On 4/14/2020 5:49 PM, Jim Wilkins wrote:
> "Bob La Londe" wrote in message
>
> I'm looking for a tiny threaded collet. ER collets are fine, but you
> can't really use them to make long reach tooling. Shrink fit is an
> option I guess. My goal is to make my own mold making tool holders to
> use modest price proper geometry end mills in long reach applications to
> have greater rigidity than a long reach mill and better cost
> effectiveness than a tapered end mill to achieve that. I know. I know.
> It already exists in some types of tool holders,but I want to make
> something a little more universal to fit into tool holders I already
> have. Harvey tools makes an end mill extension, but their current
> version isn't tapered or designed quite right for what I want. I could
> buy them and maybe modify them, but they aren't cheap. Mostly I am just
> thinking out loud right now. I recently picked up a surface grinder,
> and I am making plans for making a cylinder grinding attachment for it.
> It would be ideal for finishing hardened tool holders like this.
>
> Might actually use some of my grinder vises like they were intended.
LOL.
> ====================================================== >
> If you make extensions with integral collets by slitting them
crosswise, the closer nut could have tapered pipe threads.
>
>
The idea is to have maximal support for smaller mills when deep
machining. I would prefer in internal draw bar to an external closer
nut I think. I did a search for "straight shank end mill extension"
just a few minutes ago and found quite a number. Most use set screws.
One that came up in image search showed a collet, but when I went to
their website it they just showed a set screw type.
These would only be useful for pockets with a lot of draft angle or a
feature of the floor of a pocket, but I just finished an open casting
mold with pretty deep pockets and tool deflection affected finish
quality with a lot of tool stick out. I had to slow the job down a lot.
On the other screen I am working on a rough model. With a 3/8 Ball mill
for the angle I needed with clearance I could have just one inch of
stick out and be upto to 5/8 shank. Of course I could just continue the
taper as far back as I want to fit into the largest tool holders I have.
Once I have it dialed in to make them I could make ones with a little
more slender profile for tiny mills and less available angle clearance
too. Of course its all a trade off.
I recently engraved the bottom of some deep pockets with a company logo
using a 1/16 ball nose end mill. A tool extension sized for this
application would have allowed me to feed much faster than I had to run
with the ER collet tool holder and the long reach end mill I had to use
to do the job.
They will not be a magic cure all, but they would speed up many jobs and
improve surface finish doing it.
Morse #2 collets go up to 1/2", and you can buy a reamer for the female
socket.