Benvarine's DIY stir plate build
  • C_BC_B
    Posts: 89,069
    This discussion was created from comments split from: DIY Stir Plate Build.
    "On it. I hate software." ~Cpt Snarklepants
  • BenvarineBenvarine
    Posts: 1,606
    Just put the poly on it tonight.
    image.jpg
    2592 x 1936 - 1M
  • BenvarineBenvarine
    Posts: 1,606
    And the top.
    image.jpg
    2592 x 1936 - 1M
  • BenvarineBenvarine
    Posts: 1,606
    And the guts. I'm no electrician, but it seems to work. I am buying a stir bar tomorrow, so I'll add the tornado pic if it works.
    image.jpg
    2592 x 1936 - 1M
  • C_BC_B
    Posts: 89,069
    Ben, you should make your own build thread that thing looks awesome!
    "On it. I hate software." ~Cpt Snarklepants
  • C_BC_B
    Posts: 89,069
    C_dubbs said:

    Ben, you should make your own build thread that thing looks awesome!


    @Benvarine
    I did it for you :D

    "On it. I hate software." ~Cpt Snarklepants
  • C_BC_B
    Posts: 89,069
    Where did you get that box? I love it.
    "On it. I hate software." ~Cpt Snarklepants
  • frydogbrewsfrydogbrews
    Posts: 44,679
    looks like a cigar box, great idea
  • FuzzyFuzzy
    Posts: 49,786
    frydogbrews said:

    looks like a cigar box, great idea



    you should put some cigars in there.
    The pinnacle of lame and awesome in one singular moment. -Lake
  • FuzzyFuzzy
    Posts: 49,786
    cheap ones. tell urryone that it's tobacco powered.
    The pinnacle of lame and awesome in one singular moment. -Lake
  • ThymThym
    Posts: 122,708
    i think he mentioned somewhere else that it was from Michaels crafts store
    The only thing between me and a train wreck is blind luck..... - Kenny
  • scoobscoob
    Posts: 16,617
    Lakewood said:

    i think he mentioned somewhere else that it was from Michaels crafts store


    Yes, I believe in my my build thread.
    Jesus didn't wear pants
  • C_BC_B
    Posts: 89,069
    azscoob said:

    Lakewood said:

    i think he mentioned somewhere else that it was from Michaels crafts store


    Yes, I believe in my my build thread.

    I suppose I could have snagged another couple posts....
    "On it. I hate software." ~Cpt Snarklepants
  • BenvarineBenvarine
    Posts: 1,606
    Yes. From Michaels. But I have issues.
  • BenvarineBenvarine
    Posts: 1,606
    It won't spin the bar. It throws it around, and that is on the slowest setting. My potentiometer does not crank so low as to stop the fan. Where could my trouble be?

    Plug is 5v output from a cell phone charger.
    Potentiometer is whatever azscoob recommended.
    Fan is 12v 1.5 amp.

    Thoughts?
  • frydogbrewsfrydogbrews
    Posts: 44,679
    throws it around? like the whole box? is it just unbalanced or not centered? if you are talking electrical things, i have no input.
  • BenvarineBenvarine
    Posts: 1,606
    It throws the stir bar around. I was concerned the magnet wasn't centered, but the fan operates fine on its own. I am not sure how to officially center it. I eye-balled it, looks okay.
  • frydogbrewsfrydogbrews
    Posts: 44,679
    can you mount the box onto something heavy, like a steel plate? i have a few of those if you need one. the torque might just rip the box apart though, but that's still kinda fun.
  • BenvarineBenvarine
    Posts: 1,606
    The box is fine, it's the stir bar that won't spin properly, it just flies to one side of the flask. It means it might be spinning too fast, but that's just a guess.
  • ThymThym
    Posts: 122,708
    the balance of the stir bar,
    the concentricity of the drive magnets to the fan rotational axis
    and the spacing of the drive magnets relative to the stir bar magnets

    all play a part in how fast you can spin it before it spins off.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    how fast is the fan spinning when you are at the slowest pot setting?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    how much does the fan speed vary with the pot sweep?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    What the hell does that mean. How do I get it to spin right?
  • ThymThym
    Posts: 122,708
    can you tak a picture of how you wired the pot?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Lakewood said:

    how much does the fan speed vary with the pot sweep?



    Not much. I was expecting more. Where is the issue?
  • ThymThym
    Posts: 122,708
    Benvarine said:

    What the hell does that mean. How do I get it to spin right?



    the drive magnets (on the fan side) should be spaced roughly the same distance apart as the spin bar magnets (otherwise it wont have the strongest bond you can get)

    those drive magnets should be placed such that they are equidistance from the fan ais so they sweep out one continuous, perfect circle. if they are offset it will cause the spin bar to accelerate in multiple axis' and you wont be able to hold it at very high speed.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Potentiometer
    image.jpg
    2592 x 1936 - 2M
  • ThymThym
    Posts: 122,708
    Benvarine said:

    Lakewood said:

    how much does the fan speed vary with the pot sweep?



    Not much. I was expecting more. Where is the issue?


    might be that it's not wired right. can you take a picture?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    wiring looks correct. whats the Ohm rating on the pot?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    is it a linear or log (audio) taper?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    also the thickness of the box lid will play a big part in how strong the spin bar attaches to the drive magnets.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    the closer they are, the stronger the bond.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    so if the box lid is more that .100" you might have a problem
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Lakewood said:

    wiring looks correct. whats the Ohm rating on the pot?



    25 ohm
  • BenvarineBenvarine
    Posts: 1,606
    The magnet is a hard drive magnet. So one, curved magnet. The box lid is about 1/4" thick, maybe a little less. The fan is spaced a bit further to make room for the magnet.
  • ThymThym
    Posts: 122,708
    Benvarine said:

    Lakewood said:

    wiring looks correct. whats the Ohm rating on the pot?



    25 ohm


    ohhhh... yeah, that's not much. maybe 250ohm would work. but you could play with a couple of resistors if you can get your hands on them to find out the resistance you need for the slowest reasonable speed
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    Benvarine said:

    The magnet is a hard drive magnet. So one, curved magnet. The box lid is about 1/4" thick, maybe a little less. The fan is spaced a bit further to make room for the magnet.



    ok. so when the fan spins does that magnet make a single, tight, perfect circle, or does it have slightly fuzzy edges?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    That's what azscoob recommended. So I need a different potentiometer? 250 ohm one? That will make it run slower?
  • ThymThym
    Posts: 122,708
    Lakewood said:

    Benvarine said:

    Lakewood said:

    wiring looks correct. whats the Ohm rating on the pot?



    25 ohm


    ohhhh... yeah, that's not much. maybe 250ohm would work. but you could play with a couple of resistors if you can get your hands on them to find out the resistance you need for the slowest reasonable speed


    my gut says 1k ohm 1.5k is probably where you want to be... but i don't know.

    BTW, this is where the more complex circuit involving a linear voltage regulator works well. because the dynamics of every fan and power supply will be a little different, the resistive pot based design can vary in its result. using a linear voltage regulator takes the power supply and fan out of the equation on the control side.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    Benvarine said:

    That's what azscoob recommended. So I need a different potentiometer? 250 ohm one? That will make it run slower?



    it definitely will make it run slower.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    do you have a box of resistors laying around (i know, not many people do... but i do, so i ask)
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    or maybe some old piece of electronics that is dead that you wouldn't mind hacking apart?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    we need to get you a couple of resistors of different values.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    so you can play with adding them to your circuit to see how the fan spins
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    I have no extra parts like that. I finally got it spinning, but not fast enough to make a vortex.
  • ThymThym
    Posts: 122,708
    Benvarine said:

    I have no extra parts like that. I finally got it spinning, but not fast enough to make a vortex.



    likely due to the distance between the stir bar and the drive magnets. can you route out the underside of the box top so you can get the fan mounted closer?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Lakewood said:

    Benvarine said:

    I have no extra parts like that. I finally got it spinning, but not fast enough to make a vortex.



    likely due to the distance between the stir bar and the drive magnets. can you route out the underside of the box top so you can get the fan mounted closer?


    I can certainly try. I know just about nothing about the electronic details, I found another build thread on the Internet that used this type of box, so I went for it. I'll try and sand down and see tomorrow.
  • ThymThym
    Posts: 122,708
    Benvarine said:

    Lakewood said:

    Benvarine said:

    I have no extra parts like that. I finally got it spinning, but not fast enough to make a vortex.



    likely due to the distance between the stir bar and the drive magnets. can you route out the underside of the box top so you can get the fan mounted closer?


    I can certainly try. I know just about nothing about the electronic details, I found another build thread on the Internet that used this type of box, so I went for it. I'll try and sand down and see tomorrow.

    the only thing the needs to move closer it the ring magnet. so you could just route or sand down a circular area for that to sit in
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    This is the vortex I have now. Pretty weak.
    image.jpg
    2592 x 1936 - 2M
  • ThymThym
    Posts: 122,708
    Benvarine said:

    This is the vortex I have now. Pretty weak.



    it has a dimple. it's so cute!
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    it's actually, very pretty. i love the wood box.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    F-off. I want the tornado. I'm sanding the lid tomorrow.
  • ThymThym
    Posts: 122,708
    Benvarine said:

    F-off. I want the tornado. I'm sanding the lid tomorrow.



    yay!
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    BTW - you have a lot of water in there for the tornado. if you go to that point i would think you would have water coming out the top of the flask.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    That is about 1800ml in a 2000 ml flask. It's what I typically pitch for a starter.
  • ThymThym
    Posts: 122,708
    Benvarine said:

    That is about 1800ml in a 2000 ml flask. It's what I typically pitch for a starter.



    maybe it just looks fuller than it is.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    I measured the lid, only 1/8" thick. I had two small washers spacing the fan, I reduced that to one. It still won't work. It seems to hold up the fan. Sometimes when I turn it on, the fan won't spin. When the stir bar finally flings off, the fan picks up speed.
  • ThymThym
    Posts: 122,708
    Benvarine said:

    I measured the lid, only 1/8" thick. I had two small washers spacing the fan, I reduced that to one. It still won't work. It seems to hold up the fan. Sometimes when I turn it on, the fan won't spin. When the stir bar finally flings off, the fan picks up speed.



    and that's with it cranked all the way up on the speed control?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Yes. The bar spins a bit erratic, sounds bumpy.
  • BenvarineBenvarine
    Posts: 1,606
    If the problem is power, I don't know where the issue is, fan, potentiometer or power cord
  • ThymThym
    Posts: 122,708
    if you set the stir bar on top of the lid, does it stick firmly in one specific spot or does it sort of have the ability to stick to one side or the other? if you run it does the stir bar spin in a perfect circle or is it slightly wobbley/offcenter?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    It will snap back in place after the fan stops. It is a bit wobbly spinning pattern
  • ThymThym
    Posts: 122,708
    Benvarine said:

    Yes. The bar spins a bit erratic, sounds bumpy.



    Benvarine said:

    It will snap back in place after the fan stops. It is a bit wobbly spinning pattern



    it sounds like the stir bar is off center. if the drive magnet poles are separated more or less than the stir bar it can cause the stir bar to sit offcenter, with one pole set firmly attached and the other one just sorta 'wingin it'
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    If I just set the bar on the box, the fan won't spin it.
  • ThymThym
    Posts: 122,708
    the wobble will eat up energy, so your fan and power supply might be strong enough to do the job. but its wasting power trying to move the bar in the wobble pattern rather than just spin
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    How do I fix that?
  • ThymThym
    Posts: 122,708
    Benvarine said:

    If I just set the bar on the box, the fan won't spin it.



    the magnetic energy from the stir bar and drive magnets could be interfereing with the fan motor. did you offset the drive magnet from the top of he fan at all?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    Benvarine said:

    How do I fix that?



    we need to figure exactly what is causing the problem before we can fix it.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Lakewood said:

    Benvarine said:

    If I just set the bar on the box, the fan won't spin it.



    the magnetic energy from the stir bar and drive magnets could be interfereing with the fan motor. did you offset the drive magnet from the top of he fan at all?


    I'm gonna say no, because I don't know what that means really.
  • ThymThym
    Posts: 122,708
    Benvarine said:

    Lakewood said:

    Benvarine said:

    If I just set the bar on the box, the fan won't spin it.



    the magnetic energy from the stir bar and drive magnets could be interfereing with the fan motor. did you offset the drive magnet from the top of he fan at all?


    I'm gonna say no, because I don't know what that means really.


    just asking how you mounted the ring magnet to the fan. did you just glue it directly to the fan? or did you use some type of spacer?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Just taped it
  • ThymThym
    Posts: 122,708
    can you dissassemble the fan from the box and take a pic of it from the side?

    also take the stir bar and set it on top of the magnet, take a picture from the top.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Now it's not even mounted, it sticks without it. I was worried it could be moving however. I didn't want to glue it until I was certain it was right
  • ThymThym
    Posts: 122,708
    Benvarine said:

    Just taped it



    oh, good. so we can move stuff around without breaking things.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    Benvarine said:

    Now it's not even mounted, it sticks without it. I was worried it could be moving however. I didn't want to glue it until I was certain it was right



    it sticks because it's interacting with the magnetics of the fan drive motor. that's not good.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Fan with magnet
    image.jpg
    2592 x 1936 - 1M
  • ThymThym
    Posts: 122,708
    we need to put a spacer on top of there. something .5" thick or more should be ok
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    Benvarine said:

    Fan with magnet



    can you set the stir bar on that magnet and take a pic?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Magnet and bar
    image.jpg
    2592 x 1936 - 1M
  • ThymThym
    Posts: 122,708
    while its on the magnet, try to wiggle the stir bar. does it always snap back to exactly the same spot?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Lakewood said:

    while its on the magnet, try to wiggle the stir bar. does it always snap back to exactly the same spot?



    For the most part yes
  • BenvarineBenvarine
    Posts: 1,606
    Lakewood said:

    we need to put a spacer on top of there. something .5" thick or more should be ok



    Probably something light, not a bunch of washers per se
  • ThymThym
    Posts: 122,708
    first thing is to add a spacer to your set up. the spacer should be made of plastic, glass or wood. no metal
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    Benvarine said:

    Lakewood said:

    we need to put a spacer on top of there. something .5" thick or more should be ok



    Probably something light, not a bunch of washers per se


    defnitely no washers, they will just carry the magnetic field back down to the fan motor.

    do you have some balsa wood?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    Lakewood said:

    Benvarine said:

    Lakewood said:

    we need to put a spacer on top of there. something .5" thick or more should be ok



    Probably something light, not a bunch of washers per se


    defnitely no washers, they will just carry the magnetic field back down to the fan motor.

    do you have some balsa wood?


    scoobs PVC trick works well too
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Looking.
  • BenvarineBenvarine
    Posts: 1,606
    Plastic bottle cap
  • ThymThym
    Posts: 122,708
    Benvarine said:

    Looking.



    ok
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    Benvarine said:

    Plastic bottle cap



    that should work
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    do you have double sided tape?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • scoobscoob
    Posts: 16,617
    This is a lot of really good trouble shooting info here!
    Jesus didn't wear pants
  • BenvarineBenvarine
    Posts: 1,606
    Lakewood said:

    do you have double sided tape?


    No. Duct, painting, scotch, masking
  • C_BC_B
    Posts: 89,069
    azscoob said:

    This is a lot of really good trouble shooting info here!


    Phenomenal.
    "On it. I hate software." ~Cpt Snarklepants
  • ThymThym
    Posts: 122,708
    azscoob said:

    This is a lot of really good trouble shooting info here!



    now part of internet history
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    Also a good inventory of my garage.
  • ThymThym
    Posts: 122,708
    Benvarine said:

    Lakewood said:

    do you have double sided tape?


    No. Duct, painting, scotch, masking


    ok. we can use a couple of little pieces of duct doubled over while we get things aligned and tested.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    so the fist thing to do is mount the spacer to the fan and get it totally centered.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    cut a few pieces of tape and make tight little doubled over sections and sticke them to the flat side of the bottle cap
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    place the cap as close to the center of the fan blade as possible.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    turn the fan on slow and watch it turn, make sure its spinning as true as true can be. no wobble.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 122,708
    make adjustments as necesarry
    The only thing between me and a train wreck is blind luck..... - Kenny
Add a Comment