mangocrazy
Italian V-twin nutjob
- Messages
- 1,164
- Location
- Sheffield, UK
I'm part way through making some adaptor plates for brake caliper mounting on a motorcycle fork. I've got as far as making an accurate template in plywood and have transferred the hole drilling layout to two pieces of 7075-T6 I bought off the bay of evil. I used transfer punches to indicate drilling centres and then enlarged those using a centre punch.
When I came to drill the first hole with a centre drill everything was fine. I then followed up with an 8mm drill and after drilling to a depth of only about a mm the drill squealed and jammed in the work. I freed it off, carefully tried again and the same thing happened. On inspection there doesn't seem to be any damage to the drill or the work, but I need to find out what I'm doing wrong before I try again.
The plate I am drilling into is 10mm deep and I am using a drill speed of 890 rpm. I'm using a 4 speed Mercury Startrite pillar drill, and this is the nearest I can get to the recommended speed in my chart of 1200 rpm for a 10mm hole (final size of hole). For lubrication I'm just applying some rocol grease with a paint brush to the drill tip.
Should I be using a faster drill speed - if so what speed? I only have the following options - 530, 890, 1840 and 3840 rpm. Also, should I be using more generous amounts of cutting fluid perhaps from a squeezy bottle squirted at regular intervals?
What are the general recommendations for drilling 7075-T6? Does it need a particular cutting angle on the drill bit? I'm just using a standard HSS jobber bit.
Any recommendations gratefully received.
When I came to drill the first hole with a centre drill everything was fine. I then followed up with an 8mm drill and after drilling to a depth of only about a mm the drill squealed and jammed in the work. I freed it off, carefully tried again and the same thing happened. On inspection there doesn't seem to be any damage to the drill or the work, but I need to find out what I'm doing wrong before I try again.
The plate I am drilling into is 10mm deep and I am using a drill speed of 890 rpm. I'm using a 4 speed Mercury Startrite pillar drill, and this is the nearest I can get to the recommended speed in my chart of 1200 rpm for a 10mm hole (final size of hole). For lubrication I'm just applying some rocol grease with a paint brush to the drill tip.
Should I be using a faster drill speed - if so what speed? I only have the following options - 530, 890, 1840 and 3840 rpm. Also, should I be using more generous amounts of cutting fluid perhaps from a squeezy bottle squirted at regular intervals?
What are the general recommendations for drilling 7075-T6? Does it need a particular cutting angle on the drill bit? I'm just using a standard HSS jobber bit.
Any recommendations gratefully received.