Mainline drill guide

[Longyearfarm]

Hi all. Last week I spent a good chunk of one of my days replacing saddles and installing new ones. I don’t own a mainline drill so I have been using my cordless drill and trying my best to not blast through the bottom of the pipe. For whatever reason, I managed to mess up a handful of new saddle holes because the bit walks. I even managed to drill completely through the pipe once. Very frustrating. I looked into the commercially made tools that night with so I could get an idea on how I could fabricate one. I don’t know why I started thinking about PVC saddles, but I got to wondering if that would work as a cheap substitute. Here’s what I made in 5 minutes

[Longyearfarm]

I used a 1/4” nipple and drilled it out to 5/16”. The 3/4” bushing threads into the saddle as far as you want. I can adjust the depth of my bit by backing off the threads a bit. The 3/4” PVC saddle snaps over my 3/4” mainline easy enough. I gotta say it works pretty slick. And is light as a feather. Just wanted to pass it along in case anyone else was in my boat...

[SeanD]

I splurged for the mainline drilling tool when I first started up with mainline. I know it is way overpriced, but boy it is so simple and easy to use. With the crank-type bit, it only takes about 7-8 turns to go through the mainline - depending on how far you backed it off on the previous hole. You'd have to crank on it another 15 more times to hit the bottom of the mainline, making it (almost) foolproof. Plus, being all in one, you don't need to carry your drill. The whole thing fits in your large pocket.

I'm all for fabricating stuff and saving money. I've done that in other areas. If I would change anything on your design, I'd try to work a crank drill bit into the top.

[maple flats]

I have done it 2 ways and never owned a mainline drilling tool. My original way, I made a block of 2x4 with a hole drilled thru it in the 4" (3.5") dimension then I held my tapping bit up to the 2x4 and marked a point at that thru hole where the tapping bit just reached thru about 3/8". I marked that measurement, then cut a V in the 2x4 to center the hole over the mainline. I then cut off much of the excess wood to make it lighter and easirer to hold. To drill a hole on the mainline then I simply held the 2x4 V on the tubing and drilled. It never messed up.
My current method is that I bought a mainline drill bit from DSD. It only extends out of the chuck far enough to drill without going thru (I don't know about 1/2" my smallest mains are 3/4"). The tip is very pointed and it is made to drill plastic, it does not drift. That is what I have used the last 5 seasons.