Problem- 8 finish in an ID

[race8082]

need to achieve an 8 finish in a.437 bore hole is .700 deep material is 15-5 rc43. with .0003 total tolerance on dia. Thanks for any help.

[sti2011]

Honing or hand lapping will get you an 8 finish easy, as well as not blow your tolerance.

[MarkieMark834]

depending on the job most of the time we have had good luck with special reamers with flute polish and od polishing at lower surface footage. we achieved a number 8 with 5 flute endmill on the sides of our part im sure you can also finish that hole with the same endmill and achieve the same result

[Mcgyver]

Originally Posted by race8082 need to achieve an 8 finish in a.437 bore hole is .700 deep material is 15-5 rc43. with .0003 total tolerance on dia. Thanks for any help.

how many?

i don't know much about surface finish numbers, but a quick google reveals disparity, some reference a mirror finish, others brush etc.

is it .437 or is it .4375? makes difference if you're holding .0003....in that the first thing to try (if the later) is a sharp 7/16 reamer, run it slowly, feed it slowly and retract and slowly all with flood and you can get a good finish.

If that finish isn't good enough, its not difficult, but can be time consuming, to put a mirror finish on via lapping. ream with an undersized reamer and start lapping with progressively finer compound. mirror will start coming out at 600 and really show its stuff at 1000.

[RICHARD ZASTROW]

If useage makes it cost effective, you might consider a burnishing tool or a burnishing reamer (Shefcut or Mapal etc.).

www.cogsdill.com

Dick Z