Quote Originally Posted by charlieuk View Post
I have decided on a work area that will allow a max 1220 x 600 to be cut but with the focus on aluminium and forget full sheets for the moment.

I don't really want to do the hole epoxy level thing so will need to figure the best place to build the adjustment in to the axis's
My machine uses 100x50x3 steel box for the long X rails supports, giving around 1550mm travel so not that different to your plan. I also added steel strip inside to give me something to drill and tap for rail hold-down bolts, which is why I could manage with 3mm. However, my rails dip around 1.5mm in the centre. I don't know if the steel was bent to start with, or if it's welding distortion, or something else. The moral is, though, that unless you can really measure and control the materials and the build methods, you have to allow some way to correct the inevitable errors that creep in. I ended up using a mixture of epoxy and shimming, but I'm not saying that that's the best method, just one that worked in this case. Good luck with the build, and don't take anything (like steel box section being straight!) for granted...