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Using A Er32 Or Er40 In A Bridgeport Mill R8 Collet

Ed ke6bnl

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#1
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
 

mikey

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#2
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.
 

Ed ke6bnl

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#3
ETM is a brand of collet and collet holder? yes I was refering to the ER collet with the intigrated R8

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mikey

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#4
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.
 

Erichimedes

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#6
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
 

tomh

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#7
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 :(
 

Ed ke6bnl

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#8
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
 

mikey

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#9
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.
 

mksj

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#11
ER collets have very low TIR, usually around 0.0002", and the R8 holders are around 0.0001". Shar's has some decent nickle plated ER holders that are reasonably priced, they are nicely made and accurate. You can use a ball bearing cinching nut to make collet changes a bit quicker and requires less force to tighten. I have never had an issue with them holding an end mill, the other day I had a 1" end mill in my ER-40 collet, not something I would want to do with an R8 collet. It is important to snap the collet into the nut before it is put in the holder, otherwise it will not seat properly. I like ER system because it is a bit easier then R8 collets if you do not have a power drawbar, it usually requires two wrenches to snug up the nut, although on my knee mill I use the brake.
 

Ed ke6bnl

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#13
anything wrong or is there any advantage to and ER32 vrs. ER40, the 32 is less expensive and has a smaller head, is it good enough for most all jobs other then not going past .75 in in size??? Just sold a couple of items on ebay and now purchase this for my shop.
 

mksj

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#14
ER32 is more than adequate unless you use end mills larger than 3/4". An ER40 is bulkier, and may interfere more with certain milling operations. I would say that an R8 ER32 works very well on a mill and gives a wide clamping range. You do not need a lot of different sized collets (probably an 1/8" increment set unless you plan on using it for drills), most end mill shanks are usually a standard size relative to the cutting end. So many of my smaller end mills use a 1/4" shank.
 

sanddan

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#15
I have an ER32 setup with the R8 shank. I got it for my first bench top mill as changing R8 tools was harder (no brake on that mill). I like them but just yesterday I had an issue with a 1/2" endmill not holding. Funny but it held ok when cutting, (.240" depth of cut) but when returning the bit to the starting place wanted to ramp into the work. I tried to tighten the endmill twice but it would not hold. I went to a regular R8 collet and had no further issues. I think it's time to build a power draw bar.
 

mikey

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#16
I have an ER32 setup with the R8 shank. I got it for my first bench top mill as changing R8 tools was harder (no brake on that mill). I like them but just yesterday I had an issue with a 1/2" endmill not holding. Funny but it held ok when cutting, (.240" depth of cut) but when returning the bit to the starting place wanted to ramp into the work. I tried to tighten the endmill twice but it would not hold. I went to a regular R8 collet and had no further issues. I think it's time to build a power draw bar.
An ER-32 collet requires 100# of torque to lock down the nut. That's hard to do with the chuck in the spindle so the end mill can slip sometimes. Well, I can't do it anyway so I use a fixture.
 

mksj

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#17
Also the discussion of keeping the collets oil free. "Tormach ran some tests on their R8 collet system in order to come up with guidelines to minimize pullout. The difference on a clean and dry shank based on drawbar torque from 20 ft lb to 40 ft lb was an increase in holding force from 1850 lb to 3600 lb." I always tended to put a light coat on them wanting them not to bind and release easier. I had a recent problem with a power drawbar that would not release the R-8 collets, it would unscrew and push the spindle. Took a fair amount of force to hold the spindle up, and with your other hand on the power drawbar button, the collet and what ever it was holding would go flying. I also find that I cannot leave the R-8 shank/holder in the machine after I am done using the mill, I believe that as the spindle cools down it can lock the shank in place and makes it harder to eject.
 

MonkMan

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#18
Mike,
where can I find such a tightening fixture for R8 ER32 collet chuck?
Thanks So Much
Paul
An ER-32 collet requires 100# of torque to lock down the nut. That's hard to do with the chuck in the spindle so the end mill can slip sometimes. Well, I can't do it anyway so I use a fixture.
 

mikey

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#19
Sorry, MonkMan, I use the Tormach TTS ER chuck and they sell a fixture with a one-way bearing that allows you to loosen or tighten the chuck nut. It only holds a 3/4" shank, not an R8. Should have clarified that.
 

mikey

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#20
MonkMan, have you considered making your own fixture? If your ER chuck has flats or hex on the body itself then you can make a female fixture from aluminum that is a good fit and bolt the fixture to the bench. As long as you have working room to manipulate the nut then it should work fine.
 

petertha

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#21
Really good discussion & information here! I posed a similar question link below just for good measure. Consistent theme.
http://www.hobby-machinist.com/threads/er32-vs-dedicated-endmil-holders.54052/#post-448661

Re the size issue, I bought an ER40 setup years ago when I was getting started (read naivety). And then I added onto that tooling with 4-side & 6-side collet blocks which are really nice way to hold round things in a mill vise at different orientations. Much more compact & functional over the 5C equivalent IMO. But if I had to do this again with a clean sheet of paper, I would go for a smaller kit, like ER32, maybe even ER25 depending on how you see yourself using it.
- lower tightening torque as mentioned
- smaller nut diameter (which can sometimes be a proximity or interference issue on small end mills depending on the job)
- less expensive
- same collet blocks can be acquired, also slightly less expensive

Regular EM holders still have their place. I wanted to try a Lyndex brand (which I really like) so bought a second 1/2" socket (R8) just to try. Now what I have is a 1/2" rougher EM in one holder & a 1/2" finisher in the other. I can swap them out of the mill pretty fast & all my DRO settings are preserved since EM same diameter (+/- teir tolerance). This has been my mainstay milling setup for many parts unless different sizes are required.
 

MonkMan

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#22
MonkMan, have you considered making your own fixture? If your ER chuck has flats or hex on the body itself then you can make a female fixture from aluminum that is a good fit and bolt the fixture to the bench. As long as you have working room to manipulate the nut then it should work fine.
That sounds like a plan! The chuck is on its way so I'll check to see if that's a workable solution.
Thanks so much, Paul
 

mikey

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#23
That sounds like a plan! The chuck is on its way so I'll check to see if that's a workable solution.
Thanks so much, Paul
This is one of the things on my To Do list for my ER-40 chuck that you probably will beat me to. I was going to make mine in two pieces - one to support the chuck body to hold it level and the second to slip the flats of the chuck into. The second will probably be 3/8" aluminum plate that is screwed to the first piece that will be from some relatively soft stuff like aluminum. The first part will be screwed to a piece of plywood so I can move it into a usable position when needed and stored when I don't need it. If you build it, do a write up on it and post it on the forum; I'm sure others will follow your lead.
 
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