More than good enough for most work despite what the willy wavers may say.

Before you trammed the head, did you check the column squareness to the base in both directions (X-Z, Y-Z)?

Pretty pointless tramming the head if the column isn't square to start with IMO.

My former machine tool fitter collegues used to work to a "rule of thumb" for manual machine alignments of "a thou per foot" (0.001" per 12" or about 0.025mm per 300mm) – on CNC machines we generally aimed for half that. Your Y-Z reading of around 0.004" in 6" is around 8 times the "rule of thumb" – only you can say if this is acceptable for the class of work you aspire to, but I would not be happy with it. Time to get the scraper out !

Nigel B

"Personally I wouldn't accept an out of tram of 0.1mm over 160mm."

Whoops ! Neither would I, I misread the microns as 0.01mm. Hadn't had time for the coffee to wake me up.

No typo.

After an apprenticeship as an electrical/electronic technician specifically set on to learn all aspects of the maintenance & repair of CNC machine tools in a process control valve manufacturing plant (which I finished at Boxfords when that company closed), I spent around 18 months at Broadbent Machine Tools production wiring manual & CNC machine tools (semi-automatic Oil country lathes & CNC vertical milling machines), plant maintenance & customer service. After being made redundant there, for 27 years I worked for a machine tool rebuild / retrofit company in Halifax, variously changing CNC control systems on NC/CNC machine, rebuilding NC/CNC machines back to original mechanical specifications & replacing and upgrading the electrics/electronics, and converting manual machines to CNC (sometimes with & sometimes without a mechanical rebuild). Started as a Technician, promoted to Senior Technician & promoted again to CNC Retrofit Manager. Machines worked on varied in size from Bridegport size turret mils up to floor borers, Colchester Student size lathes up to roll turning lathes & vertical borers up 14' table diameter. Customers were in many different fields, but the later machines went mainly to aerospace subcontractors. I current work on "maintenance" of all aspects of plant for a specialist graphite machine shop – "maintenance" including sorting out CNC machine bought at auction, including control retrofits (though last week was changing the coolant pump on a 200Kva diesel generator – never a dull moment !).

"Thou per foot" does not strike me as being too arduous a spec. to aim for, even for "entry level" stuff – the Spanish (Lagun) built, Ajax branded turret mills we used to fit a complete drives & control package to were within that, as I recall. Anything with "borer" in the title was more of a problem – usually much tighter limits to work to & everything tied up – levels first, then alignments & all had to be demonstrated to the customer for acceptance, using calibrated inspection squares, levels etc. & later a Renishaw laser interferometer and dynamic ball bar system.

I only failed to have one machine accepted in the time I was there – a manual jig borer converted to CNC, on which the customer had more than halved the original builders straightness tolerances in his conversion specifications. The original spec was 0.025/300, customer had specified 0.01/300 but the best we could get was 0.014/300 on the side of the Z axis – machine not accepted for the sake of 0.004 mm !

Nigel B

It's not always as easy to interpret the diagrams as it should be

Neil

Steve – no apology required on my part. If you have a query, then post it !

How would I check column perpendicularity? I guess I'll need a huuuuuuge engineer's square and my most trusted DTI??

Basically – yes ! Doesn't need to be a huge square, but you do need to be able to trust it – likewise your DTI. Most of the inexpensive blade squares are "Workshop grade" at best & would be worth checking out before you start. A precision square is not cheap & it might be worth investigating making a cylinder square if you have a lathe that can be adjusted to turn parallel between centres. Or you could get a good idea with a precision box (or frame) level – level the machine base accurately, then check with the side of the box level how the column lies – but these are expensive toys as well.

Remove the head at the swivel point and check for burrs or dirt on the mating surfaces .

Lift the column up off the base and do the same as above .

Plus give them a rub with a "known to be flat", blued-up, surface plate to make sure that there are no high spots or burrs on all mating faces. Check the column-to-base squareness in both directions after re-assembly before bothering with tramming – you want to know that is correct before proceeding IMO.

Nigel B

I scraped the column bracket to base joint of my X2 which helped rigidity as well as allowing me to correct a slight tilt. Horrible job and using a 4" length of square HSS as a scraper is hell on your fingers!

Neil