E3D All Metal Hotend for Ultimaker

[sanjay-e3d 3]

Hi all,

Sanjay from E3D here - I do all the engineering design etc for the Hotends.

We have just released our V4 Hotend, which is still all metal, still actively cooled, but is simpler, stronger and more effective in almost all respects.

 

(Not show is the fan and printed fan coupler - you can see this and more pictures on our site: http://www.e3d-online.com )

We can reach over 300C without any real issue, the limiting factor is the thermistor we use, a thermocouple that you guys already have solves this problem, making much higher temperatures possible.

Our hotend has an extremely sharp thermal transition, filament entering the hotend remains at ambient temp, right until it gets to the stainless steel thermal break, here it transitions from ambient to 200C or so in around 2mm. This gives really precise immediate and responsive flow of extrudate.

Alaris2 posted in another thread about fitting our older V3 design to an ultimaker, he had to make some mods but managed it in the end, with good looking results.

Our new V4 Hotend is out now, it is primarily designed for repraps etc, and uses a groovemount type fitting. This is great for repraps, but we really want to get you guys printing awesome plastics like polycarbonate and nylon on your ultimakers.

It's not too hard a task to make some mods so we can get you guys some sort of solution that works out of the box, but I don't have an ultimaker to test/develop on so I would like to throw some ideas around and see what you guys think.

We can add a pneumatic push-fit coupler that is screwed into the top of the heatsink so that your bowden tube can go right into the top of the aluminium heatsink and be held there firmly solving the popped bowden tube problem once and for all - that is easy enough. the trickier part would be mounting.

My proposal is to replace the aluminium plate and laser cut part 8A with a printed part which would hold our hotend firmly to the ultimaker extruder head, this combined with pneumatic push-fit tubing couplers should provide a rock-solid super easy drop-in solution.

The mounting part can be printed in PLA without any problems, no heat ever gets up there to cause problems with our actively cooled design.

But before we prototype/develop/release I wanted to see what you guys think, if you have any suggestions, and is this something you would be interested in buying?

We have a long track-record of integrating features suggested by community and customers and would like to know what you, our customer want in a hotend.

Cheers,

Sanjay

 

[lars86 42]

Hey Sanjay, that's a beautiful part you guys have there!

I've been spending some time fiddling in Solidworks, designing my own hot end and have ended up somewhere similar to you guys. My stainless thermal break necks down to a 1mm wall thickness right now, and the loading sim tells me it will be strong enough. I'm curious how thin you have gone.

My thermal simulations are showing a very sharp transition zone in mine too, even without active cooling (certainly more so with it).

I'm also curious why you have chosen brass over aluminum for the nozzle.

I haven't even gotten my Ultimaker kit yet, so you'll have to get mounting insight from the experienced guys!

Cheers,

Lars

 

[olivierc 3]

I have not received my ultimaker yet either, so I'm probably not going to replace the hot end on day one, but it sure looks interesting. I like that you got rid of the PEEK part. So I will keep an eye on this and see if someone can mount it on an ultimaker without too much trouble

 

[am001 0]

Hi Sanjay,

I have been playing around with all sorts of hot/cold ends on the ultimaker. I would be very happy to build something up and try it if you can sell me your V4 with a push fit coupler in the top. I am in the UK which might help. You do have to be careful with your choice of coupler, some of them will not grip the very slippery PFE used for the bowden tube.

I print a lot of ABS, often in a heated chamber, and currently the PTFE component wears out in 2 weeks.

One concern is will your hotend work in a heated chamber (typically 45DegC)? If not don't worry I'm still interested.

Andrew

 

[chopmeister 0]

Hi Sanjay,

I went ahead and ordered one. I'm really looking forward to trying it out! It looks well designed and finely machined. The Included heater cartridge is a nice plus, because mine is broken (although it still works).

I was looking for a simple, all metal, hotend for quite a while now, and really got tired of waiting for the Prusa nozzle.

Tell me, how does it perform without the fan installed? Have you measured the temperature on top of the heatsink in that scenario?

Thanks,

Chopmeister

 

[lars86 42]

Have you guys experimented at all with nozzle geometry's effect on print quality? Length of the 0.4mm orifice, and the transition angle just prior, for example.

 

[sanjay-e3d 3]

Hi all,

Lars, I typed out a really detailed reply about all our thermodynamic design justifications etc the day before yesterday. But it seems to have been lost. Argh. Will get back to ALL the questions in this post within a few hours, must dash to the post office to get orders out now though!

Sanjay

[calinb 11]

My proposal is to replace the aluminium plate and laser cut part 8A with a printed part which would hold our hotend firmly to the ultimaker extruder head, this combined with pneumatic push-fit tubing couplers should provide a rock-solid super easy drop-in solution.

 

It's a bit of a shame to ditch the aluminum plate, because it could make for a great heatsink! I have a design in mind to use it in this manner--along with a new fan shroud to direct a portion of the airflow to the heatsink/aluminum plate.

 

[calinb 11]

I print a lot of ABS, often in a heated chamber, and currently the PTFE component wears out in 2 weeks.

One concern is will your hotend work in a heated chamber (typically 45DegC)? If not don't worry I'm still interested.

 

I print ABS up to 275 C (often with an idle fan) and I also use a heated build chamber (I've had it above 70 C). Since making a simple mod to my nozzle assembly, i've had no signs of overheating of the PEEK or Teflon part as I did previously. The specs I've seen limit both of these materials to about 260 C continuous.

http://umforum.ultimaker.com/index.php?/topic/1798-got-abs-you-need-a-makergear-50-cal-nozzle-and-longer-barrel/

 

[am001 0]

Hi Calinb

Very interesting to read. Thanks for that link. I am currently in a frustrating world of increasingly failing ABS prints with the V2 nozzle.

If Sanjay doesn't come through, I will try your approach.

Andrew

 

[am001 0]

Calinb.

For reference, here is my current experimental hot/cold end, a little like what you are describing.

It uses a heatsink in place of the aluminium plate (apologies for the rough machining!) and the V2 brass tube and heater. The fan is redirected through the heatsink.

It basically doesn't work, the ABS after a few minutes and some retracts becomes bonded onto the top cold section of the tube, as the trasition area is too long.

I think for this to work, I need stainless steel, not brass for its much lower conductivity in order to shorten the transition length.

 

[snowygrouch 1]

You will have a lot more luck by re-desiging your fan duct design. I almost guarantee that with the

fan airflow being asked to do a 90 degree turn almost immidiately after the exit - that the airflowrate is

almost zero through your heatsink.

I recommend sourcing a very small diameter fan, and making it flow almost straight into the heatsink, PC cooling fans

have extremely low pressure flow (big gaps between the end of the blades and the housing, low RPM, design is optimised

for low-noise not high-flow). If you ask the flow to change direction like that it will simply stagnate after the rotor and

half is probably flowing BACK out the fan in the reverse direction.

One (messy) way to test, is to get a powerful torch and some flour. Turn the lights off in your room, shine the torch on the fan, turn on the fan and dust some flower powder near the fan inlet. That will soon show you whats really happening.

You are quite correct that a stainless steel material will work alot better, but you might find that simply by using

the fan better you can also make it work.

C.

 

 

[sanjay-e3d 3]

Righty!

Thanks everyone for the informative replies and suggestions:

Lars:

We too are modelling/simulating in SolidWorks. Very nice.

Our wall thickness is 0.4mm. You have to consider both the wall thickness and it's length obviously. Fouriers thermal transfer equation is most useful in this regard. If your break is short (Like ours) then you also must consider convection and radiation. This is more of a black art and really needs to be done empirically rather than calculated.

What length of 1mm wall section do you have? How much wattage is conducting up that break?

Brass for the nozzle is for a couple of small factors - It machines much more easily for tiny holes, and the finish is less "burry" and more smooth, which makes a real difference when you want a quality exit orifice. The other is that aluminium nozzles have a very low specific heat capacity - you actually want to store some heat, for sudden extrusion bursts where melting lots of plastic sucks out heat and for keeping a smooth temperature when fans and airflow are involved. When you have a fast moving head like in an UM then you are always experiencing significant airflow.

We did experiment quite a bit, and look at the results others are getting with various nozzle orifice geometries. Our lead in angle is largely dictated by the angle of the drill bit tip - there is some room for adjustment here, but not significantly so. The main thing to get right is the ratio of diameter to length. You need to induce laminar flow in the fluid plastic for nice results, which requires length to be at least 2x orifice diameter. The other consideration here is ease of flow/backpressure versus oozing/dripping. We went for 2.4x diameter for a length of 1mm which gives a nice balance between all these factors.

am001:

We are still trying to find an appropriate push fit coupler - its not so much about gripping the PFA tubing firmly, more about having a smooth/chamfered internal path for the filament that doesn't catch as you are feeding in the filament in for the first time.

I am quite happy that this will function just fine inside a heated chamber when printing ABS - probably to around 70C but that is just a guess.

I am quite certain that your design will work just fine if you add a stainless steel break with a constriction on it. Force cooling with the fan and the angled duct should work just fine - with a good break you really don't have much heat to dissapate and your heatsink is very good, so the need for airflow is low. I do agree with snowygrouch that using a small diameter fan that is pointing in the right direction. The fan can be a little higher than the heatsink so it doesn't come lower than the nozzle, and use a duct to direct all the flow downward.

Chopmeister:

Thank you so much for your order! I really look forward to seeing what kind of solution you come up with for getting it onto your UM. If you come up with something really good we could adopt it 'officially'. In return we could keep you on as a Beta tester of sorts, some free parts to experiment with in the near future. This also goes for anyone else who wants to develop a way of using the UM with this hotend.

You help us, we'll support you.

Measuring the temp at the top of the heatsink without a fan is a bit of a moot point - if the plastic is past it's heat deflection temperature above the stainless steel break it WILL jam as it deforms into the join between the heatsink and aluminium. It's not a matter of protecting the components in the head from heat, it's about keeping the plastic filament stiff until the last moment. I imagine that you could just about get away with printing ABS without a fan. Especially on an ultimaker with fast movement of the head inducing airflow - but you will experience some decreased performance.

Calinb:

It is a bit of a shame, but the reality is that you need to keep weight down, and the hotend already has a heatsink that is much more effective per unit weight than the plate is. It therefore makes sense to remove it.

The idea of putting a force cooled sink on the plate and then mounting a stainless break right to the plate has merit though - we have done just the same thing on a Mendel90 RepRap with an aluminium X-Carriage.

Being that there is some real interest I will accelerate sorting out a bowden coupled version of this hotend, and a printable way of mounting it.

Does anyone know of good pneufit couplers that allow filament to pass smoothly through them?

Regards,

Sanjay from E3D

 

[thingster 0]

Currently I print ABS at 250 °C which is quite low for that material. It works also with the default UM V2 nozzle I use, but I'd also like to go a little bit higher to about 270 °C or so for a better flow, but those temps aren't recommended for the UM hot-end. Maybe your new hot-end could be a solution to this. How big is it and would it waste any space of the UM's print volume?

 

[calinb 11]

It basically doesn't work, the ABS after a few minutes and some retracts becomes bonded onto the top cold section of the tube, as the trasition area is too long.

I think for this to work, I need stainless steel, not brass for its much lower conductivity in order to shorten the transition length.

 

Yes--my plan is to actually shorten the entire hot end (providing even more Z-range too ) and extend the stainless cold end tube up into the wooden box. There's not a lot of room (~1/4" OD SS tube) inside the box, but there is just enough room!

 

You will have a lot more luck by re-desiging your fan duct design. I almost guarantee that with the

fan airflow being asked to do a 90 degree turn almost immidiately after the exit - that the airflowrate is

almost zero through your heatsink.

 

A new fan orientation and new duct is the plan. I refuse to add a second fan to the head.

 

It is a bit of a shame, but the reality is that you need to keep weight down, and the hotend already has a heatsink that is much more effective per unit weight than the plate is. It therefore makes sense to remove it.

 

Your hotend already has a heatsink but my Ultimaker already has the plate! The plate may not become my entire heatsink, but the surface area of the plate could be increased somewhat with some milling--perhaps even surpassing the surface area of your hotend heatsink. I don't know yet.

 

Currently I print ABS at 250 °C which is quite low for that material. It works also with the default UM V2 nozzle I use, but I'd also like to go a little bit higher to about 270 °C or so for a better flow, but those temps aren't recommended for the UM hot-end. Maybe your new hot-end could be a solution to this. How big is it and would it waste any space of the UM's print volume?

 

I'm printing Ultimachine and Protoprinter ABS currently The Ultimachine requires high temps! I'm printing it at 275 C. The simple mods that I made have kept my new PEEK and Teflon part pristine (unlike my pre-mod PEEK, which was showing signs of over-temp).

I don't think my MakerGear barrel and nozzle and mods result in the optimum configuration for ABS printing on the UM, but it's working and I probably won't find time to play with my more challenging fabrication project for a while.

 

[lars86 42]

Your hotend already has a heatsink but my Ultimaker already has the plate! The plate may not become my entire heatsink, but the surface area of the plate could be increased somewhat with some milling--perhaps even surpassing the surface area of your hotend heatsink. I don't know yet.

 

Having the print head plate serve as your "heat sink", is a bad idea in my eyes. This means that any heat that you intend for it to dissapate, has to be conducted up the entire tube, which leads to a very large zone which is well above the glass transition temp of the filament.

I think the idea of minimizing this zone, in the pursuit of having cool, rigid filament right up to the melt zone, has a lot of merit.

 

[lars86 42]

Righty!

Thanks everyone for the informative replies and suggestions:

Lars:

We too are modelling/simulating in SolidWorks. Very nice.

Our wall thickness is 0.4mm. You have to consider both the wall thickness and it's length obviously. Fouriers thermal transfer equation is most useful in this regard. If your break is short (Like ours) then you also must consider convection and radiation. This is more of a black art and really needs to be done empirically rather than calculated.

What length of 1mm wall section do you have? How much wattage is conducting up that break?

Brass for the nozzle is for a couple of small factors - It machines much more easily for tiny holes, and the finish is less "burry" and more smooth, which makes a real difference when you want a quality exit orifice. The other is that aluminium nozzles have a very low specific heat capacity - you actually want to store some heat, for sudden extrusion bursts where melting lots of plastic sucks out heat and for keeping a smooth temperature when fans and airflow are involved. When you have a fast moving head like in an UM then you are always experiencing significant airflow.

We did experiment quite a bit, and look at the results others are getting with various nozzle orifice geometries. Our lead in angle is largely dictated by the angle of the drill bit tip - there is some room for adjustment here, but not significantly so. The main thing to get right is the ratio of diameter to length. You need to induce laminar flow in the fluid plastic for nice results, which requires length to be at least 2x orifice diameter. The other consideration here is ease of flow/backpressure versus oozing/dripping. We went for 2.4x diameter for a length of 1mm which gives a nice balance between all these factors.

 

Great info Sanjay!

Wow, 0.4mm is THIN! My 1mm thick section is 2mm long. In that zone I plan on using a stainless steel washer, backed on both sides by isulative ceramic tape. The tape should keep it relatively isolated from conductive and convective heating and the SS washer should act to reflect some radiation too.

According to SW, the power conducted up my stainless tube is ~7W, I'm not sure if that is correct, or if I need to make some reference geometry to get a better number. What are you seeing conducted up your mini,mini tube?

Interesting point on the heat capacity. Have you been able to demonstrate that issue with an aluminum nozzle? I ask because I did some hand calcs for how much power is consumed to melt a mass/volumetric flow of filament and found a very low number. I used a feed rate of 2.5mm/s of 3mm ABS (which I have since been told is about double a normal extrusion rate), and came up with 5.3W consumed to bring it from 25*C to 220*C. That seems a modest amount of power, so I'd expect the fluctuations to be even smaller. Having access to very fast thermal conduction from aluminum and a powerful heater would seem to negate any issue with nozzle temps dipping. Thoughts?

I'm with you on the nozzle geometry too. It would seem like making a customized tool that cuts a transition profile from 3.2mm to 0.4 could be a big help. Having the 0.4mm entry comprise a steep angle (118*), with a sharp edge is certainly not helping produce laminar flow. If you could move from a very shallow angle, through a radius, and in... that would be awesome. Tiny fuggin tool though! I just got a couple 0.4mm bits in the mail and couldn't tell two were stuck together at first! hahaha.

Lars

 

[kitwashere 1]

I am wondering if the components that come with this kit are plug and play electrical wise? I didn't see any info on what type of thermocouple or heater are included and if I will need different firmware on my machine. Sort of a newbie when it comes to these things. I'm playing with sketchup now making a mount for this thing! Can't wait to get it up and running

 

[sanjay-e3d 3]

Hi all again,

We have ordered some really nice looking POM (Delrin) push fit pneumatic fittings. These definitely have a permissive OD for the filament, and POM is a very low friction material so these should work nicely, just need to get a hold of them for testing now.

Calinb:

 

Your hotend already has a heatsink but my Ultimaker already has the plate!

 

From the point of view of making your own on a one-off basis this is all well and good, but from a marketable retrofit version you have to consider that our heatsink is designed as an efficient heatsink, and that plate is designed as.. a plate. That said, we have had really good results with a plate as a combined heatsink and X-Carriage, with a 3mm SS heatbreak poking right out of the bottom of the plate, leading directly to the heater/nozzle. This gives really low Z profile which is nice. We did need to add a PC heatsink/fan combo to the plate, just like am001 has in his photos.

Lars:

0.4 is indeed quite thin, but no challenge for most modern production companies - it is also perfectly strong enough, I cannot break the SS part by hand - I have to use a spanner and the chuck of a lathe to grip it firmly enough so I am not worried about mechanical strength at all.

7W seems about right for you CSA and length with stainless - this is quite a lot considering that your average hotend needs about 10-15W at idle to maintain temperature. Pushing more power into it to compensate shouldn't really be a problem, but remember that heat you then have to get rid of (quite rapidly and sharply) at the heatsink. My advice would be to consider going longer or thinner. How are you planning to manufacture?

KitWasHere:

We will try and make the ultimaker kit accept the existing thermocouple/amplifier combo. Which should make it plug and play. Can anyone get me info on the OD of the TC? Apparently 3mm?

 

[kitwashere 1]

Yes the stock TC is just under 3mm OD.Mine is 2.97 to be exact, just measured it.

I am hoping that the included components will work as I have already received my kit (I placed a pre-order the day you guys put it on the site) and will have to modify it to get the old TC in there. The stock heater fits in this nicely if I ever have to use it though

 

[lars86 42]

Sanjay:

Good to know that 0.4mm is plenty strong... obviously, the thinner, the better for this piece!

I'm glad my simulated conductive transfer is in the ballpark too. The stock UM hot end uses a brass up tube which my simulations show to conduct a vast amount more heat. I put a few images up in a gallery from my tests. The first compares a brass nozzle and uptube, to a stainless steel up tube, and finally stainless tube with heat sink. The next compares the original 3 fin heat sink I modelled to the heat sink I made yesterday.

All tests were run with 50 W/m2K convection on exterior surfaces, 40W heater power added to the cartridge bore, and 4W lost to the filament in the melt zone.

For the time being, most parts will be made on the manual lathe. I made a custom 1mm slotting tool yesterday and created a heat sink with it. The up tube will start as a stainless steel 8x1.25 bolt, and I'll machine it to my design shape.

 

Hi all again,

We have ordered some really nice looking POM (Delrin) push fit pneumatic fittings. These definitely have a permissive OD for the filament, and POM is a very low friction material so these should work nicely, just need to get a hold of them for testing now.

Calinb:

From the point of view of making your own on a one-off basis this is all well and good, but from a marketable retrofit version you have to consider that our heatsink is designed as an efficient heatsink, and that plate is designed as.. a plate. That said, we have had really good results with a plate as a combined heatsink and X-Carriage, with a 3mm SS heatbreak poking right out of the bottom of the plate, leading directly to the heater/nozzle. This gives really low Z profile which is nice. We did need to add a PC heatsink/fan combo to the plate, just like am001 has in his photos.

Lars:

0.4 is indeed quite thin, but no challenge for most modern production companies - it is also perfectly strong enough, I cannot break the SS part by hand - I have to use a spanner and the chuck of a lathe to grip it firmly enough so I am not worried about mechanical strength at all.

7W seems about right for you CSA and length with stainless - this is quite a lot considering that your average hotend needs about 10-15W at idle to maintain temperature. Pushing more power into it to compensate shouldn't really be a problem, but remember that heat you then have to get rid of (quite rapidly and sharply) at the heatsink. My advice would be to consider going longer or thinner. How are you planning to manufacture?

 

[sanjay-e3d 3]

Hi all,

KitPrinklers:

Thanks for the early order! There are two holes for temp sensors on the heater-block. One is 2mm going all through the block, and another is 2.5mm and only goes in 4mm or so. Unfortunately it looks like you might need to get the drill out and use a 3mm bit to expand one of the holes. Be careful about not drilling through into the holes for other bits, it's quite close in there! Let me know how you get on.

Lars:

Awesome work! Really like the comparisons. Having a nice small groove/turn tool with a carbide tip is a godsend ISCAR do a cracking one. We too started out M8, but rapidly moved to M6 as it's much close to what you want to end up with. Having only a small diameter of SS inside the heatsink helps too, the less SS you have the closer the al heatsink is to draw heat. Having a larger diameter piece of SS acts like an insulator. Also A4/316SS is quite a bit thermally better than A2 alloys. With all that said, I expect your design will work just great as it is, but perhaps a little hot at the heatsink. Would be really nice to see how your sims match reality. Good luck!

 

[lars86 42]

Sanjay:

Thanks for the feedback!

Yeah, the threaded size has competing properties. Larger threads have more surface area, which enhances conduction from the tip/heater block, but that heat must now travel a longer distance through the insulative SS to reach the up tube. I'll play with both configs and see which wins.

I also tried bumping the 1mm section length to 3mm and did not see an appreciable difference.

I did a few hand calcs to compare the brass vs aluminum nozzle. Aluminum actually has a much better heat capacity (mass based) than brass. If you pretend to be volumetrically limited (which we really aren't) and factor in density, I find that brass has ~26% higher volume based heat capacity. But aluminum is at least 63% more thermally conductive. I think that aluminum wins in this regard, especially considering that you can bump the aluminum nozzle size up 26% to achieve the same energy density, along with much better conductivity.

I am playing with a design that has a 1" diameter nozzle with the heater built in. Even with a simulated layer of insulation on all exposed nozzle surfaces, I am seeing temps ~5*C higher on one side of the melt zone than the other in transient simulations. The single heater cartridge is inherantly prone to this. My original idea was to have a flexible heater element that would do at least one wrap around the perimeter for even heating. I really think that even twin smallers heaters, 180* opposed would be enough.

Sourcing electrical components that can be driven with the existing power supply circuit, and will provide similar heat output, is out of my realm of expertise. I'm a mechanical design guy! Can someone recommend a twin heating element solution that would be a plug and play replacement for the Ultimaker cartridge? I guess roughly half the wattage and twice the resistence , wired in parallel?

Lars

 

[kitwashere 1]

Damn, that is going to be troublesome. I will see if I can find one of my friends with a drill press.

In the mean time I will do some research and see if/how I can get this included TC to work for me.

I am now trying to get my Ultimaker to print a mount a just designed as a prototype, which is an uphill battle as usual with the stock hot end. I've attached what I've come up with so far, maybe someone can criticize while I fight my Ultimaker haha. I still need to add a way to guide the bowden in.

http://www.thingiverse.com/thing:73243

 

[chopmeister 0]

Thankfully there is no chance of plugging on the bowden/alu interface with this hotend, so all that's necessary is to keep the bowden in place precisely enough the filament slides in where it should. It doesn't have to be leak proof, which gives us many creative possibilities with mounting, and less potential problems if you miss the bowden length by a fraction of a mm. Which is the single worst thing about the V1 hotend I'm still stuck with.

I don't really intend to use this hotend with a bowden setup, but to test a completely different extruder I'm working on, though I'll try to whip out an easy mounting scheme when I get it. I do suspect a loss of a cm or two in print area on either XY or Z axis, in order for it to function properly.