Re: Thread milling, and yeah, I know it's OT

--- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers <rogersmach@y...> wrote:

> I'm not confusing anything with anything. The original poster

indicated that "standard" collets have a range of acceptability in
regards to diameter. This is simply not true. No gray area. Its one of
the very basic fundamental rules regarding "standard" one piece
collets. R-8 or 5C. Its a big no-no. Any machinist knows this. Its
part of the first day in the shop orientation for new recruits. Not my
rule just the industry practice. Taps don't belong in a spindle. Thats
why they dont fit. They belong in tap handles and tapping
heads...where they were designed to be used.

> Ron

For some strange reason, I don't take kindly to being "corrected" by
someone who obviously has no idea what the hell they're talking about,
when what I said was absolutely correct in the first place. Next
time, you might consider reading up on what the manufacturers state
concerning DA, TG, or ER collet systems, and the acceptable collapse
range for each, since, regardless of your vast array of experience, it
would appear they're devices you don't even know to exist. Then, it
won't be necessary for you to push a topic OT by posting erroneous
information and causing others to respond to correct it. Wrong
information is worse than no information at all.

To add a bit of information which I believe would be on topic, for
anyone who has converted, or is converting a machine with an R8
spindle to CNC, there are several sources for collet chucks with R8
shanks. They're usually designed to hold ER collets. While they're
not cheap, generally in the $400 to $500 range for the chuck and a set
of collets which cover the full range, they will allow you to hold
fractional, number, and letter drills plus any other metric or
odd-size shank tool in your machine without needing to repeatedly
purchase odd size R8 collets that may only be used once in a while.
There's no availability of cheap R8 collets in odd sizes, so when you
start buying them from Hardinge at 30 bucks apiece or more, it doesnt
take long to spend the price of a collet chuck, and there's still an
infinite number of sizes you DON'T have.