ER collets vs. R8

[mickri]

I went with ER32 collets. I have an r8 to er32 adapter for the mill/drill and mt2 to er32 adapter for the lathe. I plan to either make or buy an er32 collet chuck for the spindle on the lathe. I went with the er32 metric collets because the spindle bore on my lath is 7/8 which is just under the maximum size of er32 collets and unlike imperial er32 collets there are no gaps in coverage with the metric er32 collets.

I can't easily reach the draw bar on the mill/drill. So tooling changes that require loosening the draw bar are a PITA. I have found that changing er32 collets is a breeze. No big deal. Everybody seems to mention how tight er32 collets need to be and that they are hard to tighten. I have not found this to be a problem. But then I have a very large wrench that fits on the collet chucks. There is something to be said for leverage.

The biggest advantage to using er32 collets is on the mill/drill. I have found that I rarely have to raise the head to change tooling. Unscrewing the collet nut provides more than enough room to change tooling. I am thinking about buying more collets nuts so that the collets I use the most will have their own collet nut.

ER32 collets have worked very well for me.

 

[P. Waller]

I used a Bridgeport mill today that employed a system that uses a retention knob on the end of the tool holders, it was fast.

It does not use R8 collets only R8 tool holders but I imagine that ER collet holders with the modified R8 taper drawbar system are easily purchased.
Someone above has mentioned this, I do not know what it is called.
The tool holders look like this

The key way is not used, I suspect that the tool holders and mechanism to hold them will cost a good deal more then many hobbyists would like to spend, it is a slick system for light milling however.

 

[mikey]

I have PM-25MV mill and it uses an R8 collet. I remember before buying the mill, some posters recommended going with ER collets.

I don't know too much about ER collets, as I see way too many of them ER numbers. ER32, ER8, ER11...

What's the difference between those?

right now, i have 1 `12 piece R8 collet set

Is it easier to swap tooling with ER? Which ER number is the one to get? Is it compatible with R8?

I guess that's a no then.

I'll just have to get more R8 collets for in-between endmill sizes.

I think you need to re-read the responses and then learn about the difference between the R8 and ER systems before making a choice. There are advantages and disadvantages to both.

The R8 system is great if minimizing loss of Z-space is your main concern. It is also very easy to change tooling - just loosen the drawbar, give it a whack to disengage the tool, change the tool, re-tighten the drawbar and you're off. Run out with R8 collets varies with the maker and at the hobbyist level it should be just fine. Truthfully, you really only need the common collet sizes to fit your tooling. I would imagine that the largest tool your lathe can handle is maybe 1/2"; a 3/4" end mill would be pushing the limits of what your mill can handle, I think. So, if you had 1/8", 3/16", 1/4", 3/8" and 1/2" R8 collets then you could probably handle almost any end mill you're likely to use. You do NOT need every possible size collet.

Go and look up info on the ER system; don't just ask here. The different ER systems vary in their clamping ranges, primarily. So, why even consider an ER system if all you do is give up headspace due to the chuck hanging out there? Well, ER collets have the potential to be very accurate; they are the commonest tool holding option in the industry for a reason. They also damp vibration better than any other system in widespread use and that affects finishes, tool wear, tool life and accuracy. While an ER collet can clamp down on a range of tool shank sizes and has a range much broader than an R8 collet, the ER collet is intended to clamp most accurately on shanks very close to the stated size of the collet. That is, if your tool shank is 1/2" then a 1/2" ER collet will hold it very accurately. You can hold smaller shanks but run out will increase when you do.

The key advantages of an ER system, again, are accuracy and vibration dampening. This has a direct bearing on tool performance, tool life, accuracy and finishes. For cutting tool holding, it is a better system. For holding other tools like drill chucks or fly cutters, the R8 system is fine. I have and use both systems and I use them exactly this way. In reality, the choice of systems is not an "either/or"; it is a "both/and" but as always, it is your choice.

 

[ddickey]

One thing about drill bits is unless you use a common size you won't be able to hold in an R8 collet. Same goes for a tap, shank sizes are not common.
That's an advantage I can see for an ER system.