Question about Lathe/Milling Spindles

[jho5820705]

I am trying to learn more about the machines I bought and have been using for several years now. My question is: How do i increase the accuracy of the machines. I know ball screws will help, but what can I do about run out at the spindle. My lathe is OK, but I can't seem to get that last few tenths of accuracy that I would like to have. The same is probably true of the milling machine but I haven't noticed it there because I don't usually require better than 2 or 3 thousandths. Can I change the spindle or bearings and increase accuracy? I have a small Grizzley 6X36 that I bought 5 years ago so I really don't expect great accuracy, but would like repeatablity better than a couple of thousandths that I am getting now. Any suggestions or information about spindles and how to make them more accurate would be appreciated.

[Crevice Reamer]

Here's a method for testing and truing the chuck:

http://www.varmintal.com/alath.htm#Truing

CR.

[jho5820705]

I will have to give that a try. I don't have a tool post grinder but can rig my electric die grinder to do the job. Just wish I knew more about spindles and how they relate to accuracy in general. I feel like I am working in the dark when I work on the machines.

[BobWarfield]

Here is some info on tuning up your lathe spindle:

http://www.arceurotrade.co.uk/projec...ges/index.html

It may not be quite perfect in every detail given your type of lathe, but it gives you some idea where to start. Rumor has it that upgrading to SKF bearings and following these procedures makes a noticeable difference.

Best,

BW

[jho5820705]

Thanks BW,

The bearings could be part of the problem. Might explain some of the chatter I get with the cutter when machining steel. Guess I will have to try to cross the current bearings with SKF and see if I can find a better replacement. Wish I knew more of the theory behind spindles and how they are designed, it might make it easier to understand what each of these changes accomplish.