Introduction: Kitchen Science Test Tube Rack

Build a rack to hold your test tubes full of supplies ready for Kitchen Science.

Step 1: The Idea

I loved the idea and presentation of the front cover of Make:'s Illustrated Guide to Home Chemistry Experiments.

The whole science-techno vibe is cool in a steampunk kinda way. Surely a test tube rack would be the most iconic image of a "science lab", and what better way to bring it into the kitchen than as a spice rack?

This gift was made for a relative, recently moved out of home, who is beginning to get into cooking.

Step 2: The Concept

I played around in Pro/Engineer, a 3D CAD program, designing a basic rack for the tubes. Commercial test tube racks are both expensive and not particularly attractive.

The width and thickness of the base and top peices was based on the scrap wood that I had lying around - re-use for the win!

This let me try out various combinations of row/columns, separation, and upper level height.

Step 3: Safety Gear

This step is applicable at multiple points of this instructable - wear appropriate safety gear for each peice of equipment

Step 4: Cut the Wood

Cut the wood you have chosen for the uppr and lower levels. I used a table saw, and cut two peices to size together to ensure they were identical.

I cut the two peices to 200mm length

Step 5: Clean As You GO

Again another oft-applicable step. Clean up as you go - it's easier in the long run. Do it after you make a mess in each step.

Step 6: Tape 'Em Together and Mark 'Em Up

Tape the two pieces together so that in the next few steps everything remains aligned. I labelled one end of both pieces to make sure I remembered which sides went together when I removed the tape.

Mark the centres of the test tube holes on the top level with a pencil. I used a 45mm spacing both vertically and horizontally.

Step 7: Drill Pilot Holes

Drill a pilot hole on each centre. I used a 2.5mm bit, but use whatever you've got that would be suitable.

I used the drill press stop to drill right through the top level and approximately 3mm into the bottom layer.

If you are using a hand drill or press without a stop, a trick it to mark the depth that you should stop drilling on the drill bit using masking tape or similar.

Step 8: Drill Post Holes

Flip the taped pieces over. Drill a hole in each corner for the corner posts. I located the holes 10mm in from the ends and edge.

Drill through the bottom level and approximately halfway into the top level.

I am using 8mm dowel for the posts, so I used a 7.5mm drill bit so that the dowels would be an interference fit with a tiny bit of sanding.

Step 9: Drill the Tube Holes

Cut the tape and separate the top and bottom levels.

Use a spade bit or other large bit as applicable to drill the full through holes to hold the test tubes in the top level.

My test tubes were 21mm OD, so I used a 22mm bit.

Although it looks like I haven't separated the layers in the photo, the lower piece is just a scrap piece of wood.

Step 10: Admire Your Work So Far

Take a break and admire your handiwork.

Step 11: Create Divots

Make "divots" in the bottom level that will help keep the tubes standing straight. Use the pilot holes as centres. The diameter of the divots should be about half to 2/3rds the diameter of the tube. Don't go larger, you don't want to be able to see the divots when the tube is in place.

I couldn't fink my countersinking bit, so I used the bottom of a step-drill bit. I beleive dremel-type tools have round head bits that would be suitable.

Step 12: Cut the Dowel and Insert

Cut the dowel into equal length pieces. I used 100mm length.

Insert into the base level, hammer down until flush with the underside. I needed to sand them down just a LITTLE to get a good tight fit.

Step 13: Add Felt Bumpers

I added 10mm wide adhesive-backed felt bumpers to each hole to make a better fit between the tubes and the holes. The tubes should be a bit more stable.

Step 14: Put on the Top

Place the top level on and knock down gently. Use the markings you made early to ensure the holes line up perfectly. Use something like a rubber hammer or another piece of scrap wood on top to spread the impact.

Step 15: Slim Down Corks

Of course you can buy corks designed for test tubes - but they are OUTRAGEOUSLY expensive. I saved some corks from the bin, and reduced their diameter on a sanding belt.

Use precaution for this step - it would be easy to also reduce the diameter of your fingers.

I used the end of the belt to take a bit off each side going around the cork, then used the top of the belt to smooth out the sides.

Take off a little bit at a time until the cork is a good fit. Don't take off too much each go - it'll end up being too loose.

Step 16: Fill the Tubes

The tubes themselves are something you want to buy new rather than used. I bought mine at The Test Tube Factory in Sydney, Australia. Check your local directory for "laboratory supplies".

Clean the test tubes using soapy water and allow to dry completely.

Fill using kitchen supplies that you (or your reciept) will find useful. I also went for contrasting colours for aesthetics...

I used:

- mixed herbs
- hundreds and thousands
- salt
- pepper
- peppercorns
- tumeric
- curry powder

and left one empty for my recipients choice.

Step 17: Enjoy

Admire your completed kitchen science test tube rack.
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