ultracentrifuge
Richard Proctor
called Portescap who manufacture very high RPM brushless motors that
can hit in excess of 70,000 RPM or 200,000 G .
My main concern is whether the material in 3D printing can really deal
with those kind of forces.
The balance must be that the thing is light enough to not cause the
motor to lower its RPM but be stable enough to not cause eppendorf
bullets :-s
thoughts anyone....i'll be running FEA analysis on selection of
polymers in the next week.
C.R.S.
--
You received this message because you are subscribed to the Google Groups "DIYbio" group.
To post to this group, send email to diy...@googlegroups.com.
To unsubscribe from this group, send email to diybio+un...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/diybio?hl=en.
Zebedeeboy
Sent from Samsung Mobile
John Griessen
> whether the material in 3D printing can really deal
> with those kind of forces.
It's a quick calculation -- 200,000 * weight of half the part that
extends to the full radius is the force. Say the weight is .1 gram.
Force is 20kg
For extruded plastic with some voids or sintered plastic with some voids
it could only hang together if in a sphere solid shape. The cross section
with 20kg force pulling it apart would be maybe 25 mm squared area if solid.
Since it is a hollow thin shape to hold a removeable tube,
answer is no. Area might be as low as 5mm square area.
Does sound like an app for Ti metal.
Daniel C.
<richard...@gmail.com> wrote:
> im going to be working on cathals dremelfuge. ive found a US company
> called Portescap who manufacture very high RPM brushless motors that
> can hit in excess of 70,000 RPM or 200,000 G .
Are those speeds/forces really necessary?
-Dan
Nathan McCorkle
Those speeds/forces are needed for ultracentrifuge.
Titanium is what the ultracentrifuge Tories here use, but it holds ~50ml tubes, not eppendorfs (which under those forces could crush themselves)
Richard Proctor
Richard Proctor
Ti it mayyyy be possible
Phil
> 200,000g would probably mean Ti rotors and an armour plate centrifuge chamber. If you really want that scale of speed and can manage with small volumes ie ~100uL consider using compressed air instead (a la Beckman airfuge). Only one moving part in the fuge, and you can hit 500,000g. Still going to need a Ti rotor and armour plate though...
$50. You'll have to buy an aluminum rotor for it, for about $1800,
from Beckman. Do not try to build your own ultracentrifuge rotor.
You will probably want to run the Airfuge inside a refrigerator
anyway, and that will provide some protection in case of disaster.
Jeswin
> You will probably want to run the Airfuge inside a refrigerator
> anyway, and that will provide some protection in case of disaster.
>
How about in a concrete filled washing machine?
John Griessen
> Do not try to build your own ultracentrifuge rotor.
Why make such statements on a DIY list?
John Griessen
> You will probably want to run the Airfuge inside a refrigerator
It might be its own refrigerator by expansion cooling.
If not, putting a flow orifice a little upstream of it would do some
refrigeration -- probably so much you'd need to control it to avoid freezing.
Cathal Garvey
John Griessen <jo...@industromatic.com> wrote:
>--
>You received this message because you are subscribed to the Google
>Groups "DIYbio" group.
>To post to this group, send email to diy...@googlegroups.com.
>To unsubscribe from this group, send email to
>diybio+un...@googlegroups.com.
>For more options, visit this group at
>http://groups.google.com/group/diybio?hl=en.
--
Sent from K-9 Mail on Android
John Griessen
> Because an ultracentrifuge can kill you and is highly prone to explosion if used without training?
Isn't this list about training? I see it going on all the time. We have someone
researching ultracentrifugation and why not evolve a design? Not me saying
"Do it this way and you'll be guaranteed safe.", but what guarantees are there
with anything DIY?
So, we've had comments about concrete for mitigating centrifuge risk, and that's
good. Concrete is good. Steel plate is good. They go together well.
Concrete is easy to form around any plastic as a mold that releases easily.
So, a containment well with tapering narrower as it goes up top can easily be made
for the motor/rotor to fit in with a 1/2 in steel lid over it. All the kinetic energy
of the ultra rotor is angular and won't change easily, so forces are sideways and gravity
keeps it down. Precession can change the angle a little, so sloping inward sides
are good to keep it down, not let it climb even if it starts precessing around the
containment well interior. Lining the cast concrete interior with smooth plastic
such as HDPE would be great for keeping the concrete surface from crumbling by an
attacking loose rotor -- how would you hot spray coat that plastic?
Let's talk about it, OK?
Make your ultra rotor 6 cm across of Ti metal on an air bearing, driven by
an air turbine. Let it hold vials with a cone bottom that are 2 cm deep and 1 cm across
holding maybe 1.2 ml at the full mark. What turbine parts are out there that can be re-purposed?
What bearings does the Portescap motor company recommend for their 70,000 RPM motors?
Why not talk about it?
Cathal Garvey
John Griessen <jo...@industromatic.com> wrote:
Phil
> On 03/01/2012 12:06 PM, Cathal Garvey wrote:
>
> > Because an ultracentrifuge can kill you and is highly prone to explosion if used without training?
>
> Isn't this list about training? I see it going on all the time. We have someone
> researching ultracentrifugation and why not evolve a design? Not me saying
> "Do it this way and you'll be guaranteed safe.", but what guarantees are there
> with anything DIY?
1% chance
of accidentally killing someone, there's a 63% chance someone will
die.
If one person in the world gets killed by a homemade centrifuge,
governments around the world will use that as an excuse
to crack down on home biology.
We have representatives
from centrifuge manufacturers inspect all our rotors periodically.
AFAIK there are only 2 methods to ensure your rotors don't break.
Either inspect them regularly with X-ray equipment or some
other imaging technology; or have them manufactured by the
same equipment that has already produced several hundred identical
rotors which are being tested and monitored to know how much
usage the rotors made in this way can handle; and keep a log of
how often you use your rotor, and throw it out when it has been
spun a number of times calculated from that stress-testing data.
There are risks worth taking, but at the present time I doubt that any
DIYer has an experiment planned that requires an ultracentrifuge.
My not-very-educated opinion is that, if an experiment is valuable
enough to justify the risk of using a home-made ultracentrifuge rotor,
it's valuable enough to justify spending $2000 on an ultracentrifuge
rotor.
If you're a mechanical engineer and you know how to build things
out of aluminum or titanium, your opinion is more valuable than mine.
I don't know if it's a good idea to buy a used ultracentrifuge rotor.
On the one hand, the odds are very good that it was thrown out
because it had reached the end of its lifespan as computed from
the vendors' lifespan data, which should leave it enough more spins
for a DIYer who might use it a few times a year. On the other hand,
it could have been thrown out because it failed a rotor inspection.
I would be more interested in a DIY design to build a speedometer
for an Airfuge. The standard Airfuge has no way of measuring how
fast the rotor is spinning; you just measure the air pressure you're
feeding it. There are Airfuge tachometers, but they are rare and
expensive
(fetching about $400 used on ebay). All they are is strobe lights
that flash
off a spinning disc visible thru a window that alternates between
white
and black with each spin of the rotor. (Like the tool you used to set
your timing belt on an old car.) You could probably build something
using LEDs and photoreceptors for $30.
Airfuge rotors are made from aluminum. It would probably be
possible find a shop somewhere in the U.S. to manufacture them.
The design patents have expired, so there is no law to prevent
you from cloning Airfuge rotors at perhaps one-twentieth of the price.
But I don't know how you would ensure the quality of the resulting
rotors.
You certainly don't want to outsource that to China to save a few
bucks.
Zebedeeboy
Sent from Samsung Mobile
-------- Original message --------
From: John Griessen <jo...@industromatic.com>
To: diy...@googlegroups.com
CC:
> Because an ultracentrifuge can kill you and is highly prone to explosion if used without training?
Isn't this list about training? I see it going on all the time. We have someone
researching ultracentrifugation and why not evolve a design? Not me saying
"Do it this way and you'll be guaranteed safe.", but what guarantees are there
with anything DIY?
Nathan McCorkle
> --
> You received this message because you are subscribed to the Google Groups "DIYbio" group.
> To post to this group, send email to diy...@googlegroups.com.
> To unsubscribe from this group, send email to diybio+un...@googlegroups.com.
> For more options, visit this group at http://groups.google.com/group/diybio?hl=en.
>
--
Nathan McCorkle
Rochester Institute of Technology
College of Science, Biotechnology/Bioinformatics
John Griessen
> The standard Airfuge has no way of measuring how
> fast the rotor is spinning; you just measure the air pressure you're
> feeding it. There are Airfuge tachometers, but
.
.
>
> Airfuge rotors are made from aluminum. . . .
> The design patents have expired, so
Now this is good discussion about centrifuges, ultra or not.
The ultra speeds sound like "to avoid" if they're that close to
material failure they need an inspection program.
When you have an airfuge tachometer, what is its speed relative to the
70K RPM of the "ultra" centrifuges? 1/10th that might be a design goal
to aim at with low enough risk...
Phil
> could you build a chamber yourself using thick scrap metal?
"Evaluation of a class III biological safety cabinet for enclosure of
an ultracentrifuge", Applied + Environmental Micriobiology Nov 1979:
934-949. They drilled holes in a titanium rotor for a Beckman L5-50
centrifuge, then repeatedly spun it at 50,000 and powered it off until
it broke (at 53,000 RPM, which is odd since they said they were only
going up to 50,000).
The centrifuge itself was armored to contain the rotor in case of
rupture, and it did. The question was whether dangerous microbes or
viruses would be sprayed through the air and escape the BSC. Their
tests indicated that they didn't. The BSC didn't rupture when the
centrifuge jumped and smashed into the wall, but it did jump a few
inches. This looks like a 4-foot-long BSC, which would probably
weigh, I don't know, 600 lbs. OTOH I am confident the glass would
have broken if it had jumped towards the glass instead of towards the
steel wall. Anything that can knock a BSC weighing several hundred
pounds a few inches... well, do the math if you're curious, but I
doubt that a bullet could do that. Half (I think?) of the energy in a
bullet goes into the gun, and a gun is a lot less massive than a BSC.
Note that the BSC itself was not the armor that stopped the rotor; the
centrifuge armor stopped it and transferred its energy to a big heavy
thing, which is the objective.
50,000 rpm is about the lowest speed that can be called an
ultracentrifuge. The Airfuge can go up to 110,000 rpm or about
200,000g. Tabletop bucket centrifuges can do something like 25,000g
and are not considered ultracentrifuges.
A protocol calling for an ultracentrifuge might be successfully
changed to use a slower refrigerated centrifuge for a much longer time.
Daniel C.
> Half (I think?) of the energy in a
> bullet goes into the gun, and a gun is a lot less massive than a BSC.
The M16 fires a NATO 5.56x45 round (11.8 grams) at a muzzle velocity
of 948 m/s, which means the round has an initial force of about 11.2
newtons. (Source is Wikipedia's page on the 5.56 round.)
The force of gravity on the Earth's surface is ~9.8 newtons / kg. So
if you're creating 200,000 gravities that's 1.96 million newtons / kg,
or 23,128 newtons (for an 11.8 gram / .0118kg object). So your
ultracentrifuge can generate a little more than 2,000 times the force
of a military assault rifle.
All of this, of course, is subject to my math and physics being
correct. Neither of these subjects have ever been my strong point -
please correct me if I've made a mistake.
-Dan
Simon Quellen Field
Half (I think?) of the energy in a
bullet goes into the gun, and a gun is a lot less massive than a BSC.
Anything that can knock a BSC weighing several hundred
pounds a few inches... well, do the math if you're curious, but I
doubt that a bullet could do that.
John Griessen
> 2,000 times the force
Maybe, but energy flow and kinetic energy conservation are more illuminating
for design criteria.
A huge force for a nanosecond is small energy transferred...
Probably more important for containing ultracentrifuge angular momentum and stopping
it from causing big jerks of massive containers is to have multiple layers
of slippery sacrificial materials the spinning rotor chunks can ricochet off of,
then slide along the hopefully still round container walls.
Another important design criterion would be keeping the walls close to the
rotor edge so there is always a small angle between chunks that could aim at the walls.
Worst case would be rotor splits in two evenly. Then the two chunks take flight
straight line along a line from their centers of mass perpendicular to their radii
at the center of mass. At least that's the closest approximation I can do in my head
for the max min calculus problem it implies is the worst case for angle of hitting the wall
and kinetic energy, which is more and more toward the edge and zero for the point
at center of rotor. The kinetic energy of a new fractured chunk goes part into angular
spin, not all into straight line velocity, but since the wall is always close to the outside
fast moving high energy part of the rotor, it must not lessen straight line velocity much --
the outer edge part will hit the wall before it can twirl much. It will average the speeds
and have a new center of mass instantly though -- that will mean velocity is closer to half radius
instantaneous rotating velocity than to edge velocity near the wall.
Patrik
putting it in a hole in the ground is probably a lot safer than trying
to build your own armor. Just an idea...
Richard Proctor
down on the knees to fit the samples but it would save a heck of a lot
on cost of armour etc.
the areas to look into for this would be a low cost way to line a hole
in the ground to allow for decent temp and moisture control.
Phil
> In the case of a 2.25 kg pound rifle firing a 9.7 gram bullet, less than
> half a
> percent of the energy goes into the rifle, and more than 99.5% goes into the
> bullet.
bullet is equal to the fraction of total mass made up by the rifle.
This makes no sense to me.
An explosion between the bullet and the rifle should transfer about as
much energy into the bullet as into the rifle.
A person in body armor can be shot with a shotgun at close range and
not knocked down; and the kick from firing a shotgun is enough to
knock someone down who isn't braced for it; so the magnitude of these
forces must be similar.
>Let's say it came to rest in a single second, so the speed is 0.1 meters
per second.
surprised if the speed was less than 10 meters per second. If you
knew the coefficient of friction you could compute the minimum force
needed to make the thing start moving and the speed at which it would
move.
Put it this way: If you fired your 420j .38 into an armoured BSC, I'd
be very very surprised if it moved at all. So it does not make sense
to say it moved 10cm after absorbing 3 joules.
Richard Proctor
centrifuge?
Is this idea of sticking it in the ground worth exporing?
mad_casual
mad_casual
On Wednesday, February 29, 2012 9:49:14 AM UTC-6, Richard Proctor wrote:
im going to be working on cathals dremelfuge. ive found a US company
called Portescap who manufacture very high RPM brushless motors that
can hit in excess of 70,000 RPM or 200,000 G .
My main concern is whether the material in 3D printing can really deal
with those kind of forces.
Dan Wright
Sent from my iPhone
--
You received this message because you are subscribed to the Google Groups "DIYbio" group.
To view this discussion on the web visit https://groups.google.com/d/msg/diybio/-/_Act0BgKPc4J.
mad_casual
This is an ANALYTICAL ultracentrifuge people, not a preparative one!
To unsubscribe from this group, send email to diybio+unsubscribe@googlegroups.com.