My first router was built from MDF. It moved with temperature, humidity, phase of the moon, gravitational attraction of anyone standing nearby, or if it felt like it. It could do useful work (I profiled up to 25mm teak with it, slowly, and bed was something like 750x400mm) but it needed continual adjustment (both for bed levelling and general bearing clearances) and could not be relied on for very high accuracy or, towards the end, anything approaching decent surface finish. It was good fun, did some useful work for me, and taught me a lot but Mk2 currently being commissioned is all-welded steel, Hiwin rails and ballscrews for a reason!