How to insulate hot end?

I would like to put some insulation around the hot end (around the nozzle) to prevent it from getting cooled down by the cooling fan.

I tried to put some cotton-like fiber glass insulation material around it with Kapton tape, and it didn't work out very nicely. It was just so messy...

Do you guys insulate your hot end? If you do, how do you do that?

I saw someone using a piece of one of those oven mitten silicon rubber thingy. I think that's a neat idea and much cleaner way than using fiberglass... if I can convince my wife to buy a rubber oven mitten (my wife thinks they are ugly) and then explain what a little hole in the new oven mitten is to her. LOL

I think there are some "insulation tapes" also, most of which seem to be for different application - like for automobile exhaust pipe and etc. but as long as their temperature rating is high enough for the hot end, I should be able to use them, too.

I have a 25mm fan pointed directly at my hot end running full sped constantly and have never had an issue with reaching temperature. Most of the time the hot end reaches its temp LONG before the bed. I got the fan to use with my j-head for printing PLA, but i've also accidentally had it turned on for ABS and have had no difficulty reaching 230 degrees.

I've had a lot of experience in wrapping hot ends in fiberglass. If you do it a certain number of times, you'll get a decent looking bundle, but the first couple you do will look like rubbish. I'd like to think I have it down to a science, but it's really an art form. ebay

I offer a suggestion which, admittedly, I haven't tried in this situation.
Here in the UK we wrap thin PTFE tape around pipe threads before we screw together plumbing fittings. I believe that PTFE is pretty heat proof (Wiki says it's melting point is 600K, and as the Teflon brand it is the coating on non-stick frying pans). Even if you wind layer upon layer, it gives a nice smooth finish. It's not expensive, is available on rolls, and is about 1/2 inch wide. I reckon a number of layers would provide quite good insulation. Most people in the UK will be familiar with it, but if anybody elsewhere would like me to post a picture of it wound on something, just let me know.

jbernardis Wrote:
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> I have a 25mm fan pointed directly at my hot end
> running full sped constantly and have never had an
> issue with reaching temperature. Most of the time
> the hot end reaches its temp LONG before the bed.
> I got the fan to use with my j-head for printing
> PLA, but i've also accidentally had it turned on
> for ABS and have had no difficulty reaching 230
> degrees.

Well, I wasn't exactly having a problem reaching the needed temperature, but I am afraid I may be putting unnecessary, too much load on the PSU.

I have Molex connectors for all my units on the extruder (motor, thermistor, resister, and fans) so that I can replace the extruder easily. And, the other day I forgot to connect the fan until the late. The hot end was at around 175 C (was on its way climbing up to 180 C), as soon as I connected the fan, the temperature reading dropped good 10 C. Then it had to climb up again.

I admit my hot end still reaches to 180 C or 230 C whatever the temperature setting far before the heated plate to reach 110 C, but it's still slower than it used to, before I installed the fan.

ohioplastics Wrote:
-------------------------------------------------------
> I've had a lot of experience in wrapping hot ends
> in fiberglass. If you do it a certain number of
> times, you'll get a decent looking bundle, but the
> first couple you do will look like rubbish. I'd
> like to think I have it down to a science, but
> it's really an art form.
> [url=http://www.ebay.com/itm/251276893017?ssPageNa
> me=STRK:MESELX:IT&_trksid=p3984.m1586.l2649]ebay[/
> url]

I checked the link and you weren't kidding. It is a form of art. LOL

I don't know about other people, but my hot end is pretty messy as it is.. It doesn't take me long to have the melted plastic to gunk up all over and sometimes it finds its way to climb up to the side.. where the insulation material will be wrapped around.

Maybe over time I would become better at it.. if I keep on trying, that is. Well, I just hope there's a better and neater way, so that I don't have to try too hard.

3Diddy Wrote:
-------------------------------------------------------
> I offer a suggestion which, admittedly, I haven't
> tried in this situation.
> Here in the UK we wrap thin PTFE tape around pipe
> threads before we screw together plumbing
> fittings. I believe that PTFE is pretty heat proof
> (Wiki says it's melting point is 600K, and as the
> Teflon brand it is the coating on non-stick frying
> pans). Even if you wind layer upon layer, it gives
> a nice smooth finish. It's not expensive, is
> available on rolls, and is about 1/2 inch wide. I
> reckon a number of layers would provide quite good
> insulation. Most people in the UK will be familiar
> with it, but if anybody elsewhere would like me to
> post a picture of it wound on something, just let
> me know.

Oh yeah, I've seen/used it, too (not for insulation though). If I am not mistaken, I believe you are referring to what we call Teflon tape in US.

Hmm.. I think it's worth trying. I have an extra hot end, so that I can connect it to power, wrap this Teflon tape around it, and see if it withstands the heat. Even if it melts or deforms, it wouldn't be too hard to clean up (I hope) since the hot end is not attached to the printer.

Not sure when I would be able to perform this experiment, but I will definitely try it and I will let you know how it worked out.

Thank you.

I've taken apart a few laser printers and one of the rollers is generally a heat resistant rubber. I just cut a section off and wrap it around the hot end then tape with kapton. It's nice and thick without and no wrapping skill required. I like the idea of Teflon tape. That sounds easy, and if you get a few layers down near the tip it will help avoid extruded plastic sticking where it shouldn't.

Okay, today I went to a neighborhood hardware store to get myself a role of Teflon tape... because I couldn't find the one I already have. I must have at least 4-5 of these in my house - they are so small, so rarely used, and so hard to find. LOL

Anyway, I have conducted my little experiment with this Teflon tape and my extra hot end.

I wrapped the nozzle (the brass/metal area) with the tape a few times. I've also covered the bottom and that narrow neck area where it the metal meets PEET body (I have J Head, by the way). So the only metal exposed was the nozzle tip.

I set the temperature of the hot end at 190 C and watched.

When it was just reaching 190 C, I saw a small amount of white smoke coming out. After a little while the smoke was gone. I wonder if that was from the PLA residues suck on my nozzle from the previous use burning out (by the way, if anyone has a tip on how to clean these gunk out, please share with me).

Nothing caught on fire.. no Teflon tape turning brown.. every thing seemed okay. So, I turnted the temperature up to 200 C.

Still no issue.

Well, this is only half the success. My bigger doubt was actually on how effective this thinner than paper thin tape would be for insulation.

So, I measured the temperature of outside - it read 137 C.

And, I tore out the Teflon tape still keeping the heat on - by the way I don't think the heat has weakened Teflon tape, either, that while it was as easy to spread out and tear as it was in room temperature, I had to pull it hard to snap it, again just like it was in room temperature. Then I measured the temperature at the same spot, and I got 169 C reading.

I don't think my multi meter is broken - I know from the past experience that the temperature reading from outside can vary a lot and very different from inside temperature, depends on which spot I read the temperature from.

So, seems like it did provide some insulation.. 30 C difference.

I am not sure if this 30 C difference is substantial/efficient enough to declare the Teflon tape as good insulation method, but at least it's better than nothing for sure. Also, I only put a few layers, less than 10, more like 4-5. So, I think I can increase the R value by putting more Teflon tape.

I have repeated the same experiment, this time setting the hot end temperature at 230 C and keeping it for good 10-15 minutes. Still no sign of turning brown, deteriorating, catching fire.. none of that. Cool.

Also, as I did not tore out the Teflon tape in my second experiment, I could see the hot end temperature goes down a lot more slowly than without insulation, especially at lower temperature (< 100 C). So again, this Teflon does provide some insulation.

I think this is good enough for me to move on and try it on the hot end I currently have installed on my printer. I can let the hot end reach the operating temperature with the hot end fan off, and then turn the fan on to check how much the hot end temperature drops, too. Without any insulation the fan brought the hot end temperature down good 10-15 degrees.

Wow.. so wrapped the Teflon tape around the hot end installed in my printer. Heated it up to 200 C and let it sit there for a while. Then I turned the hot end fan on...

Not even a single degree drop in the hot end temperature!!

This is great. This time I put plenty of layers of Teflon tape, and it seems to be doing its job.

My one two concerns now is...

1. Long term use.

Both deterioration from prolonged exposure to the high temperature and physical damages from normal printing operation - oozed out plastic often curls up and sticks to the bottom of the nozzle, which I have to remove with a pair of small tweezers. Also from time to time the nozzle bumps into curled up printed objects or other stuff (out of my carelessness).

This Teflon tape obviously is not very strong, so I wonder how it would hold up to the daily usage and abuse. It's dirt cheap to replace, but it would be a hassle if I have to replace it too often

2. Effectiveness of the hot end fan

I know the hot end fan is only supposed to cool the cold part of the hot end - PEET body, but apparently before the insulation it was also cooling the hot part of the hot end a little bit, too. I think what I have now (with insulation) is the correct setting, but just because having a jam and not having one is such a delicate balance (in my opinion anyway, based on my own nightmarish experience), I'm just a bit afraid if I have broke such a delicate balance...


Well, only way to find out is to print some stuff!

Quote
I wonder if that was from the PLA residues suck on my nozzle from the previous use burning out (by the way, if anyone has a tip on how to clean these gunk out, please share with me).

To clean my nozzles of any built up PLA residue I up the nozzle that has been removed from the hotend on a piece of stiff wire and then hold the nozzle in the flame of a cooker burner. The PLA will burn out and then just hold the nozzle in a steam of water from a tap to cool it down.
You will find that the nozzle is perfectly clean and ready to use again.

I actually thought about that, but my thermistor is really stuck so I couldn't get it out.. I hear some cracking sound when I tried to pull it out, so I stopped right there.

Well, I've actually ordered some thermistors (not for the cleaning purpose, but for something else). I am waiting for them to be shipped from UK - I ordered a different kind of thermistors from US vendor, but I had to order some other parts which were only in stock in UK warehouse, so since I was paying for the extra one time freight fee, I ordered a couple of thermistors (of the same type as I currently have).

Once I got the replacement thermistors - just in case it gets completely broken when I take it out of the nozzle - and the next time I have to re-wrap the Teflon tape, I will definitely try this method.

regpye Wrote:
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>

Quote
I wonder if that was from the PLA residues
> suck on my nozzle from the previous use burning
> out (by the way, if anyone has a tip on how to
> clean these gunk out, please share with me).
>

>
> To clean my nozzles of any built up PLA residue I
> up the nozzle that has been removed from the
> hotend on a piece of stiff wire and then hold the
> nozzle in the flame of a cooker burner. The PLA
> will burn out and then just hold the nozzle in a
> steam of water from a tap to cool it down.
> You will find that the nozzle is perfectly clean
> and ready to use again.

Thank you guys who tried out my teflon tape idea: Interesting results! I couldn't have done it, coz I'm still building my first printer (Prusa i3). I take Yamster's point about oozed out plastic curling up and needing to be cleaned off. That makes me think - for easy cleaning - I bet that people who manufacture the nozzles in batches could find a company who would dip them in the same tough, non-stick teflon with which they coat the inside of non-stick frying pans! Sounds like a similar application, no? The nozzles could be dipped before they drill the tiny hole. 100% effective or not, sounds to me like a good, money-making selling point for any nozzle manufacturer who wants to pick this up & run with it!

3Diddy , I think you are spot on, once again.

When I wrapped the Teflon tape around the metal head of the hot end, I couldn't help wrapping the bottom as well. I didn't intend to put insulation there, but as the Teflon tape get stretched when I put them around the side of the metal head, the edge of the tape wrinkled up (because the edges are not stretched as much) and got over to the bottom.

So, I had to put a few layers of Teflon tape at the bottom to tidy it up a little, and the nozzle tip punctured through the Teflon tape by itself most of time, but few layers which still didn't get punctured, I cut them away with my finger nail and sharp knife around the nozzle tip. By the way, this Teflon tape is so soft, which made it a bit tricky to play with, but once I got used to it, it's pretty easy material to work with.

Anyway, this Teflon tape at the bottom, which was one one of my two concerns, actually had a benefit I haven't expected (but you actually have!).

The oozed out plastic actually tends to stick to the bottom less... quite a bit less. As a matter of fact, I don't really need to use tweezers to remove them any more - they just don't stick! They either fall by gravity, or rubbed off heated bed when my printer is printing a rim!

Also, before the insulation, I could see the heat from the the metal head literally "pulling up" the ooze out and make it curl up and stick. The heat used to suck it up like a magnet, but since there's less heat thanks to the insulation, it doesn't do that any more!

This is really great. I actually would highly recommend people to put some Teflon tape, if not for the insulation purpose, but then to keep the bottom of the metal head clean!



3Diddy Wrote:
-------------------------------------------------------
> Thank you guys who tried out my teflon tape idea:
> Interesting results! I couldn't have done it, coz
> I'm still building my first printer (Prusa i3). I
> take Yamster's point about oozed out plastic
> curling up and needing to be cleaned off. That
> makes me think - for easy cleaning - I bet that
> people who manufacture the nozzles in batches
> could find a company who would dip them in the
> same tough, non-stick teflon with which they coat
> the inside of non-stick frying pans! Sounds like a
> similar application, no? The nozzles could be
> dipped before they drill the tiny hole. 100%
> effective or not, sounds to me like a good,
> money-making selling point for any nozzle
> manufacturer who wants to pick this up & run with
> it!