[CNC-Dude]

Have been trying to find a place where I can buy both of:

1. 90 degrees spot drill AND
2. 82 degrees spot drill

or

1. Drill Tip countersink drill for 6M screws AND
2. Drill Tip countersink drill for 5/16" screws

This is for aluminum so HSS or Cobalt should work fine.

Thanks for any recommendation you may be able to offer!

[handlewanker]

Incredulous..........you can't grind a drill?????
Ian.

[CNC-Dude]

Hey man, I am a hobbyist, with no machining education, helping out a friend make some parts. Didn't even occur to me that is how professionals on this realm do it! May give it a try and see if surface finish ends up being acceptable.

[LeeWay]

Here is a link.
McMaster-Carr

[louieatienza]

Have been trying to find a place where I can buy both of:

1. 90 degrees spot drill AND
2. 82 degrees spot drill

or

1. Drill Tip countersink drill for 6M screws AND
2. Drill Tip countersink drill for 5/16" screws

This is for aluminum so HSS or Cobalt should work fine.

Thanks for any recommendation you may be able to offer!

MSC, ENCO, Fastenal....

[handlewanker]

Hey man, I am a hobbyist, with no machining education, helping out a friend make some parts. Didn't even occur to me that is how professionals on this realm do it! May give it a try and see if surface finish ends up being acceptable.

Hi..........if you're going to have a go at grinding a drill, better do some dry running practice beforehand.

A drill only stops cutting when the point is blunt.

The knack of drill grinding is to get the off centre swing action that gives you the drill tip angle AND the back clearance or the drill won't cut but just rub.

Take a fairly large drill.....12 mm diam would be OK.........and with the bench grinder NOT RUNNING, hold the drill in both hands....(left hand near the point and right hand at the end of the shank)......... with the point at the angle of the drill against the front of the grinding wheel.....not the side....and both cutting edges on the horizontal plane

Practice the action that....... with the left hand holding the drill point against the grinding wheel....... forefinger resting on the grinding wheel rest.... the right hand rotates the drill point a half turn against the grinding wheel while at the same time it drops the end down slightly.....NOT TOO MUCH.

If you want to see this action more clearly, mark the end of the drill with a black marker pen and hold the point against any flat vertical surface while doing the rotating swing action.........the marking will show you where the drill point touches the surface.

The second important thing is to do this to both cutting edges as you go without too much on one edge, checking the angle with a drill gauge......this will enable you to get and keep the point on centre and at the right angle.

Before you actually do any grinding, you'll need a drill point gauge.......which is just a piece of steel plate with an angled offset at the end to put the drill against to get the angle right.

Normal drills are ground at 58 degrees per side.....you will need an adjustable angle gauge like a protractor with a moving rule that can give you the 45 and 41 deg angles.....(half the drill point angle per side).

A quick tip to test the drill point for centrality is to lay it on a flat surface with the point against a vertical face and scratch it across the face, rotating the drill 90 deg each time.....it should have one line if the point is on centre.

BTW...........do I have to tell you to use SAFETY GLASSES when on a grinder.......sigh.....OK, also make sure you have a can of water to FREQUENTLY dip in to keep the drill cool.

Grinding little and often is a better way than forcing a blunt drill to work.
Ian.

[CNC-Dude]

AHA! Thanks Handlewanker. This is great input! Will definitely give it a try.