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View Full Version : Eccentric end-mills



Elninio
09-24-2010, 01:04 AM
Do you need a special machine or speed to run this end-mill? It looks like its made for high-speed machining of aluminium, so is it balanced? What's the tread at the end for (what's it fit into) ?

http://img824.imageshack.us/img824/5492/img00012201009232127.jpg (http://img824.imageshack.us/i/img00012201009232127.jpg/)
http://img839.imageshack.us/img839/9262/img00013201009232127.jpg (http://img839.imageshack.us/i/img00013201009232127.jpg/)
http://img16.imageshack.us/img16/3852/img00017201009232128.jpg (http://img16.imageshack.us/i/img00017201009232128.jpg/)

EddyCurr
09-24-2010, 01:24 AM
Do you need a special machine or speed to run this end-mill? It looks
like its made for high-speed machining of aluminium, so is it balanced?
What's the thread at the end for (what's it fit into) ?
That looks to be an end mill with a Weldon Shank


WELDON TOOL HISTORY (http://www.endmills.com/history.asp)

Carl Bergstrom believed that using a straight-fluted end mill was not
the best method for removing metal so he developed the first helical
end mill with flutes of 30 degrees. To compensate for "pull out" forces,
and to drive his new end mill, he subsequently developed the Weldon
straight shank with a drive flat. This product, known as the Weldon
Shank, is accepted today as the industry standard.

.

EddyCurr
09-24-2010, 01:29 AM
Weldon Shank Adapter (http://www.exsys-tool.com/pf_weldon.html)

The PRECI-FLEX® Weldon Shank Adapter is primarily important for larger
diameter tools where the collet’s clamping force is insufficient to avoid
slippage. Because collets are not utilizing the Weldon connection, the drills
and end-mills have a tendency to slip in the collet which leaves a bad finish
and generate tremendous heat in the collet pocket. The most common
problem when slippage occurs is tool breakage, fortunately, the Weldon
Shank Adapter has an internally ground bore and uses a set screw to pull in
the end-mill or drill and properly fasten it with the most rigidity available.
Each adapter is equipped with a set screw at the bottom of the chuck to
act as an adjustable stop.

.

Elninio
09-24-2010, 03:20 AM
Weldon Shank Adapter (http://www.exsys-tool.com/pf_weldon.html)

The PRECI-FLEX® Weldon Shank Adapter is primarily important for larger
diameter tools where the collet’s clamping force is insufficient to avoid
slippage. Because collets are not utilizing the Weldon connection, the drills
and end-mills have a tendency to slip in the collet which leaves a bad finish
and generate tremendous heat in the collet pocket. The most common
problem when slippage occurs is tool breakage, fortunately, the Weldon
Shank Adapter has an internally ground bore and uses a set screw to pull in
the end-mill or drill and properly fasten it with the most rigidity available.
Each adapter is equipped with a set screw at the bottom of the chuck to
act as an adjustable stop.

.

Why would such clamping force be needed for an aluminium cutting end mill? Unless perhaps its not an aluminium cutting endmill ...

macona
09-24-2010, 05:54 AM
The end mill is just a kind of center cutting two flute. The threads usually are for installation in an automated machine of some sort. I wouldnt say the mill if for aluminum. Not much gullet depth.

Also just because you are machining aluminum dosnt mean that there are not a lot of cutting forces involved.

Ian B
09-24-2010, 06:02 AM
If the thread n the end is 20 tpi, then it would probably fit a Clarkson Autolock chuck as well as a Weldon holder.

As far as the eccentric flutes go, I'd think this is so the end mill (or slot drill as us Brits would probably call it) can be plunged into the work. If it was ground symmetrically, it'd leave a spot right in the centre that wouldn't be cut.

Ian

MuellerNick
09-24-2010, 06:05 AM
Not exactly a mill for aluminium. It would have deeper and polished (or at least nicely ground) flutes. This one is for steel (or very cheaply made).


Nick

beanbag
09-24-2010, 06:29 AM
A "High speed aluminum machining" end mill would be carbide, high helix, and Zrn Coated, not some old skool 30 degree helix HSS end mill like you have.

EVguru
09-24-2010, 06:44 AM
It's what we would call a slot drill in the UK. The asymetric cutting edges means that it is centre cutting and can be plunged. The threaded end is for use in an Autolock, or Posilock chuck, which if this board is anything to go by is an almost unknown system in the US.

You can just see the reflection from a centre hole at the threaded end. The endmill or slot drill is threaded into an appropriate collet and inserted into the chuck where it seats against a centre, so the system is dead length.

http://www.denfordata.com/bb/files/autolock1_124.jpg

http://www.denfordata.com/bb/files/autolock2_187.jpg

Ian B
09-24-2010, 09:20 AM
Paul,

I also use Clarkson Autolock & Dedlock chucks for end mills, and love them. They never slip and are easy to use. When I see the Weldon system (with a screw making single point contact and trying it's best to push the endmill off centre), it always occurs to me that it would be almost impossible to invent a worse system!

I've often wondered why the Autolock system wasn't more widely used.

One thing that puzzles me about the Autolock system is that, whatever the diameter of the end mill / collet, the thread is always 20 tpi. I can't see much point is sticking to one pitch, as you'll never be trying to hold a 1/2" shank cutter in a 1" collet.

Ian

JCHannum
09-24-2010, 09:42 AM
The Clarkson system never caught on over here as it adds unecesssary cost and complexity in tool retention. The Weldon system is quite positive and properly manufactured holders are ground to compensate for clamping forces.

airsmith282
09-24-2010, 05:23 PM
i have a few end mills like that one, i have used them with aluiim steel stainless steel, just use some lube with aluim and dont take to deep of cut and dont spin it to fast or she just might cloge up a bit, pain when that happens, but i just slap them end mills in my collets and make chips.. if it fits your collets it will make chips,