Something I learned long ago came back around again,so I thought it would be a good discussion.
In the smaller sizes drill bit quality can vary wildly even in the same batch of drills.This job came in at work to drill 460 -1/16" diameter holes in 1/4" thick 304 Stainless.My go to drill for drilling stainless is a good quality cobalt split point.So I ordered up a few drills and having been down this road before I ordered 3 dozen.
So I got my material and I got my drills,ran the numbers and 20-40 fpm was recommended in the mfg's literature with cutting oil for lube.I tested out a few holes on some drop material and found 1450 rpm to be the ticket,or a little less than 25 fpm.Feed rate,well this is 304,so it's whatever the drill would take with no screwing around(dwelling).Set the job up in the B-port and just for fun decided to record how many holes each bit would produce.
Bit #
1- 9
2- 7
3- 14
4- 5
5- 19
6- 11
7- 15
8- 21
9- 3
10- 11
11- 31
12- 16
13- 28
14- 38
15- 17
16- 22
17- 36
18- 41
19- 0
20- 11
21- 18
22- 21
23- 27
24- 15
25- 11
26- 13+
In the picture is #19 right next to #26.Notice the s-bend,that drill is soft as butter and didn't even mark the surface
In the smaller sizes drill bit quality can vary wildly even in the same batch of drills.This job came in at work to drill 460 -1/16" diameter holes in 1/4" thick 304 Stainless.My go to drill for drilling stainless is a good quality cobalt split point.So I ordered up a few drills and having been down this road before I ordered 3 dozen.
So I got my material and I got my drills,ran the numbers and 20-40 fpm was recommended in the mfg's literature with cutting oil for lube.I tested out a few holes on some drop material and found 1450 rpm to be the ticket,or a little less than 25 fpm.Feed rate,well this is 304,so it's whatever the drill would take with no screwing around(dwelling).Set the job up in the B-port and just for fun decided to record how many holes each bit would produce.
Bit #
1- 9
2- 7
3- 14
4- 5
5- 19
6- 11
7- 15
8- 21
9- 3
10- 11
11- 31
12- 16
13- 28
14- 38
15- 17
16- 22
17- 36
18- 41
19- 0
20- 11
21- 18
22- 21
23- 27
24- 15
25- 11
26- 13+
In the picture is #19 right next to #26.Notice the s-bend,that drill is soft as butter and didn't even mark the surface
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