Bimetalic domes
N_Cook
continuous curving with temperature, these are 0.5 inch diameter and make a
definite flip from concave to convex at a specific temperature. About 1mm of
abrupt movement gives a very positive transition for the switch contacts.
Would it be possible to change the characteristic temperature by grinding
back a spot/ring/radii? on one face? which face? or would it just destroy
the action/activation force?
Steve Lusardi
Steve
"N_Cook" <div...@tcp.co.uk> wrote in message news:hd608l$u0r$1...@news.eternal-september.org...
William Sommerwerck
You might find one of the sort that used to be used in kitchen appliances,
that could be inserted in a grill, waffle maker, cookpot, etc. These have
adjustable settings, which (I assume) are varied by changing the pressure on
the sensor.
N_Cook
news:hd683k$jvj$00$1...@news.t-online.com...
According to patent
"Laser adjusted set-point of bimetallic thermal disc"
it is done at production , for precise adjustment, but no specific details
of patterns/which surface/degree of variation. I'm more interested in
adjusting otherwise useless batch made for set point of 16 degree C up to
50 or 60 degree C, with no great precision, +/- 10 deg C would be fine
William Sommerwerck
> "Laser adjusted set-point of bimetallic thermal disc"
> it is done at production , for precise adjustment, but no specific details
> of patterns/which surface/degree of variation. I'm more interested in
> adjusting otherwise useless batch made for set point of 16 degree C up to
> 50 or 60 degree C, with no great precision, +/- 10 deg C would be fine
If you could find the patent for the controller I described (it's a famous
patent, from a man who patented many devices in the 50s and 60s), it might
show how this is done.
N_Cook
news:hd6ik6$eip$1...@news.eternal-september.org...
probably a John Taylor
http://content.yudu.com/A15ex7/Apro9/resources/8.htm
but no further forward, I'll suck some and see
William Sommerwerck
> http://content.yudu.com/A15ex7/Apro9/resources/8.htm
I'm not sure. The guy I'm thinking of is American.
N_Cook
remain froststats. Surprising ping and bounce as much as six inches on
change of state, the loud ping is somewhat damped when inside the casing.
Need freezer spray to change the state of these discs (hysteresis and all
that). When back to body temp I tried grinding a spot in the centre of the
concave side, no change in set temp. Tried 4 diametrical marks on the
concave side , no change in response. Tried deeper but small 8 cuts just on
the perphery, now no ping but slowly migrates from one state to the other ,
still requiring freezer spray. I wonder how they "weld" these 2 materials
together.
Jeff Liebermann
>As used in thermal switches. Instead of in form of a bimetal strip and
>continuous curving with temperature, these are 0.5 inch diameter and make a
>definite flip from concave to convex at a specific temperature. About 1mm of
>abrupt movement gives a very positive transition for the switch contacts.
Like this?
<http://www.google.com/patents/about?id=VQ4XAAAAEBAJ&dq=5903210>
or this?
<http://www.google.com/patents/about?id=BygyAAAAEBAJ&dq=3852697>
>Would it be possible to change the characteristic temperature by grinding
>back a spot/ring/radii? on one face? which face? or would it just destroy
>the action/activation force?
I don't think so (but I'm guessing). Grinding might change the
deflection or force but probably not the transition temperature. Below
some force level, it simply will not transition. My guess(tm) is that
the transition temperature is controlled by the curvature which is
rather difficult to modify.
Note that some discs are "manual reset" or "single operation" and act
as thermal fuses.
Search Google for "bimetallic snap disk".
<http://www.cpi-nj.com/snap.htm>
<http://www.thermodisc.com>
(etc...)
I tried to find the vendor of the actual discs, which might include
design information, but couldn't find anything useful.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Gunner Asch
Have you considered fire alarm heat sensors? They use a bimetal switch
internally.
Gunner
"IMHO, some people here give Jeff far more attention than he deserves,
but obviously craves. The most appropriate response, and perhaps the
cruelest, IMO, is to simply killfile and ignore him. An alternative, if
you must, would be to post the same standard reply to his every post,
listing the manifold reasons why he ought to be ignored. Just my $0.02
worth."
Baron
>As used in thermal switches. Instead of in form of a bimetal strip and
>continuous curving with temperature, these are 0.5 inch diameter and
>make a definite flip from concave to convex at a specific temperature.
>About 1mm of abrupt movement gives a very positive transition for the
>switch contacts. Would it be possible to change the characteristic
>temperature by grinding back a spot/ring/radii? on one face? which
>face? or would it just destroy the action/activation force?
I belive "Clixon" in the UK make these.
--
Best Regards:
Baron.
Michael A. Terrell
That is 'Klixon', which was a division of Texas Instruments.
Now it's a division of Sensata
<http://www.sensata.com/klixon/thermostats-thermostat.htm>
--
The movie 'Deliverance' isn't a documentary!
Baron
Thanks for the spelling correction and link. Its a lot of years since I
played about with them. They were very popular in water heater
circuits at one time.
--
Best Regards:
Baron.
Jeff Liebermann
>I wonder how they "weld" these 2 materials
>together.
Probably by electroplating one of the meterials onto the other.
Michael A. Terrell
They still are, but a lot of their thermal motor starters are
discontinued.
Martin H. Eastburn
Simple as that.
Martin
N_Cook
news:mxLJm.189672$Jp1....@en-nntp-02.dc1.easynews.com...
I would have thought friction welding, probably many to a spin and then
press cut to small discs
whit3rd
wrote:
> N_Cook wrote:
> > I wonder how they "weld" these 2 materials
> > together.
>Explosive welding.
>Simple as that.
This might be the correct answer, but there are fill-metal/reducing
atmosphere/heat solutions that might do a kind of brazing for lower
cost
if you get the materials right. Explosive welding is used for US
coins
because it was possible to mimic the electromagnetic properties of
silver well enough to keep lots of vending machines in service.
I've gotta believe the requirements for a thermostat bimetal system
are loose enough to allow for alloys that don't require explosive
welds.
Baron
I was under the impression that two sheets of material were hot rolled
together and the discs just stamped out complete with the dome shape.
--
Best Regards:
Baron.
N_Cook
news:MB%Jm.24082$Wd1....@newsfe15.iad...
>
> "Baron" <baron....@linuxmaniac.nospam.net> wrote in message
> news:hd9vjc$bu7$1...@news.eternal-september.org...
to
> remove material around the outside diameter? would that alter the point
at
> which the dome went PING? i was just wondering if the outside edge is
> constrained in a bezel, if there was more room to expand there if that
would
> alter it's temperature rating?
>
> b.w.
>
>
The use I see them is located fairly loosely in a well in a bakelite disc
that is itself located loosely in the bakelite outer housing
N_Cook
news:dhahf59546oirlspq...@4ax.com...
> On Mon, 9 Nov 2009 16:13:19 -0600, "William Wixon"
<wwi...@frontiernet.net>
> wrote:
>
>
> >
> >
> >how about instead of removing material from the flat surface of the dome
to
> >remove material around the outside diameter? would that alter the point
at
> >which the dome went PING? i was just wondering if the outside edge is
> >constrained in a bezel, if there was more room to expand there if that
would
> >alter it's temperature rating?
> >
> >b.w.
> >
>
point.
>
> Mark Rand
> RTFM
I might try that , will require adding a small well for the spring
Winston
I wonder if one could paint the convex face with fingernail polish as
an etch resist and put the disc in an etching solution to thin the
concave side? Would the relatively smaller 'concave mass' shift the
trigger temperature upwards?
--Winston
--
On YouTube, all the tools have volume controls.
William Sommerwerck
> and make a definite flip from concave to convex at a specific temperature.
> About 1mm of abrupt movement gives a very positive transition for the
> switch contacts. Would it be possible to change the characteristic
> temperature by grinding back a spot/ring/radii? on one face? which
> face? or would it just destroy the action/activation force?
Heaven knows, I don't like reinventing the wheel, but unless you can find
documentation (such as a patent) that explains in detail how these devices
work, and how a particular temperature is set, you're going to have to
experiment.
I again recommend looking for one of those interchangeable thermostats.
Perhaps ripping it apart will reveal the secret!
http://www.gopresto.com/products/products.php?stock=07211
http://www.acehardwareoutlet.com/(uahrtsrsnq0tcxf1wt3tllmg)/productDetails.aspx?SKU=998000074
http://www.advertisingcookbooks.com/si/004123.html
The Presto "Control Master" has been around at least 40 years, and Presto is
still making appliances that use it. (I don't know whether the internal
design or operating principles have changed. The probe part does appear to
be longer and narrower in the current version.)
dca...@krl.org
I have been waiting for someone to suggest that the temperature at
which they switch is controlled by how domed the discs are. At least
that is my guess. Suggest you get some rubber and a ballpein hammer.
Test what the temperature is that one switches at, and then make in a
bit more domed and see if that changed the temperature at which it
switches. My guess is that more domed means more change from ambient
temperature before it switches.
Dan
N_Cook
news:453facae-8a15-42ea...@33g2000vbe.googlegroups.com...
Dan
I will give it a go with large ballbearing in a cup and a press. But the
full range of temp (10 to 220 deg C at least) switches all come in the same
size package and the internal spaces and activation pins are the same
dimensions including degree of doming, all that changes is the materials or
construction within the domes. Normally open for the same temp normally
closed is simply just the same dome in, the other way up
Ned Simmons
wrote:
><dca...@krl.org> wrote in message
. My guess is that more domed means more change from ambient
>temperature before it switches.
>
> Dan
>
>I will give it a go with large ballbearing in a cup and a press.
Another thing to try is local heating and quenching in order to change
the distribution of internal stresses in the dome.
--
Ned Simmons
isw
Ned Simmons <ne...@nedsim.com> wrote:
It's bimetal; I don't think you want any "unexpected" stresses.
Isaac
Paul Hovnanian P.E.
> As used in thermal switches. Instead of in form of a bimetal strip and
> continuous curving with temperature, these are 0.5 inch diameter and make
> a definite flip from concave to convex at a specific temperature. About
> 1mm of abrupt movement gives a very positive transition for the switch
> contacts. Would it be possible to change the characteristic temperature by
> grinding back a spot/ring/radii? on one face? which face? or would it just
> destroy the action/activation force?
Pretty difficult to calibrate that change. I'd try mounting a small coil
spring so as to work with or against the direction of the snap. A setscrew
can then be used to modify the spring preload and adjust the snap point.
--
Paul Hovnanian pa...@hovnanian.com
----------------------------------------------------------------------
Have gnu, will travel.
steamer
inversely proportional to the radius of curvature; i.e. greater radius
translates to smaller temp changes to make it flip. I was working on what I
call a 'kinetic solar cell' which works very well in theory...
--
"Steamboat Ed" Haas : Currently broke and
Hacking the Trailing Edge! : looking for a job...
www.nmpproducts.com
---Decks a-wash in a sea of words---