I am sure many of you know this (and already practice this) and this may be published somewhere else. After buying drill set with letter, Imperial, and decimal drills (cheap set from Amazon), I started experimenting with making holes slightly smaller than the kit instructions. I have even reverse painted the blanks and tubes (very light coat of paint - Krylon brand). I only use epoxy to glue..acts as a lubricant. Here is what I started drilling:
Instructions state = left justified measurement. Smaller diameter on the right.
8mm ------> 5/16
3/8 ------> Letter U
10mm -----> 13/32
27/64 ------> Letter Z
12.5mm ----> 31/64
That is as far as I got. Did this with wood, acrylic, and hybrid. The best thing is you can always test fit the tube in the smaller hole. I have found there to be less slop going this route.
For what it is worth.
Instructions state = left justified measurement. Smaller diameter on the right.
8mm ------> 5/16
3/8 ------> Letter U
10mm -----> 13/32
27/64 ------> Letter Z
12.5mm ----> 31/64
That is as far as I got. Did this with wood, acrylic, and hybrid. The best thing is you can always test fit the tube in the smaller hole. I have found there to be less slop going this route.
For what it is worth.