micron
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Home-made rotary evaporator
I have pondered that thought almost a six month by now. First I thought I would buy it, but they are not very common in European different ebay
markets for some reason for a quite a while by now and if they are avalaible they are too expensive (my limit would be about 200-280EUR max) as I'm
poor university student. As I don't know what parts are needed I really don't know is it worth to start buying rotavap pieces to put it together
myself. The heating bath wouldn;t be no problem as I can do it myself very easily, nor the stand. Now there are some buchi motors for sale in ebay and
quite often a condensators also(and of course the flasks). But I don't know exactly in what size condensator I need that would fit and what other
little parts I would need. If I would know all the needed items I can calculate the total sum and buy the needed pieces and put it together. Can
someone who knows all the rotavap principes could help me here what adapters and other small items I would need beside motor, condensator, flasks,
metal clips for joints. I have asked from sellers but they say that they don't know nothing. Big thanks for all those who can help me out and others
who might have interesting ideas and comments.
Here are motor that are for sale:
the price is 80EUR
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Hexavalent
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Have you tried looking through manuals and technical spec sheets first?
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micron
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yeah that would be good idea for first, but I;m sure there are many ways how to put it together, maybe someone knows the most straightforward way.
I'll check out some sheets. I have looked before some patents only and they contain lots of different small items but they have been quite an old
also.
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Hexavalent
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a) Have you checked eBay recently? Sometimes you can get professional models at great prices.
b) If you're at university, have you looked in the waste/refuse centre? A few members here have scored some nice stuff that would otherwise have been
thrown away.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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Lambda-Eyde
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One possible solution would be to have a glassblower make an adapter for you, so you can fit a standard ground glass condenser to the threaded port on
a rotavap. Büchi condensers can be had on eBay for several hundred €, while a standard condenser (think large dimroth with cooling jacket) can be
had for much less.
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kristofvagyok
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I would mention two little but important things about rotavaps.
We have currently 2 non working rotavaps in the lab and this causes a lot problem. Why are they not working? One has an old PTFE sealing (between the
rotator motor the "steam pipe" -or how it's called and the condenser), the other one has a fixed steam pipe and the result is: both are rotating, but
there is NO vacuum in them.
The PTFE sealing costs 50-80Euro the steam pipe is at 150-200euro and these are the cheapest part of the rotavap.
If you want to make one at home from differently purchased parts with a low budget like this, then you have to be really lucky to get perfect, well
sealed, not damaged parts, elseway it won't work.
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Lambda-Eyde
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Quote: Originally posted by kristofvagyok  | I would mention two little but important things about rotavaps.
We have currently 2 non working rotavaps in the lab and this causes a lot problem. Why are they not working? One has an old PTFE sealing (between the
rotator motor the "steam pipe" -or how it's called and the condenser), the other one has a fixed steam pipe and the result is: both are rotating, but
there is NO vacuum in them.
The PTFE sealing costs 50-80Euro the steam pipe is at 150-200euro and these are the cheapest part of the rotavap.
If you want to make one at home from differently purchased parts with a low budget like this, then you have to be really lucky to get perfect, well
sealed, not damaged parts, elseway it won't work. |
If a glassblower could make a custom adapter like I mentioned in my previous post, I think that such a part could be modeled around a much cheaper and
readily available PTFE seal serving the same purpose (I'm guessing the steep price is due to Büchi's "monopoly" and not the actual price of PTFE...),
or a skilled machinist could make this seal himself.
[Edited on 30-9-2012 by Lambda-Eyde]
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kristofvagyok
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| Quote: Originally posted by Lambda-Eyde |
If a glassblower could make a custom adapter like I mentioned in my previous post, I think that such a part could be modeled around a much cheaper and
readily available PTFE seal serving the same purpose |
The adapter what we have problem with is a repared one by our best glassblower (more than 50years doing it), so if I wouldn't use it I would say that
there is no problem. But there is a less than half mm angle in it (where it was broken) and there is 0 vacuum with it.
The PTFE sealing is also not a thing what I would make with OTC methods, because if the rubber gets old, or any else problems, then also 0 vacuum will
be in the apparatus.
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Dr.Bob
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Yes, unless you have parts for a pieced together rotovap, then it will be very hard to make the parts work together unless perfect. They used to
sell the pieces as separate items, where their was the rotary vacuum adapter as one piece, then you could supply your own condenser and water bath
(often heated with steam via a coil of copper). Those were easy to put together as they were designed with simple fittings at each end. Newer
parts like the RE 120 are designed only to fit and work with Buchi parts, and thus are a pain, unless you have more Buchi parts. And the few glass
blowers I know left alive charge $100 / hour to fix things, so that is much more expensive than buying the parts used. You can buy many of these
parts on Ebay used for cheap, but this only works if shipping is not too much, you read the manuals so you know which pieces fit together, and you
trust the seller on Ebay.
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leu
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If you would have used:
http://www.sciencemadness.org/talk/search.php?fid=5
you would have found:
http://www.sciencemadness.org/talk/viewthread.php?tid=7128
reading which could prove illuminating  The end results from the effort applied
Chemistry is our Covalent Bond
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chemrox
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Although the search engine here does not always yield the results it should - I nominate this reply as a sticky! I further suggest it be a global
sticky; if there could be such a thing. It is perfectly concise and utterly to the point. Thanks, leu.
I edited to add:
There are a number of cheaper options for making a rotary evaporator. I've go the glass parts for a simple one that runs on an aspirator and a motor.
I had one that was a motor with a 24/40 pass through to an aspirator. I can think of no cheap way to build one from Buchi parts but there could be
if you are a good machinist and have lots of seals lying around. The problem with the cheap solutions is the solvents go down the drain. As soon as
you incorporate a trap you've likely gone to more expense than buying a decent used evap from me for $1800.
[Edited on 1-10-2012 by chemrox]
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smaerd
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We have a thread on this with a hand-full of articles describing some designs. Hopefully I'll be finishing my build by the end of the month. Depends
on the pay-check and time available.
Buying a motor and putting it on a stand isn't really what I'd call 'home-made'.
[Edited on 2-10-2012 by smaerd]
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