Drill Bits - Need some help and advice

[FredH]

Fred. I've had a Drill Doctor for now for about 15 years and had no idea Darex was the manufacturer. Maybe your wife should bring one of these home to check out....

XT3000 Drill Sharpener and Grinder - XT3000 Manual - Drill Sharpeners and Grinders.



Terry

Yea , I Already Tried That !!!!:thumbsup: She won't even Ask .

Fred H.

 

[Big Barn]

Yea , I Already Tried That !!!!:thumbsup: She won't even Ask . Fred H.

I'm currently bidding on one locally but bidding is already up to $1350 with 3 days to go.

Terry

 

[dragoneggs]

Here is a cheap and easy way to check the proper angle of a drill bit. Most of us here have two of these.

Ha ha... Pretty close with that shop tool... only 2 degrees off. Can't say I have ever measured anything with my nuts though.

 

[Mace Canute]

You're not likely to soften HSS by grinding. You can silver solder it to a boring bar (red hot) and it will still be hard when it cools. Carbon steel is a different story.

Hardening is speed dependent. If you heat a soft carbon steel above the Curie point fast cooling will make it hard. If you reheat that same steel above the Curie point and then very slowly cool it, it will be soft again. HSS will become soft when it is heated to high temperatures but the speed that it cools at in air is sufficient to make it hard but it does not become as hard again as it was in it's preheated state. You might start at 67-70rc and then end up at 58-60rc which is still hard enough to be a good cutting edge.

 

[Sodo]

Ha ha... Pretty close with that shop tool... only 2 degrees off. Can't say I have ever measured anything with my nuts though.

Yeah nobody will know the units but you can usually count with them. For example the number of degrees off. Or you could count the number of people who know the angle is wrong.

 

[the old grind]

Adherence to the 118^ drill point is to avoid being sued by Apple (TM) for patent infringement.

They invented the 120^ angle too ...

 

[dragoneggs]

Yeah nobody will know the units but you can usually count with them. For example the number of degrees off. Or you could count the number of people who know the angle is wrong.

Typically I measure the degrees by the size of the nuts.

 

[oldtimer 66]

Quench and temper is all I know. Never heard of a tool steel that would go to 67/ 70. Stratified yes uniform no. M4 vacuum melt degassed best 62/64. Carbide yes on a different scale..

 

[Mace Canute]

Quench and temper is all I know. Never heard of a tool steel that would go to 67/ 70. Stratified yes uniform no. M4 vacuum melt degassed best 62/64. Carbide yes on a different scale..

The M40 series and T15 can be hardened to 70rc according to Machinery's Handbook 29th Edition.

 

[cormier]

Here is what i use to get me in the ballpark. mild steel 80sfm x 4 = 320 rpm for a 1 " drill. So just divide it from their. if 1" =320rpm then 1/2" = 640rpm and 1/4" = 1280rpm and so on. For Stainless steel i cut the speed by 1/2 and aluminum i go about 25% faster This gets me in the ballpark and i dont burn up my drill bits.