R8-ER32 Collet question

[darkzero]

I don't own er collets but if the spec for tightening a 32 is 100ft lbs. I find it hard to believe it's being done with two 6" wrenches opposed done in one hand. I've been turning wrenches for 25yrs and 100ft lbs on my 18" torque wrench is alittle effort. I would imagine a lot of user are under torquing the nut? Just my 2cents.

I worked in automotive so I have a good idea on what it takes to torque to 100 ft/lbs & higher. I highly doubt anyone is torquing ER-32 or ER-40 to recommended spec while in the spindle. Need a fixture for the collet chuck to acheive that kind of torque. There are no fixtures for R8 ER collet chucks, would need to hold them in a vise.

It's recommended torque, more so for running high RPMs & feeds mainly in CNC. In a manual machine you can get away not using the recommended torque specs. I snug me ER collets by hand in the spindle with a wrench the nut spanner, I've never had an issue with slipping, not even with a 1" indexable end mill in my ER-40. I'm not alone on this.

Which makes me wonder. Is there a torque spec for R8 collets/drawbar & does anyone use a torque wrench on the drawbar? I've never heard of it. Just saying that much of what we do is by feel & judgement, hopefully good judgement.

 

[mmcmdl]

Never used a torque wrench in my life , on a mill anyway . Never had an endmill slip either . Drop her in low and use the brake . The ER collets we used years ago had holders that we tightened them in . Still no torque wrenches , but they were tight . They were going into Makinos , G&Ls , DeVliegs etc . The only incident that I can remember was a time an endmill pulled out of the holder to the other end of the flat , while milling a keyway . That was an apprentice error that scrapped a very large Worthington Pump shaft .

 

[ddickey]

We have some Worthingtons at work.

 

[mmcmdl]

We have some Worthingtons at work.

One of the biggest shafts I ground fell off the truck and broke our drivers leg . Same shaft killed a guy up in Pa . unloading it . Did a whole lot of pump shafts for Worthington back in the original shop . Turned them up on an American Pacemaker lathe , and ground them on a very large TOS universal grinder . II actually had to stretch it a few times !

 

[Rich V]

Most ER collet holders come with a solid collet nut. There are collet nuts that have a roller bearing section that greatly reduces the torque needed to tighten an ER collet.

ER 32 Ball Bearing Collet Nut

www.shars.com

ER 32 Bearing Nut

CNC Tool Holders

www.cnctoolholderstore.com

ER32 BEARING COLLET NUT MariTool

www.maritool.com

Some forum members have seen improved runout using these nuts.

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

I use them exclusively and find they are worth the extra cost.

 

[ddickey]

Techniks has a Power Coat nut that is supposed to be better than a bearing nut.

The NEW Techniks is coming!

Tooling Solutions for CNC Machines & CNC Routers

www.techniksusa.com

 

[pontiac428]

I am shocked by that 100 lb-ft torque spec. When looking at the threads by size, that's reasonable, if it were a bolt. I turned wrenches for cash and bennies for a long time, so my wrists are well-calibrated. I probably put 30 lb-ft on my ER32 stuff, and now that I'm on bearing nuts it's a little less. I might not know if a cutter is deflecting under load from lack of torque on the collet nut, so maybe I'm doing it wrong. But that's a lot of grunt to cinch down a tool. Wow!

 

[john.oliver35]

Bringing this old thread back up because I had an observation that might be relevant. I just finished making an ER32 Collet Holder for my Boxford 500 VSL Lathe. Put in my first 3/8" collet to test with a dowel pin and it measured .0015" runout. My heart sank - I just ground this taper and haven't even moved the collet chuck yet. What did I do wrong?

I remembered from somewhere that 100ft-lb mentioned as proper torquing. Grabbed the wrench and gave the nut a good pull (still way less than 100 ft-lbs though). Runout dropped to 0.0004. Repeated the same experiment with a couple of other collets and got the same results. Looks like it does take considerable torque to get an ER collet runout reduced.

 

[Tozguy]

It helps to keep the outside of the collet greased as well as the threads on the nut. Of course the inner bore of the collet has to stay squeaky clean.