Fan/stirrer does not stir

[Patrick_Hanisch]

Hello ChiBio Team,

I have a question regarding the stirrer. I have received four new ChiBios and found that none of the stirrers work right away. They go on briefly and then go off again and that’s it. After hours of troubleshooting, I found out that the stirrer or the fan only rotates when the glass vials are hanging in the air about 1-2 cm above the bottom. But this means that I have to switch off the temperature control. Do you have an idea why the stirrers do not stir when the glass vials are at the bottom, but only when they are placed higher? With an older reactor that we have from you, the stirring works with all vials.

Many greetings

Patrick Hanisch

• This topic was modified 6 months, 3 weeks ago by Patrick_Hanisch.

[harrison]

Hello Patrick,

What stir bars are you using? If you have very large stir bars it might be enough to stall the fan.

Another thing – if you have already taken the sides off – put the vial + stir bar down to the bottom and look how much clearence there is between the top of the rotating part and the bottom of the resistors under the heat plate. I have seen a couple in the past where they touch and so fail, and this only happens when the stir bar is there pulling the fan up. If this is the case you could ship them back to labmaker and ask them to fix it. Even easier, though, would be to take off the fan and put some M3 washers in there between the vertical supports and the bottom of the heat plate PCB as this will space it out a little and prevent the crashing.

Harrison

[Matt_Jones]

Hello,

We appear to have the same issue, I was wondering if you managed to fix the problem, and if so how?

Matt

[harrison]

Did the above (looking in from the sides) make it clear what was going on? At the moment I believe that is the most likely solution…

[Matt_Jones]

Yes, as you suggested the stir bar was pulling the spinning component into the heating pcb. We used some double sided tape to fix the stirrer to the fan which resolved the problem.
Thank you.

[harrison]

I do not entirely understand your statement. Wasn’t the stirrer already connected to the fan?
I think tape shouldn’t be able to fix this problem at least permanently – you’d need to add some m3 spacers (e.g. washers) onto each of the 4 columns below the heat plate to spread it out a little.

[Matt_Jones]

It has legs which held it in place rotationally when the fan spun (if that makes sense) but was not fixed to the fan, so was able to move up and down freely and lift off of the fan (which it does when there is a stir bar).

We did consider using washers below the heating plate, however there is not enough clearance between the measurement PCB and the lamp on the side PCB, so we would also have to shorten the legs between the heating PCB and the measurement PCB, or cut a slit into the measurement PCB.

Further, even if we raised it enough to prevent the stirrer being lifted off during normal operation, if it was knocked in such a way to jolt the stirrer up, it does not naturally fall back down, so we would have to take the sides off of the device to reset it, and it may not be immediately obvious.

So that is why we simply used tape to affix the stirrer to the fan, so now it cannot move up. Yes it is not a permanent fix, and so we will need to find something more permanent/occasionally replace the tape, but it does work as a simple quick fix which at least allows us to immediately conduct experiments while we sort out something better.

[harrison]

Ahh, I see. It sounds like that might be a manufacturing defect. The 3D printed part that holds the two magnets SHOULD usually be glued to the fan. The fact that it was not is a problem and indeed you will certainly need to fix it to the fan somehow. Tape or super glue (i’d do the latter if I were you) aught to do it

[Matt_Jones]

Perfect, thank you for the advice. I think we shall probably super glue it down at some point for a more permanent fix, but for now the tape seems to be working.

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