Drill bits and tolerances

[John Hasler]

They ought to only say "assembled in USA" like some products say,or something similar if only ground in USA.

They can call it "Made in USA" if more than a certain fraction of the value was added here.

 

[Flammable_Solid]

When you consider how crudely a drill bit cuts, flexes, and bends in comparison to other cutting tools, having them undersize is a boon.

 

[John Hasler]

When you consider how crudely a drill bit cuts, flexes, and bends in comparison to other cutting tools, having them undersize is a boon.

Making them undersize just adds to the unpredictability.

 

[astjp2]

Thats why you ream to final size...from what I have been taught....Tim

 

[John Hasler]

Thats why you ream to final size...from what I have been taught....Tim

I don't ream clearance holes for screws or ones I intend to tap. While drilled holes have a large tolerance, the range within which the hole diameter will fall can be predicted if the drill size is known. If some manufacturers start making their bits under-size it may become necessary to specify the manufacturer of the tool as well as the nominal size. Standards were supposed to get us away from that.

 

[Bob Korves]

I have many hundreds of drill bits. I have several older sets that were USA made, one older 115 pc. HF set that is complete and never been used (bought as backup but no longer trusted), the only other import set I have is a 29 pc black oxide coated fractional screw machine set that is actually OK. Most of my drills are purchased at garage and estate sales and from lots of tools found on Craigslist. I sharpen them myself, and know how to do it right. I use the old Craftsman jig which is just fine if you know how to use it and check each one by eye and on a drill point gauge. Bits over 3/4" I sharpen by hand, using a drill point gauge to check the progress. The old bits i buy need de-rusting, rolling on the surface plate for straightness, repairing the shanks, inspecting, gauging for size, sharpening, and oiling and labeling for storage -- but they are usually high quality drills that are worth the effort. Cheap drills are kept separate for less demanding tasks. Rehabbing drill bits is mindlessly boring but is also relaxing and satisfying. My pet peeve is that most drills I get have spun in the chuck and the shanks are buggered. Doesn't anybody know how to tighten, repair, or replace a chuck?

Looking for a nicer drill sharpener but have not yet found one at the right price/quality point and the one I have works...

 

[EmilioG]

I have many hundreds of drill bits. I have several older sets that were USA made, one older 115 pc. HF set that is complete and never been used (bought as backup but no longer trusted), the only other import set I have is a 29 pc black oxide coated fractional screw machine set that is actually OK. Most of my drills are purchased at garage and estate sales and from lots of tools found on Craigslist. I sharpen them myself, and know how to do it right. I use the old Craftsman jig which is just fine if you know how to use it and check each one by eye and on a drill point gauge. Bits over 3/4" I sharpen by hand, using a drill point gauge to check the progress. The old bits i buy need de-rusting, rolling on the surface plate for straightness, repairing the shanks, inspecting, gauging for size, sharpening, and oiling and labeling for storage -- but they are usually high quality drills that are worth the effort. Cheap drills are kept separate for less demanding tasks. Rehabbing drill bits is mindlessly boring but is also relaxing and satisfying. My pet peeve is that most drills I get have spun in the chuck and the shanks are buggered. Doesn't anybody know how to tighten, repair, or replace a chuck?

Looking for a nicer drill sharpener but have not yet found one at the right price/quality point and the one I have works...

I've seen drill bit shanks spin in chucks that had worn jaws. I learned not to clamp down on keyed chucks with excessive force.
If a drill bit hogs, something has to give somewhere, usually the chuck and sometimes the work gets spun around.

 

[benmychree]

I bought a 115 piece tin coated set Grizzly last year on their president's special. I think it was $45. It's been a good set. There are a few that I used constantly and finally broke. When that happens I run down to Marshalls and by a 6 or 12 pack of US made bits to have on hand in sizes I frequently use. If I need accuracy my small reamer collection will increase by one.

Dave

My observation of TIN (titanium nitride) drills of lesser quality manufacturers (anything Asian) is that the coating hides and tries to prop very poor quality tool steel underneath; they are not much good for demanding work, such as drilling stainless and heat treated steels. I would stick with known brands of HSS cobalt steel or even ordinary USA made HSS tools.

 

[EmilioG]

HSS works just fine for most steels other than stainless, Iconel and other hard metals. IMHO
Coatings such as Tin, TiAIN, TLCN etc.. are good but not always necessary.
I've used black oxide on brass, 40° end mills on aluminum, etc..with no problems.

I think a lot of tooling manufacturers use these features as selling points. 118° HSS drill bits
work just fine with most applications. AFA taps, I use only ground HSS, no carbon and mostly Guhring.
I favor Chicago Latrobe, Widia, OSG, Keo and Guhring. I also have some Titex, Alvord Polk, Yankee, Magfor, Niagra and others.
That's what works for me. I've never bought anything yet from HF. I have some Bosch cobalt drills that are very good.

 

[Jimsehr]

I just checked Harbor Freight price on 115 set and cost was $34 dollars' Then I checked usa made set at Amazon cost $350 dollars.
When you have $316 dollars more cost is it FAIR to compare the two sets?
jimsehr
For home shop I buy HF.