won't stretch like the bowden tube does), and it will be slippery enough to push the plug back down. It is simple to machine, doesn't require any extra threads, and makes assembly easier.
2 new wooden plates (as you need to move the clip to the top of the head), 1 connector piece of Teflon, that's all it would need.
the thing I'm not seeing anyone talk about (but wish they would) is detachable heads. (not nozzles)
I'd love to release two clamps that take the whole head off the gantry (but leaving the rods in place) and snap on an ABS head with a larger nozzle, and snap on a gigapixel imaging camera and snap on a laser for laser engraving and snap on a milling bit.. etc etc.
UM is an awesomely accurate XYZ table and can do more than just print.
I suppose someone will say, just release the gantry at the wooden blocks. but it's not a quick operation to do this as it requires re-squaring each time.
I saw a cassette style multi head on thingiverse recently which sort of went some way towards addressing this but isn't quite there yet.
How about not redesigning everything, but just put a connector piece of Teflon on top of the current PEEK? Plugs will happen in the Teflon (which won't stretch like the bowden tube does), and it will be slippery enough to push the plug back down. It is simple to machine, doesn't require any extra threads, and makes assembly easier.2 new wooden plates (as you need to move the clip to the top of the head), 1 connector piece of Teflon, that's all it would need.
Why not redesign everything?
What do you mean by a connector piece of teflon? Just a short piece of tubing? If plugs still happen then it doesn't fix anything! If the teflon is attached well to the nozzle (as in mastory's mod) then plugs won't happen. But to me that is a more significant mod than just "a connector piece". I think a really simple mod would be just to thread the PEEK all the way through (instead of having that smooth bore section at the top) and then thread the end of the bowden tube, as was talked about in an older thread about how to eliminate plug formation. Ideally you want the junction far from the hot end, so plastic cannot leak out of there.
Here's how mastory's mod can be used to make a quick release head: Make the "bowden tube" that sticks out like two inches long. Then, screw a bolt on the end of the bowden tube coming from the filament feeder, and make a bracket to fit the orifice of that tube onto the short one coming out of the nozzle. Because the junction between the two tubes is cold it doesn't have to be water tight so you have some pretty wide tolerances on tube length. Then when you want to switch out the head just unclip the nozzle-and-short-tube portion, and replace it with something else.
the thing I'm not seeing anyone talk about (but wish they would) is detachable heads.
That would be pretty sweet. I almost feel like the current gantry setup does not facilitate that. Because of the crossing axles there's not a whole lot of room to mount something without losing a LOT of build area. If only the ultimaker gantry looked like this
Awesome nozzle mod! Now if only I had a machine shop in my garage...1. How hot does it get at the top of the PEEK section? It seems like the aluminum block is closer/more thermally connected to the PEEK insulator. What's the longest print you have done with this setup?
2.How long is your hot zone and how does the oozing compare to stock?
3.How long is the nozzle orifice?
4.With this design all you need is a quick release clip at the top of the PEEK and there we go, modular low profile nozzles!
Sorry for the delay getting back on...
1.I haven't measured the temp of the peek near the top, but I it has not shown deterioration or weakness. The PEEK in the stock set-up is really just as close to the heater. With stock, the PEEK surrounds the brass piece, and is flush to the heater block. I think the longest single print so far has been just over 3 hours.
2.printing at 220C, the divide between the solid and melted PLA is somewhere between the top end of the heater block (cuff) and the bottom of the PEEK. This is hard to measure. I estimated by pulling the filament back immediately after a print and measuring. I am pretty sure the melted zone does not go above the height of the cuff on the heater block. I don't find oozing to be a problem. It may be improved because the melted region is smaller than stock. One of the goals I was aiming for was a smaller melted zone. I don't think it has hurt speed as I have printed up to 90mm/sec with a .4mm nozzle.
3.The picture shows the orifice much longer than what I actually running. Currently, I have them drilled out to what I believe to be the maximum depth. The small diameter is apprximately 1/32" or less.
4.I am changing nozzles between prints by exchanging the tips. Your suggestion could work. As shown, it is designed to "drop in" to an otherwise stock carriage. If the PEEK were threaded full length on the OD, a double jam nut set-up could offer an easy method for leveling dual nozzles.
Matt
I don't think it has hurt speed as I have printed up to 90mm/sec with a .4mm nozzle.
At what layer height?
I'm using high speeds to improve printing time. I get better prints at 0.2mm layer height and 50mm/sec than at 100mm/sec and 0.1 mm layer height. And I got the Ultimaker because they claimed "insane speed". I'll eventually figure out what causes the quality drop at higher speeds, compensate for it and print at 150-200mm/sec from then on. :-)
So while you might be happy with printing at 90mm/sec 0.1mm layer height, I'm aiming for 0.2 @ 200... :-)
Costs and complexity.Why not redesign everything?
What do you mean by a connector piece of teflon? Just a short piece of tubing? If plugs still happen then it doesn't fix anything! If the teflon is attached well to the nozzle (as in mastory's mod) then plugs won't happen. But to me that is a more significant mod than just "a connector piece". I think a really simple mod would be just to thread the PEEK all the way through (instead of having that smooth bore section at the top) and then thread the end of the bowden tube, as was talked about in an older thread about how to eliminate plug formation. Ideally you want the junction far from the hot end, so plastic cannot leak out of there.
Like this white piece:
http://daid.eu/~daid/IMG_0529.small.JPG
Costs and complexity.
The current ultimaker is made using a laser cutter, with off the shelf parts. Thus there are almost no tooling costs, besides machining the nozzle. What additional cost would be incurred by redesigning? We are doing the designing (here in the forum right now) so that's no more cost to YOU for us to keep having this conversation.
We are trying to design a system that is better, without any stipulations on complexity. I posit that the current system is non good enough thus it doesn't matter how simple or complex it is. Having the bot made of laser cut wood is a great reason to always redesign everything. You have no added cost on making something different, and all the advantage of staying ahead of your competitors.
How does the bowden tube attach to the top of that white piece? I still think mastory's design is simpler than what you have in that picture. Three pieces instead of six (counting the white clip not shown as one piece..) and an attachment point that doesn't depend on some wooden parts (assuming the bowden tube just sits on top of the 'white piece' the same way it does on the current PEEK part).
The bowden tube slides into the white piece, the top part has a ID of the bowden tube, the bottom part an ID of ~3mm.
The advantage of this part is that it is ridiculously easy to upgrade current machines with it. I do not object to a new design, but there are also a lot of machines out there that could benefit from upgrades.
(I was at UM HQ yesterday, and I've seen more stuff then I can remember. Also a bunch of new nozzles designs. But the reason for my visit will be announced later)
for those that haven't seen it -
http://www.creativemachines.co.uk/shop/ ... ucts_id=51
I think the reprap boys are using these j-heads and they come highly recommended but for those of us (like me) that don't have access to lathes cnc machines and all the other tools necessary to make mastory's very nice design, here's something you can just buy.
of course, now the question is.. how to adapt it for use with an UM?
There are many good points here but I like to disagree about the one piece barrel and nozzle suggestion.
Yes, leaks are frequent in some designs but that just shows poor design. There are millions or more industrial metal to metal joints using orders of higher pressure that works perfectly.
The problem is twofold: Poor joint design and machining of the parts and wrong assembly technique. The nozzle should be tight against the barrel and with clearance to the aluminum block. That ways the critical joint is formed at the correct place.
Taking a step back, never mind manufacturing problems, what would an ideal heater/nozzle/Bowden system look like?
I have been playing around with measurements and there are drastic force changes if I feed too slowly or wait a little bit between measurement. Presumably the melt zone extends up higher and the plastic starts to cool and there is more friction against the walls.
Bertho,
Your last points were among my design objectives. I wanted to reduce the number of connections, and improve the connection integrity. Inspiration was drawn from industrial hydraulic flared tube connections. I felt the melted zone should be smaller. It can't be too small, the melted volume needs be balanced against the therm trans rate and the flow rate so there is always a buffer of melted plastic based on the highest desired flow rate.
I don't know how to add a clearance between the insulator and the heater block. This would reduce the melted volume, and I'm not sure reducing it more would be helpful. Maybe the sides of the cuff on the heater block could be relieved?
Matt
Taking a step back, never mind manufacturing problems, what would an ideal heater/nozzle/Bowden system look like?I have been playing around with measurements and there are drastic force changes if I feed too slowly or wait a little bit between measurement. Presumably the melt zone extends up higher and the plastic starts to cool and there is more friction against the walls.
I think I've come across the same problem since upgrading my bowden tube to the new 3.2mm ID one.
twice now I've had a failure caused by a plug of PLA forming in the very end of the bowden tube. it happens slowly over a period of some hours and I think it caused by retraction.
the plug is about 5-6mm long of PLA exactly the ID of the tube and located right at the end of the tube. this is strange because the filament in both cases was quite small - 2.64mm and 2.70mm respectively.
I think what is happening is that retraction causes molten or soft PLA from the hot zone in the brass tube to be brought up into the bowden tube. we can assume the PLA inside the brass tube is close to the diameter of the tube (anyone know what that is? 3mm?) as it comes into the bowden tube it cools slightly. when the filament presses down on the soft PLA it pushes it to the side (hence the large amount of friction in my system requiring an E of 1040 and not 850?)
gradually this build up solidifies - leading to slipping at the extruder side and no more extrusion.
note this is NOT the typical bowden popping diagram where the PLA sneaks between the brass and bowden tube and pushes it up. I've checked in both cases and the surfaces were flush mating with no problems - the plug is inside the bowden tube.
this seems to be a problem where the filament diameter is less than the ID of the bowden. is there any way to avoid it in a good design?
the interface between bowden tube and brass tube is the weak point as several have rightly commented.
how do we stop plugs?
Wow! I haven't been back here in ages, got frustrated with my Ultimaker for a month, until I figured out these exact same problems:
Getting plugs and frequent jamming, due to the Bowden slipping upwards, and having the melt-zone too close to the PEEK-Bowden Interface.
I fixed it by using a new white clip I got from Ultimaker, hope it will hold for a while at least! And retraction has improved in Cura 12.07, using it on my Mac which is a plus.
So I'm back in happy printing land. But yeah it's only a matter of time before the plug of doom or "kidney stone" as I call it, returns.
I'm all for redesigning my nozzle now that I actually understand it completely haha.
How about a design where the Bowden Tube goes into the Copper Tube?
So the Bowden interface is right inside the hot zone, so no matter what, a plug will never form there.
I'm also in favour of switching to 1.75mm filament, a friend of mine is trying that with his RepRap, and Bowden friction is greatly reduced due to the increased flexibility. The thicker 3mm filaments tend to get lots of rough edges once it passes through the knurled bolt, and this causes huge amounts of friction inside the bowden.
In addition, 1.75mm filament is a lot easier to melt. So if it melts faster, maybe we don't have to be so worried about keeping a large buffer of molten plastic for fast-printing. Kinda like broadband, versus dial up - faster speed, less buffer time needed.
The heat sink I feel is necessary for keeping the transition zone between the Melt Zone and Cold Zone narrow - in addition to a melt zone and cold zone, there is always a transition zone, and perhaps (speculation) this is where plugs are forming inside the Bowden - it's kinda melty-warm, not hot, (any temp above the glass transition temp of PLA of 60C will do it) so when enough force is applied the filament expands outwards forming a plug, which solidifies between/after prints.
Perhaps this "plug" itself becomes a sort of insulator, so when you try to start the next print, it doesn't melt easily, as its within the transition zone, and not within the melt-zone exactly.
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?
some good thoughts there tachyio - the heat sink and blower arrangement is what I have been experimenting with too - altho mine is at 90 degrees to yours.
I have come to the conclusion that the PEEK serves no real purpose - perhaps someone would care to correct me - why do we want to retain heat in the brass tube near the interface with the bowden tube thus risking the PLA (especially during heavy retraction) reaching the glass transition temp at 55C and forming plugs of doom?
we surely need a cold zone above the hot zone, especially now that retraction is in common use.
IMHO, going from "hot enough to melt the plastic" to "plastic stays solid" should not happen say inside the brass.
Suppose you've been printing for quite a while with little extrusion (lots of jumps). Now everything heats up, lots of plastic melts. Next the print is finished and you shut it down for a day. Next day you try to print something.. but it may take a very long while to melt the plastic as far "up" in the brass so that it un-sticks.
What is needed is a "sudden" transition from where it melts to where it doesn't melt. This is accomplished by the changeover from brass to peek. The brass is hot, the peek should be cold (below plastic-melting-temperature).
Next, some of the molten plastic will work its way up the peek tube (or whatever you're replacing it with). With the same scenario as before, you want some extrusion the next day.... So, what we need is that the solidified plug in the peek is simply pushed down into the hot zone, and melts there.
This means that the peek or teflon needs a very low friction coefficient. This allows the plug to be pushed down as normal.
completely agreed - I think you meant to say PFA rather than PEEK tho.
note this infers the size of hole in the PFA tube to be <= that in the brass tube or you can't push it down.
unfortunately as the filament grows in diameter (which by virtue of the molten plastic working its way up into the tube it effectively does) friction increases and we can't push it down. this may be hampered by the fact the PFA tube has some elasticity and can expand slightly whereas the brass tube won't.
why isn't the hotend all metal?
eg. like
http://forums.reprap.org/read.php?1,145069,page=1
Finally someone designed what I think is the future for the nozzles. Multi colour in the same nozzle:
http://www.3ders.org/articles/20120825- ... nting.html
Would be nice to have it adjusted for the Ultimaker somehow.
awesome. I saw an earlier version(s) of this using colored markers to do the same job, but this one actually blends the colors. it's undoubtably the future, tho the bulk will need to come down before we can use it!
Finally someone designed what I think is the future for the nozzles. Multi colour in the same nozzle:http://www.3ders.org/articles/20120825- ... nting.html
Would be nice to have it adjusted for the Ultimaker somehow.
I saw this recently. was amazed.. think about 4 or 5.
not just because we can but because CMYK!
about colour printing. (cyan, magenta, yellow, Black/white)
but needs complicated nozzle integrated mixer.
all in all we could head towards full colour printing earlier than thought. :mrgreen:
Finally someone designed what I think is the future for the nozzles. Multi colour in the same nozzle:http://www.3ders.org/articles/20120825- ... nting.html
Would be nice to have it adjusted for the Ultimaker somehow.
I saw this recently. was amazed.. think about 4 or 5.
not just because we can but because CMYK!
about colour printing. (cyan, magenta, yellow, Black/white)
but needs complicated nozzle integrated mixer.
all in all we could head towards full colour printing earlier than thought. :mrgreen:
I think you would need white for the fourth instead of black. The other 3 colours mixed will produce black.
For printing parts with lots of colours its obviosly a nice thing, but for me personally (I dont
care at all about making parts with colours) I dont think its great.
First the printhead mass is enormous, secondly because there is only one nozzle you will always have
a little bit of mixing happening when the new colour pushes out the last of the old.
My interest in multi-material is purely using a water soluble material for the support. This would not be great
for that as you will have little bits everywhere of the actual model body that would wash out along with the
support.
But if you only want colours, then it obviosly works....since a tiny bit of mixing is probably almost invisible.
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By the way, I am also running Geo Hagans Extruder drive.
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