oceanobob
Plastic
- Joined
- May 18, 2014
- Location
- Oceano, CA
Took on a fab job for drilling & tapping 36 (thirty six) 1/2-13 holes in piece of 5/8" thick hot rolled plate: Flat Bar Dims 4" wide by 75" long by 5/8" thick.
Plate is about 55ksi yield - meets A36 as well as Gr50. Cold Roll too much $ as material is only 12' long, drop is too big.
~~~~~~~
Thinking of this method:
Sandblast the plate(s) to remove the mill scale
Machine avail is a vertical knee mill with a DRO. Has the larger table.
Holes are to be three repeating patterns of twelve each per pattern, the pattern O/A dim is about a little less than 20" distance.
Use 27/64" stubby screw machine drill bit to make the hole (following the pilot drill). Was wondering if I should hand (27/64") ream the hole to make sure it is round?
Lightly chamfer the start of the hole; use the tapping head with either a new spiral H3 tap or a new gun (spiral pointed) H3 tap.
Twelve holes thus made: swap the drill to the tap head and go back (DRO) and tap them.
Relocate the plate for the next group of twelve, repeat above.
~~~
They wanted one plate yesterday, but they really want three plates done.
Plate is about 55ksi yield - meets A36 as well as Gr50. Cold Roll too much $ as material is only 12' long, drop is too big.
~~~~~~~
Thinking of this method:
Sandblast the plate(s) to remove the mill scale
Machine avail is a vertical knee mill with a DRO. Has the larger table.
Holes are to be three repeating patterns of twelve each per pattern, the pattern O/A dim is about a little less than 20" distance.
Use 27/64" stubby screw machine drill bit to make the hole (following the pilot drill). Was wondering if I should hand (27/64") ream the hole to make sure it is round?
Lightly chamfer the start of the hole; use the tapping head with either a new spiral H3 tap or a new gun (spiral pointed) H3 tap.
Twelve holes thus made: swap the drill to the tap head and go back (DRO) and tap them.
Relocate the plate for the next group of twelve, repeat above.
~~~
They wanted one plate yesterday, but they really want three plates done.