I´m just from doing it, see link to my thread
http://www.practicalmachinist.com/v...g-and-inspection/stanko-semi-overhaul-348930/
Sorry I have not updated it in a while and the pictures are bad. I got some better pics to upload. It is better than it looks there and straightness, paralellism, twist etc are very ok.
I´m right now doing final fitting of the carriage to the bed ways and it´s coming in nicely.
Anyway, I got to grind it as it was too hard to scrape effectively although I did make some final scrape marks on the flat ways mainly to brake up blotches and get more uniform print.
Following lots of good advise here, dcsipo and demon73 has very good advises on the subject as rich and others as Jshaugjord and more some not on this forum.
I got a cheap straight 3" die grinder and went to town.
Condensing (my own) lessons-learnt:
Never dwell, come in with speed.
Use pressure regulator to be able to have some control of speed.
Don´t dwell, never reduce speed while in contact
At the end with more practice I preferred higher speed than initially - but not highest.
Don´t dwell, exit in speed.
Cheap grinding disc might be the ticket as they just don´t cut very well. I got some finer grit disc from Norton but they cut too fast for my liking.
Dressing the corner on the disc used for grinding is everything second only to - Don´t dwell. Use some diamond stone and try to dress a radius on the corner maybe 75% of the disc thickness approx.
Don´t bounce on the surface, go in, stay engaged, get out.
Practice on sacrificial object to get your speed, rythm and pressure consistent.
Considering hours spent (several+++) it is still good value considering time and cost for sending it out based on grinding estimate here of approx 3000$, that would then have been first class grind so comparable or not the bed ways are now straight and will allow consistent function also making the remaining jobs (carriage, crosslide and tailstock) worthwhile doing.
I´looked at several of the russian grinding videos also but the technique I ended up with is more like the one in dcsipo´s video.
It is possible to grind to very fine tolerances and depths, at the same time respect that it will also remove lots of material at the flick of your wrist.
Future improvements might include an electrical grinder in the size of a 115mm or 125 with electrical speed control running a 100mm disc or 75.
Size of the grinder is important in terms of allowing for handling control, on my small die grinder I added a handle from a drilling machine enabling more consistent manipulation/ manouvering of the grinder for sustained periods.
Do not use soft discs for so many reasons, lack of feel, edge round off etc. That´s my personal opinion.
Picture show a small hole made with soft disc approx 0,01mm below surrounding surface, now removed.
Print of outer V-way, the hole mentioned above is seen on the right side.
Early stage roughing.
Simple grinder
