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Tacho
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Melting point apparatus.
I've built this melting point determination apparatus.
Nothing really new here, but some practical details might give ideas for those who would like to built one:
1- The unit is built with commom aluminium profiles held together by screws. Most of it is hollow to allow the heating unit insertion, but the part
under the sample spot is made solid by joining many pieces of aluminium.
2- The heating unit is one from a 50w soldering iron. It has a tubular shape and fits inside the hollow unit.
3- The sample is held inside a "sandwish" made of microscope glass covers. They are cheap and therefore disposable. This sample
"sandwish" is covered with a plate to assure an even temperature distribution. This plate has a hole (window) for visualization.
4- The thermometer's bulb is inserted in a hole in the body of the unit, right under the sample.
Picture attached.
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axehandle
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Very nice..... could be useful and seems extremely cheap to build.
My PGP key, Fingerprint 5D96 E09E 365D 1867 2DF5 C2FE 4269 9C19 E079 CD35
\"Verbing nouns weirds the language!\"
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cavgdad
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MP apparatus
would you be interested in building me one (sell me one)? I am not tech inclined.
please email me if so.
thx
cavgdad@yahoo.com
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Tacho
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Sorry, can't do that. For many reasons.
I'm sure you can find someone to built it for you.
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cavgdad
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MPA
I understand. can you please post detailed intructions so i can try to do it myself. i would greatly appreciate it
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Tacho
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Sure.
I'll put some instructions together and post them as soon as possible.
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Tacho
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Here it goes:
1- Sorry, but my webcam is developing mould inside the lens, so the picture is quite blurry.
2- I’ve built the device with what I had at hand, so feel free to change the project as you like.
3- I used two extruded aluminum profiles. One is 25mm (1”), the other is 16mm, both are 3,5mm thick. Cut them in the lenghts shown in the picture.
They are easy to cut with a metal saw.
4- With a drill, make the holes to the screws. If you use a drill press (highly recommendable), you can drill the holes as you hold the pieces
together.
5- Screw the pieces to each other using screws and nuts. Put the soldering iron heating element before screwing the top plate. In my design, the
screws in the back prevent it from falling. I presume you are able to connect a plug to it. You can find those heating elements in an electronics
shop. I think Radio Shack should have it, if you live in the US.
6- Notice that using the profiles as I used, a small gap is left as shown in the picture, I used pieces of al sheet, 16mmx30mm, to fill it.
7- make the hole to the thermometer bulb. The bulb must fit as tight as possible.
8- The heating should be slow due to the thermal lag of the thermometer bulb/aluminum interface.
9- Am I making any sense?
wish you luck.
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Eliteforum
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| Quote: |
Sorry, but my webcam is developing mould inside the lens
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Where do you keep your camera?!
All that glitters isn't gold.
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Hermes_Trismegistus
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ummmm.......
Where does Tacho keep his camera?
I hate to hazard a guess, cuz I'm sometimes wrong, but my money is on Brazil.....
Arguing on the internet is like running in the special olympics; even if you win: you\'re still retarded.
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Tacho
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| Quote: | Originally posted by Eliteforum
Where do you keep your camera?! |
Exposed to humidity, greasy fingers, coffee, chocolate cookie crumbs, sneeze debris and acid fumes.
And, yes, in Brazil. Easy money huh Hermes?
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Hermes_Trismegistus
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Huh?
Humid in Brazil???
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thunderfvck
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All this talk of building MP aparati seems pretty useless to me. What's wrong with just boiling up the appropriate liquid, with a themometer
& cap. tube attached immersed in the liquid, when it melts, read the temp, and there's your melting point.
I've even read about it being done directly on the hot plate, there is a special way of doing it however. And you don't need cap. tubes or
high boiling liquids (or low boiling, depending on what mp you're taking)...Anyways, it was in Vogel. I can write it out if anyone's
interested...
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axehandle
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Not so.
| Quote: |
All this talk of building MP aparati seems pretty useless to me. What's wrong with just boiling up the appropriate liquid, with a themometer
& cap. tube attached immersed in the liquid, when it melts, read the temp, and there's your melting point.
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I disagree wholeheartedly. Geniousness lies in doing things in a non-conventional way, and I believe Tacho has very successfully done so, while he at
the same time probably had lots of fun building it.
Call me wrong and radical, but my firm belief is that, all other things being equal, if you can 1) buy it or 2) build it, you build it. Not only for
the satisfaction of a job well done, but for the fun of it.
Every once in a while, it's also cheaper.
My PGP key, Fingerprint 5D96 E09E 365D 1867 2DF5 C2FE 4269 9C19 E079 CD35
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Tacho
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Thanks axe, you know that’s exactly how I think, but I believe I can explain to Thunderfvck the more prosaic advantages of the device.
Thunderfvck,
Picture this:
It’s 1:00 a.m. You have to wake up early today. You just cleaned up the attic (or basement, or garage) while your reaction was refluxing. Everything
is tidy and clean. You are sleepy. Look at the clock and it’s time to turn off the heat. You filter that precipitate. Dry a bit with a hair dryer.
Is that what you expected? How to tell? Melting point! And now you choose:
1) Get the Tiele tube or a test tube. Pick up the silicon oil bottle, put some oil in the tube. Get a capillary tube (where the hell do you get
capillary tubes? Do you have to make them? Do you have to close one end in the flame?). Fill carefully the damn thing. Rubberband it to the
thermometer. Fix some structure to hold the test tube. Fix some structure to hold the thermometer and capillary inside the test tube (no, no, no, it
can’t touch the walls!). Get the gas tank, the Bunsen burner (where the hell did I put those matches?). Is the Bunsen burner already connected to
the gas? You are lucky. Heat until you find the melting point. Use a lens to see when the sample melts and band-aids to the burn in your nose when
you put it in the flame trying to look in the lens. Remove the thermometer and the sample. But wait, that silicone oil is HOT!!! Careful! Wash the
thermometer to remove the oil. Now wash the tube. It may take a while, because silicone oil is a bitch to remove from glass. Don’t forget the gas
tube, the fixtures, the Bunsen burner.
or:
2) Get the apparatus described and the microscope glass covers box.. Toss a bit of the sample on the glass. Cover it with another glass. Put the top
plate. Put the thermometer in the hole and plug the thing to the wall plug. When that white spot suddenly becomes transparent, read the temperature.
Turn it off. Go to bed. Tomorrow you can put everything back to the cabinet.
Maybe not as precise, but, believe me, much more practical and quick.
Edit: Hey Hermes, what's the thing about humid? We have all weathers here. Look at the size of this place in the map!
Well, maybe not the very cold ones...
[Edited on 1-5-2004 by Tacho]
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Geomancer
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I remember using a device that consisted of a polished metal bar heated at one end. The sample was sandwiched between cover slips and slid until it
crosed where the melting temperature was on the metal. The distance was measured using graduations on the device, and then some sort of correction
using a calabration curve was done. Altogether, a very smooth procedure--fast, precise, and microscale. I thought of making one, but they seem hard to
calibrate. Tacho's device has similar advantages, without the disadvantage of difficult calibration. A bit slower and less precise, perhaps. Can
any owners comment on how what they take the precision to be, and why?
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thunderfvck
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Oh, I agree with it being much more efficient. But for the person who had asked for one to be built, I'm just saying that their are other ways in
doing it. You don't HAVE to have one...but that's obvious, of course!
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Hermes_Trismegistus
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| Quote: | Originally posted by Tacho
Edit: Hey Hermes, what's the thing about humid? We have all weathers here. Look at the size of this place in the map!
Well, maybe not the very cold ones...
[Edited on 1-5-2004 by Tacho] |
Tsss......don't tell me about weather, About five days ago I noticed that the snow was almost completely melted off of my front lawn, then two
days ago it goes and snows again!
I've been mulling over this melting point apparatus and I think it's a good one.
You probably already thought of this but, I think that in making one I will try to have the thermometer the same distance from the heat source as the
sample "dish" and the reasoning is that the heat at the thermometer will be the same as that applied to the sample.
I never really gave much thought as to this apparatus, but it seems like a valuable peice of equipment.
I really like your design, I wonder if a dremel will cut the aluminum plate up or whether I'll have to put in some elbow grease.
(When I get a chance)
Since becoming enamoured with science; albeit late in life, I often feel like a two-headed dog trying to play fetch.
Problem being the dog has one head on each end.
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Tacho
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By the way, the general idea is not mine, Zubrick's describes the Fisher-Johns apparatus in the chapter 12 of 4th edition. Mine is a DIY, quick
and dirty version of it.
Vogel's third edition describes all sort of strange devices for mp determination. One of them uses an iron (the clothes one). He suggest drilling
a hole for the thermometer on the iron's side.
I believe the device described by geomancer is there too.
[Edited on 1-5-2004 by Tacho]
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If_6_was_9
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These doohickies are nice:
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axehandle
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| Quote: |
By the way, the general idea is not mine, Zubrick's describes the Fisher-Johns apparatus in the chapter 12 of 4th edition. Mine is a DIY, quick
and dirty version of it.
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As long as it works, what's the difference? (rhetorical question, the answer being "none"
My PGP key, Fingerprint 5D96 E09E 365D 1867 2DF5 C2FE 4269 9C19 E079 CD35
\"Verbing nouns weirds the language!\"
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Hermes_Trismegistus
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Credit where credit is due! Huzzah!!!
| Quote: |
By the way, the general idea is not mine, Zubrick's describes the Fisher-Johns apparatus in the chapter 12 of 4th edition. Mine is a DIY, quick
and dirty version of it.
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Sorry Norseman
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axehandle
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Credit where credit is due? Perhaps. As a matter of honour. But as a Communist, I must say that all work should be on a hired basic. You
shouldn't be able to profit from work you did 15 years ago.
My PGP key, Fingerprint 5D96 E09E 365D 1867 2DF5 C2FE 4269 9C19 E079 CD35
\"Verbing nouns weirds the language!\"
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Tacho
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| Quote: | Originally posted by Hermes_Trismegistus
(snip)
Sorry Norseman |
| Quote: |
Credit where credit is due? Perhaps. As a matter of honour. But as a Communist, I must say that all work should be on a hired basic. You
shouldn't be able to profit from work you did 15 years ago.
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Sorry, but I don't get it.
Was there a dispute that I missed in some other thread?
If_6_were_9,
That's a beautiful piece of equipment, does it work well?
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If_6_was_9
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If_6_were_9,
That's a beautiful piece of equipment, does it work well?
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It seems to be pretty accurate. Its in a hinged wooden box which is unusual for modern melting point apparatus. I bought it about 25 years ago from
a head shop. Head shops are illegal now in the USA, but shops that look like head shops are around. They just can't sell paraphernalia.
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Hermes_Trismegistus
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nope.
just a convenient seque into politics
http://dictionary.reference.com/search?q=segue (for those who don't have english as a first language)
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