Quote Originally Posted by Robin Hewitt View Post
Come on, don't be shy, 'fess up, what's the tolerance and finish like? :naughty:

Tell me I haven't been wrong all these years about the need for lots of cast iron

I'll even go first with a pic, iron cut .001" deeper than intended, biro tip for scale.
Robin, I don't think your wrong about the need for lots of cast iron for a solid machine, I did my apprenticeship at British Rail (a few years back!) and spent a good chunk of my time in the heavy machine shop operating a Noble & Lund plano mill. Bed was about 10m long x 4m wide and the whole machine must have weighed about 100-130 tonnes, 5mm depth of cut with a 15" face mill no problem at all and a nice finish, but you could still find the limits of the machine when you pushed it.

As for my mini plano mill!, I did not expect it to turn out as good as it did if I'm honest and I am not expecting miracles from it. Accuracy on the 30mm holes that I put in the plate was fairly good, measured them on the X and Y plane and they are 29.94 and 29.97 so slightly oval but not too bad. Finish could be a bit better but I just roughed them out, will have a go tonight with a 0.5mm finish cut climb milling to see how it performs and post up some pics.