Hi guys, I have a question about er40 collets. My milling machine has an R8 spindle so I bought an R8-er40 collet off ebay. I stupidly got one of the cheaper sets with collets etc, and when I got it I tried to assemble it with one of the collets and found that I couldn't even get the nut to thread on. I understand that the nut and collet are supposed to click together, right? Not a chance! Man is this thing junk! So I look inside the nut and there is a flange or a ring inside that is machined way out of concentricity to the bore of the nut. I have no idea how they screwed that up so spectacularly. So now my options are limited. Try to send it back to get another one, taking who knows how long (cross border and all) or just stick it in the lathe and butcher it up to make it useable. so that s what I did. cut the flange out completely, and assembled it in my mill with a end mill and checked runout. .002" . wow . the piece of junk is better than I thought. Still not happy, so what I am wondering is if it is worth trying to find just a nut? Are these nuts all the same thread etc? what would you do? Just run it and fugedaboudit?
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Tool ER40 collet nut
- Thread starter garageguy
- Start date
Tool
I have an ER32 collet chuck set from Little Machine Shop and the nut and chuck are very nicely done. Also have a ball bearing nut that I use when I really want to go fancy 
Not all of them are machined badly.
I expect this one would be a good one.
Not all of them are machined badly.
I expect this one would be a good one.
KEVIN_D
A grinder and paint make the fabricator I ain't!
I have had one bad arbor show up to my door. And it too was way off, definitely a lemon. Everything else I have had shipped from china has been of excellent quality. Although, I generally don't pay the lowest price.
You do understand the Nut and Collet click together by tipping and pushing the collet into the nut before installation onto the arbor? I've seen guys just tighten the nut onto the arbor and collet and really mess the nut up. The ring that retains the collet in the nut is quite eccentric by design.
As for run out mine generally were under half a thousandth (0.0003") if I recall out of the box. But how you tighten the collet, proper collet/endmill sizing, tapping the endmill into concentricity... etc all did matter. IE metric collets to inch size endmills weren't nearly as good as metric-metric or inch-inch size combos.
You do understand the Nut and Collet click together by tipping and pushing the collet into the nut before installation onto the arbor? I've seen guys just tighten the nut onto the arbor and collet and really mess the nut up. The ring that retains the collet in the nut is quite eccentric by design.
As for run out mine generally were under half a thousandth (0.0003") if I recall out of the box. But how you tighten the collet, proper collet/endmill sizing, tapping the endmill into concentricity... etc all did matter. IE metric collets to inch size endmills weren't nearly as good as metric-metric or inch-inch size combos.
Yes. And nothing should be in the collet.
Dead on. In fact you can loosen a collet nut so that it is finger movable and yet the item in the collet is stuck tight. Keep loosening the nut and it hits a difficult to turn with fingers point again. Another 1/4 turn or so and the collet is now loose and what's in it can be slid out.you are not the first, and not the last to come to this spot with ER collets
I’m afraid you probably did.
Looks like others have already helped you out…
I would buy a new nut. The nut is very important in that collet system. You will most likely get much better runout than the 0.002” you measured with your modified nut.
Your vendor probably sells nuts separately. I’d contact them to see what they say.
Good luck.
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Unfortunately he doesn't really show the snapping collet into nut process.
Hey @garageguy, I'm late to the party. Looks like you already have your answers.
I am of the view that your collet holder probably can't be rescued. Even if it does hold and release, it probably won't hold well enough EVERY TIME.
If you can't get a nut as per @RobinHood s suggestion, you might be able to get the whole R8 collet holder with a nut and just keep all your collets.
It's a very common mistake. I'd only add that tipping the collet is almost essential to installing or removing it.
I am of the view that your collet holder probably can't be rescued. Even if it does hold and release, it probably won't hold well enough EVERY TIME.
If you can't get a nut as per @RobinHood s suggestion, you might be able to get the whole R8 collet holder with a nut and just keep all your collets.
It's a very common mistake. I'd only add that tipping the collet is almost essential to installing or removing it.