New Hotend possible I have been working on a new design of hotend and if there is enough interest I will start a production run. This hotend is based on my previous design that has been very successful. Expressions of interest please so I can determine if I should go ahead with a small production run. Differences with the new model. It will be much shorter in total length. It will be fitted with a 16mm diameter mount that has a groove that fits E2D and J-head designs. Can be fitted with a Quick Connect Bowden hose fitting if needed or used without for Wade type mounting (no Bowden) Same good features' Still will be all CNC machined. Still will retain the heat break design. Still will use the male thread type nozzle fitting and sealing lands. Still will have the heater block that takes either a power resistor or a cartridge heater. [img]http://regpye.com.au/images/hotend/Genie-MK2.jpg[/img] I am also working on another design that will be first fully tested before announcement. That model will be an all metal hotend for higher temperature filaments, it will be a different type of heat break from the Genie MK1 and MK2 models https://reprap.org/forum/read.php?344,397616,397616#msg-397616 Fri, 17 Jul 2026 05:11:14 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?344,397616,466946#msg-466946 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,466946#msg-466946 rcjoseb Smart_Rap Fri, 06 Feb 2015 10:18:12 -0500 https://reprap.org/forum/read.php?344,397616,466631#msg-466631 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,466631#msg-466631
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?]]> cristian Smart_Rap Thu, 05 Feb 2015 18:19:39 -0500 https://reprap.org/forum/read.php?344,397616,452313#msg-452313 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,452313#msg-452313 vegasloki Smart_Rap Wed, 07 Jan 2015 20:52:40 -0500 https://reprap.org/forum/read.php?344,397616,452295#msg-452295 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,452295#msg-452295
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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.]]> regpye Smart_Rap Wed, 07 Jan 2015 18:39:44 -0500 https://reprap.org/forum/read.php?344,397616,452282#msg-452282 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,452282#msg-452282 loidor Smart_Rap Wed, 07 Jan 2015 17:55:32 -0500 https://reprap.org/forum/read.php?344,397616,449104#msg-449104 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,449104#msg-449104 loidor Smart_Rap Tue, 30 Dec 2014 09:54:50 -0500 https://reprap.org/forum/read.php?344,397616,449005#msg-449005 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,449005#msg-449005
Quote
regpye
Quote
loidor
If you weren't so far away I'd come by with a case of beer. Totally amazing :D

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]]> regpye Smart_Rap Tue, 30 Dec 2014 02:34:05 -0500 https://reprap.org/forum/read.php?344,397616,448909#msg-448909 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,448909#msg-448909
Quote
loidor
If you weren't so far away I'd come by with a case of beer. Totally amazing :D

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]]> regpye Smart_Rap Mon, 29 Dec 2014 17:53:32 -0500 https://reprap.org/forum/read.php?344,397616,448677#msg-448677 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,448677#msg-448677
Anyway, you should have an order to Sweden for a hotend and a 0.5 nozzle. Great Scott, this will be fun!]]> loidor Smart_Rap Mon, 29 Dec 2014 07:03:55 -0500 https://reprap.org/forum/read.php?344,397616,448659#msg-448659 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,448659#msg-448659
Quote
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.]]> regpye Smart_Rap Mon, 29 Dec 2014 05:35:42 -0500 https://reprap.org/forum/read.php?344,397616,448656#msg-448656 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,448656#msg-448656
EDIT: Ah, nevermind. Just look at what one can find when one reads text properly :) Of course it comes with a fitting!]]> loidor Smart_Rap Mon, 29 Dec 2014 05:21:17 -0500 https://reprap.org/forum/read.php?344,397616,436582#msg-436582 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,436582#msg-436582
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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.]]> cristian Smart_Rap Tue, 25 Nov 2014 12:56:30 -0500 https://reprap.org/forum/read.php?344,397616,436510#msg-436510 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,436510#msg-436510 loidor Smart_Rap Tue, 25 Nov 2014 09:57:31 -0500 https://reprap.org/forum/read.php?344,397616,436313#msg-436313 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,436313#msg-436313
Quote
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.]]> regpye Smart_Rap Mon, 24 Nov 2014 20:37:27 -0500 https://reprap.org/forum/read.php?344,397616,436310#msg-436310 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,436310#msg-436310
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.]]> BackEMF Smart_Rap Mon, 24 Nov 2014 20:18:42 -0500 https://reprap.org/forum/read.php?344,397616,435857#msg-435857 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,435857#msg-435857 loidor Smart_Rap Sun, 23 Nov 2014 17:20:04 -0500 https://reprap.org/forum/read.php?344,397616,435661#msg-435661 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,435661#msg-435661
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.]]> BackEMF Smart_Rap Sun, 23 Nov 2014 09:02:50 -0500 https://reprap.org/forum/read.php?344,397616,435428#msg-435428 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,435428#msg-435428
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.]]> loidor Smart_Rap Sat, 22 Nov 2014 15:58:11 -0500 https://reprap.org/forum/read.php?344,397616,426502#msg-426502 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,426502#msg-426502
Quote
cristian
Quote
regpye
I have added a section on my website showing how to re-assemble a Genie MK2 hotend, just in case someone needs to know how to do it correctly.
The link is on the hotend page, part way down the page.

Thanks Reg. I have to admit that the link is not that easy to find...
Yes I am aware of that, but I will be making changes soon and making in the main menu system.
Also I have found a better way to assemble, so I will be changing the whole of that assembly page.
I will try and get it done over the weekend if I can.]]> regpye Smart_Rap Thu, 30 Oct 2014 23:00:45 -0400 https://reprap.org/forum/read.php?344,397616,426499#msg-426499 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,426499#msg-426499
Quote
regpye
I have added a section on my website showing how to re-assemble a Genie MK2 hotend, just in case someone needs to know how to do it correctly.
The link is on the hotend page, part way down the page.

Thanks Reg. I have to admit that the link is not that easy to find...]]> cristian Smart_Rap Thu, 30 Oct 2014 22:55:11 -0400 https://reprap.org/forum/read.php?344,397616,424107#msg-424107 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,424107#msg-424107 The link is on the hotend page, part way down the page.
There are a few things to watch, so that you get the best performance.
The same information can be used on all MK1and MK2 hotends that will be sent out from now on, as the improvements are being added to both models.]]> regpye Smart_Rap Sat, 25 Oct 2014 01:02:55 -0400 https://reprap.org/forum/read.php?344,397616,422783#msg-422783 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,422783#msg-422783
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mikefiatx19
Hi Reg,
Genie Mk 2 ordered.
I found a fan at [www.thingiverse.com] and it worked well on my Jhead lite for cooling the hotend and the part.
But i want to upgrade anyway as I sometimes have issues with the extruded plastic not coming out straight down and it tries to curl up the side of the nozzle.
Looking forward to trying the new Genie Mk 2 when it arrives.
Regards
Mike

I am sure you will be pleased with it, everyone else has been.]]> regpye Smart_Rap Wed, 22 Oct 2014 01:45:29 -0400 https://reprap.org/forum/read.php?344,397616,422664#msg-422664 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,422664#msg-422664 Genie Mk 2 ordered.
I found a fan at [www.thingiverse.com] and it worked well on my Jhead lite for cooling the hotend and the part.
But i want to upgrade anyway as I sometimes have issues with the extruded plastic not coming out straight down and it tries to curl up the side of the nozzle.
Looking forward to trying the new Genie Mk 2 when it arrives.
Regards
Mike]]> mikefiatx19 Smart_Rap Tue, 21 Oct 2014 15:35:58 -0400 https://reprap.org/forum/read.php?344,397616,422262#msg-422262 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,422262#msg-422262
dysonfan2.jpg


so then you can place the fan at the end of the printbed and still have enough airflow.
You can print one, or just buy one very cheap and assembled from China
]]> BackEMF Smart_Rap Mon, 20 Oct 2014 19:10:10 -0400 https://reprap.org/forum/read.php?344,397616,421752#msg-421752 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,421752#msg-421752
Quote
cristian
The lazy way: a 2mm aluminum wire to hold the fan. It can be attached anywhere on the X arm and it allows re-adjusting the fan in all the positions and directions.

Sometimes simple is best ha..ha.. Good one Cristian.]]> regpye Smart_Rap Sun, 19 Oct 2014 19:43:34 -0400 https://reprap.org/forum/read.php?344,397616,421490#msg-421490 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,421490#msg-421490 cristian Smart_Rap Sun, 19 Oct 2014 08:10:46 -0400 https://reprap.org/forum/read.php?344,397616,421376#msg-421376 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,421376#msg-421376
Quote
BackEMF
I use a 80 mm fan like that on the Smartrap and there is always a way to make a fancy fan duct. If you need to..

Or do something with bernoulli in mind.

Yes You are right Mano, and on the MagicMakers I placed a fan behind the nozzle, mounted on an aluminium plate that was bent about 45 degrees and put a 40mm fan on that.
It blew across the piece as it was being printed and also controlled by the Mega.

Maybe something like this could be made for the SmartRaps?












]]> regpye Smart_Rap Sat, 18 Oct 2014 22:10:40 -0400 https://reprap.org/forum/read.php?344,397616,421374#msg-421374 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,421374#msg-421374
Or do something with bernoulli in mind.]]> BackEMF Smart_Rap Sat, 18 Oct 2014 21:56:48 -0400 https://reprap.org/forum/read.php?344,397616,421345#msg-421345 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,421345#msg-421345
Quote
mikefiatx19
I had a look at the I3 on your website. I dont think fitting the 80mm fan like that would be an option on the smartrap due to the space needed.
Regards
Mike

Yes you are quiet right. I use a stand that is movable on the SmartRaps, I can place the stand where ever convenient
I am also thinking about what is the best way to mount a piece cooling fan, it is not an easy solution.]]> regpye Smart_Rap Sat, 18 Oct 2014 19:49:01 -0400 https://reprap.org/forum/read.php?344,397616,421321#msg-421321 Re: New Hotend possible https://reprap.org/forum/read.php?344,397616,421321#msg-421321 Regards
Mike]]> mikefiatx19 Smart_Rap Sat, 18 Oct 2014 18:26:20 -0400