Hey all. I have an old bolt action rifle that had a scope installed with a mount bolted to the top of the receiver. Unfortunately it was drilled and bolted crooked originally and I wanted to repair it. I TIG welded the old mounting holes and smoothed out the receiver. I then wrote a program to place and drill the new holes in the repaired surface. I am attempting to drill two 0.166" holes in this receiver that is 0.170" thick mild steel. I used a 3/8" carbide spot drill down to 0.050" to start the hole. I then used a HSS .0166" twist drill to complete the hole, or well I tried that. The spot drill worked flawlessly, but the twist drill didn't even make a dent before shattering. I was running 1000rpm at .5ipm which I thought to be fairly conservative. I loaded up another bit and reduced the feed by 70% and it did not drill either. It just loaded up and I backed it off before breaking. The tip was completely wiped out. I then grabbed a 1/8" carbide end mill and plunged the feed manually 0.0001" at a time and managed to break through. After that I decided to write a program that would helix the 1/8" carbide to depth in 0.170" diameter. This worked on the first hole, but broke the carbide end mill on the second hole. How the heck am I going to get both holes to spec? I already have a bit of a mess as the hole was drifting slightly when the twist drills were breaking. The plunged end mill holes are straight and square, but are still too small. Any ideas?
Thanks in advance.
Thanks in advance.