Collet Use

[Tyro 001]

I finally got the Wells-Index assembled and running, so I ordered a set of ER 40 collets and a collet holder to fit the R-8 spindle on the mill. I have a few basic questions:
(1) Should I lubricate the holder and the spindle so it goes into the spindle/releases easier; or is best to leave them dry for maximum grip.
(2) I assume it's best to oil the collet, nut and internal taper of the holder.
(3) Since I have no experience with a milling machine, it took me a while to figure out I needed to snap the collet into the nut before I inserted the collet into the holder, so I have that part of the procedure right; but I thought since the collets collapse 1/32", I should be able to insert a 15/64" drill bit into a 1/4" collet, hand tighten the nut and I wouldn't be able to turn the drill bit in the collet by hand. Not only wasn't the drill bit not hand tight, but it fell out of the collet. I had to use a wrench to tighten the nut enough to make it tight enough I couldn't turn the bit by hand. Is this normal?
(4) I just remembered I did see something on here about torquing the nut down to approx 60 ft-lbs. Is that correct?

[oldtiffie]

Tyro.

I hope this answers your questions. I have interleaved it with your post.


I finally got the Wells-Index assembled and running, so I ordered a set of ER 40 collets and a collet holder to fit the R-8 spindle on the mill. I have a few basic questions:
(1) Should I lubricate the holder and the spindle so it goes into the spindle/releases easier; or is best to leave them dry for maximum grip.
Leave dry.

(2) I assume it's best to oil the collet, nut and internal taper of the holder.
Collet and adaptor internal taper - no.

Nut and screw threads - yes.

(3) Since I have no experience with a milling machine, it took me a while to figure out I needed to snap the collet into the nut before I inserted the collet into the holder, so I have that part of the procedure right; but I thought since the collets collapse 1/32", I should be able to insert a 15/64" drill bit into a 1/4" collet, hand tighten the nut and I wouldn't be able to turn the drill bit in the collet by hand.

Not so. The nut has to comress two tapers on the collet, one with bears on the adaptor inner taper and the other on the taper in the nut. The collet "grip" range is "nominal" less 1mm (~0.040") so a 1/4" ER collet should clamp a 15/64" drill, but the collet spanner will be required.

Not only wasn't the drill bit not hand tight, but it fell out of the collet. I had to use a wrench to tighten the nut enough to make it tight enough I couldn't turn the bit by hand. Is this normal?

Yes - see previous response.

(4) I just remembered I did see something on here about torquing the nut down to approx 60 ft-lbs. Is that correct?

Nope- just tighten it to "firm" as "too much" may strain or distort the collet.

[dp]

Nice treatise, Tiffie. No profundity, simple and concise. That's the way a good FAQ is built.

[Peter Neill]

(4) I just remembered I did see something on here about torquing the nut down to approx 60 ft-lbs. Is that correct?

Nope- just tighten it to "firm" as "too much" may strain or distort the collet.

Our survey said Uh-Uhh.

ER40 nuts have a recommended tightening toque of 176Nm or around 130 ft. lbs. The torque requirements get progressively smaller as you move down the ER series, with ER32 at 100 ft lbs, ER20 at 60, and ER11 at 22 ft lbs.

Peter

[Bill Pace]

ER40 nuts have a recommended tightening toque of 176Nm or around 130 ft. lbs. The torque requirements get progressively smaller as you move down the ER series, with ER32 at 100 ft lbs, ER20 at 60, and ER11 at 22 ft lbs.



Gad:eek: ---does anybody actually DO this? ---well, I guess after some of the bearing discussions ------

[Tyro 001]

Thanks for the advice. Looks like I'm going to need a torque wrench. I think I heard something about a nut that has a ball bearing face which reduces the friction against the collet. Is that a good idea? Again, thanks for the info.