[ranchak]

Awhile back I found a chart that told you how deep to run a countersink to obtain a fixed diameter. I can't seem to find where I found it and I can't find my printout of it. I know there are calculator programs that you can buy, but this was a really cool chart. It had all dimensions for 82', 90' and 100' countersinks. Does anybody know where to find something like this?

[easymike29]

I can compose an Excel spreadsheet for this if you're interested. I can't do it overnight however. As I get older I get slower. If you want it, I'll do it. Let me know.

Gene

[Curley]

Here is a calculator that solves for depth: http://janproducts.com/countersink_calculator.html

[wms]

Drill Point Angle >>>> Factor


(60 degree)>>> .866 x Dia = Point Depth
(82 degree)>>> .575 x Dia = Point Depth
(90 degree)>>> .500 x Dia = Point Depth
(118 degree)>> .300 x Dia = Point Depth
(120 degree)>> .388 x Dia = Point Depth
(135 degree)>> .207 x Dia = Point Depth

Dia is hole chamfer diameter, not tool diameter.
Point depth is how deep to drill to get the desired chamfer diameter with that drill point angle.

[journeymachine]

Ok,

so if my diameter of my countersink of the material is .75 of 82 degrees, im going to take .575x75=.43125 for depth. isnt that a little bit to much...should i take that awnser .43125/2=.215625

[deputydawg]

90 degrees would be .375" deep. You'd have to go deeper with an 82 degree, so .43125" is the answer you're looking for.

[aerospacer1]

Drill Point Angle >>>> Factor


(60 degree)>>> .866 x Dia = Point Depth
(82 degree)>>> .575 x Dia = Point Depth
(90 degree)>>> .500 x Dia = Point Depth
(118 degree)>> .300 x Dia = Point Depth
(120 degree)>> .388 x Dia = Point Depth
(135 degree)>> .207 x Dia = Point Depth

Dia is hole chamfer diameter, not tool diameter.
Point depth is how deep to drill to get the desired chamfer diameter with that drill point angle.

Thank you so much!

[the_gentlegiant]

Ok,

so if my diameter of my countersink of the material is .75 of 82 degrees, im going to take .575x75=.43125 for depth. isnt that a little bit to much...should i take that awnser .43125/2=.215625

Hi Journey,

Yes for a 3/4 diameter chamfer, 0.4312 is your depth. I use these constants all the time and they work great. They are also what you would use to calculate the tip length of a drill. This will help make sure that you drill deep enough, but not wastefully too deep when drilling thru a part. Stock thickness + drill point length + fudge factor to clear/break exit burr. (0.050 - 0.10 or so depending on diameter.)

Keep in mind that these numbers work the best on pointed 3 flute chamfers and near perfect on drills too, but many chamfers like the 6 flute kind from MaFord and similar have a truncated tip. This truncation diameter needs to be measured or is given in their literature and has to be accounted for. Otherwise you will drill your first countersink way too big. All you do is subtract the tip diameter from the countersink diameter you want and multiply that against the constant and you're good. No head scratching or jumping thru hoops needed.

[the_gentlegiant]

Hi Journey,

Yes for a 3/4 diameter chamfer, 0.4312 is your depth. I use these constants all the time and they work great. They are also what you would use to calculate the tip length of a drill. This will help make sure that you drill deep enough, but not wastefully too deep when drilling thru a part. Stock thickness + drill point length + fudge factor to clear/break exit burr. (0.050 - 0.10 or so depending on diameter.)

Keep in mind that these numbers work the best on pointed 3 flute chamfers and near perfect on drills too, but many chamfers like the 6 flute kind from MaFord and similar have a truncated tip. This truncation diameter needs to be measured or is given in their literature and has to be accounted for. Otherwise you will drill your first countersink way too big. All you do is subtract the tip diameter from the countersink diameter you want and multiply that against the constant and you're good. No head scratching or jumping thru hoops needed.

Ha-ha... I just responded to a ten year old thread. Sheesh! Pay attention dude!

Two head slaps in one week. Maybe I need a vacation.