Is this the sort of grind you are contemplating.
Not the best video presentation, but still illustrated the point quite well

Bill

That brad point sharpener technique looks pretty amenable to a jig or two to ensure the angles are equal and the grind central. I'd think a look at Howard Halls methods would be inspirational.

The presentation seems classic apprentice instructor style. Show and tell then walk round correcting the trainees technique as they try for themselves. I rather like the lack of flash but it doesn't really translate well to the modern YouTube age. If only thre were a way to link print out pictures to do the equivalent of teachers blackboard in a classroom.

Clive

Further to my earlier post here is a video showing how to make a wooden jig to do brad points using the same technique. The method of cutting the point is sligtly different and, possibly, more accurate. Metal version could be smaller.

https://www.youtube.com/watch?v=U0jGbXY3rUY

Can't make the embed thing work!

PS That is the video referenced by DC31K who posted whilst I was struggling.

Clive

Edited By Clive Foster on 24/07/2022 08:46:39

They are very easy to grind freehand on a bench grinder. Woodworkers do it all the time. Get some old drill bits and practice on them. You grind the standard pointed drill bit down flat across the end first and then hold the cutting edge on the corner of the wheel to put the angle on each side, leaving the "tit" in the middle, which can be finely shaped to a point agan on the corner of the wheel. You grind the OD tips down so the tit in the middle sticks out a little further than the the OD tips. That way the tit in the middle acts as a sort of centre drill as you go.

This type of drill point is also very good for drilling thin sheet metal. Just lay the sheet on a piece of wood first so the centre tit goes through into it and then the two OD tips cut out the outer circle to a nice hole with no grabbing and burring like you get with a 118deg point on thin sheet. It's a sort of trepanning action.

It's a very handy skill to develop. Worth wasting a few old drill bits on to learn.

Edited By Hopper on 24/07/2022 09:23:16

The purpose of a brad point is to create a clean entry hole in soft material; it has no bearing on straightness and I'd guess probably makes it worse.

Drilling an accurate hole in 300mm of wood is a challenge; some more information about the workpiece and setup might be helpful. Generally, though, the advice would be to start off with a stub drill one size under, ream to size, then step up drill lengths. The drill will still wander but it will get progressively worse instead of veering off sideways from the start.

If that isn't sufficient, you will need to leave the world of twist drills behind and investigate things like D-bit drills and gun drills.

Hafta disagree with Calum as to the action of brad point drills.

Correctly ground they cut from the outside edge inwards. The actual cutting edge should be slightly concave. Good quality commercial ones have a very shallow lip on the circumference projecting slightly forwards of the cutting edge.

As the brad point stabilises the centre the cutting forces on flat material will be balanced at the outside diameter of the drill so there should be no net deflection forces. Unlike a conventional drill where the cutting edges are offset from the centre creating a net deflection force. The deflection force remains even when the cutting edges of a conventional drill are fully engaged but generally they are overwhelmed by the stabilising effects of cully engaged cutting edges and, on deeper drillings the hole walls. If the deflecting forces are not fully overcome the drill wanders.

As with a conventional chisel point a brad point doesn't properly cut. Its more ore less forced into the material. Hence the general restriction to softer materials. The concave shape of the cutting edge means a brad point drill is much worse than a conical point at clearing the extruded material produced when the point is forced into the material being drilled. Another reason for the restriction to soft or thin materials. Generally if the material is thicker than the brad point lenght things start getting iffy on more resistant materails.

Clive