Lasercut electrophoresis gel tray & combs

Heather and I made some more tweaks to the design from my earlier post, such as adding tabs to the comb supports to make removing them easier. We also added some gaps to the slots for the combs as the lasercutter’s tolerances are incredibly fine, making parts fit really snugly together. So snug that they’ll slot together quite securely without glue. It looks very cool.

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The 1.5mm acrylic that I had ordered from RS came in so we took ourselves off to go and cut it. The tray is 6mm clear acrylic and the comb supports are 3mm black acrylic from an offcut we found under the lasercutter. It looks pretty good assembled. (Yes, we reversed every other comb.) We had a couple of issues with the fit between the tabs and cutouts of the tray base and sides but 5 minutes’ work with a file sorted that out so that Heather could superglue it together.

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Heather specified the dimensions of the comb teeth so that she could use a 12 channel multipipettor to load amplicons straight from her PCR plates. I’m going to have to ask her to remind me why there’s thirteen teeth…. ? I design things to be fixable so if one of the teeth gets broken you can simply undo the bolts to replace it.

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Heather ran some gels on it today and she was very happy, although it turns out the distance between the combs isn’t quite optimal for her samples so in future she’s going to use every other row to give more distance for the bands to separate. Pics to follow tomorrow.

I will post the laser files here when I get a chance too. Or maybe I should upload them to thingiverse??

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Designing and lasercutting custom electrophoresis gel trays and combs.

I’ve been approached by my squid scientist friend, Heather, to make a custom tray and combs for casting agarose electrophoresis gels so that she can run 96 PCR products at a time. Gel combs are pieces of plastic which are plunged into the liquid agarose before it sets to form wells in the solid slab that you can load with the product of your PCR run.

comboutfig7-lg

This is the kind of lab gear which costs fantastic sums to purchase from vendors, particularly with any sort of bespoke customisation. Have a look at Thermo Scientific or Sigma Aldrich’s web site, where you will find these little pieces of plastic on sale for around NZ$100 each.

This type of thing is a very straightforward object to design and make for anyone with a few CAD skills and access to a lasercutter. I knocked up a design in about 5 minutes to demonstrate this to Heather and she got very excited and set off to measure up exactly what she wanted.

squid gel comb screenshot from 2016-08-30 20-42-50

Here’s the OpenSCAD code for this object:

translate([0, 0, 13 /2])
cube([133, 1.5, 13], center=true);

translate([0, 0, -3 /2])
cube([122, 1.5, 3], center=true);

for(x = [-6:1:6]) {
translate([x *9, 0, -6.5])
cube([4.5, 1.5, 10], center=true);
}

Pretty simple, huh?

I have some clear 6mm thick acrylic sheet which I can use for the gel-casting tray and I’m going to order some 1.5mm acrylic sheet from RS to cut the combs from. In exchange for my help I get to post the design here on my blog so win-win!

 

Update

I’ve sketched out the design and its looking great. I’m going to do a test cut in MDF first to see how it fits together.

Screenshot from 2016-09-03 23-20-20

design: magazine rack

My wife keeps a large number of glossy magazines around the house which always seem to end up in piles wherever I want to put my cup of tea down. So I set about designing a rack I could laser cut out of 6mm MDF and then screw to the wall to provide my dearest with somewhere convenient yet tidy to keep them. Once I had the basic design I set about crudely baroquing it as I like pretty patterns. 

😀

This is a single rack design which I think might be appropriate for the bathroom. I’m also going to tweak the design to add racks vertically or horizontally to house more extensive collections.