ER40 collet retaining nut is bad! Check your items as soon as you get them!

Sigh.....this is the ER40 collet bearing nut from Mari Tool. I didn’t ask for anything but this on their web site.

Here is the detail from their sheet...notice it says that it fits most tool holders regardless of brand!

Product Info
View complete catalog page »

  • Bearing Collet Nut holds all ER40 collets
  • Fits most tool holders, regardless of brand
  • Made from alloy steel hardened to 54 - 56rc
  • Precision ground ID thread and taper
  • Has an internal thread of M50 X 1.5 pitch
  • Outside diameter is 2.470 inches (62.7mm)
  • This nut is a bearing nut and has internal ball bearings
  • Our TG100-WRENCH works on this collet nut
  • Internal cam removes collet when unscrewed
  • Black oxide finish
  • MariTool Part# ER40-BNUT

ER40 BEARING COLLET NUT MariTool

www.maritool.com www.maritool.com

Here is the photo of the Mari Tool collet bearing nut from above on my R8 ER40 tooling. I am not sure how to show you anything more than this that it fits and isn’t a special thread or anything else.....perhaps you should call Mari Tool, ask for Frank Mari. He will get you sorted out.

292298
 
PT Doc said:
I just bought a bunch of Techniks Stuff. ER collet chucks, drill chuck, milling chuck, ER collets and milling chuck collets and extra collet nuts. Their quality is VERY nice. Their ER collet nut has some serious claims behind them. Looks like more holding power than bearing nuts.
Click to expand...
Yes the torque value for the standard style nut is higher than the bearing nut. Mari says the bearing nut is 20% lower. One other forum member had terrible results in terms of runout when measured with the stock nut and cut the results about in 1/2 to an acceptable performance level with the bearing nut. You just have to watch the bearing nut tighten up a collet and you can understand how thestock nut might not uniformly load the collet given that the clamping mechanism also puts a torque component to the collet.
 
Firstgear said:
You just have to watch the bearing nut tighten up a collet and you can understand how thestock nut might not uniformly load the collet given that the clamping mechanism also puts a torque component to the collet.
Click to expand...

Have a care with this one, Firstgear. A bearing collet nut uses 20% less torque because the balls cannot handle excessive amounts of torque, not because they are so superior in clamping that they require less torque. I have not heard that a solid nut puts torque on a collet that would affect the accuracy of the assembly before. Can you tell me where you got this information from? I'm not hassling you. I really want to know the source.

Most of the top tier ER collet makers recommend a hardened coated nut for maximum tool holding power and accuracy. Given that these same makers also produce bearing nuts, it infers that there may be something to this solid nut business, or at least it seems that way to me. In my own tests between ETM and Rego-Fix solid coated nuts VS two Asian bearing nuts from two separate sources, I found the solid nuts to be at least twice as accurate as those cheap bearing nuts. This means absolutely nothing except to me. I have no clue how a Maritool bearing nut would compare but if someone wants to buy me one, I'll test it and offer a report. ;)

Anyway, on to my point. I suggest you test that Maritool nut. Measure the static spindle run out and the run out at the chuck taper. Then chuck up a precision gauge pin in the best collet you have and check the static run out of the assembly. Then you will know what the nut can do. If it is within 0.0001" - 0.0002" TIR then you have a good collet and nut.
 
www.hobby-machinist.com

ER 32 Collets

I wanted a cheap back up set of ER 32 collets, for my Rockwell vertical milling machine (#21-100). On the 2 larger mills, a Jet JVM-836 and a 1940s era Bridgeport, for the last 10 years or so, I used a SYOZ 25 (EOC 25) series collet chucks and collets, for the Rockwell, I was given a LMS R8 x ER...
www.hobby-machinist.com www.hobby-machinist.com
 
Yeah, I got the same results - 0.0007" TIR with the Asian bearing nuts tested on my ETM chuck, which is unacceptable to me. In contrast, an ETM solid nut will run out in the neighborhood of 0.0001 - 0.0002" TIR using a ETM collet in an ETM ER-40 chuck that has 0.0001" TIR at the chuck taper. That is a BIG difference in run out and that translates into a difference in tool life, finishes and accuracy.

Run your own tests so you know what your system can do. Don't believe what other guys say; believe what you say.
 
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Bearing nuts are all hype, all us hobbyists have been tricked into spending money on them! :big grin:

All these inexpensive bearing nuts weren't really around when I bought bearing nuts. I have Lyndex bearing nuts & they weren't easy to get. I do have China bearing nuts on my ER-40 collet blocks but only cause they were dirt cheap when I bought the collet blocks, $8.50 ea. Maybe they're too cheap. Lol. I never tested them, I probably should. They should be fine for my collet blocks but if they're junk I'll just put my standard Rego-Fix nuts or Bison nuts on them.

If I could do it all over I would have got ER-32 with standard nuts rather than ER-40. Wish I could but too late to turn back now. I'm happy with my ER-16 chuck & slim nut though.
 
I have to stand corrected on the bearing nut thing. When I looked into this over 5 years ago there wasn't much info available. However, Rego-Fix did a video that I just found and it appears that they fixed the ball bearing nut issue they had and the performance of their nuts is surprisingly good. Have to re-evaluate my thinking now.
 
Yeah back when I bought my bearing nuts I couldn't find much info either. Again, there weren't all the China bearing nuts readily available like there are now. I bought the Lyndex bearing nuts based on a recommendation from a machinist on another forum I used to frequent (not a machining forum) long before I found/joined this site.

IIRC Rego-Fix didn't even make ball bearing type nuts back then. Which reminds me, I remember buying a Rego-Fix nut on ebay that was a friction bearing nut. I forget if I sold it or have it stashed somewhere. I'll check tomorrow.
 
There is a Haas tip of the day that discusses the different kinds of nuts and the benefits of each. Collet twist is a real thing that adds error into your assembly. Basically, friction between the nut and the collet causes the top of the collet to twist relative to the bottom (which is fixed in the much steeper lower taper). This can cause uneven spacing of the slits in the collet which pushes the tool off center.

 
Interesting Macardoso- I wonder if the problem is worse with larger tool shank diameters?
mark
 
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