Using A Er32 Or Er40 In A Bridgeport Mill R8 Collet

Ed ke6bnl

Registered
Registered
Joined
Nov 20, 2014
Messages
755
Why don't we ever see any mills using an ER32 or ER40 to R8 tool holder??? I can see one possible disadvantage of the ER as having a little more stick out, but not necessary to reach to the top to release the R8 collets. I was thinking of going to this system. Whats ya think
 
Are you referring to an ER chuck with an integrated R8 shank? If so, they work fine. I have an ETM ER-40 chuck like that and an ER-32 chuck that fits Tormach's TTS system. Both work well. The ER-32 slips out of the TTS 3/4" R8 holder easier for bit changes. The ETM one requires a spindle wrench up top to hold the spindle still while I loosen and tighten the ER chuck nut down below. Its a bit more cumbersome but the chuck and ETM collets are really accurate.
 
ETM is a brand of collet and collet holder? yes I was refering to the ER collet with the intigrated R8

Sent from my SM-G930V using Tapatalk
 
Last edited:
Yeah, ETM is a brand, a pretty accurate one and is part of the Iscar line of companies. Watch Ebay. They come up for stupid cheap on occasion. The only issue I have is that sometimes they do chew up a bit of Z-space so on a tall project an R8 collet is more useful.

Otherwise, I like ER chucks on the mill. They are versatile and pretty accurate. You don't realize how important that is until you have to cut a woodruff keyseat; use an inaccurate collet/chuck and you get a slip fit instead of an interference fit.
 
I had just started thinking about this. I got an ER32 collet chuck for my Diamond horizontal mill so I don't have to reach around behind it and pound the drawbar out every time. But now that I have some collets, I'm thinking of getting a collet chuck for the Bridgeport too. Using z-space actually doesn't bother me much, because I like the idea of being able to switch between my 14N and the ER chuck between ops and not have to raise or lower the table like 5 inches.

I'd like to hear more arguments for why I should get one :D
 
Just a word of caution
when using a ER collet chuck on a mill the cutter can work itself out of the collet creating a neat ramped cut in your work.
I had this to happen two times, The first time While cutting a key slot in a shaft I figured that I did something wrong, after that I always made sure that the collet and cutter was clean and the nut was tight. But after the second time I decided that enough is enough and stopped using ER collets. Now I only use dedicated holders and tooling with the flat on them. For me its easier to knock the draw bar out than make a new part.
If you have Ever wondered why you occasionally see a neat ramped cut in milling tables and think how someone could do that, now you know. I haven't done that but I came close :(
 
Is there a ER collet nut that uses something like a thrust bearing so it is easier to tighten and therefore will hold tighter for the same tightening force
 
Yup, there are nuts exactly like that. https://www.maritool.com/tool-holde...437/er32-bearing-collet-nut/product_info.html

I have some from ArcEuro Trade and they work fine for most stuff. When I need to make a really accurate cut I use a hardened nut from ETM and torque it down. I didn't think it made much of a difference until I was troubleshooting why my woodruff keyseat cutter was producing a slip fit instead of an interference fit. Turns out that my collet and nut were not up to the task. Switching to my ETM collet and nut did the trick.
 
Back
Top