Potting Compound for Small Heating Elements

C

Computer Nerd Kev

Guest
I've wanted to (and in a few cases tried to) make small heating elements
for various things in the past, but I've never worked out a good way to
keep the heating elements in place and stop them shorting out.

I've seen the ceramic-like (to the touch) potting compound used in things
like soldering iron elements, which I presume to be this sort of stuff:
http://measuretech.com.au/potting-compounds/91-durapot-810-highly-thermally-conductive-potting-compound.html

But, well, $335.17 for one Pint!

I haven't had much luck finding other prices, but that's a long way
off the sort of money I'd want to pay. Indeed all their potting
compounds are in the same price range:
http://measuretech.com.au/39-potting-compounds

Epoxy can be rated for high temperatures, between 200-300C, but being
a poor thermal conductor, I'd be worried about cooking the epoxy from
the inside before the surrounding metal heats up.

Nichrome wire isn't hard to get a hold of, so is it unreasonable to
expect potting compound or something equivalent to be likewise? Have
I been missing some obvious solution?

Details you might not need to read follow:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

PAST ATTEMPTS:

I've previously tried weaving Nichrome wire in Kapton tape on top of
a flat solid base, but the adheasive of the Kapton weakens at higher
temperatures and it didn't prove a very solid solution to keeping the
wires from shorting out.

I also had a go at using VeroBoard with tracks soldered together. This
works at lower temperatures (under about 80C, maybe a bit less), but
as it gets hotter it tends to shrivel up and expel a strong vapour
that also coats nearby objects in a sticky yellowish substance and
causes nearby objects, clothes, and humans to stink for days. I
concluded at the time that my target temperature of 160C wansn't going
to work, and that I don't want to know the health implications of the
experiment.

CURRENT ATTEMPT:

I'm still working on a good method for desoldering ICs from circuit
boards (you might remember my topic on the matter from about a year
ago). So far: hair straighteners can't go hot enough (though can work
on leaded solder and single sided boards), blowtorching the back of
a board and hitting it against something doesn't force the ICs out,
even with their pins straightened on the bottom, and it's also easy
to cook parts when you get desperate (that was yesterday's attempt,
might try a more subtle flame in the future when I get one that will
stay alight), and I'm still no good with a solder sucker.

Now I'm looking at either building a vacuume desoldering iron (as
was my first plan last time, but I'm now tempted to do it completely
from scratch as I've got small a thick walled copper tube that might
be perfect), or a large heated block of copper the width of an IC
that can melt the solder on one whole side of a chip at once.

I think I've got a way to make the heating element in the
block-o-copper solution with just Kapton tape for electrical insulation
from the Nicrome heating wires. I might test the method first by just
heating it with my blowtorch.

However I can't work out a way that seems reliable by which to build a
heating element for the vacuume desoldering iron. I really need to be
able to encase it in something. Power resistors, besides being too
large and difficult to mount, don't seem to be rated up to the required
temperature.

--
__ __
#_ < |\| |< _#
 
F Murtz <haggisz@hotmail.com> wrote:
Where? need some for my best radiator,used to get it at motor winding
wire places,few and far between now.

http://tinypic.com/r/28sg83/8

I take it you mean the Nichrome wire.

Jaycar sell it, but only one type, 13.77R/m (cat. WW-4040)

Wiltronics have a better range, but you have to buy a full reel.

I haven't checked RS and Element 14, but they might stock it too.

I bought a small length from Ebay once, from "Spiratronics". I think
they were in the UK, though I might be confusing that with another part.

I got the stuff I'm using now for nothing. It's so old it was made in
Great Britain, and it's on a wooden spool.

--
__ __
#_ < |\| |< _#
 
Techman <junkemail@bogus.com> wrote:
On 19-Jul-15 9:15 AM, Computer Nerd Kev wrote:

Nichrome wire isn't hard to get a hold of, so is it unreasonable to
expect potting compound or something equivalent to be likewise? Have
I been missing some obvious solution?

Fibreglass tape (adhesive backed like sticky tape) & exhaust / muffler
putty.

Thanks.

Looks like the fiberglass tape won't go up to soldering iron temperatures
(260C max from what I can find), but the muffler putty stuff looks good,
even if it might not be all that thermally conductive.

I'll look for some next time I'm near a car parts place.

--
__ __
#_ < |\| |< _#
 
Computer Nerd Kev wrote:
I've wanted to (and in a few cases tried to) make small heating elements
for various things in the past, but I've never worked out a good way to
keep the heating elements in place and stop them shorting out.

I've seen the ceramic-like (to the touch) potting compound used in things
like soldering iron elements, which I presume to be this sort of stuff:
http://measuretech.com.au/potting-compounds/91-durapot-810-highly-thermally-conductive-potting-compound.html

But, well, $335.17 for one Pint!

I haven't had much luck finding other prices, but that's a long way
off the sort of money I'd want to pay. Indeed all their potting
compounds are in the same price range:
http://measuretech.com.au/39-potting-compounds

Epoxy can be rated for high temperatures, between 200-300C, but being
a poor thermal conductor, I'd be worried about cooking the epoxy from
the inside before the surrounding metal heats up.

Nichrome wire isn't hard to get a hold of, so is it unreasonable to
expect potting compound or something equivalent to be likewise? Have
I been missing some obvious solution?

Details you might not need to read follow:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

PAST ATTEMPTS:

I've previously tried weaving Nichrome wire in Kapton tape on top of
a flat solid base, but the adheasive of the Kapton weakens at higher
temperatures and it didn't prove a very solid solution to keeping the
wires from shorting out.

I also had a go at using VeroBoard with tracks soldered together. This
works at lower temperatures (under about 80C, maybe a bit less), but
as it gets hotter it tends to shrivel up and expel a strong vapour
that also coats nearby objects in a sticky yellowish substance and
causes nearby objects, clothes, and humans to stink for days. I
concluded at the time that my target temperature of 160C wansn't going
to work, and that I don't want to know the health implications of the
experiment.

CURRENT ATTEMPT:

I'm still working on a good method for desoldering ICs from circuit
boards (you might remember my topic on the matter from about a year
ago). So far: hair straighteners can't go hot enough (though can work
on leaded solder and single sided boards), blowtorching the back of
a board and hitting it against something doesn't force the ICs out,
even with their pins straightened on the bottom, and it's also easy
to cook parts when you get desperate (that was yesterday's attempt,
might try a more subtle flame in the future when I get one that will
stay alight), and I'm still no good with a solder sucker.

Now I'm looking at either building a vacuume desoldering iron (as
was my first plan last time, but I'm now tempted to do it completely
from scratch as I've got small a thick walled copper tube that might
be perfect), or a large heated block of copper the width of an IC
that can melt the solder on one whole side of a chip at once.

I think I've got a way to make the heating element in the
block-o-copper solution with just Kapton tape for electrical insulation
from the Nicrome heating wires. I might test the method first by just
heating it with my blowtorch.

However I can't work out a way that seems reliable by which to build a
heating element for the vacuume desoldering iron. I really need to be
able to encase it in something. Power resistors, besides being too
large and difficult to mount, don't seem to be rated up to the required
temperature.
Where? need some for my best radiator,used to get it at motor winding
wire places,few and far between now.

http://tinypic.com/r/28sg83/8
 
On 19-Jul-15 9:15 AM, Computer Nerd Kev wrote:
I've wanted to (and in a few cases tried to) make small heating elements
for various things in the past, but I've never worked out a good way to
keep the heating elements in place and stop them shorting out.

I've seen the ceramic-like (to the touch) potting compound used in things
like soldering iron elements, which I presume to be this sort of stuff:
http://measuretech.com.au/potting-compounds/91-durapot-810-highly-thermally-conductive-potting-compound.html

But, well, $335.17 for one Pint!

I haven't had much luck finding other prices, but that's a long way
off the sort of money I'd want to pay. Indeed all their potting
compounds are in the same price range:
http://measuretech.com.au/39-potting-compounds

Epoxy can be rated for high temperatures, between 200-300C, but being
a poor thermal conductor, I'd be worried about cooking the epoxy from
the inside before the surrounding metal heats up.

Nichrome wire isn't hard to get a hold of, so is it unreasonable to
expect potting compound or something equivalent to be likewise? Have
I been missing some obvious solution?

Details you might not need to read follow:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

PAST ATTEMPTS:

I've previously tried weaving Nichrome wire in Kapton tape on top of
a flat solid base, but the adheasive of the Kapton weakens at higher
temperatures and it didn't prove a very solid solution to keeping the
wires from shorting out.

I also had a go at using VeroBoard with tracks soldered together. This
works at lower temperatures (under about 80C, maybe a bit less), but
as it gets hotter it tends to shrivel up and expel a strong vapour
that also coats nearby objects in a sticky yellowish substance and
causes nearby objects, clothes, and humans to stink for days. I
concluded at the time that my target temperature of 160C wansn't going
to work, and that I don't want to know the health implications of the
experiment.

CURRENT ATTEMPT:

I'm still working on a good method for desoldering ICs from circuit
boards (you might remember my topic on the matter from about a year
ago). So far: hair straighteners can't go hot enough (though can work
on leaded solder and single sided boards), blowtorching the back of
a board and hitting it against something doesn't force the ICs out,
even with their pins straightened on the bottom, and it's also easy
to cook parts when you get desperate (that was yesterday's attempt,
might try a more subtle flame in the future when I get one that will
stay alight), and I'm still no good with a solder sucker.

Now I'm looking at either building a vacuume desoldering iron (as
was my first plan last time, but I'm now tempted to do it completely
from scratch as I've got small a thick walled copper tube that might
be perfect), or a large heated block of copper the width of an IC
that can melt the solder on one whole side of a chip at once.

I think I've got a way to make the heating element in the
block-o-copper solution with just Kapton tape for electrical insulation
from the Nicrome heating wires. I might test the method first by just
heating it with my blowtorch.

However I can't work out a way that seems reliable by which to build a
heating element for the vacuume desoldering iron. I really need to be
able to encase it in something. Power resistors, besides being too
large and difficult to mount, don't seem to be rated up to the required
temperature.

Fibreglass tape (adhesive backed like sticky tape) & exhaust / muffler
putty.
 
On 20 Jul 2015, F Murtz wrote:

Computer Nerd Kev wrote:
Techman <junkemail@bogus.com> wrote:
On 19-Jul-15 9:15 AM, Computer Nerd Kev wrote:

Nichrome wire isn't hard to get a hold of, so is it
unreasonable to expect potting compound or something
equivalent to be likewise? Have I been missing some
obvious solution?

Fibreglass tape (adhesive backed like sticky tape) &
exhaust / muffler putty.

Thanks.

Looks like the fiberglass tape won't go up to soldering
iron temperatures (260C max from what I can find), but the
muffler putty stuff looks good, even if it might not be
all that thermally conductive.

I'll look for some next time I'm near a car parts place.

Wrap it on mica, probably another hard to get stuff

Have got some Mica, albeit TO-220 shaped. But I believe Kapton
tape should be OK up to 400C or more, so I'll use that for
thin insulation and hopefully this muffler putty to keep the
elements in place (unless someone knows of something designed
to be thermally conductive).

Might first try my Kapton-only approach putting a heating
element in my new lump-o-copper desoldering iron, I tested it
out heating with a blowtorch yesterday and it seemed somewhat
promising. It cools down too quick to be usable like that
though.

--
__ __
#_ < |\| |< _#
 
On 20 Jul 2015, F Murtz wrote:

Computer Nerd Kev wrote:
On 20 Jul 2015, F Murtz wrote:

Wrap it on mica, probably another hard to get stuff

Have got some Mica, albeit TO-220 shaped. But I believe
Kapton tape should be OK up to 400C or more, so I'll use
that for thin insulation and hopefully this muffler putty
to keep the elements in place (unless someone knows of
something designed to be thermally conductive).

Old elements used to use sheet mica, which will split thin,
wrap it round and wind a layer of nichrome the another thin
layer of mica then another layer of nichrome etc.

Ok thanks, maybe I could cut down some of the stuff they're
selling as microwave waveguide covers on Ebay, though I'm not
sure if it's really Mica.
http://www.ebay.com.au/itm/281522988135

Might be interesting trying to split it. I think I'll go for
the putty first, it might be more fool-proof.

--
__ __
#_ < |\| |< _#
 
Computer Nerd Kev wrote:
Techman <junkemail@bogus.com> wrote:
On 19-Jul-15 9:15 AM, Computer Nerd Kev wrote:

Nichrome wire isn't hard to get a hold of, so is it unreasonable to
expect potting compound or something equivalent to be likewise? Have
I been missing some obvious solution?

Fibreglass tape (adhesive backed like sticky tape) & exhaust / muffler
putty.

Thanks.

Looks like the fiberglass tape won't go up to soldering iron temperatures
(260C max from what I can find), but the muffler putty stuff looks good,
even if it might not be all that thermally conductive.

I'll look for some next time I'm near a car parts place.

Wrap it on mica, probably another hard to get stuff
 
Computer Nerd Kev wrote:
On 20 Jul 2015, F Murtz wrote:

Computer Nerd Kev wrote:
Techman <junkemail@bogus.com> wrote:
On 19-Jul-15 9:15 AM, Computer Nerd Kev wrote:

Nichrome wire isn't hard to get a hold of, so is it
unreasonable to expect potting compound or something
equivalent to be likewise? Have I been missing some
obvious solution?

Fibreglass tape (adhesive backed like sticky tape) &
exhaust / muffler putty.

Thanks.

Looks like the fiberglass tape won't go up to soldering
iron temperatures (260C max from what I can find), but the
muffler putty stuff looks good, even if it might not be
all that thermally conductive.

I'll look for some next time I'm near a car parts place.

Wrap it on mica, probably another hard to get stuff

Have got some Mica, albeit TO-220 shaped. But I believe Kapton
tape should be OK up to 400C or more, so I'll use that for
thin insulation and hopefully this muffler putty to keep the
elements in place (unless someone knows of something designed
to be thermally conductive).

Might first try my Kapton-only approach putting a heating
element in my new lump-o-copper desoldering iron, I tested it
out heating with a blowtorch yesterday and it seemed somewhat
promising. It cools down too quick to be usable like that
though.
Old elements used to use sheet mica, which will split thin, wrap it
round and wind a layer of nichrome the another thin layer of mica then
another layer of nichrome etc.
 
On 2015-07-19, F Murtz <haggisz@hotmail.com> wrote:
Computer Nerd Kev wrote:
Techman <junkemail@bogus.com> wrote:

Looks like the fiberglass tape won't go up to soldering iron temperatures
(260C max from what I can find), but the muffler putty stuff looks good,
even if it might not be all that thermally conductive.

probasbly just the adhesive. I think exhaust bandage is a fibreglass
fabric, and some sort of plaster.

I'll look for some next time I'm near a car parts place.

Wrap it on mica, probably another hard to get stuff

if you need hobbyist quantities collect some junk appliances.
nichrome and mica are toaster elements, hair-dryer elements too.
mica is also the ceiling in many microwave ovens




--
umop apisdn
 
Jasen Betts <jasen@xnet.co.nz> wrote:
On 2015-07-19, F Murtz <haggisz@hotmail.com> wrote:
Computer Nerd Kev wrote:
Techman <junkemail@bogus.com> wrote:

Looks like the fiberglass tape won't go up to soldering iron temperatures
(260C max from what I can find), but the muffler putty stuff looks good,
even if it might not be all that thermally conductive.

probasbly just the adhesive. I think exhaust bandage is a fibreglass
fabric, and some sort of plaster.

OK, easy to test by holding it against a soldering iron. Though the
Kapton tape I've got should serve much the same purpose anyway.

I'll look for some next time I'm near a car parts place.

Wrap it on mica, probably another hard to get stuff

if you need hobbyist quantities collect some junk appliances.
nichrome and mica are toaster elements, hair-dryer elements too.
mica is also the ceiling in many microwave ovens

I pulled apart a large (actually pretty giant) microwave a while
ago, but I think I would have tossed the mica, not relising what
it was.

--
__ __
#_ < |\| |< _#
 
On 2015-07-20, Computer Nerd Kev <not@telling.you.invalid> wrote:

Ok thanks, maybe I could cut down some of the stuff they're
selling as microwave waveguide covers on Ebay, though I'm not
sure if it's really Mica.
http://www.ebay.com.au/itm/281522988135

It looks like the real thing, I'd risk the hassle of demanding a
refund if Ineeded more mica.

--
umop apisdn
 
Computer Nerd Kev wrote:
On 20 Jul 2015, F Murtz wrote:

Computer Nerd Kev wrote:
On 20 Jul 2015, F Murtz wrote:

Wrap it on mica, probably another hard to get stuff

Have got some Mica, albeit TO-220 shaped. But I believe
Kapton tape should be OK up to 400C or more, so I'll use
that for thin insulation and hopefully this muffler putty
to keep the elements in place (unless someone knows of
something designed to be thermally conductive).

Old elements used to use sheet mica, which will split thin,
wrap it round and wind a layer of nichrome the another thin
layer of mica then another layer of nichrome etc.

Ok thanks, maybe I could cut down some of the stuff they're
selling as microwave waveguide covers on Ebay, though I'm not
sure if it's really Mica.
http://www.ebay.com.au/itm/281522988135

Might be interesting trying to split it. I think I'll go for
the putty first, it might be more fool-proof.

http://www.alibaba.com/product-detail/Natural-Mica-Thin-Sheet_126593779/showimage.html
 
Jasen Betts wrote:
On 2015-07-20, Computer Nerd Kev <not@telling.you.invalid> wrote:

Ok thanks, maybe I could cut down some of the stuff they're
selling as microwave waveguide covers on Ebay, though I'm not
sure if it's really Mica.
http://www.ebay.com.au/itm/281522988135

It looks like the real thing, I'd risk the hassle of demanding a
refund if Ineeded more mica.
That is not what we used I posted a link elswhere here it is again
http://www.alibaba.com/product-detail/Natural-Mica-Thin-Sheet_126593779/showimage.html
 
On 19-Jul-15 9:15 AM, Computer Nerd Kev wrote:
I've wanted to (and in a few cases tried to) make small heating elements
for various things in the past, but I've never worked out a good way to
keep the heating elements in place and stop them shorting out.

I've seen the ceramic-like (to the touch) potting compound used in things
like soldering iron elements, which I presume to be this sort of stuff:
http://measuretech.com.au/potting-compounds/91-durapot-810-highly-thermally-conductive-potting-compound.html

But, well, $335.17 for one Pint!

I haven't had much luck finding other prices, but that's a long way
off the sort of money I'd want to pay. Indeed all their potting
compounds are in the same price range:
http://measuretech.com.au/39-potting-compounds

Epoxy can be rated for high temperatures, between 200-300C, but being
a poor thermal conductor, I'd be worried about cooking the epoxy from
the inside before the surrounding metal heats up.

Nichrome wire isn't hard to get a hold of, so is it unreasonable to
expect potting compound or something equivalent to be likewise? Have
I been missing some obvious solution?

Details you might not need to read follow:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

PAST ATTEMPTS:

I've previously tried weaving Nichrome wire in Kapton tape on top of
a flat solid base, but the adheasive of the Kapton weakens at higher
temperatures and it didn't prove a very solid solution to keeping the
wires from shorting out.

I also had a go at using VeroBoard with tracks soldered together. This
works at lower temperatures (under about 80C, maybe a bit less), but
as it gets hotter it tends to shrivel up and expel a strong vapour
that also coats nearby objects in a sticky yellowish substance and
causes nearby objects, clothes, and humans to stink for days. I
concluded at the time that my target temperature of 160C wansn't going
to work, and that I don't want to know the health implications of the
experiment.

CURRENT ATTEMPT:

I'm still working on a good method for desoldering ICs from circuit
boards (you might remember my topic on the matter from about a year
ago). So far: hair straighteners can't go hot enough (though can work
on leaded solder and single sided boards), blowtorching the back of
a board and hitting it against something doesn't force the ICs out,
even with their pins straightened on the bottom, and it's also easy
to cook parts when you get desperate (that was yesterday's attempt,
might try a more subtle flame in the future when I get one that will
stay alight), and I'm still no good with a solder sucker.

Now I'm looking at either building a vacuume desoldering iron (as
was my first plan last time, but I'm now tempted to do it completely
from scratch as I've got small a thick walled copper tube that might
be perfect), or a large heated block of copper the width of an IC
that can melt the solder on one whole side of a chip at once.

I think I've got a way to make the heating element in the
block-o-copper solution with just Kapton tape for electrical insulation
from the Nicrome heating wires. I might test the method first by just
heating it with my blowtorch.

However I can't work out a way that seems reliable by which to build a
heating element for the vacuume desoldering iron. I really need to be
able to encase it in something. Power resistors, besides being too
large and difficult to mount, don't seem to be rated up to the required
temperature.

If you are looking for mica like material, grab a toaster from a verge
throwout collection.
 
On 20-Jul-15 2:26 PM, Jasen Betts wrote:
On 2015-07-19, F Murtz <haggisz@hotmail.com> wrote:
Computer Nerd Kev wrote:
Techman <junkemail@bogus.com> wrote:

Looks like the fiberglass tape won't go up to soldering iron temperatures
(260C max from what I can find), but the muffler putty stuff looks good,
even if it might not be all that thermally conductive.

probasbly just the adhesive. I think exhaust bandage is a fibreglass
fabric, and some sort of plaster.

Muffler putty / jointing compound is putty, muffler bandages are, well,
bandages.

The muffler putty in the old days was some sort of refractory cement +
asbestos.



I'll look for some next time I'm near a car parts place.

Wrap it on mica, probably another hard to get stuff

if you need hobbyist quantities collect some junk appliances.
nichrome and mica are toaster elements, hair-dryer elements too.
mica is also the ceiling in many microwave ovens
 
On 19/07/2015 11:15, Computer Nerd Kev wrote:
I've wanted to (and in a few cases tried to) make small heating elements
for various things in the past, but I've never worked out a good way to
keep the heating elements in place and stop them shorting out.

I've seen the ceramic-like (to the touch) potting compound used in things
like soldering iron elements, which I presume to be this sort of stuff:
http://measuretech.com.au/potting-compounds/91-durapot-810-highly-thermally-conductive-potting-compound.html

But, well, $335.17 for one Pint!

I haven't had much luck finding other prices, but that's a long way
off the sort of money I'd want to pay. Indeed all their potting
compounds are in the same price range:
http://measuretech.com.au/39-potting-compounds

Epoxy can be rated for high temperatures, between 200-300C, but being
a poor thermal conductor, I'd be worried about cooking the epoxy from
the inside before the surrounding metal heats up.

Nichrome wire isn't hard to get a hold of, so is it unreasonable to
expect potting compound or something equivalent to be likewise? Have
I been missing some obvious solution?

Details you might not need to read follow:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

PAST ATTEMPTS:

I've previously tried weaving Nichrome wire in Kapton tape on top of
a flat solid base, but the adheasive of the Kapton weakens at higher
temperatures and it didn't prove a very solid solution to keeping the
wires from shorting out.

I also had a go at using VeroBoard with tracks soldered together. This
works at lower temperatures (under about 80C, maybe a bit less), but
as it gets hotter it tends to shrivel up and expel a strong vapour
that also coats nearby objects in a sticky yellowish substance and
causes nearby objects, clothes, and humans to stink for days. I
concluded at the time that my target temperature of 160C wansn't going
to work, and that I don't want to know the health implications of the
experiment.

CURRENT ATTEMPT:

I'm still working on a good method for desoldering ICs from circuit
boards (you might remember my topic on the matter from about a year
ago). So far: hair straighteners can't go hot enough (though can work
on leaded solder and single sided boards), blowtorching the back of
a board and hitting it against something doesn't force the ICs out,
even with their pins straightened on the bottom, and it's also easy
to cook parts when you get desperate (that was yesterday's attempt,
might try a more subtle flame in the future when I get one that will
stay alight), and I'm still no good with a solder sucker.

Now I'm looking at either building a vacuume desoldering iron (as
was my first plan last time, but I'm now tempted to do it completely
from scratch as I've got small a thick walled copper tube that might
be perfect), or a large heated block of copper the width of an IC
that can melt the solder on one whole side of a chip at once.

I think I've got a way to make the heating element in the
block-o-copper solution with just Kapton tape for electrical insulation
from the Nicrome heating wires. I might test the method first by just
heating it with my blowtorch.

However I can't work out a way that seems reliable by which to build a
heating element for the vacuume desoldering iron. I really need to be
able to encase it in something. Power resistors, besides being too
large and difficult to mount, don't seem to be rated up to the required
temperature.

Perhaps this will not be as much fun as making your own element, but you
can buy small cartridge heaters like this one, $7:
https://www.bilby3d.com.au/DispProd.asp?CatID=11&SubCatID=131&ProdID=ptHeatCart40

I suspect that it would work ok at soldering temperature. I guess you
just drill and ream a hole the right size in the block of copper and
push the element in.

Chris
 
On 19/07/2015 9:15 AM, Computer Nerd Kev wrote:
I've wanted to (and in a few cases tried to) make small heating elements
for various things in the past, but I've never worked out a good way to
keep the heating elements in place and stop them shorting out.

I've seen the ceramic-like (to the touch) potting compound used in things
like soldering iron elements, which I presume to be this sort of stuff:
http://measuretech.com.au/potting-compounds/91-durapot-810-highly-thermally-conductive-potting-compound.html

But, well, $335.17 for one Pint!

I haven't had much luck finding other prices, but that's a long way
off the sort of money I'd want to pay. Indeed all their potting
compounds are in the same price range:
http://measuretech.com.au/39-potting-compounds

Epoxy can be rated for high temperatures, between 200-300C, but being
a poor thermal conductor, I'd be worried about cooking the epoxy from
the inside before the surrounding metal heats up.

Nichrome wire isn't hard to get a hold of, so is it unreasonable to
expect potting compound or something equivalent to be likewise? Have
I been missing some obvious solution?

Details you might not need to read follow:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

PAST ATTEMPTS:

I've previously tried weaving Nichrome wire in Kapton tape on top of
a flat solid base, but the adheasive of the Kapton weakens at higher
temperatures and it didn't prove a very solid solution to keeping the
wires from shorting out.

I also had a go at using VeroBoard with tracks soldered together. This
works at lower temperatures (under about 80C, maybe a bit less), but
as it gets hotter it tends to shrivel up and expel a strong vapour
that also coats nearby objects in a sticky yellowish substance and
causes nearby objects, clothes, and humans to stink for days. I
concluded at the time that my target temperature of 160C wansn't going
to work, and that I don't want to know the health implications of the
experiment.

CURRENT ATTEMPT:

I'm still working on a good method for desoldering ICs from circuit
boards (you might remember my topic on the matter from about a year
ago). So far: hair straighteners can't go hot enough (though can work
on leaded solder and single sided boards), blowtorching the back of
a board and hitting it against something doesn't force the ICs out,
even with their pins straightened on the bottom, and it's also easy
to cook parts when you get desperate (that was yesterday's attempt,
might try a more subtle flame in the future when I get one that will
stay alight), and I'm still no good with a solder sucker.

Now I'm looking at either building a vacuume desoldering iron (as
was my first plan last time, but I'm now tempted to do it completely
from scratch as I've got small a thick walled copper tube that might
be perfect), or a large heated block of copper the width of an IC
that can melt the solder on one whole side of a chip at once.

I spent not a whole lot on a desoldering station and have never looked
back. So simple to salvage or effect a repair now.
 
Computer Nerd Kev wrote:
I'm still working on a good method for desoldering ICs from circuit
boards (you might remember my topic on the matter from about a year
ago). So far: hair straighteners can't go hot enough (though can work
on leaded solder and single sided boards), blowtorching the back of
a board and hitting it against something doesn't force the ICs out,
even with their pins straightened on the bottom, and it's also easy
to cook parts when you get desperate (that was yesterday's attempt,
might try a more subtle flame in the future when I get one that will
stay alight), and I'm still no good with a solder sucker.

If you can't justify a desoldering station low melting point solder
(eg *Chip Quik*) makes it pretty easy if you're only looking to
recover the IC's. Cleaning up the board can be a PITA though.

It's not particularly cheap but a small amount goes a long way.

--
John H
 

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