Hi all, I need to heat a steel rod 12inches long and half and inch in
diameter up to around 40 degrees centigrade and keep it within 2degrees. It
will need to be kept constantly at this temperature. it can only be heated
at one end, the other end needs to be un cluttered.

Any suggestions how I can do this?

Cheers!

Steve

"R.P.McMurphy" wrote in message
...
Hi all, I need to heat a steel rod 12inches long and half and inch in
diameter up to around 40 degrees centigrade and keep it within 2degrees.
It will need to be kept constantly at this temperature. it can only be
heated at one end, the other end needs to be un cluttered.

Any suggestions how I can do this?

Get an electronic aquarium heater/stat and set it to 40C in a gallon or two
of water.
Put the end of the bar in it..
wrap the rest in a couple of inches of insulation..
job done..
or is it?

You don't actually supply enough info to be sure what can be done or even if
its possible.

R.P.McMurphy wrote:
Hi all, I need to heat a steel rod 12inches long and half and inch in
diameter up to around 40 degrees centigrade and keep it within 2degrees. It
will need to be kept constantly at this temperature. it can only be heated
at one end, the other end needs to be un cluttered.

Any suggestions how I can do this?

Cheers!


You need to provide more information...

I assume that the rod is solid?

I assume that the rod is suspended in free air?

I assume that there is no dynamic thermal load bearing? (i.e. nothing
randomly comes into contact)

I assume the environment is reasonably controlled? (i.e. not placed in a
draught)

I assume there's no limitation on the heating technology?

I assume that the environment is cooler than the rod - that we're
talking heating and not cooling!


If my assumptions are broadly correct, then I'd suggest machining two
bore holes , connected at the far end, and pump water or oil through
these channels, pre-heated to 40c. (pro: with an adequate sump of
pre-heated water/oil) this would provide good stability under differing
thermal loads and a good (flat) temperature gradient across the length
of the bar)

Another option is to machine a single hole, and insert a straight
heating element down the length of the hole. If temperature control is
vital, then make this a multi-stage element, each stage with some
thermal control to modulate power to each stage of the element (con:
difficult to maintain a stable temperature gradient across the length)

Another option, again requiring the machining of a single hole, is to
run a conductor to the far end of the rod (internally) and use the rod
itself as a heating element, passing a current through the internal
conductor to the far end and have the supply return at the near end.
Would also need an embedded temperature monitor (con: likely to be slow
to heat and have poor response to thermal loading)

The easiest option, of course, is to change the environment to present a
constant 40c around the bar, however, I'm guessing that this is not a
solution for your problem.

More info please!!!

Mike

"Mike
R.P.McMurphy wrote:
Hi all, I need to heat a steel rod 12inches long and half and inch in
diameter up to around 40 degrees centigrade and keep it within 2degrees.
It will need to be kept constantly at this temperature. it can only be
heated at one end, the other end needs to be un cluttered.

Any suggestions how I can do this?

Cheers!


You need to provide more information...

I assume that the rod is solid?

it can be solid or hollow.

I assume that the rod is suspended in free air?

i want it to sit on a base of some sort that acts as a heater and so that
the rod protrudes from it and the rod stands upright.

I assume that there is no dynamic thermal load bearing? (i.e. nothing
randomly comes into contact)

no, but the temperature must be stable so will need some kind of automatic
and manual adjustment of temperature.

I assume the environment is reasonably controlled? (i.e. not placed in a
draught)

the item will be kept indoors, away from draughts.

I assume there's no limitation on the heating technology?

no, but i dont want hight running costs and a big bulky item.

I assume that the environment is cooler than the rod - that we're talking
heating and not cooling!

yes, rod will need to be heated from room temperature and held at 40
degrees.

If my assumptions are broadly correct, then I'd suggest machining two bore
holes , connected at the far end, and pump water or oil through these
channels, pre-heated to 40c. (pro: with an adequate sump of pre-heated
water/oil) this would provide good stability under differing thermal loads
and a good (flat) temperature gradient across the lengtrtfh of the bar)

Another option is to machine a single hole, and insert a straight heating
element down the length of the hole. If temperature control is vital, then
make this a multi-stage element, each stage with some thermal control to
modulate power to each stage of the element (con: difficult to maintain a
stable temperature gradient across the length)

Another option, again requiring the machining of a single hole, is to run
a conductor to the far end of the rod (internally) and use the rod itself
as a heating element, passing a current through the internal conductor to
the far end and have the supply return at the near end.
Would also need an embedded temperature monitor (con: likely to be slow to
heat and have poor response to thermal loading)

The easiest option, of course, is to change the environment to present a
constant 40c around the bar, however, I'm guessing that this is not a
solution for your problem.

More info please!!!

Mike

many thanks for your help Mike! Can you suggest any actual components that
I could use for the heating/monitoring?

Cheers

Steve

"R.P.McMurphy" wrote in message
...
Hi all, I need to heat a steel rod 12inches long and half and inch in
diameter up to around 40 degrees centigrade and keep it within 2degrees.
It
will need to be kept constantly at this temperature. it can only be
heated
at one end, the other end needs to be un cluttered.

Any suggestions how I can do this?

Besides all the comments here about how to go about this, it might be an
idea to say what you are using this for - someone might have an easy
suggestion for you to achieve your aim.

Paul

Cheers!

Steve

"R.P.McMurphy" wrote in message
...

"Mike
R.P.McMurphy wrote:

i want it to sit on a base of some sort that acts as a heater and so that
the rod protrudes from it and the rod stands upright.


Don't know what sort of temp this thing gets up to but it may be possible to
cannibalize this )

http://tinyurl.com/8xgon

Mogweed.

"Paul Andrews" wrote in message
...
"R.P.McMurphy" wrote in message
...
Hi all, I need to heat a steel rod 12inches long and half and inch in
diameter up to around 40 degrees centigrade and keep it within 2degrees.
It
will need to be kept constantly at this temperature. it can only be
heated
at one end, the other end needs to be un cluttered.

Any suggestions how I can do this?

Besides all the comments here about how to go about this, it might be an
idea to say what you are using this for - someone might have an easy
suggestion for you to achieve your aim.

Paul

I'd love to tell you, but if i told you, i'd have to kill you!

I'm a bit of an inventor, this only one part of the gadget i am currently
working on. Any help to solve this problem as simply and as cheaply as
possible is most helpful!

Cheers

Steve

R.P.McMurphy said the following on 04/02/2006 23:21:
Hi all, I need to heat a steel rod 12inches long and half and inch in
diameter up to around 40 degrees centigrade and keep it within 2degrees. It
will need to be kept constantly at this temperature. it can only be heated
at one end, the other end needs to be un cluttered.

Any suggestions how I can do this?

Cheers!

Steve


How about trace heating cable?

See he http://tinyurl.com/c9xe4

You will need a dimmer (at the very least) to adjust the temperature.

You will need some kind of PID temperature controller to maintain
closed-loop feedback of the temperature.

In article
R.P.McMurphy wrote:
Hi all, I need to heat a steel rod 12inches long and half and inch in
diameter up to around 40 degrees centigrade and keep it within 2degrees. It
will need to be kept constantly at this temperature. it can only be heated
at one end, the other end needs to be un cluttered.

Any suggestions how I can do this?

Heating at one end means the other end may be significantly cooler
unless it's insulated, amd presumably insulation counts as clutter.
Copper would be a better choice as it would heat more evenly because of
its better thermal conductivity. But you haven't given many clues, such
as what's happening at the other end.

On Sun, 5 Feb 2006 13:20:52 -0000, "R.P.McMurphy"
wrote:


"Paul Andrews" wrote in message
...
"R.P.McMurphy" wrote in message
...
Hi all, I need to heat a steel rod 12inches long and half and inch in
diameter up to around 40 degrees centigrade and keep it within 2degrees.
It
will need to be kept constantly at this temperature. it can only be
heated
at one end, the other end needs to be un cluttered.

Any suggestions how I can do this?

Besides all the comments here about how to go about this, it might be an
idea to say what you are using this for - someone might have an easy
suggestion for you to achieve your aim.

Paul

I'd love to tell you, but if i told you, i'd have to kill you!

I'm a bit of an inventor, this only one part of the gadget i am currently
working on.

I would hope you'll be sharing out the royalties from the production
of the gadget...

:-)

--
Frank Erskine

"Frank Erskine" wrote in message
...
On Sun, 5 Feb 2006 13:20:52 -0000, "R.P.McMurphy"
wrote:


"Paul Andrews" wrote in message
...
"R.P.McMurphy" wrote in message
...
Hi all, I need to heat a steel rod 12inches long and half and inch in
diameter up to around 40 degrees centigrade and keep it within
2degrees.
It
will need to be kept constantly at this temperature. it can only be
heated
at one end, the other end needs to be un cluttered.

Any suggestions how I can do this?

Besides all the comments here about how to go about this, it might be an
idea to say what you are using this for - someone might have an easy
suggestion for you to achieve your aim.

Paul

I'd love to tell you, but if i told you, i'd have to kill you!

I'm a bit of an inventor, this only one part of the gadget i am currently
working on.

I would hope you'll be sharing out the royalties from the production
of the gadget...

well if it makes any money, I will remember my friends!

Steve

In article ,
R.P.McMurphy wrote:

.......... Can you suggest any actual components that
I could use for the heating/monitoring?

Rough calcs suggest that you need about 2-3 Watts
to raise that sized bar (20 sq inches) about 20C
above ambient. It looks rather low, so my calcs
could be wrong (probably are).

Might be worth looking at a tube, filled with oil,
heating resistor(s) and temperature sensor (diode?)
mounted at the bottom. Four wires coming out of the
bottom of the tube, which is to be solidly plugged,
and the top of the tube lightly plugged... enough
to hold the oil in, but something that allows air in
and out as the oil expands/contracts.

Temperature control circuitry mounted in the base.

--
Tony Williams.