I picked up some of the 1/4" copper couplings from Home Depot and tried inserting them into the 3D printed pocket hole jigs. The hole is quite a snug fit, so I tried heating up the copper with a soldering iron (actually a woodburning iron but technically the same) and sliding it in. I completely melted the interior shaft of the first jig! I guess I held the iron to the copper too long and it got much too hot.
The subsequent ones worked fine, though I found it was sometimes easier to run the drill bit through and grind the spinning coupling into the plastic. Once it was in I heated it up a bit to try and get a press fitting. I also received the four 3/8" drill bits from Amazon, but unfortunately one was missing the set screw on the collar so it was pretty much useless to me. I printed off a return label and will post it back tonight.
I tried out the DIY jigs in class today and they worked well -- for a little bit. For the most part they held up but one jig got destroyed when the drill went in on a funny angle. Two or three more had the copper coupling fall out; I re-seated them with the soldering iron and they seemed to last the rest of the block.
Overall, I wouldn't do it again just to save money. The Kreg jig is much sturdier, perhaps because the coupling runs the entire length of the drilling shaft or maybe the plastic is a bit tougher. And since one of my new drill bits was missing it's collar due to the set screw I was also down one station. Much easier just to buy the package all together and you know it all works.
