v3 hotend!

[snowygrouch 1]

Drilling stainless is one of those things thats counter-intuitive. You think its really a hard material so back

off the feed rate to preserve the drill-bit, but thats fatal.

If you back off the cutting rate you will slide the bit tip over the same bit of metal, heating it and then

instantly hardening it. Making it them impossible to machine at all. So keep a good cutting rate and dont slack off or you will harden it and then be left with an essentially un-machinable part (unless you are a lucky boy and have

solid carbide tooling !)

High dosage of cutting fluid is essential to keep the bit cool.

Regards

C.

[alaris2 1]

I'll second that. and probably a carbide bit is a good idea anyway. the work hardens very easily and then becomes impossible to drill - I found going slow was a really bad idea on some test pieces.

I've ordered some carbide bits and a reamer too for good measure, I'll see what happens if I open the tube out by 0.1mm.

meanwhile I now have a config 3 - E3D nozzle, E3D SS section, UM V1 heater block and heater, E3D cooler block. This is a totally V2-less solution for those wanting to go straight from V1 to V3. I've improved the fan design slightly and will post some pics shortly. I think I'll stick with the 'hanging' bowden solution since it seems to work better than expected. (I can even get the calipers in there or a marker pen to color the filament as it goes into the nozzle!)

[alaris2 1]

pleased to say I got it working today on all accounts. it did take several tries however.

I'm now using my 'config 3' (see above) with an improved heatsink and fan design to blow the warm air down onto the bed to help with bridges etc. this is necessary since I've hooked the fan up to where the original cooling fan went but I still want to have bridging capability.

I got a bottle brush, drill, and some polishing paste and went mad polishing the inside of the nozzle and stainless steel section. they were already well polished and I'm not sure I opened up the ID much if any, but it made me feel better.

anyway it prints NYLON at 280C and it prints it well. the cold end is cold enough to touch (I would guess 40C) so will be OK for PLA also.

I need to tweak all the slicer settings big time, getting layers to stick is hard, edges are a bit wobbly right now and infill is a mad squiggly mess.

I also printed at 150% extrusion to stress test. no leaks, a little bit of burning smell (I think it was the heatsink compound), no pops (since it's not possible anymore!) and a constant stream of 0.6mm material (from a 0.4mm nozzle).

oh. and did I mention the NYLON and the 280C, no more PEEK for me!

(hey maybe I can extrude PEEK, that might be fun)

[Daid 306]

(hey maybe I can extrude PEEK, that might be fun)

Have you smelled the stuff after it got too hot and melted? I wouldn't want to try to extrude that.

[alaris2 1]

maybe out in the garage then.

I'll probably have to move everything out there anyway - ABS, NYLON, PEEK etc. are all a bit smelly compared with PLA.

and even PLA can give headaches..

but I doubt I could get PEEK in 3mm rods anyway?

[destroyer2012 0]

SWEET CITY!

Don't forget to put pictures of the items printed in nylon! Where did you get your nylon filament/feedstock?

[alaris2 1]

a couple of pictures of the pros and cons -

in natural nylon 6/6. a sample i obtained from a friend but since it works i've now ordered some myself. someone on here (sorry forgot who you were) suggested using nylon welding rod. good tip, although suppliers seem few and far between. for now i've had to use what i think is intended as strimmer line, but am sticking to the white natural stuff since I don't want to accidentally get fiberglass in my nozzle thanks!

nylon seriously needs a heated bed as you can see from the left sample - nice curling effect there. some blobbing, and stringing evident too, especially in the right sample. the nozzle tends to drip and retraction doesn't work the same for nylon. the rules are a little different as I also found for layer height and overlap. the infill is messy (think I mentioned that before) and the top layers are a problem still - for some reason minimum layer time works differently and the layers don't quite align so it just falls to bits (hence the broken top piece)

would be great if someone else wants to try and swap experiences, it will hasten the learning process somewhat of these new materials!

[destroyer2012 0]

Those prints look pretty good I'd say! Are they flexible? How good is the layer adhesion? Can you make a replacement extruder gear with this stuff?

If you are experiencing poor layer adhesion perhaps the answer is a higher extrusion temperature? Are you using a fan when extruding this? I know when I first started printing in ABS I was cooling it too much and all my parts came out brittle, so I increased the extrusion temp (240 now!) and turned down the fan and now my parts come out (dare I say) perfectly.

[alaris2 1]

I'll try that, thanks destroyer. yes I think it's fair to say it's more like printing with ABS than PLA - my fan has been replaced with the cold sink fan, so I only have a nearby desk fan for cooling which I had on for the first print (right) and off for the second (left). I'm not sure how important cooling is for ABS/NYLON? for PLA it was critical and of course this also affects min layer time so maybe is related.

neither part is particularly flexible, but that's because i printed at 50% infill for the second one. the first one is naturally strong due to its shape. maybe i'll try printing something long and flat.

the piece on the left is almost indestructible - even that flat section at the top with the hole barely moves (actually it does flex very slightly now i try it again)

layer adhesion - I was going to print a test piece and hit it with a hammer. seems as good a test as any (not very scientific i know) but extruder gears should be no problem provided that curling is taken care of.

I may try a chambered approach like you have and see if it helps.

[destroyer2012 0]

My general experience with ABS is just don't worry about cooling. When I print, I only turn the fan on for making perimeters, and even then only at half speed. I think the chamber helps a bit but it's really not hot enough (since I don't have a dedicated chamber heater/ convection fan) to prevent all warp, so you should be OK with a heated bed + no cooling on the part.

I'm glad to hear those parts are solid! I wonder then if you can replicate the 2BEIGH3 results in terms of print flexibility/solidity

http://www.instructables.com/id/Combina ... -Overview/

He doesn't even use a heated platform, and he also uses blue tape to make the nylon stick.

Definately going to try to make a v3 nozzle myself.

[alaris2 1]

I have no clue how he got those to stick - that part on the right I had to superglue onto the bed and nearly broke the bed prising it off. w/o glue it curls like on the left part.

I think your setup is probably ideal for this destroyer - but if you haven't upgraded your extruder you may wish to - you need a ton of force to push that slippery nylon through a 0.4mm nozzle! I have a Bertho extruder + V2 bolt at present - it seems to be holding up (that's why I tested it at 150% to see what would happen and if I was marginal or not)

conclusion is, when manually extruding, expect it to be way more difficult than PLA (and probably ABS but I never tried that)

[calinb 11]

I'm interested in printing stronger parts that can also handle elevated service temperatures. ABS is fine for now, but I'm designing a new hot end and would like to resurrect this forum thread. I'm not interested in more fans or active cooling unless absolutely necessary. It seems to me the associated additional complexity can be avoided by selecting more expensive materials. I already have a bunch of grade 2 and 5 titanium, but I think the much lower thermal conductivity of Macor is the way to go.

It's interesting that UM Ltd. chose to use PEEK instead of designing a single piece PTFE/Teflon part for their V2 hot end. Both materials have similar maximum operating limits (about 260 C for long term exposure). They also have nearly the same thermal conductivity. It seems to me that the PEEK and V2 Teflon tube could have been integrated into a single part. Perhaps the parts UM Ltd. selected were "off the shelf" and therefore machining or fabricating a new integrated part was avoided. Looking at the McMaster Carr site, Extreme-Temperature Slippery PTFE is actually less expensive than PEEK. PTFE has poor tensile strength, but I think it could handle the mostly compression forces in this application.

Regardless, Teflon and PEEK can only reliably handle the temperatures required to extrude ABS and I want to get beyond the 260 C service limits and extrude materials like polycarbonate at 300 C or nylon at 320 C. I think I'll machine an extra tall version of the PEEK insulator from Macor (pricey stuff). I can design it to accept the V2 Teflon tube on the upper (cold) end but, more importantly, I can use an internal diameter that's slightly smaller than the brass tube ID on the hot end. This will reduce the likelihood of plugs forming at this hot junction of the parts. The Macor insulator can be designed to be quite long (up to 2.5") and still fit in the Ultimaker hot end wooden box. The PEEK is 0.674" long so there's a lot of heat-dissipating improvement room available for reducing the "cold end" temperature by making the conductive path to the cold end and Bowden tube longer.

I can bore, tap (I hope), and turn a new Macor part on my lathe. Carbide tooling is apparently required, which I have, but I don't have a threading tool sufficiently small in carbide to cut the internal threads. I might have to make one. 3" of 0.625 round Macor rod is $48.61 or I could buy 6" and machine two Macor insulators for $79.58 and have an extra part to sell.

I plan to install V1 nozzles in this high-temp hot end. They are more commonly available with different size orifices and I don't think the extra heat isolation provided by the V2 brass pipe (with the circular flange contacting the PEEK insulator instead of the aluminum heater block) offers a significant heat transfer reduction--especially if I maximize the Macor insulator length to 2.5 inches. However, the V2 setup should work with my Macor part too.

From top down, I'm planning:

1. Bowden tube (PFA, Teflon/PFA, or Teflon--doesn't really matter much).

2. Macor insulator (Bowden tube will slip-fit into the Macor part and I'll dispense with the V2 Teflon tube).

3. V1 brass pipe (or equivalent made from a Maker Gear "heater barrel").

4. Aluminum heater block.

5. V1 nozzle (or Maker Gear "BigHead" nozzle milled down to correct height).

Again, the V2 nozzle and brass pipe should fit too.

Macor has higher thermal conductivity than PEEK, PFA, Teflon PFA, and Teflon so I hope 2.5 inches of length will be sufficient to keep the cold end temperatures below the melting point of the filament. I guess I could calculate the predicted temperature. If the cold end temperature is too high, the next design complication would be to stack a PEEK section on top of the Macor section. The Macor part would withstand the temperatures required for polycarbonate and nylon extrusion and the PEEK would provide better insulation for the cold end. The Macor part would just need to be long enough to keep the PEEK under 260C.

-Cal

Edit:

>If the cold end temperature is too high, the next design complication would be to stack a

>PEEK section on top of the Macor section.

No--this strategy would not help, because all the plastic materials (PEEK, Teflon, Teflon/PLA, PLA) have a similar maximum temperature limit of 260 C. The Macor part will need to be long enough to obtain 260 C or less at the Bowden tube. I don't think it will be difficult to achieve--only expensive (Macor)! According the UM Ltd. discussions of the V2 hot end, the more thermally isolated aluminum heater block (due to the V2 brass tube design) would help a little and reduce the minimum length of Macor required..

This product looks interesting. If my arithmetic is correct (and it probably isn't ) the thermal conductivity spec works out to 5.7 to 11.4 W/mK. Though not designed for joining parts, it might work for gluing threaded pipes to nozzles to aid component dis-assembly (the parts separate where desired).

http://www.stovepaint.com/Products/Prod ... #Technical

Data

Now I'm leaning toward building it with a V2 style nozzle and brass tube, made from shortened Maker Gear BigHead nozzles and barrels that are glued together. The BigHeads come in a wide variety of orifice sizes and ship cheaply within the U.S..

[snowygrouch 1]

Well before you ditch any ideas about active cooling, its worth knowing that the 40mm fan AND duct I use are a collective weight of 20grams.

You certainly can make the hotend of sufficient size with enough surface area to dissipate the heat you need to prevent heat creeping upwards, but do some calcs on what mass you are adding to do that. I will be pretty surprised if you can do it for less than 20g extra.

Anyway, I will watch your progress with interest.

C.

[alaris2 1]

wow, long post. interesting stuff too.

but.. erm. why?

just use the £50 hotend I used from E3D. all metal. no temperature limits. has been in service now for several months and is totally outperforming V1 and V2 UM nozzles.

basically it just kicks ass. why reinvent that wheel?

if you want a smaller nozzle, use one of the makergear ones for extra accuracy. if you want to keep the heater and thermistor electronics from UM, just reuse the heater block. it's all interchangeable.

no 'popping' no blockage no mess no hard work reinventing wheels

I'm building a dual head version now it was so successful.

nik

[calinb 11]

snowygrouch: I'm not motivated to ditch active cooling because of concerns over adding mass to the hot end. Rather, I prefer to not add more wires and powered elements that have the potential to fail more often than a simpler design that features attention to the selection of materials and mechanical details. One fan is inconvenient enough (and I often wish it were not in the way). I'll try to find time to run some numbers but I suspect I can get by with much less than 2.5" of Macor. The goal is not to reduce the temperature of the cold end by dissipating heat, as with active cooling. The goal is to select a material that can withstand the higher temperatures while minimizing heat conduction in the first place. Though you are right; materials with greater thermal conductivity must dissipate the additional heat somehow--either with active cooling or more surface area. Macor is not as good as PEEK for minimizing conduction, but it's still much better than titanium and stainless steel.

alaris2: Again--I'm reinventing the wheel to realize a passive solution for printing at 300 to 320 C. I already have Makergear nozzles (both smaller and larger than my original UM nozzle). They can be easily adapted to the UM on my lathe or mill and I'm currently running a modified UM V1 nozzle in what I call a "hybrid V1/V2" configuration. Finally, I would not pay E3D prices, especially after shipping charges to the U.S.. I often order from McMaster-Carr. I can add a small Macor rod to an order and the shipping will cost me little, if anything. I plan to reuse all my UM components, except the PEEK and the V2 Teflon tube I could still use the V2 Teflon tube, if I find hot plastic sticking way up at the Bowden tube / Macor insulator interface.

[msurunner 2]

There is a certain satisfaction from seeing your creation at work, too. Interested to see where this goes. I'd be curious what your cost would be after everything's done (both with and without labor estimates) so we could get a comparison on what the cost to build and buy a comparable setup should look like.

[jeremy 0]

For what it's worth, I've extruded the taulman3d nylon at 255 degrees and it works great. Layer-to-layer bonding strength at that temperature is far beyond any other material I've printed with - so unless you need to print a particular grade of high-temp nylon, or some other material like PEEK, I don't see why anything higher than 300 is necessary.

I've also tested some polycarbonate from ProtoParadigm using an all-metal actively cooled hot end I made and found that it flows well at 265~270. The problems I had with it were more with the temperature of the build environment than the extruder. I had my platform set at 130C to get it to stick, but anything built more than ~1cm above the bed was crap (layers separated before the print was even finished). So what I concluded was that if I want to be serious about printing PC, I need an enclosed, heated build environment... not just a high temp extruder. Could be wrong though...

[alaris2 1]

what problem(s) do you anticipate with an active cooling system with the fan switched off or removed (ie. pretty passive really at 300C?

if the answer is 'the bowden tube' then simply don't have it in contact with the metal. a number of us (me included) have suspended the tube above the opening. air is an excellent and really cheap insulator

we called this design a hybrid V1/V2 nozzle - it includes a V1 nozzle, and either the V2 teflon insert or 'thin air' insert - maybe it's similar to what you have, I can't be sure, but it's discussed in detail in another thread.

the 'active' can be switched off if ambient temperature permits, or material temperature is low (I don't use it for PLA for example, actually I don't even have a fan attached at all right now)

the only reason for the active is when you move to a chambered approach with a heated chamber or you want to carefully adjust the print temperature quickly or accurately (eg. printing with wood)

MSU is right tho, it's always more fun to make something than buy it, so we look forward to seeing some photos! good luck!

[calinb 11]

260 C is the maximum PEEK long term service limit. I'm running a hybrid V1/V2 now, but I start worrying about the PEEK when printing much above 260 C. My black Ultimachine ABS doesn't even bond well at 260 C at modest print speeds, though it's very good when printed at elevated temperatures. Other ABS works fine at 240 C. It's amazing how variable ABS (and I assume PLA) can be! For piece of mind and also looking forward to printing higher melting point plastics, I have:

I can easily double the total length of the PEEK with a Macor insulator (MI) and a Macor rod long enough to make to MIs costs $50. I'll do the machine work myself. The top part of the MI will fit into the existing hot end by cutting out the corner of the wooden hot end box. (It's already partially cut-away in the V2 hot end.). I'd like to try to use Thurmalux Hi-Temp Lab Metal to bond a long 6mm threaded brass pipe into the threaded bore of the MI, though theading should not be essential if the Hi_Temp Lab Metal holds well. The section of brass pipe protruding out the bottom of the MI will be long enough to create a small air gap between the MI and the aluminum heater block.

Assembly will be to drop the MI assembly (brass tube already bonded in place) though the hole in the aluminum mounting plate. Then thread the aluminum heater block onto the bottom of the brass tube until it contacts the MI. Next, a nozzle (MakerGear BigHead) should be selected and tightly threaded onto the brass tube (the brass tube is turned down at the nozzle end and seals nicely inside the BigHead nozzle). After tightening the nozzle on the brass tube, the aluminum heater block can be screwed back down tightly against the nozzle, establishing the air gap above and locking everything in place on the threads. The TC and heater connections and the rest of the assembly is conventional.

One advantage of the design is it eliminates many junctions where plastic can leak into threads (and even out of the hot end). I don't know if I'll use a Teflon tube on the top of the MI, install a Teflon Bowden tube, or just use an air gap. I don't know how readily molten plastic sticks to Macor and I don't know if it'll be too hot for Teflon (and every other commonly used Bowden tube material) up there.

[snowygrouch 1]

I think you might want to reconsider the one piece brass tube right up the middle.

In the end this will conduct heat straight upwards, giving a tall hotzone. Which is bad, and since

you have a solid metallic conductor (the brass rod) all the Marcor is doing by being an insulator is actually

helping to keep the brass rod hot all the way up by stopping conduction out of the brass.

I would say that if you want a metal part there, brass is only ever done because its easy to machine.

Thats about all it has going for it. Stainless steel will conduct alot less heat, as well as being

alot stronger than typical "brass" (unless you want to get some special alloy).

Just my thoughts on that.

C.

[calinb 11]

Yes--stainless or titanium would be better for the hot barrel/pipe and I have both of these materials on hand. And yes, Macor is somewhat worse than PEEK. (Low thermal conductivity is the main benefit of PEEK, because it's not particularly resistant to high temperatures.)

Nevertheless, many printers use a brass tube right up through the middle of the insulator, including the UM (it goes nearly to the top of the PEEK too.) It's only necessary to keep the temperature of the Bowden tube or Teflon tube below 260 C to prevent hardware failure. Depending on the material extruded, too much heat at the Bowden tube can cause jams, which is what inspired some of the UM V2 changes but, if a printing temperature appropriate for the material is used, I hope that this is not a problem with the increase in thermal conductivity incurred by using Macor.

I once selected "Preheat ABS" on my UM Ulticontroller by accident when running PLA. Not noticing the high nozzle temperature, I rammed a new spool of PLA filament into the head by hand to get it "primed" and... instant jam! If the correct temperature is selected for the material, I don't think the UM design needs to change much to support plastics with higher extrusion temperatures. My goal is to select hot end component materials that can withstand the higher temperatures and then deal with the higher thermal conductivity with a longer hot end insulator That's my hope, anyway. Yes--air gaps, and a stainless or titanium barrel/pipe would help too.

[alaris2 1]

SG has said the most important thing I was going to respond with - having learnt from bitter experience (re-made the head about 7 times now) the brass inner tube to PFA tube is key and having an insulator around it (PEEK or otherwise) simply exacerbates the problem.

I didn't have the luxury of being able to work SS, which was why I bought the E3D kit, but if you can make a SS tube, that's definitely the best investment. you then don't need an insulator anywhere (it serves no purpose), instead take the SS tube into an AL block and join it with the existing Al bottom plate on the head to spread the heat.

for PLA temperatures, I can easily touch this (no active cooling required) at 20C ambient.

I can also leave the UM on, at temperature and not have to worry about jams which is nice (and not possible with the V2).

everything you're saying makes a lot of sense - especially about not much needing to change. I'd propose the thing(s) to change is (in order of how much effect it has) -

1) brass tube -> SS tube

2) press fitting the bowden against the tube -> introduce an air gap of a few mm

3) PEEK -> AL block.

for my hybrid V1/V2 i've not bothered with #3, or even with #1 - this works fine for PLA, but for nylon I have to actively cool the tip of the brass tube or I get instant jam as you describe.

for my all metal hotend, that problem doesn't occur, even at 30C ambient.

I can attach a photo if it helps (not sure if my description made sense or not) - I guess the jist of what i'm saying is that rather than trying to keep heat in with insulators, it seems to be better to spread and remove it - whether active or passive isn't so important.

nik

[calinb 11]

SG has said the most important thing I was going to respond with - having learnt from bitter experience (re-made the head about 7 times now) the brass inner tube to PFA tube is key and having an insulator around it (PEEK or otherwise) simply exacerbates the problem.

 

You mean brass to stainless, right?

 

1) brass tube -> SS tube

2) press fitting the bowden against the tube -> introduce an air gap of a few mm

3) PEEK -> AL block.

 

I already have plenty of stainless and aluminum so that's an easy list to try (far cheaper than Macor). I would actually try running my hybrid hot end with polycarbonate (or maybe run the V2 configuration to reduce the temperature of the PEEK slightly), if PEEK were an acceptable material for use with temperatures above 260 C.

My design ideas are focused on simply changing hot end materials to handle slightly higher temperatures, while retaining the design concepts of the UM hot end. I find the current design to work well and it's simple to maintain.. Given that Macor is still a much better insulator in comparison to any metal, I suspect that simply making a PEEK out of Macor with no other changes would safely permit the higher temperatures I need--especially if an air gap is provided at the aluminum block, like the V2. The limit becomes the temperature at the Bowden tube, but higher temperatures will only be present when printing materials requiring higher temperatures to melt. I suspect that backing-off temperatures to PLA levels will result in performance and behavior very similar to the current hot end using PEEK.

Sure--too much heat at the top just causes jams, but the UM designers must have had a reason for insulating the brass tube/filament "furnace") when they designed the printer. Then they retained the PEEK, however unpopular in user opinions, when they revised the design with the V2. They must have their reasons.

It might seem difficult to make a case for PEEK in the UM given that:

1. The PEEK doesn't help to protect the Bowden cable (or Teflon tube in the V2) from heat, because the brass tube runs all the way up to the Bowden tube (or V2 Teflon tube) junction anyway and brass conducts heat well.

2. The PEEK doesn't handle extended temperatures itself. Like the other plastics used in the hot end (Teflon, Teflon PFA, or PFA), PEEK is limited to 260 C maximum continuous service temperature.

3. The PEEK might make the "cold end" too hot and exacerbate jams.

I think the case to be made for the PEEK is that it insulates a significant portion of the heat chamber (barrel/brass tube) from the air, which improves the speed at which plastic can be extruded and reduces the duty cycle on the heating element necessary to maintain temperature. It probably increases the maximum rate that plastic can be melted and extruded over bare metal plumbing.

Similar to the situation with exposed metal plumbing, I've heard that the V2 might be inferior to the V1 in maximum extrusion rates possible. In the V2, the PEEK does not contact the aluminum heater block, which slightly reduces the heat conducted to the brass tube. However, in the V2, UM Ltd. was interested in reducing the temperature at the top of the PEEK to reduce the likelihood of jams. I believe UM retained the PEEK but reduced the temperature of the cold end slightly with the air gap at the aluminum block. It was a simple design change to tweak the temperature at the cold end a little.

[alaris2 1]

You mean brass to stainless, right?

 

stainless steel, yes. it's even better if you feel like adding the heat break and have a lathe handy, but it's not a necessity.

the reprap boys did a ton of tests on this - the link to their thread is included somewhere earlier in this discussion - and came to similar conclusions so I'm not sure we'll ever know why UM decided to use (and keep) the PEEK.

[joergen 2]

Did I post the info about the new Prusa hotend already?

http://prusanozzle.org/index.html

http://hackaday.com/2012/11/27/prusas-nozzle-prints-polycarbonate-peek-nylon/