ER 40 Collet Chuck Runout

WobblyHand said:
Sometimes you get a bum part. You could try again with them. Or start the search again.

I've had quite a few off spec parts come my way. All you can do is to keep on trying. Or you can make some of your own tooling. Have to say, it seems to come with the territory.

As for being in spec, what counts is the installed performance - as used. Of course that implies your equipment is in spec too. Sometimes it isn't. Check it , as it's more difficult to get low TIR if your spindle or equipment is an error contributor.
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i checked my spindle runout--less than .0001. Some of my R8 collets indicated on an endmill have .0001 TIR so i dont think its the machine. hell, even my drill chuck w rod get .0005.
 
weejax said:
i checked my spindle runout--less than .0001. Some of my R8 collets indicated on an endmill have .0001 TIR so i dont think its the machine. hell, even my drill chuck w rod get .0005.
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Out of curiosity, how do you check runout? Half a thousandth is really good on a drill chuck.
 
How often do you use an empty ER40 collet? Never? Put a gauge pin in it and measure runout.
 
I’d think you want to indicate the taper of the ER chuck. If that’s good, then any runout is in the collet.
 
A problem with indicating the taper is that a single measurement doesn't tell you if there is angular runout. You can have zero runout at the taper but a test rod mounted could still have runout an inch outside the collet. You really need to measure runout at two places on the taper. Even then, because the distance between the measurements is so short, you could see barely noticeable runout at the two measurement points but still have significant runout on a test bar.

Additionally, the ER nut also contributes to the runout measurement and there is no practical way that I can think of to measure that contribution directly.

A solution to this would be a test bar made to fit the ER taper, as is done for checking spindle runout with a Morse taper test bar.
 
RJSakowski said:
A problem with indicating the taper is that a single measurement doesn't tell you if there is angular runout. You can have zero runout at the taper but a test rod mounted could still have runout an inch outside the collet. You really need to measure runout at two places on the taper. Even then, because the distance between the measurements is so short, you could see barely noticeable runout at the two measurement points but still have significant runout on a test bar.

Additionally, the ER nut also contributes to the runout measurement and there is no practical way that I can think of to measure that contribution directly.

A solution to this would be a test bar made to fit the ER taper, as is done for checking spindle runout with a Morse taper test bar.
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I get what you mean. Im getting alot of runout measuring the insider taper of the chuck. have not progressed beyond that. i ordered one from little machine shop--will see how that does.
 
Invest in a high quality branded nut & collet, then try it out. Also, try the collet in different positions; this may reveal the cause.
 
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