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pacificpuzzleworks

Merkaba Puzzle (5 intersecting tetrahedra)

by pacificpuzzleworks Aug 29, 2018
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I believe I have found an error in the instructions for this project which caused me considerable confusion initially. In the description of the Merkaba puzzle, the instructions specify the purchase of quantity 60 of the following product:

https://www.kjmagnetics.com/proddetail.asp?prod=D24

which is a 1/8" diameter, 1/4" long, axially magnetized cylindrical magnet. However, I believe that a maker actually needs quantity 120 of the following product:

https://www.kjmagnetics.com/proddetail.asp?prod=D22

which is a 1/8" diameter, 1/8" long, axially magnetized cylindrical magnet (there is a stronger version of this product, part D22-N52, but I think that is probably excessive for this application). Thus, there is one magnet in each of the four shallow cylindrical holes in each of the 30 pieces printed for the puzzle, and not one magnet for each pair of holes, as I was inferring from the original instructions. The instructions specify that "6 identical pieces are held together by 12 magnets to form each tetrahedron," whereas the text should read "6 identical pieces are held together by 24 magnets to form each tetrahedron." The shape and orientation of the pair of holes at each end of a piece are not appropriate to accommodate a single 1/4"-long magnet.

Hello 1d2d3d4d thank you for this detailed comment, and I appreciate your enthusiasm for this puzzle but I am sorry to tell you that you’re wrong to say that I made a mistake in the instructions. It is possible to make a version of this puzzle with 2x quantity magnets that are half as long as what I have specified (maybe with some glue to hold them into the holes?) , but if you do it this way then the puzzle itself will not hold together well in comparison to how well the puzzle works if you follow my instructions properly. For anybody else reading this, please do not follow 1d2d3d4d’s advice here.

If this is the case, then much better instructions need to be provided as to how to insert the 1/4" magnets into the openings provided in the pieces as designed -- preferably with a video demonstrating a successful insertion. I simply don't believe it can be done, without drilling a new opening or risking damage to the printed piece -- the dimensional tolerances are simply too restrictive. There may be a reason why no other successful builds have been shared on this site.

Hello again, thanks for your suggestion that I make better documentation about the post production work needed in order to get a satisfying fit for the magnets. At some point in the future I would love to put some more time toward that but as you so delicately pointed out, this is not a particularly popular model here on thingiverse so I don't see much need to hurry on it just yet. I'm sorry that you found my existing instruction confusing, but please look again at the summary info which has a whole paragraph explaining how to hand-finish the pieces so that the magnets fit well.

When I designed this puzzle I experimented with different sizes and shapes for those holes in order to try to get geometry which didn't need to be hand finished very much; to some degree I feel that I have been successful yet over the course of my prototyping process I discovered that "loose fitting" geometry (which doesn't need to be finished by hand) doesn't have the same quality tactile feel of the sliding magnetic action in comparison to pieces which were printed a little bit tighter and then subsequently touched up in the manner I've suggested in the instructions.

If your #1 priority here is having printed parts which do not require any post production work, then an easy fix here would be to simply scale up the model by 1-2% but I think you will have more fun playing with the end result if you leave it at 100% original size and do the post production work in order to get nice fitting holes.