Sciencemadness Discussion Board - Variable Speed Overhead Stirrer

Variable Speed Overhead Stirrer

aga - 4-3-2018 at 08:31

Today i needed an overhead stirrer.

Found one in the kitchen with variable speed.

The stirrer & tube are all stainless steel.

Texium - 4-3-2018 at 08:38

Lima bean puree in the making?

Sulaiman - 4-3-2018 at 08:48

I'm using a motor from a hand blender, with eBay ptfe rod/paddle,
they are quite high speed, mine had a rectifier (full-wave = Hi, half-wave=Lo )
so i use a triac dimmer controller for speed control,
e.g. https://www.ebay.co.uk/itm/220V-4000W-AC-SCR-Voltage-Regulat...
the ptfe stirrer rod&blade allows use via ground joints etc.

How slow can that model be adjusted ?
600W is amazingly powerful for such a small motor.

[Edited on 4-3-2018 by Sulaiman]

aga - 4-3-2018 at 09:20

Yep. Bean Paste with acetone. Yum !

This blender goes quite slow when turned down - too slow to get that thick bean sludge to move.

As an actual stirrer the blades would need bending thru 90 degrees to make them into paddles.

The tube/blade detaches, so it should be do-able to 3D print an adapter to accept a teflon rod/paddles.

wg48 - 4-3-2018 at 10:58

Quote: Originally posted by Sulaiman

I'm using a motor from a hand blender, with eBay ptfe rod/paddle,
they are quite high speed, mine had a rectifier (full-wave = Hi, half-wave=Lo )
so i use a triac dimmer controller for speed control,
e.g. https://www.ebay.co.uk/itm/220V-4000W-AC-SCR-Voltage-Regulat...
the ptfe stirrer rod&blade allows use via ground joints etc.

[Edited on 4-3-2018 by Sulaiman]

Can you post a pic of it. I am interested in how you seal the stirrer shaft, couple the shaft to the motor and how you mount the motor. How fast can you allow it to go before the vibration or the shaft wobble gets to high!

Sulaiman - 4-3-2018 at 14:48

I can't say how well it runs at high speed,
I've only run it at low to medium speed, (I'm not even sure what rpm I used, I ran it off a 0 - 30 V power supply.) at atmospheric pressure,
except for the motor, from a damaged hand blender, I used all eBay parts,
. a controller similar to the one that I pointed to above, but lower voltage
https://www.ebay.co.uk/itm/PWM-DC-Motor-Speed-Control-Switch...
. https://www.ebay.co.uk/itm/Electric-overhead-stirrer-mixer-s...
. https://www.ebay.co.uk/itm/Flexible-Motor-Shaft-Coupling-Ste...
Too cold to do much at the moment, I'll do a mock video indoors, maybe soon.
I fancy seeing how fast it can run safely.

EDIT: 05Mar18, made a quick video https://www.youtube.com/watch?v=ziRxiFSaZsA&feature=yout...

Note: in addition to the above, a dc power supply will be required, 1, 2 or 3 x 12 V batteries, 24 Vac transformer + rectifiers etc.

If the hand blender pointed to by aga goes slow enough then that should make a better solution.

Caution: the motor is d.c. with a brushed commutator - a 'sparky' motor.
I have some metal gauze (not shown) to (hopefully) mitigate the risk of igniting flammable vapours.
I have a series of tests to run to determine the ignition hazard of this motor, and my d.c. motor peristaltic pumps,
I intend to make a video of ethanol, diethyl ether and CS₂ being ignited, or not,
by electrical sparks from dc motors, with and without mitigation measures............ comming soon - maybe.

P.S. at the moment the motor is held by a retort clamp that no longer has a screw due to chlorine ... oops.
I'll probably araldite the motor to the clamp once all details are worked out.

Trivia: sometimes during the video a bunch of 1.2m long earth rods can be seen bottom left, some will be for a retort frame as lab jack (or diy equivakent), heating mantle, flask, claisen etc are stacked up, it gets quite tall, and unstable on the economy stands that I'm using.
For the video I used the stand backwards to make a little more height, so the plate is ballasted.

[Edited on 5-3-2018 by Sulaiman]

Sulaiman - 6-3-2018 at 02:30

Sorry to double post - too late to edit:

The heaviest stirring requirement that I have had so far was calcium sulphate slurry,
For hobby chemistry, what is the most viscous or heavy load that a stirrer might be expected to work with ?
or can someone recommend a 'test load' ?

aga: sorry I've hijacked yur thread.

aga - 6-3-2018 at 04:25

no worries. enjoy !

This bean paste is the most goopy thing i've ever needed to stir.