drillbits , dirt cheap + tips
- FWIW ...harbor frt has coupons for 29 bit set w/ index box , coated , for 9.99 .....originally abt $30 ...PROBLEM is more than 1/2 are unusabe due to negative relief/ unequal lips .....( unbelievabley bad grinds )
.... since i hand sharpen ,abt 20 min later they are usable .....compared to $ 50 + /set , i am quite happy w/ circa $80 /hr for sharpening ....pleased snuf to get 3 more sets , even thou i have 2 others at different machines.......have had no noticeable problems on 1018 & drill rod....BUT since i hand grind , a dull bit is usable in less than 10seconds....& in home shop . i dont have to get 100 holes / grind ..........
fwiw #2 ,....when hand sharpening OR if you want a hole closer to nominal on any bit , pre drill a size under ...then the point doesent guide the final bit & any unequal lips are mitigated to the point of not a problem .......almost like reaming ......holes will be nominal to a couple thou over ,depending
fwiw #3 ....slight rounding of the lips where they join the shank of the drill & you have a pretty fair reamer cutting on size, all else true
FWIW #4 the closer to abt 5 thou undrsize of final hole size , the truer the reamer size will be even thou specs say 15 thou for MACHINE reamers ...for the penultimate in accuracy, a few metric bits are in order for staying around 5 thou under on commonly used holes
FWIW #5.,,,,in an emergency , a milling cutter makes a good counter bore , OR A drill bit GROUND FLAT ON END W/ LIP RELIEF ..center up on the hole first w/ a drill bit , then change to the endmil or flat drill
- It's a bit late for a quick death, but it would be a welcome one. Then too, I don't really have to read it, do I? Choices, choices...Rick H
On Tue, Oct 1, 2013 at 10:53 AM, David Weaver <abigalesdad@...> wrote:
Maybe I’m not alone in requesting this thread die a quick death.
The way i see it and the way i was tought and trained buy the best quality products one can find. China is not at fault it is the manufacturers that wanted to make more profits. I am talking about our people.
Suggest that for a different perspective on the foreign manufacturing process readers may want to purchase
"Poorly made in China" by Paul Midler. Copyright by Wiley & Sons, 2009, 2011. ($16.95)
This book focuses on the manufacturing of shampoo and other personal care products. However, the behind the scenes factory tours should explain the variability many have noted in machine tool products.