extruder nozzle insulation

i was surfing the net randomly, and i found Cotronics website. they
are makers of high material stuff like epoxy and something very
interesting: ceramic tape. "ultra temp 390" looks pretty ideal:
tough and cheap.

[www.cotronics.com]

the catalog i ordered said $8.95 / roll for 1" wide 50 foot rolls.
would this work as a drop in replacement for the ptfe tape? (i
accidentally overheated the ptfe, it burnt off and the heater coil
shorted and failed) with this stuff that would never happen.

the only quesion i have is whether it would transfer enough heat to
the heater barrel. dont know my physics well enough.
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Interesting stuff. So tell me, are you going to use it to keep the nichrome off of the extruder barrel? Is that the plan?

I gather from the data sheet that this stuff isn't tape in the sense of being adhesive tape. How do you plan on keeping in in place on the extruder barrel?

Just curious.

yeah, using it as electrical insulation was the idea. if it doesnt
have adhesive, i could always use jbweld to tack it onto the barrel.
that stuff is good up to 600F and strong. i could also get some sort
of matching high temp epoxy from the same supplier.

~Zach

On 6 Apr 2007 14:07:20 +1200, RepRap Forum Mailer wrote:
> Author: Forrest Higgs
> Username: Forrest Higgs (206-55-252-246.adsl.sta.mbay.net)
> Subject: Re: extruder nozzle insulation
> Forum: Developers
> Link: [forums.reprap.org]
> Approved: Yes
>
> Interesting stuff. So tell me, are you going to use it to keep the nichrome off of the extruder barrel? Is that the plan?
>
> I gather from the data sheet that this stuff isn't tape in the sense of being adhesive tape. How do you plan on keeping in in place on the extruder barrel?
>
> Just curious.
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> Developers@reprap.org
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>
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600 F should do the job.

I especially liked that woven insulation down toward the bottom of the page you linked us to. If I were wanting to insulate my extruder barrel that stuff would be just about perfect.

Quoting Zach Hoeken :

> i was surfing the net randomly, and i found Cotronics website. they
> are makers of high material stuff like epoxy and something very
> interesting: ceramic tape. "ultra temp 390" looks pretty ideal:
> tough and cheap.
>
> [www.cotronics.com]
>
> the catalog i ordered said $8.95 / roll for 1" wide 50 foot rolls.
> would this work as a drop in replacement for the ptfe tape? (i
> accidentally overheated the ptfe, it burnt off and the heater coil
> shorted and failed) with this stuff that would never happen.
>
> the only quesion i have is whether it would transfer enough heat to
> the heater barrel. dont know my physics well enough.

It would certainly be tougher than the PTFE. But - as you say - it
might not transfer enough heat to the barrel. The only way to find out
would be to try it*. Have you got the insulated wire that Forrest
found? That works really well with the BBQ paint, and seems to make a
good thermal coupling with the barrel.

* Well - you could try solving Fourier's equation for the system, but
the interface between the wire and the tape would be almost impossible.

Best wishes

Adrian

Dr Adrian Bowyer
[staff.bath.ac.uk]
[reprap.org]
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***Well - you could try solving Fourier's equation for the system, but
the interface between the wire and the tape would be almost impossible.***

Rule of thumb might be a lot easier. From experience it takes me about 40 seconds to go from an ambient temperature 20 degrees C on the surface of a low thermal inertia extruder barrel to 195 using 2 amps of 12v electricity. Kicking on the polymer pump will get me extruded HDPE 5-15 seconds later.

Fuzzy logic rules! :-)

Edited 1 time(s). Last edit at 04/06/2007 05:31PM by Forrest Higgs.

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Quoting Zach Hoeken :

> i didnt realize you could get insulated nichrome wire. i purchased some and
> am going to go the nichrome + jbweld route =)

Check out:

[www.pelicanwire.com]

Best wishes

Adrian

Dr Adrian Bowyer
[staff.bath.ac.uk]
[reprap.org]
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Quoting Zach Hoeken :

> yup, thats my supplier.
>
> how does the gauge of the wire effect the heating element? do i just get a
> longer coil to match the 12ohm impedance with the thicker wire?

That should work - watts are all that matters. On my latest extruder
I've cut it to 8 ohms; this gives a little more zap when the lab is
cold, and Simon's control software handles it just fine. One thing I
do do is to use the extruder exerciser panel to warm it gradually when
it's starting from completely cold. I set it to 40, then 50 a while
later, and so on. I've never burnt out a heater, and I think that
ramping it up helps. Eventually we can build that into the Java, of
course.

Best wishes

Adrian

Dr Adrian Bowyer
[staff.bath.ac.uk]
[reprap.org]
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***One thing I do do is to use the extruder exerciser panel to warm it gradually when it's starting from completely cold.***

I've turned mine on full-blast close to a hundred times so far with no ill effects.

----- Original Message ----
From: Adrian Bowyer
To: developers@reprap.org
Sent: Friday, April 6, 2007 3:24:17 PM
Subject: Re: extruder nozzle insulation

Quoting Zach Hoeken :

> yup, thats my supplier.
>
> how does the gauge of the wire effect the heating element? do i just get a
> longer coil to match the 12ohm impedance with the thicker wire?

That should work - watts are all that matters. On my latest extruder
I've cut it to 8 ohms; this gives a little more zap when the lab is
cold, and Simon's control software handles it just fine. One thing I
do do is to use the extruder exerciser panel to warm it gradually when
it's starting from completely cold. I set it to 40, then 50 a while
later, and so on. I've never burnt out a heater, and I think that
ramping it up helps. Eventually we can build that into the Java, of
course.

Best wishes

Adrian

Dr Adrian Bowyer
[staff.bath.ac.uk]
[reprap.org]
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Edited 1 time(s). Last edit at 04/06/2007 06:46PM by Forrest Higgs.

Quoting Forrest Higgs :

> Have you burned a heater coil out just turning it on? I've turned
> mine on full-blast close to a hundred times so far with no ill
> effects.

No - but I once did set fire to the insulation I was using at the time
(a folded kitchen wipe...)

Best wishes

Adrian

Dr Adrian Bowyer
[staff.bath.ac.uk]
[reprap.org]
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Ah, I don't insulate mine. That just adds to the thermal time constant and I don't want that.

----- Original Message ----
From: Adrian Bowyer
To: Forrest Higgs
Cc: developers@reprap.org
Sent: Saturday, April 7, 2007 9:11:32 AM
Subject: Re: extruder nozzle insulation

Quoting Forrest Higgs :

> Have you burned a heater coil out just turning it on? I've turned
> mine on full-blast close to a hundred times so far with no ill
> effects.

No - but I once did set fire to the insulation I was using at the time
(a folded kitchen wipe...)

Best wishes

Adrian

Dr Adrian Bowyer
[staff.bath.ac.uk]
[reprap.org]







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