Mach Discussion > General Mach Discussion
Wire Alignment
John Mac:
Thank you Ian
I made up a grinding device and ground it. Having a known reference line and levels allowed me to work to those. This lathe has double v’s for the saddle. The tailstock uses a V and flat. Total run out for the tail stock ways was about .005 end to end not bad for 30 years. I used that for the grinding head guide. The important point was knowing the error I could allow for it as I ground to compensate. It was a slow process. It is not perfect, but good enough for most of the work I give it. The saddle was bedded with Moglice. Epoxy bearing material No scraping there. Sending it out for a regrind in Melbourne Australia would almost cost more than it would cost to replace the whole machine. With an Asian built machine. Don’t forget freight both ways for a crane truck. No I would not do another but learnt a lot in the process.
Cheers
John Mac
Ian Ralston:
John,
You wrote :-
"No I would not do another but learnt a lot in the process. "
But you have to do it to prove that you can. :)
This quite a practical group, have a look at the Show and Tell section. They do like pictures here. I for one would like to see your carriage grinder setup.
Ian
John Mac:
A couple of images of the precision level and the measuring stage cludged up from scrap.
Cheers
John Mac
RICH:
How did you know the wire was true about the lathe head axis / front and rear bearings of the head?
Maybe another way of saying it, what's assumed correct?
RICH
John Mac:
Hi Rich
For testing: I first leveled the bed in the X and Y direction, then mounted the wire using some blocks milled from mild steel at each end of the bed. They were adjustable to enable the wire to be positioned exactly.
By moving the wire (not the jig) that aligned the wire to the bed, end to end. The wire was set low, level with the centre of the V’s horizontally, making all 3 in line, to avoid parallax errors.
The head axis is aligned to the bed by the front and rear V ways which showed the original manufacturers scraping marks, it is not adjustable I do not have an Autocollimator so used a precision 18” inspection grade square and a dial indicator swung on a bar mounted in the chuck, the alignment to the bed was fine. Horizontally it appears fine using a test bar.
The saddle prepared to be set in Moglice http://www.google.com.au/search?hl=en&q=Moglice&meta= by fitting inverted V blocks with cap screws to the 4 corners of the saddle. They were adjusted jacking up the saddle until it was perfectly aligned in all planes using the level and careful measurement to set the lead screw and control bars back on axis. Then all that remains is to very carefully remove the saddle and apply the Moglice to the saddle V’s and replace it over the bed. The next day the saddle was removed and the squashed out epoxy trimmed away. Am trying to find the CD to post some photos.
Cheers
John Mac
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