Ultracentrifuge

[Anonymous No.1216174]

I'm looking to make a centrifuge using this 3D printed rotor https://thingiverse-rerender-new.s3.amazonaws.com/renders/9c/5b/4b/aa/81/Dremelfuge_Chuck_Edition_V4_preview_featured.jpg or similar, but that spins a little faster. G-forces on the sample are proportional to rpm^2, so a little extra speed would really help.

Question is, what tool goes faster? I have a 30k rpm Black and Decker rotary tool, basically a dremel, but I'm seeing air die grinders and pencil grinders that go 60k rpm, like this https://www.intlairtool.com/chicago-pneumatic-cp9104q-pencil-grinder-1-8-collet-60-000-rpm-05-hp/.. This would give 4 times the g-forces as a standard dremel.

But I know nothing about air tools. Would the pencil grinder be able to spin a sample of this size(8cm diameter plastic rotor with a few mL of water in the tubes)? Would the spindle bearing shit itself at the slightest imbalance? Can I run an air tool at way less than full speed if I want? Is the air from such a tool directed forwards? If so, it would probably knock the rotor out of true.

Is there a class of tools that I'm not thinking about that would be better(faster) than a dremel for this task?

Thanks

[Anonymous No.1216182]

>>1216174

I would be EXTREMELY hesitant of spinning an 80mm, 3D printed rotor at 30kRPM, especially with those cutouts drastically weakening it. Those sharp inside corners also reek of stress concentrations.

If you insist on trying, any kind of rotary tool or die grinder would work, assuming you're able to fit the thing into the collet.

[Anonymous No.1216183]

>>1216174
What kind of g's are you aiming for? If I remember correctly microcentrifugetube centrifuges run at approximately 40000g max. Eppendorf-centeifuges, that is.

[Anonymous No.1216187]

>>1216182
Yeah, I plan on doing the whole thing in a very thick steel chamber.

>>1216183
There are some epiies for ultracentrifuges that can go faster (however they are pressed against a rotor on their outsides. This design just holds them by the cap....who knows). I'm aiming for 100,000-200,000g

[Anonymous No.1216202]

>>1216187
I work in a lab and our plastic centrifuge rotors max out at 15k but average about 13k depending on the machine. I'd use a solid rotor and not that spoke looking one. The more weight you have then the more your going to notice wobble. We try to get them roughly the same volumes and usually if it's above 10 ml then it's not going above 2k rpm. A lot of the 13k rpm stuff are just 1.5 ml eppendorf tubes. We do have 500 ml tubes what use a stainless steel rotor. I don't want to be around that shit if it breaks. I think the plastic will break at the spindle, the long part that connects to the drive motor, with what youre going to be doing unless it's balanced very well.

[Anonymous No.1216205]

>>1216202
I'll add, all of our plastic rotors have metal spindles.

[Anonymous No.1216215]

>>1216202
Yep, definitely not trying to spin anything bigger than a 1.5 mL eppie (I'll use the high speed kind, I know they are good around 100kG). Keeping a small plastic rotor and operating inside a thick casing makes me not so worried about failure causing injury.

You think the break point is where the arms attach to the spindle? Guess I could redesign to make a less sharp cornered attachment, and maybe angle the arms forward a bit

[Anonymous No.1216253]

>>1216215
Why do you need such large amount of g:s? What are you trying to separate? Do you have a reference to the article where such separation methods have been used?

[Anonymous No.1216311]

>>1216174
>Is there a class of tools that I'm not thinking about that would be better(faster) than a dremel for this task?

a router would work. they spin up to 20,000 rpm.

heres a cheap ryobi 1/2" shank router used to cut a round corner in steel

https://youtu.be/b5doYjuDN_s?t=588

[Anonymous No.1216381]

This looks like a world of trouble OP. You can't spin this shit with a dremel-like tool without the stress destroying the piece, severing the connection, or mangling the motor bushings.

[Anonymous No.1216385]

what are you really using this for? there are few applications and people buy these bomb flying shrapnel chambers for a reason

[Anonymous No.1216420]

>>1216311
A Dremel can spin 30k+ Rpm depending on the model.

The only thing I can think of for more speed would be a pneumatic die grinder.

[Anonymous No.1216425]

>>1216174
Yes, air tools can be under/over pressured and/or modified in various ways to change the rotation speed.

Air tools are self cooling thanks to the air expansion, but it's still possible to fuck the bearings if you overspeed too much. If the flow rate is too high you can actually freeze the thing.

[Anonymous No.1216430]

>>1216182
The sharp corners should be filleted to avoid stress concentrations.

You'll also need to balance it very accurately, similarly to a wheel balance on a car; the print accuracy will not be enough.

[Anonymous No.1216573]

>>1216425
Long runs on a centrifuge heats them obviously up. In some laboratory tests this might pose a problem as heat speeds up chemical reactions, especially in very diverse samples like tissue.
Cooling isn't bad.
But I'd still like to hear OP's idea about why high rpms are needed. Just pit of curiosity. Highest I ever needed while doing biological research was 40000rpm which translated to x g.

[Anonymous No.1216595]

>>1216573
Extremes of temperature change the way the parts fit together.

[Anonymous No.1216598]

>>1216253
>>1216385
>>1216573
Subcellular fractionation, need about 115,000g for my purpose (I want the membrane).

>>1216430
"filleted" - awesome, learned a word. I'll redesign the rotor with this in mind. Do you know why disk break rotors https://upload.wikimedia.org/wikipedia/commons/6/68/Bike_disc_brake_rotor.jpg have their arms angled towards the stopping force (pads) instead of away?

>>1216573
Yep, it'll probably have to be in a vacuum in order to keep heat and turbulence down. I'm thinking of just using some 1/4" steel square pipe around the whole apparatus, and hooking up a vacuum line to that

[Anonymous No.1217079]

>>1216598
>arms angled towards the stopping force (pads) instead of away?

The stress on the support is closer to being only compressive that way. Flipping it around, you get a substantial bending moment instead. Obviously, it's much weaker to that kind of load.

>>1216381
>You can't spin this shit with a dremel-like tool without the stress destroying the piece, severing the connection, or mangling the motor bushings.

The last (and only) time I stuck a CD in the mandrel of a rotary tool, I managed all of the above, plus the destruction of the mandrel.