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Spindle Runout ?

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Forum topic by Hockey posted 03-11-2018 10:45 PM 325 views 0 times favorited 6 replies Add to Favorites Watch
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Hockey

131 posts in 434 days


03-11-2018 10:45 PM

On the issue of measuring spindle runout (concentricity) of a wood lathe , I am a little perplexed.

If I measure the runout on my friend’s lathe inside the morse taper and get less than .0001” (one ten thousandt), and then measure the flat part just past the threads and get .001”, and then measure the step up from that and get about .00020” and then measure the large spindle shoulder right next to the bearings and get about .002” (all these measurements start at the inside the morse taper end of the spindle and work their way back).

So, which is the most accurate of the measurments, or all they all unreliable?


6 replies so far

View Richard Lee's profile

Richard Lee

123 posts in 797 days


#1 posted 03-12-2018 12:18 AM

How old is the machine ?
You could be measuring the wear.
Is it clean ?
Or are there dings and dents ?
Where was the machine made?
Are the bearings good ?
What kind of dial are you using ?
Could be your method of indicating.
Insert a tool or sleeve into the MT socket ,how does it run ?

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Hockey

131 posts in 434 days


#2 posted 03-12-2018 01:49 AM

Thanks. New. Asian made machine. Asian made dials, one with the lever type arm and the other plunger type. Looked at measurments again and the .002” stated above is only actually around .00125”. All of the measurments are relatively close and certainly within woodworking lathe tolerances of an Asian lathe.

But, I am very curious as to whether the measurments that vary are less reliable than the morse taper one. Using common sense (not necessarily always applicable), I would think that the one inside the morse taper, being the furthest out should be the most reliable one. It is also the most consistent one measuring at different depth points with the lever type indicator.

View msinc's profile

msinc

421 posts in 526 days


#3 posted 03-12-2018 01:57 AM

Well, it sounds like you are reading inside the Morse taper at different locations. You could simply be getting differences in the taper itself. This could be due to some wear from having various tooling put into the taper. It could also be nothing more than the way it is machined. What counts with a Morse taper is how well it can center up something placed in it. I would suggest that you get a known good Morse taper adapter or something like a dead center and seat it and check for runout on that. I wouldn’t suggest you use a live center because that has a bearing and could maybe give a false bad runout reading. Once you have checked the adapter or dead center mark it with a sharpee and remove it. Reinstall it 180 degrees out from test one and read it again. The numbers you are quoting don’t really sound that bad for a wood lathe. But again, what counts is when some type of tooling is placed in it.

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Hockey

131 posts in 434 days


#4 posted 03-12-2018 02:20 AM


Well, it sounds like you are reading inside the Morse taper at different locations. You could simply be getting differences in the taper itself. ...

- msinc

Yes, I am reading the numbers at different locations in the morse taper; but, the readings are identical in the morse taper.

View Woodknack's profile

Woodknack

11771 posts in 2402 days


#5 posted 03-12-2018 02:37 AM

Strictly speaking, we would have to observe the measurements and test the DI to answer questions about accuracy. Practically speaking, every part of the lathe will have runout in varying amounts because wood lathes are built to sloppy tolerances compared to metal working machines. I measure the inside of the morse taper and measure the rest by chucking a forstner bit into my lathe chuck and measuring runout. It will be the sum of runout from all parts, shoulder, threads, chuck, and bit. Are you trying to identify the cause of a specific problem or just curious about the amount of runout and how best to measure it?

-- Rick M, http://thewoodknack.blogspot.com/

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Hockey

131 posts in 434 days


#6 posted 03-12-2018 04:06 AM

Just curious, Rick. Thanks.

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