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nic
 
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Default End mill holder vs collett

I've used both of them, and find that the end mill holders are great when
you are using cutters with "weldon" flats on them. I'm sure if you want to
grind a flat on all of your end mills then the holder will work fine. I am
kinda cheap and find that you can buy double-end end mills for lesss than
you can buy single-end end mills and they are usually too long to fit in the
collet type holders.
I can't really comment on the accuracy, they have both performed adequately
for me.


"Keith Marshall" wrote in message
.com...
BTW the mill is the mini-bench top unit sold by Harbor Freight. I made

the
"Mistake" of dropping in on the store in South Carolina :-)

I seem to recall a friend telling me they have an outlet/surplus store
somewhere in SC. Is that the one you're talking about and if so would you
mind telling me where it is?

Best Regards,
Keith Marshall


"The universe is full of magical things,
patiently waiting for our wits to grow sharper."
-Eden Phillpotts, A Shadow Passes, 1934
"Bradford Chaucer" wrote in message
...
I just acquired am benchtop vertical mill that takes R8 colletts. It

comes
with a drill chuck which I know is not advised for milling. I have seen
sets of both R8 colletts and R8 endmill holders. The difference as I see

it
is that the endmill holder protrudes from the end of the sleeve more

than
the collett does and it has a set screw for clamping on the flat on an

end
mill.
My question is whether a collett is sufficient for holding endmills or

am
I
advised to opt for the end mill holders??

BTW the mill is the mini-bench top unit sold by Harbor Freight. I made

the
"Mistake" of dropping in on the store in South Carolina :-)
Anyone have any comments or suggestions for improving tweaking this unit
(aside from you shouldn't have bought it!!)






  #2   Report Post  
Daniel A. Mitchell
 
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Default End mill holder vs collett

Collets are more convenient, and clamp with less potential 'runout', but
do not hold the cutter as securely as an end mill holder. Sooner or
later you will likely have a collet slip under the cutting force of the
mill. This can (and likely will) cause damage to workpiece and or
cutter, and could cause damage to the operator or machine.

Unless you confine yourself to making very light cuts, end mill holders
are more dependable in the long run. That said, many just use collets
with only rare problems. I HAVE had collets slip, but I still use them
on occasion (odd cutter shank sizes, etc.), though I prefer end mill holders.

Dan Mitchell
==========

Bradford Chaucer wrote:

I just acquired am benchtop vertical mill that takes R8 colletts. It comes
with a drill chuck which I know is not advised for milling. I have seen
sets of both R8 colletts and R8 endmill holders. The difference as I see it
is that the endmill holder protrudes from the end of the sleeve more than
the collett does and it has a set screw for clamping on the flat on an end
mill.
My question is whether a collett is sufficient for holding endmills or am I
advised to opt for the end mill holders??

BTW the mill is the mini-bench top unit sold by Harbor Freight. I made the
"Mistake" of dropping in on the store in South Carolina :-)
Anyone have any comments or suggestions for improving tweaking this unit
(aside from you shouldn't have bought it!!)

  #3   Report Post  
Len S
 
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Default End mill holder vs collett

Some have said that on *really* heavy work and end mill can be
"sucked" out of a collet - a small amount, but enought to ruin a
precise job. I have not seen this, but also don't anything super
heavy.

One advantage of holders is that you would not have to mess with the
drawbar. On my mill I have to flip up the pully cover to change
collets. Having said this, I still use collets - I'm not that lazy yet
;-)
  #4   Report Post  
Gary R Coffman
 
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Default End mill holder vs collett

On Wed, 06 Aug 2003 22:54:44 GMT, Bradford Chaucer wrote:
My question is whether a collett is sufficient for holding endmills or am I
advised to opt for the end mill holders??


End mill holders are designed to hold end mills. Collets are workholding
devices. That said, you can use a collet to hold an end mill. The problem
is that there's no way to lock the end mill in the collet to prevent it from
sucking out while cutting. That could ruin a work piece in which you'd
invested a lot of time. You can probably get away with it indefinitely on
a small machine taking light cuts, but it is something to consider.

Gary

  #5   Report Post  
JMartin957
 
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Default End mill holder vs collett

End mill holders are designed to hold end mills. Collets are workholding
devices. That said, you can use a collet to hold an end mill. The problem
is that there's no way to lock the end mill in the collet to prevent it from
sucking out while cutting. That could ruin a work piece in which you'd
invested a lot of time. You can probably get away with it indefinitely on
a small machine taking light cuts, but it is something to consider.

Gary


Although there are some collets specifically designed to hold end mills. Don't
know if they are available in R8 or not, but I have a couple of 40 taper collet
chucks for my horizontal mill that take TG100 collets. Most of the collets are
plain, but some are "No Pull" styles which have a plug that locks into the flat
on a Weldon shank. Can't use them on a regular shank, though, unless you
remove the plug.

John Martin


  #6   Report Post  
Mike Graham
 
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Default End mill holder vs collett

In article , Len S wrote:

Some have said that on *really* heavy work and end mill can be
"sucked" out of a collet - a small amount, but enought to ruin a
precise job. I have not seen this, but also don't anything super
heavy.


It doesn't need to be heavy. It's happened to me twice, and not too long
ago it happened to the foreman at work. He immediately bought a set of
endmill holders.

--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Mike Graham | Metalworker, rustic, part-time zealot.
|
http://www.metalmangler.com| Caledon, Ontario, Canada
  #7   Report Post  
ATP
 
Posts: n/a
Default End mill holder vs collett

Gary R Coffman wrote:
On Wed, 06 Aug 2003 22:54:44 GMT, Bradford Chaucer
wrote:
My question is whether a collett is sufficient for holding endmills
or am I advised to opt for the end mill holders??


End mill holders are designed to hold end mills. Collets are
workholding devices. That said, you can use a collet to hold an end
mill. The problem is that there's no way to lock the end mill in the
collet to prevent it from sucking out while cutting. That could ruin
a work piece in which you'd invested a lot of time. You can probably
get away with it indefinitely on a small machine taking light cuts,
but it is something to consider.

Gary


Are double angle collets any better? I'm getting a set of DA400 that I plan
on using with my Nichols Miller so I don't have to disassemble the drawbar
to change endmill sizes.


  #8   Report Post  
Pep674
 
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Default End mill holder vs collett

not too long
ago it happened to the foreman at work. He immediately bought a set of

endmill holders.

me too..........
Paul in AJ AZ
  #9   Report Post  
Too_Many_Tools
 
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Default End mill holder vs collett

I find the subject of this discussion to be of great interest. I
recently acquired a Rusnok vertical head that will be mounted on a
small horizontal mill. The Rusnok head uses Y collets which are double
angle collets. While I would much rather use an end mill holder for
the reasons stated in earlier posts, I seriously doubt that I will
find any end mill holder that will fit this Rusnok head. If anyone
knows differently, I would love to hear about it.

TMT


"Daniel A. Mitchell" wrote in message ...
Collets are more convenient, and clamp with less potential 'runout', but
do not hold the cutter as securely as an end mill holder. Sooner or
later you will likely have a collet slip under the cutting force of the
mill. This can (and likely will) cause damage to workpiece and or
cutter, and could cause damage to the operator or machine.

Unless you confine yourself to making very light cuts, end mill holders
are more dependable in the long run. That said, many just use collets
with only rare problems. I HAVE had collets slip, but I still use them
on occasion (odd cutter shank sizes, etc.), though I prefer end mill holders.

Dan Mitchell
==========

Bradford Chaucer wrote:

I just acquired am benchtop vertical mill that takes R8 colletts. It comes
with a drill chuck which I know is not advised for milling. I have seen
sets of both R8 colletts and R8 endmill holders. The difference as I see it
is that the endmill holder protrudes from the end of the sleeve more than
the collett does and it has a set screw for clamping on the flat on an end
mill.
My question is whether a collett is sufficient for holding endmills or am I
advised to opt for the end mill holders??

BTW the mill is the mini-bench top unit sold by Harbor Freight. I made the
"Mistake" of dropping in on the store in South Carolina :-)
Anyone have any comments or suggestions for improving tweaking this unit
(aside from you shouldn't have bought it!!)

  #10   Report Post  
Daniel A. Mitchell
 
Posts: n/a
Default End mill holder vs collett

Once a cutter is clamped in an end mill holder, the holder may be
removed and then later reinstalled with the cutter remaining in
(closely) the same position. Not precise (depends on how tight you pull
the drawbar), but good enough for may purposes. certainly far more
reproducible than collets.

With collets, the cutter is just randomly (with the usual collets like
R8) located. Without some kind of 'collet stop' the cutter can locate
(longitudinally) most anywhere. Worse, as you tighten a collet the
cutter position changes substantially as the collet 'draws in' (FAR more
than with an end mill holder). You can't get the cutter back in the same
position without using an indicator or gage block of some kind. Once you
get it tight and find it's in the wrong position, you can't adjust it
dependably without loosening it, which changes it's position unpredictably.

Of course, you can adjust the spindle or mill head, but that's not
what's being discussed.

Double angle collets have the same problem as above, unless both tapers
are the SAME angle (NOT the usual case). Such collets may be more
suitable to having a 'collet stop' of some kind fitted.

And as others have pointed out, there ARE special collets that both
locate and hold end mills properly, but again that's not what's being discussed.

Dan Mitchell
==========

ATP wrote:

Gary R Coffman wrote:
On Wed, 06 Aug 2003 22:54:44 GMT, Bradford Chaucer
wrote:
My question is whether a collett is sufficient for holding endmills
or am I advised to opt for the end mill holders??


End mill holders are designed to hold end mills. Collets are
workholding devices. That said, you can use a collet to hold an end
mill. The problem is that there's no way to lock the end mill in the
collet to prevent it from sucking out while cutting. That could ruin
a work piece in which you'd invested a lot of time. You can probably
get away with it indefinitely on a small machine taking light cuts,
but it is something to consider.

Gary


Are double angle collets any better? I'm getting a set of DA400 that I plan
on using with my Nichols Miller so I don't have to disassemble the drawbar
to change endmill sizes.



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Jack Erbes
 
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Default End mill holder vs collett

On Fri, 08 Aug 2003 10:48:28 GMT, "ATP"
wrote:

Are double angle collets any better? I'm getting a set of DA400 that I plan
on using with my Nichols Miller so I don't have to disassemble the drawbar
to change endmill sizes.


In theory, the double angle collets are not pulled towards the spindle
as they tighten so the cutter extension or offset does not change.

Also the collets in many of the double angle collets (like the ER
series) have a much larger gripping range. Those typically have a 1
mm or .040" range while collets like R8 and 5C only have a few
thousandths.



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  #12   Report Post  
DoN. Nichols
 
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Default End mill holder vs collett

In article ,
Jack Erbes wrote:
On Fri, 08 Aug 2003 10:48:28 GMT, "ATP"
wrote:

Are double angle collets any better? I'm getting a set of DA400 that I plan
on using with my Nichols Miller so I don't have to disassemble the drawbar
to change endmill sizes.


In theory, the double angle collets are not pulled towards the spindle
as they tighten so the cutter extension or offset does not change.


Hmm ... I could see this with a single-angle, with a shoulder at
the back, and the nosepiece closing it at the front only. (I guess that
you could consider this double-angle, with the rear angle being 90
degrees. :-)

With a double-angle, with identical angles at front and back, I
would expect the collet to move in half the distance of the nosepiece
travel (once compression starts). In other words -- reduced travel, but
not zero.

For ones like the ER, which have a shallow angle at the back,
and a steep angle at the nose, I would expect the collet to move in
excess of that half of nosepiece travel.

I think that the shallower the rear angle, the better the
possible concentricity.

Also the collets in many of the double angle collets (like the ER
series) have a much larger gripping range. Those typically have a 1
mm or .040" range while collets like R8 and 5C only have a few
thousandths.


Agreed -- "ER" stands for "Extended Range" after all. I've got
a set of those for my Compact-5/CNC (which also fit the C5 milling head,
although that is actually mounted on a separate X-Y base, instead of to
the back of the lathe bed as was originally intended when it was
designed. :-)

I can certainly testify to the pull-in in the ER series of
collets used as either workholding or toolholding collets.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
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