25 mm square aluminium tube drill guide
by alisonleanne, published
use this guide for drilling 5mm hole to join two 25 mm aluminium square tubes at 90 degree with 25mm x 3mm aluminium flat bar and 4.8 mm pop rivets. the drill passage can be replaced with fresh ones for precise drilling. drill holes before cutting off the 3mm thick flat bar for better alignment. the last file is for the original one piece guide with guiding hole that can not be replaced.
the first pair of guides is for joining a tube with lip with a no-lip tube, the second pair is for joining 2 lipped ones. they all share the same removable drill passage (the square plug with a 5mm hole through the center). added corner support today. when you lay your parts on the floor to make a retangle or square, put the drill guide on one corner and supports on the other corners. 27Dec12: improved corner support, can use the same square plug as end stops.old one removed