PCR Tube Magnetic Racks

thingiverse

I *loved* the racks <https://www.thingiverse.com/thing:1132367> designed by destroyer2012 - way better than racks that require gluing the magnets, but I felt the need for some modifications: # 4-Tube PCR Magnet Rack This is only slightly modified from https://www.thingiverse.com/thing:1132367 - in the original the spaces in the back of the rack are closed, so you can't see in the PCR tubes there. I opened up the back so the tubes there are as visible in the front. It is 4 tubes wide, so it holds 8 tubes total. Magnets are the same as the original: combine a 0.5 inch magnet <http://www.kjmagnetics.com/proddetail.asp?prod=B842> and 0.75 inch magnet <http://www.kjmagnetics.com/proddetail.asp?prod=BC42> to make a "synthetic" 1.25 inch magnet. Original says to align the poles of the magnets, but I put them N to S so they stick together and they worked fine. # 6-Tube PCR Magnet Rack Expanded from the (modified) 4-tube rack so that it holds 6-tubes, but the real benefit is that this rack fits a single 2 inch magnet <https://www.kjmagnetics.com/proddetail.asp?prod=BY042>, so you don't need to fiddle with two magnets, as is necessary with the 4-Tube rack. The fit for the magnets is even tighter than the 4-tube rack, but you can get them in there! It is 6 tubes wide, so it holds 12 tubes total. Spacing on both racks is 9mm (center to center), so they fit a multichannel pipette # Magnet Shover The *magnet shover* does exactly that, it helps seat the magnets all the way into their slot. Once the magnets are in the slot enough to be secure, I set the rack magnet-side-down on a sturdy flat surface, and push down on the rack with all my weight to get the magnet flush with the bottom of the rack. Next I use the shover to push the magnet in enough that the shover is stabilized by the lip of the rack, then use the shover to seat that magnet all the way in.