@@AFARCO-PnP exactly! and do you know why those hiwin mgn12 have holes along whole length not only at the ends? because they were not designed to self support. they need to be not even screwed, but precisely torqued to specs on flat support to retain accuracy. these ones unsupported must bend, flex and twist easily within 1/10 of a mm on high load and chew itself up in a year... while properly installed and maintained linear rail can deviate from ideal about a micron and easily outlive single person...
