How to Change a Collet

Some collets are unusually sticky and stubborn. Here is how to reason with them. April 30, 2009

Question
I work at a small cabinet shop and we recently purchased a CNC router. I was wondering if there is a special tool required to change the collets. I need to take out a 1/2" one and insert an 1/8" one I purchased. The collets are type E32. Any advice would be appreciated.

Forum Responses
(CNC Forum)
From contributor J:
You would need a set of E32 collet wrenches and the proper size collet for the desired shank.



From contributor S:
There is no tool required to remove and insert a collect. It snaps in and out of the collet nut with the push of your hand. A "collet wrench" doesn't remove the collet, it removes the nut from the tool holder. Who trained you to operate a CNC router without training you how to change a collet and a bit?


From contributor K:
Don't tell us that you didn't snap the collet into the nut before you inserted it and tightened the nut. If you did you will have to destroy the collet, after you get the bit out, to get it out.


From the original questioner:
The collets I use are Techniks ER32 Spring collets. Yes my problem is getting the collet out of the collet nut. They are made to easily pop in but not pop out. As far my training, this is a family business and I learned from a friend.

From contributor K:
It looks like that collet is made to snap out of the nut just like any other collet. Push is sideways from the back and it should pop out.


From contributor J:
I have had occasion where the collet was full of dust and needed to be blown out before it would release and it will not do it with the bit still in.


From the original questioner:
Thanks for the advice. I pushed sideways on the back and it popped out. I had tried so hard to pull it straight out. I donít think the man who taught me ever changed his collets. His machine was setup when he bought it and he only milled basic cabinet parts. I'm trying to do some carvings and sign making.


From contributor B:
When I purchased my first tool changing HSD ES-915 spindle I had a devil of a time getting the collets to snap out of the collet nut. I actually had to punch them out with a light blow from a mallet and a short 3/4" piece of dowel. As such I had the same initial question. I was told "just lean it out from the back", but it took so much pressure to do this that it just didn't make sense.

I lived with this for about a year until I purchased a new replacement nut for the spindle. Low and behold the problem went away and it was easy to lean the collets out of the new nut. Turned out the original nut was not precisely sized! So guys, be a bit more patient with these kinds of questions. Things can, and often do, go wrong that totally defy logic.



From contributor T:
While not "scientific", this is the method I not only used for decades as a machinist, but is how I train people today to remove/install ER series collets.

1. Loosen collet nut while in holder (must have appropriate wrench).
2. Remove tool from collet.
3. Continue to loosen nut and remove nut and collet assembly from holder.
4. Place nut and collet on flat surface. Orient so that the rotational "axis" of both the nut and collet are parallel to the flat surface/table.
5. Use one hand and secure the nut by by holding it firmly to the table. When holding the nut correctly, the collet axis will be parralel to the table and not touching the table.
6. Use a "karate" like action with the side of your other hand and strike the edge of the collet, freeing it.

To install
1. Place clean ER series collet on flat surface. Orient collet so that larger end is up.
2. Place collet nut on top of collet.
3. Place palm of your hand on collet nut and press down until nut "snaps" onto collet (if done correctly nut and collet are now one assembly.)
4. Begin to thread nut/collet assembly into holder.
5. Install tool into collet - note - never install any tool in a collet where the gullets of the cutter are inside the collet. Do attempt to install the tool so that the gullet of the cutter is as close to the collet as possible for rigidity.
6. Continue to secure the nut/collet/tool with collet wrench.

While doing the above, cleanliness is stressed throughout! Hope this helps, although I realize practically visual aids would probably be more beneficial.