Spot Facing a hole that is not accessable.
Spot Facing a hole that is not accessable.
(OP)
The picture below shows a portion of a very large casting.
The holes in the top flange are drilled thru with the bottom end spot faced.
How does the machinist spot face the bottom of these holes ? Does he do it from the top with a special mill from the top ?

Jerry J.
UGV5-NX11
The holes in the top flange are drilled thru with the bottom end spot faced.
How does the machinist spot face the bottom of these holes ? Does he do it from the top with a special mill from the top ?

Jerry J.
UGV5-NX11
RE: Spot Facing a hole that is not accessable.
RE: Spot Facing a hole that is not accessable.
Jerry J.
UGV5-NX11
RE: Spot Facing a hole that is not accessable.
"Wildfires are dangerous, hard to control, and economically catastrophic."
Ben Loosli
RE: Spot Facing a hole that is not accessable.
One important different requirement from normal machining is the tool: Normally, pressure from the drill or milling machine "pushes" the tool back into the drill chuck or milling machine taper adapter. More pressure means a better "grip" between the mill and the tool holder and the cutting surface into the work.
For back facing, the energy of each cutting surface on the mill is pulling the back-face mill itself "out" of the tool holder and "out" away of the mill's socket. They make adapters to resist the pulling force, you just have to pay extra to get a back-face tool that you don't use very often.
Timewise, for each back-face hole, you have to take the milling tool holder apart, put the the cutting head through the hole, re-attach the holder and tool, re-attach the tool holder into the mill, pull up everything tight, then start machining. Takes a while if you have to cut thousands of holes.
RE: Spot Facing a hole that is not accessable.
Look at the video I posted, no tool disassembly needed. The cutting head is moved in or out by the rotation of the spindle.
"Wildfires are dangerous, hard to control, and economically catastrophic."
Ben Loosli
RE: Spot Facing a hole that is not accessable.
RE: Spot Facing a hole that is not accessable.
Jerry J.
UGV5-NX11
RE: Spot Facing a hole that is not accessable.
RE: Spot Facing a hole that is not accessable.
RE: Spot Facing a hole that is not accessable.
RE: Spot Facing a hole that is not accessable.
A very similar question came up in tool making class 40 years ago.
RE: Spot Facing a hole that is not accessable.
The backface cutter in my earlier video is the easiest method and can be done with a CNC.
"Wildfires are dangerous, hard to control, and economically catastrophic."
Ben Loosli
RE: Spot Facing a hole that is not accessable.
RE: Spot Facing a hole that is not accessable.
https://www.youtube.com/watch?v=3X-fV6XUjVI
John Joyce
Manufacturing Engineer
NX 11 & 12.01 Vericut 8.0.3
If I asked people what they wanted, they would have said faster horses
- Henry Ford