I am thinking of buying some plastic test tubes to make a bunch of weed-pots (or single-stem flower in water) pots for a church craft fair.
How much extra room should I allow for glue around the tube?
The options for plastic test-tubes are 13mm wide (just over 1/2") or 16mm wide (just over 5/8"). Drill bits get more expensive over 1/2" so I don't want to buy several and try them out. I will wait until the test tubes come so I can measure real outside diameter, but then how much extra space should I allow or glue or wood movement?
I also am looking at 100mm long vs 150mm long. Might be a price difference from 4" to 6" if drill depth.
And my final question for the moment, this will be end grain drilling in various random pieces of wood. I assume I want a regular twist drill. How about a brad point or spade bit (I assume not because it will be end grain.). Maybe forstner?