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Magnetic Rack for 8, 1.5mL Tubes

by acadey, published

Magnetic Rack for 8, 1.5mL Tubes by acadey Apr 24, 2013

Description

This is an 8 tube magnetic rack for 1.5mL tubes. These things are insanely overpriced and are a perfect thing to 3D print - the major cost is the magnets which are ~70 cents a piece. This design has little arm things that hold your tubes in place snugly and can even hold them in when upside down. I recommend using these magnets: kjmagnetics.com/proddetail.asp?prod=B824 and using some epoxy to glue the magnets in. The easiest way to glue them in is to glue an outer one first, then put a tube in to hold it in place, then do the same to the third position tube, then the second one can be glued in since it will have equal magnetism to the left and right. Repeat for the rest of the rack. This design is optimized to use less plastic and prevent warping during printing, though I still recommend printing a raft just so it gets started easier.

I updated this model with a different base (it now has more room for you to look at the beads when pipetting) and also a version where the tube grabbers are printed without an overhang as per suggestion in comments.

Also if you are a grad student and are trying to convince your PI to buy a 3D printer - making just a few of these more than pays for the printer itsself!

EDIT: Added sketchup files for the 8 & 4 tube versions. Also a user made the comment about the direction of the magnets. It may be better to use these: kjmagnetics.com/proddetail.asp?prod=B842 instead, though it is currently untested.

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Sorry for the delayed response - I uploaded the sketchup files (where I designed them) Hopefully this will help.
Hi acadey, love your design of the magnetic stand and am about to order some magnets. Why did you go for the side to side magnets kjmagnetics.com/proddetail.asp?prod=B824 rather than the top on top magnets kjmagnetics.com/proddetail.asp?prod=B842 and does it make a difference? Also, they have the top to top magnets in a higher strength (B52), do you think that will improve the stand? Cheers!
The non-overhang model has internal faces. Netfabb was unable to fix them, can you remove them please? Or provide some STEP/IGES files so I can edit it? Thanks

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Hi acadey, love your design of the magnetic stand and am about to order some magnets. Why did you go for the side to side magnets kjmagnetics.com/proddetail.asp?prod=B824 rather than the top on top magnets kjmagnetics.com/proddetail.asp?prod=B842 and does it make a difference? Also, they have the top to top magnets in a higher strength (B52), do you think that will improve the stand? Cheers!
The non-overhang model has internal faces. Netfabb was unable to fix them, can you remove them please? Or provide some STEP/IGES files so I can edit it? Thanks
Sorry for the delayed response - I uploaded the sketchup files (where I designed them) Hopefully this will help.
Great design - Thanks acadey for the brilliant design - saved me a ton of money!
So I've had one of these printed on Shapeways (which works great) and I successfully scaled it down for 0.6ml tubes (which also worked great at 0.75 scale) on my own printer, but I've not been successful in printing this scaled up to 5.0ml (scaled up 1.53) Eppendorf tubes. I keep having warping issues with it, which is not surprising since the scaled up version is the exact same width as my build platform! This is really frustrating since from the one position which was not warped, the tube fit perfectly.

I was wondering if you would consider releasing a version of this with only 4 tubes?
It shouldn't be too difficult for me to cut it in half and be a 4-tube version.

Actually very easy - just did it! Let me know how it works out for you.
Awesome! I'll be sure to post pictures of the set.
So I just printed this to use in my lab, it works perfectly! Thank you so much for making this it was a great idea. Slight problem in that sometimes the tubes tend to pop out of the holder if you try to put them in all the way. I would love it if you designed a good pipette holder, perhaps also magnetic so you could attach it to a shelf above the bench.
So I finally got around to posting these. They work well for our shelves and pipettes, but may need to be adjusted depending on the model / shelf ledge width you have. Here is the thing: thingiverse.com/thing:153334
Funny you should say that - we actually have pipette holders that attach to the shelf above the bench that were designed by a colleague of mine already getting heavy use in the lab. Right now they come down a bit low for my liking but are great for shorter people or anyone with a shelf a bit higher up. I have been meaning to design one that keeps them up a bit higher. I will design the other version and then upload them both in the near future.

Glad to hear this magrack is working out for you. To get rid of the pop-out problem we have a cylinder file that can take off a bit of the plastic inside the slots that seems to work out well, so maybe try filing it down a little bit.
How do you handle the overhanging piece? Interior support to print?

If you add some support yourself, it could be printed without that. It would not be in the way of the tubes
It actually prints it fine without supports. The overhang is actually at a gradient, so there is no large jump extending over empty space - it adds on ~1mm extension per layer, however that edge is never super-clean.

A support would certainly work and not be in the way. I am actually still tweaking this design and will post an updated version in a bit - I will play around with support ideas. Thanks for the suggestion!
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