Does anyone know of a chart or formula to help me find drill depth for KEO combined drills and countersinks to give me a finish countersunk hole in my programming? Or do you use spotting drill instead? Thanks Jack
Does anyone know of a chart or formula to help me find drill depth for KEO combined drills and countersinks to give me a finish countersunk hole in my programming? Or do you use spotting drill instead? Thanks Jack
They call them 'combined drills and countersinks' but they have a 60 degree taper on the 'countersink' part which is not correct for a flat head countersunk screw. Right now I can't remember exactly, but the angle for a countersink is 87 or 89 degrees so even a spotting drill at 90 degrees is not exactly correct. I have been told it is possible to get spotting drills with the correct angle but have never seen them; for non-critical work the 90 dgrees is often okay. Using a spotting drill also gives the advantage that you can spot for the hole location to stop the drill wandering on entry, and go deep enough to leave the countersink at this step; saves a bit of time on multiple holes.
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they have the formula there.
this is from txcncman...don't know how well it works.
TXCNCMAN thanks this works well - I Used to have a printed chart that had a formula for standard center drills - it had coffee stains all over it. I lost it and now I can't believe it is so hard to find another one.
I took some time to review the posted excel file and found the numbers were not the same as what I use when programming. So I have added some additional information. Let me know if I'm on the right track or not.
Try here: Center Drill Dimensions
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A No. 5 Center Drill will make a MAX 0.4375 Diameter Chamfer. The example on this page [URL="http://www.webmachinist.net/centerdrilldimensions.html"] may NOT work
I know this is an old post but awesome share guys. Very useful excel sheet!
I was looking to see of anyone had the math to calculate center drill depth, every I looked I got a different answer. I drew a #4 center drill on MasterCam and found a solid solution. If you have a Texas Instruments TI-84 Plus, below is the code that calculates the depth needed for a given diameter. This code does account for the pilot tip, which no one else seems to do...weird. Calculate the depth, touch the tip to your material surface, set Z, go.
Disp "DESIRED DIA.":Input A
Disp "PILOT DIA.":Input B
Disp "CENTER DRILL DEPTH IS..."
(A/2)-(B/2)?C
C/tan(30?D
(B/2)/tan(59?E
D+E+B
stet