Lego Microtome

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Introduction: Lego Microtome

A what?
A microtome is a machine which cuts (usu.) biological specimens into very thin sections. The sections are typically mounted on microscope-slides.

This was an idea I had, I did it, and I've demonstrated it with garlic
It creates slices 250 microns thick*

*calculated



If anyone is actually thinking of building one of these see the last step. You can also PM me if you need more

L

Step 1: Construction: Base and Mount Runners

The specimen sits on a platform which is cranked forwards by gears. The mounting plate is driven by a rack and pinion mechanism geared very low from a hand crank, such that it moves .25mm with each turn of the handle. The platform rests on the red smooth-faced strips, which were lubricated with Johnson's Baby Oil (paraffin).

These images show the base of the device and the red runners for the specimen platform, also the final drive to the rack.

Step 2: Construction: Mount Plate

The plate upon which the specimen is mounted is essentially two smooth runners (lubricated as the previous step), and a rack.
Being Lego, the plate can be easily customised to hold a variety of samples.

Step 3: Construction: Upwards Towards the Gear-train

Not much to see in this step, I tried to get LDD to work but it hangs ever time (without fail). Perhaps using red instead of black would have been better?
In this sequence you see the front rails that hold the blade assembly being added (yellow and grey)

Step 4: Construction: Gear-train

Most of this is low-gearing from the hand-crank.

Step 5: The Blade

I hacked a disposable Bic safety razor for a blade (note that once these blades are out of the plastic, the word "safety" no longer applies - I cut myself twice through carelessness.)

Step 6: Construction: Finishing

In this step (for the purposes of publishing) I got tired of tedious image-editing, and I'll probably never feel like improving the look of these...
All the way to the end:

Step 7: Additional

With the rack-drive movement can be a little "lumpy", which is why I oiled it. A screw-drive would be better, or something with a worm-gear in it.
The gear-train to the blade cranks is a bit too long: all the gears make it a bit loose. It would work better with lever connections.
The blade assembly (grey) needed glue - it picked-off afterwards, but it's not strong enough without.
As you can see from the video it does work, but I needed to be a bit careful.

Your main considerations are:
A good solid platform that is fairly tight
Similarly for the blade
A lot of reduction from the crank. I work out 3 x 5:1 giving 125:1

Disposable razors tend to be held together with little plastic rivets. You can find these as round blobs on the underside - cut these off with a sharp knife and carefully prise the thing apart with the knife. These blades are very sharp and you'll tend to see blood before you feel anything.
To glue it on - I put the blade and Lego on a sheet of cling-film stretched over a tile, and carefully dribbled 2-part epoxy down the edge.

Best wishes

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    60 Comments

    Looks like a great way to avoid damage fingers often encountered while using a hand microtome. Do you have a parts list assembled someplace? (Need a shopping list for the Lego store! )

    So, I'm about to attempt this as a gift to my histotechnology prof.. Wish me luck!

     Impressive lemonie! Good work

    I should get the Lego out again, and probably will.

    L

     Ever since I was a kid I have been dying to get my hands on one of those lego mindstorm robotics kits (I've played/programmed with them before, they're a hoot!), but alas never have as they originally cost over $350!!!!

    Do you have any good ideas for implementing something similar with regular lego? Like how would I go about making a robot/remote control car out of plain legos? I have a giant blue tub of lego from when I was a kid, and I'm sure super-glued together would make one hell of a sturdy frame if designed right?

    What kind of software do you use to design lego builds? I know there is software that basically lets you build something on the computer first, before you try it, so you can make sure it will work.

    If you want something a bit cheaper, maybe you should try something like Arduino. It's not Lego-manufactured, but I've seen plenty of Arduinos users that have hacked lego Technic motors to control them. Mail me if you want resources.

    And come on, this is INSTRUCTABLES.COM! I know you can find SOMETHING on here.

    Go find the lego website (old link step 3) and they'll let you download Lego Digital Designer for free. I'm the sort of person that builds stuff, rather than designs though.
    Yea, gluing a frame would work, I think what you want maybe that liquid-glue for making models with (kit military & such). The RC bit, I'd just pull from something else.

    L

    Put a bug in there. Watch the yellow goo gush out.


    Cruelty to insects is not one of my favorite pastimes. Still, I appreciate that you had an alternative thought about this.

    L

    cool... btw can u please tell me the gear ratio u used between the blade crank and the shaft to move the garlic (i m familiar with lego parts)