DIY Centrifuge

[Subin e k]

Hey Guys,
                     I am designing a Centrifuge for my collage. our centrifuges don't have the capacity to carry 100ml tubes in it it came as a big problem for us . So collage is willing to fund me for making a centrifuge and to put the data as open source. I need your suggestion for choosing the motors for it . Presently i am having 3564 B BLDC motors with 25k rpm(dont have that much torque) and a multirotor with 2.1kg thrust(which i used to make a quad copter) , I am not sure these two are not a good options for  centrifuge motors. All you guys are expert in these area , So please give your suggestions for that

ill post the designs when my term exam is over :)

[Nathan McCorkle]

Not sure about specifics, but BLDC should give a pretty long life.

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-Nathan

[Filip Hasecke]

Hi Subin,

are you going to use some commercial rotor, or do you plan to build your own rotor?

I hope you don't plan to build your own one, as small imbalances might have massively destructive effects ^^

I'm speaking from experience... we had a big Beckman centrifuge and some bottles were imbalanced and the whole maschine (really big, like 1m³ in size) jumped through the room and destroyed everything in its path.

So be really careful with everything that rotates at high speeds and with a lot of weight.

Do you already have some kind of chassis and rotor?

Cheers

Filip

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[John Griessen]

On 02/04/2015 11:17 PM, Subin e k wrote:
> BLDC motors with 25k rpm(dont have that much torque)

That sounds OK. Like Flip mentioned -- it needs to be designed so it cannot come unbalanced, or
if it is possible for liquid to escape holder wells, that the unbalanced rotor is contained
in a big strong chamber as it spins down.

The motor is the easy part.

A rotor that could not come unbalanced would have slanted wells
with no exit for liquid from a broken vial. If there was a swing out mechanism for a vial, it would be surrounded
with a strong containing zone -- strong as in machined all of them from one aluminum cylinder -- such that
escaped liquid would stay in the same angle position slot, and just move outward some so as to minimize
the unbalance. Swing out mechanisms make design tricky. They could fail. Lose them somehow.

If machining a big rotor for lots of 100ml vials seems too much, you could make a strong steel
containment zone and a light rotor with swing outs and make the motor to rotor connection flexible and break-away
in case of imbalance and let the destruction stay in the container. Also make the container weigh
20X the payload of vials and rotor weight. The strong lid needs to lock in place.

[Nathan McCorkle]

On Thu, Feb 5, 2015 at 2:37 AM, Filip Hasecke
<filip....@googlemail.com> wrote:
> I'm speaking from experience... we had a big Beckman centrifuge and some
> bottles were imbalanced and the whole maschine (really big, like 1m³ in
> size) jumped through the room and destroyed everything in its path.

Seems like an accelerometer could monitor vibrations and shut-down if
things get violent, or how about a radio-controlled (BLE?)
kill-switch?

--
-Nathan

[Otto Heringer]

I don't know if you have access to 3D printers or something else for digital fabrication, but I keep asking myself if a big 3d printed rotor would work... Digital fabrication could deal with the imbalances, if well designed.

I'm imaginig a hacked washing machine with it axis jointed with a 3D printed rotor that fits perfectly - it would looks like an awesome hack of a washing machine.

Does anyone tried this before!? I mean, it is an easy idea. Found just mentions or comments with a rapid google search, but not an open and well documented project for centrifuges of bigger volumes (by the way, I found this nice project).

--
-Nathan

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[Nathan McCorkle]

On Thu, Feb 5, 2015 at 1:24 PM, Otto Heringer <ottowh...@gmail.com> wrote:
> I don't know if you have access to 3D printers or something else for digital

> Does anyone tried this before!? I mean, it is an easy idea.

There's of course the classic DremelFuge, brought to us by Cathal:
http://www.indiebiotech.com/?page_id=16
http://www.popsci.com/diy/article/2013-07/how-build-your-own-diy-centrifuge

--
-Nathan

[Subin e k]

I tried some experiments on my BLDC but its getting slower on applying weight....:(
 Blenderkid The balancing part is the bigger risk. I forgot to think about that and fixing a kill swich on incresed vibration will be a good decision thanks for that suggestion..
Otto heringer The funniest thing is that my team http://rignitc.com/ (Robotics club ) had made a 3D printer but we are having a error about 5mm . So its not a solution for me

I think the better way is to make to mold rotor head and to do balancing with assistance of industries
Thats better right

[Subin e k]

That's a lot of knowledge thank you :) 

[John Griessen]

On 02/07/2015 07:59 AM, Subin e k wrote:
> That's a lot of knowledge

It's all theory based on my experience with much smaller much less dangerous things
than a 3 to 5 pound energy storage flywheel, (AKA DIY centrifuge for 100ml vials).
Please understand any of this will need plenty of testing, and strength of materials
analysis before you release it as a product. But if you are only interested in DIY,
and won't do testing or analysis, please make the steel container out of
3/8" welded plate with a good weld on each seam, and then grind that down smooth
and put a 3/8" connector plate over the seam and make welds on each edge all along
its length for the full length of any seam.

Then cast concrete 9" thick around it and add plenty of 3/4" rebar that wraps all the way
around. And the lid needs some real latch to hold it down during a flywheel explosion,
and a doglegged path out so nothing gets out at speed, not even liquid. The lid needs to
be several inches smaller than the largest inside diameter of the containment chamber
so only bounces of random pieces hit it during the inevitable flywheel explosion.

So, wouldn't you rather make/buy a dinky one for 5ml vials and run more in series to
get your volumes?

[Subin e k]

It is not a product i just need DIY

Better than concrete covering a 5mm thick aluminium sheet is enough right 

[John Griessen]

On 02/07/2015 08:56 AM, Subin e k wrote:
> It is not a product i just need DIY
> Better than concrete covering a 5mm thick aluminium sheet is enough right

Sure, when your lab is in the woods and you turn it on only when 200 meters away, right.

[Nathan McCorkle]

On Feb 7, 2015 6:16 AM, "John Griessen" <jo...@industromatic.com> wrote:

>
> Then cast concrete 9" thick around it and add plenty of 3/4" rebar that wraps

Sounds like you're targeting an ultra centrifuge, even then I don't think out school's 'fuge is that tough. In addition, some 'blood' centrifuges for 100mL tubes are pretty much a painted steel bowl, just larger than you might have for mixing a very large salad for 10-15 people.
http://www.uniconinstruments.com/Centrifuge%20machine%20GE-160.jpg

If they go faster than a 'blood' 'fuge then they have a bit more housing, but still little enough that a normal person could carry the device from one room to another.

The only 'fuges I've seen so heavy you can't move them are ultra and refrigerated centrifuges.

[Nathan McCorkle]

On Feb 7, 2015 6:16 AM, "John Griessen"

> than a 3 to 5 pound energy storage flywheel, (AKA DIY centrifuge for 100ml vials).

That definitely seems heavy for a rotor, even for the ultra centrifuge. For the blood 'fuges the rotor is sometimes just more than stiff wires bent to a frame.

For larger 'fuges, I'd say the rotors were around a pound, and I seem to remember the ultra centrifuge rotor being a special material and that it was pretty light, maybe lighter than the rotor for the washing-machine sized refrigerated 'fuge we had (these come in floor and benchtop models).

[Subin e k]

      Going for a powerful centrifuge seems like a bit of risk and lot of problems . So i think better make a smaller centrifuge for 1.5ml eppendorf with my 12v little 20 k motor and a 3D printed tube holder ,That won't be a bigger risk and i can analyse what errors will came on designing a bigger centrifuge .... Kind of a learning process

I think making the smaller model ill be the best thing before the bigger party :)

[Subin e k]

:P Grissen .. even if some water is spilled on the lab floor Department will kill me 

[Priya Phalak]

an Centrifuge with 25k rpm ah ha.. sounds interesting but can you elaborate more about the practical 

application of your centrifuge , there are several types of Centrifuge like Microcentrifuges, Ultracentrifuges 

and  High-speed centrifuges with an angular speed varying from 500 rpm to 70k rpm in theory but when coming to 

practical applications like Fractionation process and cell Separation processes we don't need such hi-speed angular speeds

in general what we do usually in labs is if the angular speed is less then we increase time of centrifuge.. 

but you boys always want to have a fastest machine hehe..

any way have a look into this link

https://www.youtube.com/watch?v=uqa1JNLLB78&noredirect=1

its pretty simple centrifuge used from a bad HDD innovative idea but it defiantly needs an en-closer for safety purposes

and it runs at 6k to 12k which is pretty good ...

and i wish you all the best in your diybio venture to build a centrifuge @25krpm but do remember safety comes 

good luck

Priya Phalak

[John Griessen]

On 02/08/2015 07:39 AM, Subin e k wrote:
> I think making the smaller model ill be the best thing before the bigger party :)

Very good. Glad to hear. Sorry if I said anything badly, because you *can* make a big one if
you want to enough and approach it well, and keep spinning mass to a minimum, and actually calculate
the worst case forces your containment needs to withstand in a worst case event.

Instead of concrete, maybe two layers of spun metal with plenty of ductility in it by annealing
would stop a projectile launched from 3 inches away at max speed, and then the whole thing can be lighter
and become an OSHW product design some day.

On 02/08/2015 07:41 AM, Subin e k wrote:> even if some water is spilled on the lab floor Department will kill me

You can use the above idea on a small one... A Thailand soup pot of spun aluminum with central chimney
can become a centrifuge containment enclosure. It might tempt people to check if the soup is done though...

[Subin e k]

Priya ,

            i never said i am making a 25 k centrifuge , :) i said i am having a 25k little motor it won't even give 10k if i put some weights on it , Atleast i could use for a plasmid prep.

Priya phalak you are from india right ? . You are a student /faculty / working in Industry ?   I asked this because i only see a few Diy guys from india 

and there should be meet of these Diy guys and Yashas (IISC Bangalore) will surely help for that

[Subin e k]

Thank you for the Idea john ;) it is so cool...

Centrifuge inside some cool stuff ill be amazing ...:)

This Friday when my exams over i am on it ..

[Pieter]

Perhaps a design I made some time ago can help you get going: https://github.com/PieterVanBoheemen/RWXBioFuge

However, even with small 8 place or 20 place rotors that I 3D printed, I could hear the filament getting loose and flying against the sides. So I would certainly not go for even bigger 3D printed rotors

[Nathan McCorkle]

On Wed, Feb 11, 2015 at 1:37 PM, Pieter <pieterva...@gmail.com> wrote:
> Perhaps a design I made some time ago can help you get going: https://github.com/PieterVanBoheemen/RWXBioFuge
>
> However, even with small 8 place or 20 place rotors that I 3D printed, I could hear the filament getting loose and flying against the sides. So I would certainly not go for even bigger 3D printed rotors

I wonder if that could be fixed with optimized g-code? Something that
caused the filaments to print in a different direction (radially
instead of circularly)?

[Otto Heringer]

Sure, but I mean a "big" one for big rotors, for bottles of hundreds of mL.

I'm curious if the plastic would resist in low filling percentages...

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[Subin e]

 I hope it can be corrected using the cad to g code conversion software . Replicator G have an option for that to choose the method of printing

[Subin e]

 Pieter ,
              Your Centrifuge seems like a nice one , I think u should make a small metal couple to connect your 3D printer part with the motor rather than connecting it directly

[John Griessen]

On 02/12/2015 01:18 AM, Subin e wrote:
> I think u should make a small metal couple to connect your 3D printer part with the motor rather than connecting it directly

Let's see a sketch of what you're thinking.