New Hotend possible

Hah, I haven't even built my repstrap yet, and I'm already interested in this one

Does it need direct cooling?

Does it need kapton wrapping? All the pictures seem to have it, but from what I've read there's ptfe sleeves and grub screws holding stuff inplace...

Also, is the postage with international tracking? If not, I could just as well go with airmail and save some cash

Anyway, I'll most likely buy one later this year, when the smartrap is starting to come together.

Hi Loidor,

I'm using Regs Genie hotend (and i'm very pleased with it)

I'm cooling it with a 12V fan constant on 5V. This cools enough and doesn't make any noise.
Mine has Kapton wrap, it can probably be build without Kapton but for me it's ok with the kapton
Shipping from Australia to the Netherlands was $18 and it took a few weeks.

All right, that doesn't sound that hefty. Do you have mk1 or mk2?

I have both actually. The mk2 I have not used yet. When I build build second machine it turned out to be easier to put the mk1 on.

Both hotend's are build the same way, the mk2 is a shorter so on the SmartRap that will give you a few cm of extra build height.
Compared to the Huxley hotend it heats up faster, stays at temperature more consistently, and I was able to print at higher speeds.

All in all i'm very pleased with it.

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BackEMF
Hi Loidor,

I'm using Regs Genie hotend (and i'm very pleased with it)

I'm cooling it with a 12V fan constant on 5V. This cools enough and doesn't make any noise.
Mine has Kapton wrap, it can probably be build without Kapton but for me it's ok with the kapton
Shipping from Australia to the Netherlands was $18 and it took a few weeks.

It can be used without the Kapton tape. The heater cartridge is held in place with a set screw (grub screw) and the thermistor is held in a screw hole with silicone adhesive.
The Kapton tape is used to help retain some heat in the heater block, but can be left off. Best to use with the Kapton tape if possible.

MK1 and MK2 are identical for the lower section, the differences are only in the upper heatsink area, MK2 being much shorter.
If the hotend is not placed within a cowl you don't need to use an active cooling fan, as long as air can get to the cooling fins there is no problem.
MK1 fits most machines, MK2 was specially designed for machines like the SmartRap that need a bit of extra print height or a shorter hotend.
The MK1 has a 15mm diameter grooved nut with a 3mm wide groove, while the MK2 has the same grooved nut that fits E3D hotends, 16mm diameter, 4.5mm wide groove. Both grooved nuts are interchangeable and can also be reversed around on the E3D end so that a different fitting can be used. Both are made to accept pneumatic fittings for Bowden delivery, or can be used without for Wades type of extruder, or can be mounted on a supplied adaptor plate for the extruders that have a 50mm wide bolt mount, or can be attached with a supplied M6 nut to an aluminium plate mount that some machines have.
Comes with a supplied 100K thermistor and several mounting types. Comes with a 0.4mm nozzle and 0.3mm and 0.5mm nozzles are available if wanted.

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

Sounds really, really nice Well, I'll at least finish my repstrap first, and I'll get one of those for the Smartrap.

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loidor
Sounds really, really nice Well, I'll at least finish my repstrap first, and I'll get one of those for the Smartrap.

It's not just nice: it's a wonderful piece of metal. I caress it from time to time to let it understand how much I appreciate the way it does its job.

I will also test its little brother MK2 within some days.

Right, I'm about to order one, but I'm curious wether it comes with a pneumatic fitting or not.

EDIT: Ah, nevermind. Just look at what one can find when one reads text properly Of course it comes with a fitting!

Edited 1 time(s). Last edit at 12/29/2014 05:23AM by loidor.

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loidor
Right, I'm about to order one, but I'm curious wether it comes with a pneumatic fitting or not.

EDIT: Ah, nevermind. Just look at what one can find when one reads text properly Of course it comes with a fitting!

Not only the pneumatic fitting, but a thermistor, an adaptor plate for 50mm bolt spaced extruder, spare piece of PTFE tube, Grooved nut that is interchangeable with either model hotend.
Standard with 0.4mm nozzle or 0.3mm and 0.5mm available instead, and a M6 stainless steel nut for fitting to a metal plate.

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

If you weren't so far away I'd come by with a case of beer. Totally amazing

Anyway, you should have an order to Sweden for a hotend and a 0.5 nozzle. Great Scott, this will be fun!

Edited 2 time(s). Last edit at 12/29/2014 07:04AM by loidor.

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loidor
If you weren't so far away I'd come by with a case of beer. Totally amazing

Anyway, you should have an order to Sweden for a hotend and a 0.5 nozzle. Great Scott, this will be fun!

Already packed and ready to post Erik.
It will be in the post today if the Post Office is open, otherwise it will be posted on the 2nd.

Thanks

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

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regpye

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loidor
If you weren't so far away I'd come by with a case of beer. Totally amazing

Anyway, you should have an order to Sweden for a hotend and a 0.5 nozzle. Great Scott, this will be fun!

Already packed and ready to post Erik.
It will be in the post today if the Post Office is open, otherwise it will be posted on the 2nd.

Thanks

Was posted this morning Erik. Tuesday 30 Dec

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

Aww, thanks! I'll let you know as soon as it arrives

It arrived today and is extruding molten plastic like a charm! Now it's just the rest of the repstrap that needs tuning =D

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loidor
It arrived today and is extruding molten plastic like a charm! Now it's just the rest of the repstrap that needs tuning =D

Hey it got there pretty quick for Christmas time, only 9 days from Australia to Sweden, amazing.

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

I just got one of each to test. I've got the MK2 up and going. Excellent quality, easy to use. PLA extrusion is as good as E3D or authentic JHead, which I consider the gold standard of FFF hotends. I got them to test on PLA only machines but will try some ABS at some point.

After several weeks I have finally managed to complete the report about my tests on the Genie MK1 and Mk2. Maybe surprisingly for somebody, the tests did not involve printing at all. I tried instead to do some "dry" measurements of the temperature in different points of the hot-ends, to support or disprove some conjectures about heat distribution in different situations. To do it, I built a small probe composed of a thermistor and two wires attached to it and insulated by a thin PTFE tube, less than 2mm thick as a whole. I added some marks every 5mm on the wires to use the probe as a sort of ruler. This allowed me to let it slide inside the hot-ends in the place of the plastic filament, and to sample their temperature in different heating/cooling conditions at different depths.

Necessary disclaimer: although what I did can give some hints about good and bad 3D printing practices, there is a number of reasons why it is not possible to infer directly "3D printing facts", that are:

• the head of thermistor is smaller than the diameter of the PTFE tube and the hole of the threads in the hot-ends, therefore temperature measurements may change a lot depending on how the head decides to bend itself and touch what is around;
• thermistor wires bend as well, so that the effective depth at which the temperature is measured may vary considerably from one try to the next, in particular in the presence of discontinuities (for example at the end of the PTFE tube/beginning of metal thread, which is also the most critical place since the temperature gradient is very strong);
• depth marks on the probe were done by hand with very little precision (actually they have been done and redone several times because the heat was dissolving them: the probe was not really built in the smartest way, I admit);
• the hot-end with such a wired thermistor is absolutely not the same thing than a hot-end with a melted filament, whose heat propagation happens with totally different dynamics, not to mention that the thermistor is used in a static condition while the filament "flows" in the hot-end continuously, possibly at different speeds;
• thermistors can be very imprecise, and two different thermistors brands have been used in the measurements (one mounted with the hot-end as usual, the other sliding in the hole of the filament);
• printer head was not moving during measurements, so, once more, cooling conditions are not the same than printing.

That said, I measured the temperature inside the hot-ends at several temperatures (from 175°C to about 240°C) and fan speeds (off, 10% and 50%) by

• heating the hot-end at the target temperature;
• waiting for several minutes (from 10 minutes up to 1 hour, depending on how long it took for the temperature to become stable);
• making the probe slide into the hot-end by steps of 5 millimeters to probe the temperatures at different depths,
• and then waiting some more seconds to let the thermistor settle down;
• repeating some of the probes in particular at the most critical points (for example close to the transition zone).

In the attached spreadsheet you will find the detailed data with every single measurement (averages in the cells, single measurements in the comments of every cell) made on the MK1 and MK2, and some additional measurements made on a personalized version of the Genie hot-end that I called "monster" (where the heat-sink was replaced with a crappy folded aluminum sheet), as well as some measurements on the Huxley hot-end too.
If you have questions or doubts about the measurements please let me know, I may also post some pictures if what I wrote is not clear enough (which is likely).

In the following, I will list some conjectures that I thought were true and my interpretation of the obtained data in relation to such conjectures.

You can use the Genie hot-ends without active cooling.
It depends. For the sake of clarity this conjecture must be split in the following two.

There is no increased risk of clog for the Genie hot-ends without active cooling.
True, at least in my experience, and this conjecture is also supported by my temperature measurements. Actually, as I wrote elsewhere, I never managed to clog these hot-ends (the only exception happened with Colorfabb woodfill for completely different reasons) so even if you double or triple a risk that is close to zero, it will still be close to zero. According to my temperature measurements, at typical PLA printing temperatures (I have not dared going beyond 185°C because of the next conjecture, but this temperature is already representative) the cold part of the hot-end goes slightly beyond 60°C, at which PLA becomes bendable but is still very far from melting.

These hot-ends are safely mounted even without active cooling.
It depends. As remarked in the previous conjecture, according to my measurements (that are very imprecise after the transition zone but sufficiently reliable in the cold zone), at standard PLA printing temperatures the interior of the base of the hot-ends goes slightly beyond 60°C. This means that if you are mounting the hot-end by using supports made of PLA (or whatever material with glass transition around 55-60°C), then you may have some risk of bending the PLA support after a while. If you are using other materials (plastic with higher glass transition temperature, or wood or metal) then no problem. Notice however that with the fan speed at 10% the hot-end is already cooled more than enough to avoid bending of PLA: in fact, even when heating at 240°C the temperature of the external surface of the base of the hot-end should not go beyond 50°C.

Holding the thermistor just with Kapton tape gives less accurate temperature measurements.
True. In my measurements I used Kapton tape for the thermistor of the MK1 and a drilled screw for the thermistor of the MK2. This caused a systematic increase in the measurement error of about 10°C in the case of Kapton. So I would say that it is highly advised to use a screw or thermal paste to hold the thermistor in place, to improve heat transfer and have more consistent results across different hot-end mounts (and maybe even to avoid overheating).

A good thermal insulation of the external surface of the heater block reduces the heating of the upper (cold) part of the hot-end.
False. Or maybe I failed to insulate properly the heater block? My hope was that with a good layer of Kapton tape around the heater block, the upper part of the hot-end would have stayed below 60°C thanks to a reduction of the flow of hot air from the bottom to the top of the hot-end. But this turned out completely false, probably because most of the heat passes through the PEEK insulator and the PTFE liner.

The MK2 is shorter and lighter than the MK1 but at the price of worse heat dissipation.
False. Well, of course the overall conjecture must be true, but the MK2 heat sink is already so “over sized” that at normal PLA printing temperatures (and even up to ~250°C) the difference between MK1 and MK2 is barely detectable (also because of the quite high measurement error) and in any case negligible in practice. The widest difference detected at the base of the hot-ends (lowest part of the grooved nut) was just 3°C (51°C of the MK1 vs 54°C of the MK2 with fan at 10%), when heating at 240°C. At lower temperatures or in the absence of active cooling, a bigger heat-sink does not make any remarkable difference, while at higher fan speeds both the MK1 and MK2 heat-sinks work “too” well to tell one from the other. To test the hot-end even in extreme conditions, I built a crappy heat-sink with a folded sheet of aluminum (the previously cited “monster”), to obtain a small square of about 3cm*3cm*1mm with which I replaced the original heat-sink: it worked perfectly, cooling down the cold part of the hot-end even when heating above 240°C. So now I have really no doubt about what Reg told me, that these hot-ends may work perfectly even without heat-sink at all!

A good thermal insulation of the nozzle (a couple of layers of Kapton tape around it) makes temperature more uniform across the hot part of the hot-end.
True, although this does not necessarily imply that in practice there is a real need. In the worst case among my measurement conditions (heating temperature 240°C, fan at 50%) the lack of Kapton tape around the nozzle causes a gradient of 5°C between the heater block and the nozzle itself. Notice that this difference is measured on some point close to the internal surface of the nozzle, so that such a gradient may be much bigger if one measures the temperature of the tip of the nozzle on the external surface. On the other hand, the continuous flow of hot melted plastic during printing may also overturn the situation and make the temperature sufficiently uniform. As a matter of fact I don't know how to prove or disprove any of these two sub-conjectures.


Some more conjectures that I have not tested:
A good thermal insulation of the external surface of the heater block reduces

• power consumption
• temperature fluctuations (in particular when the fan speed changes).
• heating of printed plastic on the opposite side of the fan (which usually causes dirty prints)

Further ideas?

Edited 1 time(s). Last edit at 02/06/2015 08:22AM by cristian.

Very detailed. I just ordered an MK2 and look forward to using it.