Tetrahedral Drilling Jig for Molecular Models

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Project by ironwoods posted 07-02-2012 07:07 AM 2537 views 6 times favorited 10 comments Add to Favorites Watch

Because I advertise wooden models for chemistry, geometry, and geology on my website: DrB Science Basics, I was asked by a biochemistry professor to make several custom jigs for large chemical models to be built as a summer project involving high school and university students. Those who have tried are aware that tetrahedral angles (109.47…. degrees) are very fussy and the design of a jig for accurately drilling them is not trivial. The sequence of operations for drilling a 2 1/4 ” diameter carbon atom is shown.

-- Eric, Maine,

10 comments so far

View ownafixerupper's profile


11 posts in 1052 days

#1 posted 07-02-2012 10:53 AM

The nerd part of me that remembers chemistry is definitely amused and a wee bit nostalgic. That’s a very nice-looking jig—-good job getting the angles set up just right.

View jeepturner's profile


924 posts in 1482 days

#2 posted 07-02-2012 11:27 AM

Very nice tool. Thanks for all the pictures of the sequence.

-- Mel,

View KnotCurser's profile


1843 posts in 1758 days

#3 posted 07-02-2012 11:32 AM

Love this! It’s a great jig and a great reason to build – teaching Science is SO important.

I applaud your efforts, sir!!!!


-- Robert Rhoades WoodWorks / Email: /

View Ken90712's profile


15102 posts in 1878 days

#4 posted 07-02-2012 02:17 PM

Great jig, for a great project!

-- Ken, "Everyday above ground is a good day!"

View Helkat's profile


74 posts in 986 days

#5 posted 07-02-2012 05:32 PM

Really neat jig. I’m fairly certain I wouldn’t have come up with such a simple-looking solution that that problem.

Well done!

-- Nat, UPstate NY,

View oldnovice's profile


3798 posts in 2057 days

#6 posted 07-02-2012 08:05 PM

A number of years ago I made some models similar to this using Plexiglas spheres as part of a orientation for new employees (I also made a SOMA cube out of Plexiglas cubes that looked like ice cubes).

I can understand the requirements for accurate angles and can really appreciate the fixturing designed for these chemical models!

GOOD WORK and the students will be able to “visualize” better!

-- "I never met a board I didn't like!"

View ChrisK's profile


1202 posts in 1771 days

#7 posted 07-03-2012 02:25 PM

Tetrahedral Drilling Jig for Molecular Models, not something you hear everyday. Cannot say I miss chemistry much. Great Jig.

-- Chris K

View rance's profile


4142 posts in 1850 days

#8 posted 07-06-2012 04:57 AM

Clever solution there.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View ironwoods's profile


2 posts in 893 days

#9 posted 07-06-2012 01:19 PM

Thank you for your comments. I’m a brand-new member and from the beginning have felt that this is a fine organization of creative people.

Making this tetrahedral jig requires no complex (expensive) machinery for setting a 109.47… degree angle. It requires a little trigonometry for setting the angle of the ramp. The idea for the rest of the design comes from playing with a wooden model. (Type “Tetrahedron with Enclosed Sphere” with the quotes on Google and you’ll see what I mean.) I observed that three of the spokes of the sphere are 120 degrees apart, although inclined at an angle. I only needed to set a precise 30 degree angle for the jig.

-- Eric, Maine,

View BTKS's profile


1971 posts in 2154 days

#10 posted 07-06-2012 05:04 PM

Freakin ingenious!

-- "Man's ingenuity has outrun his intelligence" (Joseph Wood Krutch)

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