Sciencemadness Discussion Board

Test Tube Holder

Yttrium2 - 12-10-2018 at 10:31

Again, I'm making a thread in regards to: How do I make a test tube holder,

the parameters; 1) There are 6 test tubes.

2) The holes are evenly spaces

3) There is a 1" margin on each side

Question: How mathematically can we determine how much space should go in between each hole?



Also


Question2: How could we determine the spacing that would need to take place to evenly space the tubes within a circle?

-- I have a top to a peanut butter jar that I figured I could use as a test tube holder. -- Not made out of gopher wood, or anything like that...

[Edited on 10/12/2018 by Yttrium2]

Sulaiman - 12-10-2018 at 11:47

Sketch the linear and circular test tube racks with letters to represent dimensions and the mathematics will follow.

Yttrium2 - 12-10-2018 at 12:37

nevermind, their is an abacus beside me. I'll use it to see how many spokes there are and then from there deconstruct what they used to measure, and how, mathematically, they found out how much distance to space the holes.

Mr. Rogers - 16-10-2018 at 17:20

You're overthinking this maybe. A drill press and a ruler is all you need to get the two haves as identical as they can be.

Abromination - 16-10-2018 at 18:46

I use a spot plate that happens to fit the diameter of my test tubes. It should fit most test tubes, it can be found on homesciencetools.com. It should be the site's only plastic spot plate.

Elrik - 17-10-2018 at 13:54

Quote: Originally posted by Mr. Rogers  
You're overthinking this maybe. A drill press and a ruler is all you need to get the two haves as identical as they can be.
As much as I believe in retaining a proficiency in trigonometry, I think Mr. Rogers is right. If your making a holder from cheap materials then a ruler for rows or a printed picture of cyclohexane or cyclopentane to guide a circle is more than good enough. I made these two with those methods and they came out fine, even if they do have a variance of ±1 mm :cool:
If you want more complexity, just remember than your right triangles angle is Sin-1(opp/hyp) or Cos-1(adj/hyp) or Tan-1(opp/adj)
Soh Cah Toa :P

200_8609.jpg - 52kB

DrP - 19-10-2018 at 02:25


These are my 3 favourite test tube holders: https://st3.depositphotos.com/10654668/14428/i/1600/depositp...

Also up there as a quality holder: https://thumbs.dreamstime.com/z/young-woman-holding-test-tub...




CharlieA - 19-10-2018 at 15:55

Dr. P, Those are the best yet!
...but I think you have too much time on your hands!:D