Using A Er32 Or Er40 In A Bridgeport Mill R8 Collet

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.
 
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.
 
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.
 
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.
 
sanddan said:
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.
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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.
 
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.
 
Mike,
where can I find such a tightening fixture for R8 ER32 collet chuck?
Thanks So Much
Paul
mikey said:
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.
Click to expand...
 
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.
 
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.
 
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