Taig expected accuracy

[Moesian]

Hi,

I recently set up my taig mill again. I found everything was out slightely when i tried to centre it. The backlash appears to have changed, but it seems to be less than before, is this normal?. Also when trying to recongfigure the backlash even when moving the y-axis in the same direction by 1mm I seemed to get changes of 0.01-0.03, is to be expected also, what are the accuracy limits of the taig?

Thanks alot

[cartertool]

Backlash could initially be less if oil/grease dried up on the threads - although this would be a temporary condition. How used is the machine? You can get localized wear on the screws and slides if you did parts all the time in the same place on the table.
When checking backlash - make sure compensation is off before checking!
Also, it's summer - if your shop is hot and the last time you checked was in the winter and your shop was cold, you could be dealing with expansion...
Now .03mm = .00118", which is usually what the minimum backlash is, .01mm=.0004" which is a very small number.
Anyway, as to the "accuracy limits", generally you can work to .001" if you have taken time to adjust for backlash correctly and the z axis is in tram on both x (easy) and y (requires shimming). This assumes you haven't worn out one area relative to the others. You can also "map" the leadscrew - the manual has instructions although I've never bothered.
Also the stock Taig control is 8000 steps per inch, or .000125" per step - moving in amounts that are not divisible by that number often causes minute errors...
Finally, if there is sticking/jamming/lack or lubrication/poor gib adjustment you can lose steps.
See here for articles on tramming/adjustment:
http://www.cartertools.com/index.html#AAT

[Moesian]

Hi Nick,

Thanks for the reply. Its been a very hot summer here so that could well be why there has been a change in the backlash. Also the machines been packed away for a while so again the machine could probably do with being oiled, whats the most suitable sort of lubricant to use?

[cartertool]

Hi Nick,

Thanks for the reply. Its been a very hot summer here so that could well be why there has been a change in the backlash. Also the machines been packed away for a while so again the machine could probably do with being oiled, whats the most suitable sort of lubricant to use?

I use a medium way oil, but Taig recommends ATF, and you can get away with a 20 or 30 wt. oil. I suggest getting on the taigtools yahoogroup - people have used other lubes with success as well.