Large diam(more than 1/2") drill bits

[alexmin]

I am shopping for quality drill bits.
Enco has a Triumph set on sale (8 pc. 9/16 to 1")

If somebody knows if there is a better deal somewhere else please let me know.

BTW
Normally I buy "machine" length drill bits. They are cheaper and more rigid. I can't find any Silver and Deming drill bits in "machine" length. Do they even exist?

Thanks

 

[precisionworks]

My experience with S&D twist drills, which are usually sold in sets starting at .562" and then increasing by .062", is that they aren't (often) used for making a precise diameter hole. A 1" S&D makes a nice starter hole for a 3/4" boring bar, etc.

The Enco set is $109.95:

http://www.use-enco.com/CGI/INSRIT?...MKANO=240&PMKBNO=2053&PMPAGE=10&PARTPG=INLMPI

Titan USA and Michigan Drill both make a similar set, both are excellent, but $150 is as low as I ever see them.

 

[wquiles]

I was recently using my Precission Twist S&D Set to make a hole of 1.03", so I started with my 1.0" drill:

When I was done I checked the hole, and it was 1.000" inches:

Close enough for space shuttle parts, right? :huh:

Will

 

[precisionworks]

Close enough for space shuttle parts, right?

You have to take a few things into account ...

A brand new drill with sharp lands of equal height plus a perfectly sharpened point with equal length lips, equal rake angles & identical relief angles. In a perfect world, a 1" drill will make a 1.000" hole. A worn drill, badly sharpened, can just as easily make a hole that is 1.030" and not concentric with the outside diameter

 

[wquiles]

You have to take a few things into account ...

A brand new drill with sharp lands of equal height plus a perfectly sharpened point with equal length lips, equal rake angles & identical relief angles. In a perfect world, a 1" drill will make a 1.000" hole. A worn drill, badly sharpened, can just as easily make a hole that is 1.030" and not concentric with the outside diameter

Ahh - so I basically got lucky this time - nothing wrong with that

 

[precisionworks]

so I basically got lucky this time

No ... the drill was perfectly sharpened & had full height lands. Any drill that fits that description should give those results. Many brand new twist drills are not well sharpened, especially those at a lower price point - if the point is just .010" off center the hole will be .020" over size.

The shop I worked in had no drill grinders, so we hand sharpened everything up to 3" diameter. I was never as good as my boss, nor as fast, but most of my sharpened drills would produce a pair of spiral chips. Only took a few months and a few thousand trips to the grinder to get the technique down pat

 

[wquiles]

Only took a few months and a few thousand trips to the grinder to get the technique down pat

Ouch!. I think for now I will just keep trying to buy quality drills - it was very nice when I was making that hole to see the perfectly equal chips. Of course, it was just Delrin, not even Al, but I am happy anyway

 

[StrikerDown]

I have never been able to get the right geometry on a drill point:sick2:. Until a few years ago when I got a Drill Doctor for Christmas! I have no idea if it is accurate as far as making the point symmetrical or not but they look good to the eye and the re-sharp drills sure cut nice compared to how they cut a few seconds before!