I'm pretty much a newbie to milling (last fall I took a manual machine tools
class at the local vo-tech and we did turning projects on 13x40 lathes,
milling on Bridgeports, and surface grinding on 6x12 and 6x18 machines).

I found a nice small mill (Schaffner vertical/horizontal, 2hp motor, a 7x30
table on a knee, but no quill) in February and brought it home. It's now
awaiting installation of a VFD to make it go. The mill takes NMTB 30
toolholders, and I've got a few endmill holders in very good visual
condition (I'll check each one with an indicator one of these days). My plan
is to be able to futz around the shop, and build up my machining skills with
small projects including robots and tools.

My first question is when would I choose to use a collet chuck, say an ER or
DA, over an endmill holder. Clearly the collets have the potential to give
lower run-out, but I'm a little worried about the tool pulling out (OK, it
didn't pull out of the R8 collet in the Bridgeport, but that seems like it
had a much larger contact area - maybe I'm wrong).

There doesn't seem to be much of a cost advantage to going with collets vs
EMHs and I'm at the decision point of which type to use as a primary
toolset. Any suggestions?

Thanks,
Pete Bergstrom
St. Paul, MN

A rule of thumb that has served me well is: Ok to use collets for holding
endmills under 3/4 inch. Above that, endmill holders are required.

Bob Swinney
"Pete Bergstrom" wrote in message
...

I'm pretty much a newbie to milling (last fall I took a manual machine
tools
class at the local vo-tech and we did turning projects on 13x40 lathes,
milling on Bridgeports, and surface grinding on 6x12 and 6x18 machines).

I found a nice small mill (Schaffner vertical/horizontal, 2hp motor, a
7x30
table on a knee, but no quill) in February and brought it home. It's now
awaiting installation of a VFD to make it go. The mill takes NMTB 30
toolholders, and I've got a few endmill holders in very good visual
condition (I'll check each one with an indicator one of these days). My
plan
is to be able to futz around the shop, and build up my machining skills
with
small projects including robots and tools.

My first question is when would I choose to use a collet chuck, say an ER
or
DA, over an endmill holder. Clearly the collets have the potential to give
lower run-out, but I'm a little worried about the tool pulling out (OK, it
didn't pull out of the R8 collet in the Bridgeport, but that seems like it
had a much larger contact area - maybe I'm wrong).

There doesn't seem to be much of a cost advantage to going with collets vs
EMHs and I'm at the decision point of which type to use as a primary
toolset. Any suggestions?

Thanks,
Pete Bergstrom
St. Paul, MN

"Robert Swinney" wrote in message
...
A rule of thumb that has served me well is: Ok to use collets for holding
endmills under 3/4 inch. Above that, endmill holders are required.

Thanks, that helps. I also found a note from Forest Addy on
www.practicalmachinist.com describing how toolholders wear.

I ended up buying a collet holder so I'll use that for the smaller size
tools.

Thanks,
Pete

On Mon, 24 May 2004 12:42:43 -0500, "Pete Bergstrom"
wrote:


"Robert Swinney" wrote in message
...
A rule of thumb that has served me well is: Ok to use collets for holding
endmills under 3/4 inch. Above that, endmill holders are required.

Thanks, that helps. I also found a note from Forest Addy on
www.practicalmachinist.com describing how toolholders wear.

I ended up buying a collet holder so I'll use that for the smaller size
tools.

Thanks,
Pete

Ive spun more than a few endmills in my 30 taper milling collets. The
engagement surface is pretty short. Some have longer "bores" than
others, so when looking for a collet holder...be advised.

Gunner

That rifle hanging on the wall of the working-class flat or labourer's
cottage is the symbol of democracy. It is our job to see that it stays
there.
- George Orwell

"Gunner" wrote in message
...
On Mon, 24 May 2004 12:42:43 -0500, "Pete Bergstrom"
wrote:

I ended up buying a collet holder so I'll use that for the smaller size
tools.

Ive spun more than a few endmills in my 30 taper milling collets. The
engagement surface is pretty short. Some have longer "bores" than
others, so when looking for a collet holder...be advised.

That was one thing I thought of. The collets are ER40, the biggest I thought
I could find for a 30 taper holder and still be able to buy them for a few
years. It's a bigger chuck, but the engagement area was important.

Thanks!
Pete

Pete Bergstrom wrote:

"Gunner" wrote in message
...

On Mon, 24 May 2004 12:42:43 -0500, "Pete Bergstrom"

wrote:

I ended up buying a collet holder so I'll use that for the smaller size
tools.

Ive spun more than a few endmills in my 30 taper milling collets. The
engagement surface is pretty short. Some have longer "bores" than
others, so when looking for a collet holder...be advised.


That was one thing I thought of. The collets are ER40, the biggest I thought
I could find for a 30 taper holder and still be able to buy them for a few
years. It's a bigger chuck, but the engagement area was important.

Thanks!
Pete


And the double angle will be a good tight fit. I like how the collet is held into
the 'Nut' and then the whole of it is screwed in.

I have that set in MT4 and R8. (holder in R8 anyway :-) )
Martin

--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder