Have any of the installers/users of the magnetic scales from M-DRO checked them for accuracy after installation ?
I finally managed to finish the installation of a 2 axis system (basic lathe console + 2 off 5 micron resolution magnetic read heads) onto a Swiss made tool presetter at work yesterday. The installation was required after the Trimos capacitive readouts died & the UK agent for the presetter quoted £2500 – £3000 (+Vat) for the original equipment units – the M-DRO setup came in at around £420 inc. Vat delivered IIRC.
Anyway, after getting it all installed, the first thing I noticed was that the diameter readout was not reading tool diameters correctly. The spindle has an accurately ground (127.00mm) outside diameter that is used to datum the X readout. When I put a tool in the spindle & checked various diameters, the readout did not show the correct dimensions – around 0.08 out on a 24mm nominal feature. Checking the vertical travel to Inspection grade slips showed a smaller error – around 0.015 at 200mm. The console has a length compensation feature – setting compensation values for both axes has got both reading correctly – though the compensation values differed widely (-600 on X, +75 on Z). As the magnetic strip was supplied as 1 piece & I cut it to suit both axes, I see 2 possibilities for the differences – the read heads require individual adjustments, or the magnetic characteristics of the slide affect the strip. As the X axis on the presetter is machined from stainless steel & the Z axis is an aluminium extrusion with inset stainless steel guides, I suspect the latter.
The magnetic systems do command a hefty premium, though – I went through the exercise of pricing a 3 axis system to suit my FB2 clone, with travels (from memory) of X 400, Y 150 & Z 400 :
Arc Eurotrade capacitive scales with 3 axis console £210
The Arc 3 axis display is much more basic than the Sino unit, but the system was included to show that a very basic 3 axis system can be installed relatively inexpensively. I discounted Arc's cheaper option of scales with remote readouts directly attached, as the accuracy quoted seems poor to me for machining metal & not directly comparable with the other systems below.
M-DRO 3 axis "economy" mill console with 3 x "Full size" scales £480
As above with 3 x "Slim" scales £545
As above with 3 x 5 micron magnetic heads, 1200mm of tape & 1500mm mounting spar £700
As above but with 1 micron magnetic heads instead of 5 micron £790
Prices "rounded up", including Vat, excluding delivery.
The price in the link from Bogstandard2 looks rather more attractive !
Regards,
Nigel B.