Archive for the ‘vendors/stores’ Category

An auction site success – $155 DNA Hybridiser.

February 26, 2012

My cost: $155 (150= auction, 5=box of rivets, only needed one)

Retail cost (new): $2000-4000

I came across a ‘working’ but damanged DNA hybridiser (which is essentially an incubator with optional rotating racks) on an auction site.  The damaged components, according to the seller, were the two parts of the door’s hinge.  I thought that I could fix it (it is just a hinge afterall).  I figured the worse case scenario was that if I couldn’t repair it, I would end up using masking tape and plastic sheeting across the front to seal it.  As is the case with life, things were a bit more complicated when I got the unit.

(Above) Hinge pre-repair.  I set a 1/4″ rivet into the hole and that allowed the door to pivot perfectly.

(Above) Hinge post-repair

(Above) Post-repair bottom hinge.  I neglected to have a picture of the bottom hinge but suffice to say it was in terrible shape.  The bottom hinge is a triangular piece of metal with a protrusion for a pivot point.  When I received it, the plate was bent two different directions.  I was surprised a lab would abuse equipment so badly!  The metal piece was small enough to fit into my vice and so I smashed it flat and reattached it with great success! The feet on the hybridiser are adjustable by rotating them clockwise or counter clockwise.  One of the feet was tilted something like 20-30 degrees.  The fix to this was to remove the foot, use pliers to bend the screw back into a straight position, and reattached the foot.

 

Going forward from this point things got frustrating.  When I turned the unit on it heated up to maybe two degrees above ambient and I immediately thought I bought a lemon.  I found the manual online and discovered there is a safety reset on the back of the unit that sometimes gets set off when the unit is moved and fortunately this fixed the problem! The second issue was the moving components of the hybridiser (see above circles within plastic brackets) – they didn’t move or make any sound.  On a whim I decided to take off some of the panels to see if maybe I could figure out the issue.  After having every other screw head strip completely and having to use a Dremel to saw off one of the heads I finally got into the unit.  Sure enough the motor that moves the components had fallen apart sometime in the past. Unfortunately I didn’t take pictures of the inner workings because I was tired and frustrated with the screws stripping and mostly I was totally focused on fixing the hybridiser.

 

On the inside there are two interconnected belt systems that feed onto 1 motor.  The belts had come off their rollers and the motor – connected to the frame only by flexible rubber spacers – was barely attached to the frame.  I used some screw spacers (the kind used to attach PC motherboards to cases) and some long screws and I remounted the motor and reattached the belts.

 

Now I have a hybridiser worth substantially more than it cost me.  My best guess is the previous owner put up with the damaged hinge up until the point that the inner-workings of the hybridiser broke and they then tried to sell it.  At any rate, I am glad they were unwilling to explore and repair it. As I have posted before, I recommend checking out old lab equipment on auction sites (i.e. eBay) but always be cautious as most sellers have never been to a laboratory before.

 

Note:  DNA hybridisers circulate heated air with a fan and while they are in essence an incubator, they can’t be used just like a typical incubator because agar plates with bacteria would get cross contaminated easily.  If I ever need to grow something I think I will try putting them into zip-loc bags before putting them into the incubator to avoid this problem.

DIY centrifuges, used centrifuges, and a fun experiment.

September 3, 2011

The background that led to the experiment

I had been thinking about building a centrifuge out of a blender but first I decided to research what other people had done before I tried my own hand at it.  I ran across a number of designs which included  “Dremmelfuge“” and a handheld centrifuge which will eventually damage something.  The best of centrifuges was one that used mixing bowls and a blender.

My own thought was to attach the caps of dry-erase board markers to a blender rotor using wire and gorilla glue.  In my design I wanted to use the blender pitcher as a safety vessel for in the likely event something went flying – but this provided a lot of design challenges.  Ultimately I decided that my idea was bad and most of the other designs were too risky.  If I were to ever revisit centrifuge construction definitely would make a variant of the blender which used mixing bowls.

All of this ended with me surfing eBay and discovering it was not too expensive to just buy a used centrifuge (from $100-150) – which I did.  I manged to find the centrifuge depicted below.  I find the aesthetic design to be quite pleasing and it is a bit sad that this style is not used anymore.  Now that I have a centrifuge, it is time to use it (see below for more)!

My little buddy. Cheap and effective.

A quick centrifuge explanation

Centrifuges spin samples around extremely fast (often >10,000 RPM).  Doing so causes centripetal force to be exerted upon the samples.  In the case of my centrifuge, it spins fast enough for the samples to have the force of 13000 times earths gravity exerted upon them.

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What happens when ketchup, milk, sriracha sauce, and russian salad dressing are exposed to 13,000 x earth gravity for 30 minutes?

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The source material precentrifugation.

Here are the specimens, precentrifugation.  From left to right we have non-fat milk (Trade Joe’s), Ketchup (Heinz), Sriracha Sauce (Huy Fong Foods) and Russian Saland Dressing (Wish Bone).

First we load the machine…

Rotor with tubes.

Next we run the machine for 30 minutes and we get….

sriracha sauce 13000 x g 30min

Separated out kind of like blood  (serum on top, cells on the bottom).  I would guess that the bottom layer is chili pepper fragments.

russian salad dressing 13000g 30min

This salad dressing has A LOT of ingredients and I will even try to guess as to which layer is what.

nonfat milk 13000g 30min

Milk proteins should be what has collected at the bottom.

heinz ketchup 13000g 30min

The ketchup surprisingly did not separate into layers.

My take home message from this experience was that sometimes the effort and danger in building something myself may not be worth it when one considers the cost and value of used equipment.

Miscellaneous supplies on the cheap.

April 27, 2011

Discount surplus stores are a ‘mixed bag’ of all kinds of oddities and commodities.  These stores should be a first stop when looking for lab supplies.   The stores themselves come in a number of names; Dollar Tree Store, Just Dollar Store , 98 Cent Store, and 99 Cent Store to name a few.  Their selection ranges wildly throughout the year.  Some stock fresh produce and some stick with non-expirable items.

Some laboratory oriented things I have found include;

  • Aluminum Foil (Reynolds Wrap Brand 2 5sq. ft. per box and Generic Brand 50 sq. ft.)

  • Krazy Glue (Super Glue)

  • Plastic Containers (I used them as secondary containment for glass collection flasks and for storing equipment)

  • Glass cookware (Microwavable staining trays, a bit classier than pipette boxes though admittedly heavier)

  • Aquarium tubing, valves, and junctions (for setting up gas lines or pumps)

  • Various tools (eyeglass kits, screwdrivers, hammers, hacksaws, wrenches, etc.)
  • Aluminum pans (the cooking type, very handy)
  • Styrofoam coolers (shipping and storage containers)
  • Light bulbs (CFL and Incandescent)
  • Speaker wiring
  • Baking soda
  • Powdered milk (blocking membranes)
  • Pain killers
Since the selection varies heavily from store store within cities and over time, I imagine the selection is even more diverse in-between states.  If you are curious, you will

 have to stop by one of the discount stores yourself.