blaztoff (Hive Bee)
01-03-02 14:48
No 252216
      Heating element assembly  Bookmark   

What would you use for a homemade heating element assembly for a mag/hotplate stirrer. I know what to use for a homemade or improved mag stirrer but not the hotplate. What would you use for the element and the control assembly for it.
(Hive Bee)
01-03-02 15:34
No 252221
      Re: Heating element assembly  Bookmark   

Glass or ceramic bowl filled with cooking oil, nichrome wire coil controlled with a rheostat made from a dimmer switch smile
(Junior Service Representative)
01-03-02 22:28
No 252302
      Re: Heating element assembly  Bookmark   

Where's the write-up on this soon-to-be ghetto hotplate/stirrer?  I'm sure it'll be added to Rhodium's Equiptment section as soon as it does exsist smile...

(Hive Bee)
01-03-02 23:05
No 252310
      Re: Heating element assembly  Bookmark   

Another method used by those that have built this type of equipment is to make the hotplate from a non-ferromagnetic metal such as copper or aluminum, and heat that with a heat source such as a torch, a bunsen burner, an alcohol lamp, or an electric heating element smile
(Hive Bee)
01-04-02 07:01
No 252467
      Re: Heating element assembly  Bookmark   

What temp would the rheostat get and where do you get the wire coil? Was thinking maybe something like a fondu pot. They are nonferous and some reach 450F which is good for most applications. Plus bieng nonferous you can mount them on your Stirrer for mag stirring. I remember in some Chem catalog they do sell heated pots that have the temp control and heating element inside them and you can dial the temp you want and have extreme temp control. Place that on youre stirplate viola. Mag stirrer and hotplate. Dont have to wait for the temp to transfer from the hoptplate through vessell to flask when you make adjustments in heat. Figure that would be great for temp controls for Frac dist. Thats what gave me the idea for the fondu pot. Havnt tried it yet though. SO dont know. Also I saw immersion heaters but dont think those reach good enough temp.
(Hive Bee)
01-04-02 15:04
No 252555
      Re: Heating element assembly  Bookmark   

What temp would the rheostat get and where do you get the wire coil?

Temperatures are determined by the amount of current applied, thus they're variable smile Nickel-chromium wire is an item of commerce, since there are only a few suppliers left, Post 13988 (Rhodium: "It is forbidden to post sources in this forum!", Chemicals & Equipment) applies. Industrial suppliers can bee helpful. Become a toaster repairman, and start asking questions at electrical suppliers, some still have them hanging on the walls smile SWIL just buys the wire wholesale and winds his own coils smile Large scientific suppliers also carry nichrome wire smile

(Chief Bee)
01-04-02 19:35
No 252631
      Re: Heating element assembly  Bookmark   

Are you saying that you are putting the nichrome wire directly into the oil bath? Wouldn't that produce local overheating/charring of the oil?
(Hive Bee)
01-04-02 20:11
No 252647
      Re: Heating element assembly  Bookmark   

No, it doesn't burn the oil, as long as the current is regulated properly smile
(Hive Bee)
01-04-02 21:32
No 252684
      Re: Heating element assembly  Bookmark   

ride down the road
notice any discarded piles of stuff
stop and look for heating type devices
toaster, radiant heaters, etc.
find a central heating electric blower unit
lots of heating element in there
dismantle and save elements, controllers, etc.
build like crazy
obtain variac, phase control device (dimmer) to vary power same as heat produced
get fancy
build parallel port controller
and on and on and on.

fire clay makes great crucible
embed elements into wet clay and dry in oven
don't energize the element fully first time
work up to the sun level

confer on various libraries concerning
fabrication of furnaces
especially Journal of Chemical Education
do search thereabouts for approipriate items

better yet forget conventional heat sources
go microwave - dude/dudess.

do search on for applicable patents
usually come with nice diagrams
(UTFSE cannot read so good)

go for it. good luck.

Ohyeah please be careful concerning
1-the electrical source
2-the heat.

just glad to bee here-----he he he
(Hive Bee)
01-04-02 21:38
No 252689
      Re: Heating element assembly  Bookmark   

more - to arrive at unknown specs on elements
(most heating devices are stamped with their ratings)

determine guage of wire and lenght
find nichrome data on internet
calculate power according to your voltage
(USA is 120 or 240vac on the wall)
hook it up
be brave
don't put in direct contact with glass
temperature differentiation with likely crack even borosilicate.

use sand bath
direct contact with elements OK on noncombustibles
reread LUGH concerning oil contact
use obvious high boiling oil
experiment with design
try small things first
take your time be patient
make mistakes during learning curve
later will cost lots more

just glad to bee here-----he he he
(Hive Bee)
01-05-02 00:04
No 252727
      Re: Heating element assembly  Bookmark   

I just bought a nice fondo pot from target 42.00 Its got a temperature control (F) but goes to 450F or 230C so that is applicable to most situations. Sawed the legs off fits nicelly over my stirrer. A few minor modifications for distance so the magnetic fields are aligned and perfect. It works. Cheap solution to a 400.00 mag/Stirrer combo. Its working great great temp control better than most hotplates except if you have a temp regulated probe but those are much more money and a waste for most bees.
Just perfecting this little gadget up. But it has been extremly interesting building or modifing a hotplate/ stirrer. Once done  f anyone interested i will post it here with pictures if i can figure out how to put pics up here. Also I have some really interesting information for newbees and like about the forces involved in mag stirring what effects them: how different stirrbars work and what situation to use them and distances and like. I see a lot of posts about people cant get there stirbar to work good enough and such. This will help people on spinouts what to do to stop them and such. Its been a lttle fun. I never really used my mag stirrer to recentlly for the O2 wacker I always used overhead stirring so was a little lesseon in basics for me.