Wednesday, September 8, 2010

Squaring, Tramming, and Checking Alignment Again...

Another picture book of a post; I tried to get pics of the readings on the Starrett 711-F Last Word DTI as I went through the steps to align the spindle and headstock of the Taig mill, but some are pretty hard to see because of the poor lighting.  Just remember that there's only 0.030" travel in this DTI, and I tried to keep preload on it right at 0.013" (with the dial turned so the preloaded point showed "0" on the indicator)...

In order this time (I had to show the clean pic first in the last post!):

If you can see or even guess the position of the DTI's arm/pointer and have followed the sequence, you'll see that I have been pretty anal about it's set up, but once that stock motor's installed, all that work was in vain.  I did use a NEW Taig headstock mounting plate and even got it aligned to 0.001" in 4.5" (and that part is factory milled, not ground, plus it's made from aluminum and it probably doesn't exactly get stored as a precision component at the factory due to the small dimples and flaws found indicating its edge, so that's not too bad for that piece).  Most of the other tolerances held, all measured again after any securing bolts, nuts, or tightening sequences and readjusted as necessary, should be an average of approximately 0.001" per 10-12 inches of travel or component length; some were better but others (like the milled headstock mounting plate) weren't as good.

The machine's still pretty new at a year old (or close enough now), but has always been used manually and although sometimes frequently it still behaves the way it did on the day it was first received.  Leadscrews show no considerable wear, all wear surfaces look good and have always been well-lubricated with way oil (as have the 'screws), the gibs still feel tight, but I'm STILL not satisfied. 

Alignment was within spec and seemed quite acceptable until the stock motor was reinstalled in the stock location; Without shims, the best I could align the headstock (side to side, column adjustment range-but that had the best tolerance of all before the motor!) was to within 0.002" in a mere 1.375" radius!  Considering the indicator used and the approximate 30-degree angle of its' mount, that still sounds like two thousandths in 1.375" to me; the motor's weight is a serious issue on this machine! 

I'll flycut some stock in the next day or two to post here to demonstrate what I mean; no matter how well you square and tram a Taig, the motor's weight is going to affect your results in some form or another.  Though my Z column and headstock mounting plate are good, this design is FLAWED from the factory IMO.  Sure it works, but I've got better ideas.  More on those later...

And pic of the tailstock of my rotary table just for good measure; I'll be using the rotary table in a short time for many operations (and probably this piece, too),  and I snapped a pic of it for another reason-to post somewhere else in response to a group post.

Details soon, and I'll try to draw up a print of my vision for the completed Taig soon.  I have hand-sketches in a rear-view and I'll start a top view soon, and I'll try to either scan those or play around with TurboCAD a bit more to see if I can show all angles in a few prints.  That'll take a while, but I'll work on that as I can and as soon as possible. 

Until next time,

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