Drill Jig

Historically I've been terrible at sharpening drill bits on a grinder, I gave up a few years back and bought a dedicated drill sharpening machine. I recently wanted to revisit this as I've got a few larger bits that don't fit the drill sharpener and was looking around at various jigs. I saw a few shops selling these but figured I'd have a go at making my own.

Admittedly I didn't follow my original plan and had to change a few things along the way, but I've updated the plans and attached them here.

• Steel Bar ~10mm to ~15mm thick
• Steel bar ~5mm thick
• M6 Bolts
• M6 Wing Nuts
• M6 Washers
• Drill Stops or old Drill Chuck
• M6 Tap and Die
• Drill Press
• Drill Clamp
• Bench Grinder
• Angle Grinder
• Triangle File
• Protractor
• Ruler
• Marking Scriber

The first step is to cut out the length of the thicker steel bar and sand/polish the sides. I had a piece that was close enough to the correct size so didn't bother to cut it down any further.

Using a protractor, ruler and scribe mark out the steel bar where the various cuts need to happen.

Use a grinder or saw to cut the corner off the bar and then sand/grind it smooth.

It can be a bit tricky to cut the channel but start by holding the steel in the vice and carefully cutting the channel with a grinder or hacksaw. I then used a triangle file to clean up the channel.

Mark out the hole location and centre punch it to stop the drill from wandering.

This is where a drill press comes in handy and is much more precise, but you could still do this step with a hand drill in a vice. You want this hole to run parallel to the channel you cut and since the channel is 60° set the table to 30° and lock it in place.

Then line up the steel block and use a Drill Clamp to lock it in place, I had to add a second clamp as it moved a little. Now drill the hole being careful to either set the drill depth stop or put some tape around the drill bit as a flag.

Don't drill a hole in your drill press!

I disengaged the motor on the drill press and used it to start tapping the hole at the correct angle. I then removed it from the drill press and finished tapping it in the vice with a tap wrench. Make sure to apply some tapping fluid or oil to lubricate it.

Now mark out the location of the second hole and centre punch it. After you have reset your drill press back to zero drill a 6mm hole all the way through. Now follow up with drilling a 10mm hole about halfway through, this is to allow you to counter-sink the bolt.

I found that in order to adjust the grinding pitch I needed to add an additional bolt that would push up against the tool rest. I marked and centred punched this on the jig and then drilled another 5mm hole and taped it out to an M6 thread. I added a small adjustment bolt that will changed the pitch of the grind as needed.

Cut off a length of the thinner bar and mark the location of the hole, drill it out a 5mm hole and then tap it with an M6 tap.

The thread on the bolts didn't go all the way to the end, so I ran the bolts through an M6 die to extend it.

Now put a washer on each of the depth adjustment bolts and use a lock nut to hold them in place, add a wingnut to each of these bolts. I used three different bolts so I can change them out depending on the length and size of the drill bit.

You can now attach the jig to your grinder and clamp it in place by tightening the bolt with a hex key. You can also change the pitch of the grind by moving the adjustment bolt in or out.

The tool rest on a lot of these grinders really is a hunk of junk and I really need to replace them with something better, if you can wiggle the tool rest you will need to be very careful when using the jig as it can move.

Make sure your grinding wheel is straight, if it's not you may need to dress it with a diamond dressing tool.

You can use the jig "freehand" and just use it to help set the correct angle, but it's designed so you can use an old drill chuck or some drill depth stops to make sure you grind a consistent depth on both sides of the drill.

I found the vibration of the grinder would make the depth adjustment bolt move, so I went back and added a wingnut to act as a lock nut once you set the depth.

If the chuck doesn't mate correctly with the head of the bolt you may need to add a washer to provide a larger surface on the depth adjustment bolt.

After sharpening the bit I tested it out on a piece of scrap metal and it cut through nicely, which is better than my normal freehand sharpening attempts.