Run out of 3-jaws chuck

Normally, no one will re-chuck the work piece to turn both ends, unless it is absolutely necessary. Especially re-chucking the 3-jaws self centering chuck will make you get into trouble.

But, checking the run out is another thing; it can be performing very easily.
I am going to use an edge finder to check the run out. Some people will use a drill rod, or the clamping end of the drill bit. All of them are work, as long as the testing rods are straight and concentric.





Because the chuck was sitting on the spindle shoulder, if you didn’t check the flatness of the shoulder, you can put the probe closer to the chuck to eliminate the whirling effect.

If the testing rod has marking on it, it’s better to avoid clamping and touching on the marking.

I was surprised that my chuck has 48 microns run out. It was a bit large. What I can do now is dissemble and clean it; to see if I can make it better or not.

3-jaws self centering chuck was dissembled and cleaned

Re- grease the chuck

Assemble the chuck

Finally, I’ve got 13 microns run out; it’s a much reasonable result!
Run out of 3-jaws self centering chuck can be varying to different chucking diameters duel to the structure of the chuck.

My suggestion is after you’ve confirmed the center of spindle was parallel to the X rail; you can turn a shock down to the common working diameter of your projects, cut off it from the chuck, and you will have your own run out testing rod.

Magnetic base mount

Sherline makes tables from extruded aluminum; I need a little piece of steel plate for the magnetic base of dial test indicator.

After I’ve finish this plate, I find that, if I put screws in both of holes, there will have no space for the magnetic base.

So, I can only remove the front screw, let the weight of magnetic base press down the steel plate. It was rigid enough for my works. I suggest using a larger steel plate to provide enough space for your magnetic base.

Lathe Spindle

I am going to check and adjust my lathe first, and then the mill will be followed.
First thing I am going to check is the spindle. There are two critical matching surfaces.

1. The shoulder; inclination and flatness check. I have 10 microns deviation, it can form 0.086mm radius turning error at the middle of x-axis (8.66”)

2. The concentricity of the taper hole. Luckily, my indicator doesn’t move! This taper was made in very good quality!

For the first problem, I‘ve used miniature file and no.800 water sandpaper and try to flatten the shoulder. Finally, I‘ve made the deviation down to 2 microns with 45 minutes hand work. The error becomes -0.017mm radius at the middle of x-axis. Of course, if you have patient, you can make it much closer to zero.

Build in error checking and adjustment

My machines were assembled and adjusted according to the instructions on the manual. The accuracy and repeatability were good for most manual operations, but not CNC running, especially the backlash problem. Although sherline provides the anti-backlash nuts on all axes, if you want ‘zero’ backlash, you may need to adjust the nut after several runs.

Before dealing with the backlash problem, I decided to check and adjust the machines first.

The major equipments for me to perform checking are:

Mitutoyo No.513-401 dial test indicator
Earth-Chain magnetic base
China made 4”x2.5” square
Riken 6” precision level
SPI 3/8” edge and center finder

And the model of my lathe and mill are 4410 and 2010

Mounting board

First thing I did just after received my machines was making mounting boards.

When I was deciding set up my shop, I have figured out some furniture that would be replaced.That means I can chop down some pieces from them and make the mounting boards.

Some people suggested that, these kinds of miniature machine tools can be fastened directly on the bench top to get the maximum stability.

In my opinion, I prefer to leave the mounting board un-bolt to the bench top. Because, I will level my machines. So leave them un-bolt will let my later work easier.

Also, you may get more chances to use special accessories for your project. (Neither custom make or purchase one) If these accessories are over hanged from the machines, increasing the overall size of the machines,

At this moment, you find you haven’t enough space to install the accessories. You will pleased for didn’t bolt the mounting board to the bench top.

You can see my lathe was bolted on the pine wood board, but the board didn’t bolt to the desk top.

I don’t have socket driver for Hex. Nut, the counter bore holes at the bottom of the board can only fit with the screw head.

I've put the screw up side down, and add some epoxy putty under the flat washer to prevent damage of the bed painting.