Thread: drilling holes in star pickets

Hello Grahame.
For difficult steel definitely reduce the rpm, use a stub drill to increase rigidity and if necessary reduce the rake angle so the drill is not so aggressive. Good brand drills are a must.
Regards
BC

Originally Posted by steamloco1954

Hello Grahame.
For difficult steel definitely reduce the rpm, use a stub drill to increase rigidity and if necessary reduce the rake angle so the drill is not so aggressive. Good brand drills are a must.
Regards
BC

Hi BC
I went back today and did all that bar using the stub drill.
I had previously written I had set the slowest speed. That was not correct due to my poor eyesight incorrectly reading the chart on the DP. I am waiting on new prescription glasses.

I had to take my linisher outside to see well enough for grinding the drill to a shallower included angle.

It was tough to get through but not as bad as it has been. The difference being, it got hard immediately just before breaking through.

I am assembling a set of stub drills by means of breaking the longer ones.

Only two more holes to drill, now. Thank goodness!

Thanks
Grahame

Originally Posted by Grahame Collins

Hi BC
I went back today and did all that bar using the stub drill.
I had previously written I had set the slowest speed. That was not correct due to my poor eyesight incorrectly reading the chart on the DP. I am waiting on new prescription glasses.

I had to take my linisher outside to see well enough for grinding the drill to a shallower included angle.

It was tough to get through but not as bad as it has been. The difference being, it got hard immediately just before breaking through.

I am assembling a set of stub drills by means of breaking the longer ones.

Only two more holes to drill, now. Thank goodness!

Thanks
Grahame

Hello again.
Changing the edge included angle may help but I was referring to grinding the flute to decrease the edge rake angle. The rake is the spiral angle of the flute. By reducing that the edge is stronger and less prone to burst thru surge. I did a video on using bench grinders and showed how to change drill rake angle. Also good for brass and some plastics. Making stub drills is OK but those made recently don't have a web thinning process. They are fat to the tip and point split to compensate.
The best with your project. BC