lysander
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DIY overhead low-speed stirrer/mixer
I want a low-speed (30-60rpm) overhead stirrer that can take a steel stir rod. I don't need a unit sealed for use around flammable reagents. And I
don't understand why I should have to spend more than $100 for this.
My best thought right now is to drop $100 on a Harbor Freight drill press. But that has a spindle, which I don't need. And it has a motor and gears
that are far too fast. So I'd have to either buy a different motor or tear open the pulley housing and try to construct a really big pulley wheel to
get to lower speeds.
Are there any easier or better solutions?
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m1tanker78
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UTFSE. www.sciencemadness.org/talk/viewthread.php?tid=62560
If you don't want to assemble a kit or screw around with circuits, there are better things to hack than a drill press. A variable speed hand drill
should work for short term/low duration.
Chemical CURIOSITY KILLED THE CATalyst.
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JJay
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It's not generally recommended, but when I need overhead stirring, I sometimes use a drill with a triac dimmer to control the speed. That probably
voids the warranty, but the drill was inexpensive, and I haven't run into any problems with overheating.
http://www.sciencemadness.org/talk/viewthread.php?tid=64801#...
You can use a kitchen mixer as a stirrer. Be aware that drills and kitchen mixers usually have motors that generate sparks internally, so they might
not be ideal for stirring flammable mixtures. Stepper motors have been reported to work well. They don't generate sparks but require a controller; I
suspect that induction motors like they use in ventilation fans might work well too.
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Sulaiman
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Have you considered a cordless screwdriver ?
And
Adjustable torque limit may be quite useful.
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NeonPulse
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I put together an adjustable speed stirrer last year.
Basically i used a 12v motor i had laying around with a PWM speed controller bought for 5$ off ebay, attatched to this was a hollow fibreglass shaft
and from the local toy shop i bought a couple of RC boat propellers. these work incredibly well at agitating the solutions.
powered by a 12v power supply and set on a stand with a 3 fingered clamp. easy and well under the 100$ you set out to spend.
Also on ebay you can buy PTFE coated stirring paddles on shafts of various lengths for under 20$- just be sure to get the size that folds into the
mouth of your flasks.
Its advisable to get one of these if you want to stir caustics
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lysander
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Yes, I read the other threads. I am looking for something that can run for hours, so that rules out running drill motors at low speed or
through triacs. Also I am not concerned with sparking as several of the other threads were.
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JJay
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Actually, I can run mine for hours through a triac.
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semesa
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A deskfan motor may suit the requirements without modification(variac/gearing.)
They are designed for extended operation as opposed to drill's too, although it may struggle with viscous/slurried solutions.
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violet sin
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my recent endeavor
I've been toying around with a stepper motor, DVR8825 based drop in chip, and some power... Not super easy for me though. For one I noticed the
pin-out on the Chinese knockoffs are different than the polulu driver chips in a number of ways. It says they don't need a 5v logic voltage supply,
because of a built in regulator. So it is supposed to draw off Vmot stepper motor supply. Also you have to set the current limiting pot, by testing
the voltage from an open test point. But no, it goes to one of the stepper coil bank inputs. So your supposed to test from the pot top. But it
won't register any voltage unless you have the 5-45v motor power supply on, AND the separate 5v logic power supply on... Also there is some oddness
on the sleep and rest pins. So if the whole driver is not dumped in an arduino stepper shield unit it deads the output, or they either have to be
given a +5v logic input or jumpered together. But neither way was driving the stepper motor a single click. Currently I'm trying to use a square
wave generator to give it an input signal to step pin on the driver. Also not working super easy. But it was super simple to hook up, +5v/gnd with
one wire output.
So that's been my last few days, looking forward to figuring it out in the end. Not really looking for any answers from people, but I thought I'd
take a break from scavenging bits off a motherboard to share my experience.
If I master the concepts behind stepper motors, I want to build a CNC router. For carving objects  sounds like fun, and prices are getting much MUCH cheaper and more accessible. Now I'm waiting for my oscilloscope
kit to arrive. $19 for the kit, full color display, small/portable, I'll link one below.
http://m.ebay.com/itm/181925407761 DVR8825 driver chip
http://m.ebay.com/itm/NE555-Signal-Generator-Square-Wave-Pul... signal generator
http://m.ebay.com/itm/DSO138-2-4-TFT-Digital-Oscilloscope-Ki... oscilloscopes kit
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Herr Haber
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We have stores around here where people can go and get all the ingredients to make soaps, fragrances, cosmetics and all kind of beauty products.
These sometimes come as emulsions and of course, beside some really affordable plastic and metallic items to equip a lab (no glassware) they also have
this nifty tool that acts as a miniature egg beater (for lack of a comparison).
Very nice when making Lead azide 
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