A Question of Runout

[epanzella]

I just saw another video of a guy testing the TIR of a Chinese MT collet chuck in his lathe. The guy's reasoning is bugging me. He first tests his spindle and it had a .002" TIR. Then he mounts the an endmill in an MT collet chuck and it reads .0045" runout so he claims the actual runout the chuck is introducing is .0045" minus the .002" spindle runout for a net of .0025". I don't agree with that. Depending on how the collet chuck is clocked in the spindle couldn't it add OR reduce the net runout of the whole assembly? I believe the actual runout of the end mill in the collet chuck itself in this case can be anywhere from .0025" to .0065" depending on how it lines up with the spindle runout. If I'm all wet please splain this to me.

 

[DavidR8]

I think I watched that same video last night. Was he testing Banggood collets too?


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[higgite]

I agree with you about clocking a collet, but can you post a link to the video so we can see it first hand?

Also, unless the video author or you misplaced the decimal, that sure seems like a lot of runout for both the spindle and the collet.

Tom

 

[epanzella]

I think I watched that same video last night. Was he testing Banggood collets too?


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Yeah, that's the guy. It was MT4 taper in a Clausing lathe I believe.

 

[epanzella]

This is the video

 

[epanzella]

I agree with you about clocking a collet, but can you post a link to the video so we can see it first hand?

Also, unless the video author or you misplaced the decimal, that sure seems like a lot of runout for both the spindle and the collet.

Tom

I shouldn't have relied on my memory as I was off on the actual numbers. Although the absolute numbers are differentthan what I remembered the principle that I was asking about is still unchanged. Is it valid to just subtract the runout of the spindle from the total runout to evealuate the collet chuck? I posted the video.

 

[higgite]

I guess I don’t understand what your concern is with the video. It confirms what your thinking about clocking the collet chuck changing the TIR, starting at 10:30.

Tom

 

[epanzella]

I guess I don’t understand what your concern is with the video. It confirms what your thinking about clocking the collet chuck changing the TIR, starting at 10:30.

Tom

If he marked the high point of the spindle runout I missed it. He kept flipping the collet chuck around until he got the best runout then subtracted the spindle runout from that. It seems to me there's a good possibility that the spindle runout was cancelling some of the chuck runout but he assumed it was adding to it. Maybe the flipping around he did some how accounted for what I'm talking about but if it did it went over my head. I'm a w/e warrior and I'm not even close to having all the answers. I have an ER32 set and R8 collet chuck on the way and I just want to understand the procedure to test them for TIR.

 

[Ulma Doctor]

runout is runout, no matter how you slice it
adding and subtracting decimals where convenient, doesn't give you actual data

 

[pacifica]

Also I would get class zz pin gages, .25, .5 and .75 and use them instead of an endmill and measure all 3 different diameters.