ER Sizes

[Jonathans]

Hi,
I am just starting to outfit my Central Machinery 42827 mill with some tooling.
I just ordered a hold down/clamping set, and am planning on picking up a set of cobalt end mills from Enco.
When it comes to a collet and chuck set, I am confused about the different ER diameters. Is larger better, or is there a place for the smaller diameter collets?
I was planning to get a set that ranged from 1/8" to 1" to cover any future use I may need.
Thanks

 

[darkzero]

In this case no bigger is not better, more tool overhang & you loose Z capacity. Generally for the larger benchtop mills 3/4" max is all you need or even 5/8" then a 2" facemill or fly cutters. I have a similar size mill but square column, although I went with ER40 for the 1" it's overkill & not needed.

The larger ERs will have a bigger collet nut that will get in the way if you use the smaller collets on it. I only go down to 3/8" or 1/2" with my ER40 & use ER16 for 3/8" & smaller. ER32 is good all around size, ER25 is better if you don't need 3/4".

 

[Bill Gruby]

If you plan to go to 1 inch max hold you need a ER40 set. They make to oversize collets for it also. They are 1.125 and 1 1875. Make sure your mill will be able to handle the large set. The ER40 holder is quite large. IMHO this outfit makes the besr.


http://www.maritool.com/ER-Collets

"Billy G"

 

[Jonathans]

Thanks for the info guys. I appreciate it.
So, what is the difference between the collets from a company like Maritool, and ones from Shar or Bolton? Is it the runout? Do the cheaper ones have issues?
How about the type of chuck? are certain ones better (keeping in mind the mill that I have!)?

 

[Bill Gruby]

The tolerances are the biggest difference. Maritool holds them extremely tight. They are also precision ground for a flawless finish. Meritool as far as I know anr the only company to grind oversize or even undersize to your specs. Did I mention made in USA? I have a Clausing 8520 Mill and use their ER 40 Collets and Holder with a MT 2 shank and 3/16 thread for the draw bar. I, like you thought big might be better but was wrong. My Mill is capable of using it but I could have gotten away easily with the ER 25 or even smaller.

My guess here is that you will never need over a 1/2 inch shank end mill. The ER20 collet goes to 9/16. If I were recommending a size to you, that would be it.

Expensive, yes but I highly recommend them.

"Billy G"

 

[Wreck™Wreck]

Stick with the R8 collets they are cheap and plentiful in the used market.
A mill that small doesn't have enough power to pull an endmill out of a tight R8 collet.

You can buy a 25 peice R8 set for less then $150.00, I have owned an R8 spindle BP mill for 24 years and have collected a total of less then 12 different sizes, I do this for a living as well (-:

 

[darkzero]

If breaking the bank is an issue, Techinks collets are the best for the buck. Great quality made in Taiwan & is what I use. Maritool are the only ones I have seen that make oversized ER collets. Rego Fix (who designed the ERs), Lyndex, Ultra Dex, ETM, & Bison all make great quality collets. I prefer not to use China collets & would only buy the one mentioned but that's just me.