I am trying to drill a 4" deep hole .406" in diameter through 6061-T6. Supposed to be decent aluminum from Kasier.
I bought this spot drill. I was under the impression I should spot at a wider angle than the drill point.
I have tried drilling with a Titex parobolic drill and also 135 deg split point cobalt.
I am drilling a block that is machined on all sides in a vise on a VMC. No through spindle coolant. After I drill the hole I measure from the hole to the edge at the top and at the bottom. The bottom on the worst block measures .030" different. So the hole is off .015"
Here are some of the procedures I have dried.
1. Spot with 142 deg spot drill. Peck drill with Titex drill. Initial peck of 1.5" each peck after was .406" 1650rpm, 13ipm.
hole was visibly off on a 2 block.
2. Spot with a 142 deg spot drill, then drill .1" deep with a 135 deg cobalt screw length drill, drill with titex. Not much better.
3. Drill 3.4" deep with 135 deg cobalt, no spot, finish with titex to get depth.
a little better but not a lot.
I kept thinking the problem was the drills. Finally I started looking at the spotting tool as it was new and I was not that familiar with it. I spotted a new piece to .410" diameter. I put layout ink in the holes and brought down the 135 deg screw length and fed it down by hand until it rubbed and I could see it. The drill was hitting about 1/2 way up the spot. I thought it should be hitting right in the point. You can actually hear the first peck sound terrible like the drill is trying to find center. So I thought I would just spot it with a cobalt screw length drill then switch to the cobalt jobber length. Both are from Precision Twist. I did the exact same thing as above with the layout ink and same problem these 2 drill were not even the same point.
If anyone has any suggestions I would really appreciate it.
I don't mind buying some tools, hence the spot drill and titex drills were brand new specifically for the job.
The parts will work just fine if they are off .010" as it is only a bolt clearance hole, I would like them a little closer if possible.
I have never drill any deep holes so I am not really sure how much drill wandering is expected. Anyone have any typical walk amounts.
I was also told the problem was the aluminum as it may not be very uniform and harder spot could be causing the problem.
I bought this spot drill. I was under the impression I should spot at a wider angle than the drill point.
I have tried drilling with a Titex parobolic drill and also 135 deg split point cobalt.
I am drilling a block that is machined on all sides in a vise on a VMC. No through spindle coolant. After I drill the hole I measure from the hole to the edge at the top and at the bottom. The bottom on the worst block measures .030" different. So the hole is off .015"
Here are some of the procedures I have dried.
1. Spot with 142 deg spot drill. Peck drill with Titex drill. Initial peck of 1.5" each peck after was .406" 1650rpm, 13ipm.
hole was visibly off on a 2 block.
2. Spot with a 142 deg spot drill, then drill .1" deep with a 135 deg cobalt screw length drill, drill with titex. Not much better.
3. Drill 3.4" deep with 135 deg cobalt, no spot, finish with titex to get depth.
a little better but not a lot.
I kept thinking the problem was the drills. Finally I started looking at the spotting tool as it was new and I was not that familiar with it. I spotted a new piece to .410" diameter. I put layout ink in the holes and brought down the 135 deg screw length and fed it down by hand until it rubbed and I could see it. The drill was hitting about 1/2 way up the spot. I thought it should be hitting right in the point. You can actually hear the first peck sound terrible like the drill is trying to find center. So I thought I would just spot it with a cobalt screw length drill then switch to the cobalt jobber length. Both are from Precision Twist. I did the exact same thing as above with the layout ink and same problem these 2 drill were not even the same point.
If anyone has any suggestions I would really appreciate it.
I don't mind buying some tools, hence the spot drill and titex drills were brand new specifically for the job.
The parts will work just fine if they are off .010" as it is only a bolt clearance hole, I would like them a little closer if possible.
I have never drill any deep holes so I am not really sure how much drill wandering is expected. Anyone have any typical walk amounts.
I was also told the problem was the aluminum as it may not be very uniform and harder spot could be causing the problem.