Checking runout

J.T.450r

J.T.450r

Chesapeake Custom Cues
Silver Member
Let me start with this is a deluxe cuesmith lathe, I took apart the chucks to clean and repair one of them that had a bur. I checked my runout using metal dowel provided with lathe, at about 1.5" away from chuck I am getting 0.002 runout more when I move further from chuck less when I get closer. First off is that how to measure it? 1.5" away? Should I bore out my chuck or is this ok? Thanks for any help.
 
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Re-chucked on the dowel 5 more times and consistantly got 0.002 at 1.5 away from chuck.
 
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You have checked that the chuck mounting is running true so there is no swash.?
Other wise what Rocket said.
 
.002" @ 1.5 away without shimming. I would be elated with any 3 jaw. :smile:
 
conetip said:
You have checked that the chuck mounting is running true so there is no swash.?
Other wise what Rocket said.
Click to expand...

Conetip/Neil,

I googled "swash" but could not find anything related to lathes.

I searched this forum and the Cue Machinery forum and you have used the term a couple of times.

I initially thought it meant the linear alignment of the spindle to the ways, but now I'm not sure.

Could you explain further or point me to a URL?

Thanks!

Gary
 
I'm not sure exactly what he meant but I took it "swash" as play in the bearings on the headstock. But maybe someone could clarify. Thanks.

GEBrown said:
Conetip/Neil,

I googled "swash" but could not find anything related to lathes.

I searched this forum and the Cue Machinery forum and you have used the term a couple of times.

I initially thought it meant the linear alignment of the spindle to the ways, but now I'm not sure.

Could you explain further or point me to a URL?

Thanks!

Gary
Click to expand...
 
swash

Swash is when the chuck mounting surface is not perpendicular to the rotational axis of the spindle, causing a wobble. Think a car with a bent(not dented) wheel.
GOOGLE "SWASH PLATE". MUCH INFO
 
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more swash

A rod in a chuck that runs out will describe a cylindrical path when turned, that is, the rod's center axis will be parallel to the spindle axis and "orbit" around it. Swash will yield a conical path in which the rod's center axis is NEVER parallel to the spindle axis.
So if the runout increases with distance from the chuck, this suggests swash.
Robin Snyder
 
carguy said:
A rod in a chuck that runs out will describe a cylindrical path when turned, that is, the rod's center axis will be parallel to the spindle axis and "orbit" around it. Swash will yield a conical path in which the rod's center axis is NEVER parallel to the spindle axis.
So if the runout increases with distance from the chuck, this suggests swash.
Robin Snyder
Click to expand...

This is correct.

It is like a wobble or the faceplate not true to the run of the spindle. Turbine compressors suffer from swash problems as well. So it is balanced but the front or back face does not run true or zero. In a turbine situation the faster it spins more out of true it will run and eventually cause a strike with the housing which becomes a disaster.
lathes just run further out from the chuck, but hold the workpiece not true.
Even though you bore the chuck jaws, when swash is present,the jaws will only be correct at that exact size. As the jaws open up, the position changes and so a test bar of a different diameter will be different and not run true.
On my lathes I face the chuck mount true,then I set up the 4 jaw chuck.
Turn a piece of steel and close the chuckjaws onto that.I put a DTI (dial test indicator) on the now backface that is facing the tailstock.I give it a light skim cut to make it true.I also check the front face to see how that is. After getting it correct, I usually face the front face with a skim cut after it is assembled back on the lathe. I also check the back face to ensure it is running zero when it is placed onto the spindle.
 
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