Very good, not "excellent" quailty,
September 29, 2008
By MilesDfrom Virginia
"Drill dimensions were determined by micrometer measurements to be precise to the nearest ten thousandth of an inch below a quarter inch diameter, and precise to the neared thousandth of an inch above that diameter. This probably meets SAE standards, but not ASME standards.
Drills are sharpened to an "average" angle between the angle used for very hard steels and the angle used for soft metals such as copper or brass. Thus steel drilled with these bits will chip as brass should when brass is drilled, and steel does not leave twisted fragments as it would if the face angle was steeper. If extremely close tolerance holes are needed to be set in steel, this is not accepable.
Thus for close tolerance holes in steel, the drills would need to be re-pointed - but it that is done, the cobat coating (which is only about .0.0005 inches thick ) will be lost - and so will the durability the cobalt coating provides."
What is your level of technical expertise?:
Professional
Overall Rating:
5
/ 5
Fantastic Wife Gift to Husband,
January 14, 2008
By SJMBfrom California
"I am not educated in what drill bit sets are about, and originally I came home with a "screwdriver set" from a retail outlet, when my husband said he needed a "drill bit set". Looked the same to me!! Anyway, I found the 145-piece set in a neighbor's catalog, and had it sent to him (my husband would immediately open it on delivery, if he saw it was from Northern Tools) and he was thrilled with his Christmas gift, which is already using, although I don't know how in the world ANYONE could use ALL of those bits. But men tend to make something out of everything and accomplish it!! Thanks for making THIS Christmas gift so easy!"
What is your level of technical expertise?:
Beginner
