Quote Originally Posted by Rich View Post
Jazz, so you're saying the epoxy method, as described by Clive and Silyavski is the best way to go because it achieves what level of accuracy?
Let me respond instead.

It achieves the level of accuracy of your straight edge + your intention of accuracy.

You need a straight edge that should be at least as long as your machine is wide, to check the result and later square the gantry. Your intention of accuracy will help you see small mistakes if any and using shimming and checking against the edge will help the desired accuracy. Anyway you will need the edge to mount the rails straight in the other direction. The more accurate you want it to be, the more you will check and adjust and generally the more time it would take you.

For an example i did 3 separate pours of epoxy on my 3m long rails, when happy with the epoxy i mounted and dismounted 2 times the left rail and 4 -5 times the right one until i was happy. It took a week with helper, only adjusting the rails. The only reason to do that was because i will use that machine to surface other smaller machines and gantries in it and not mess in the future with epoxy if not building something huge. If this machines purpose was not meant for that, i would have shimmed the first unsuccessful pour and finish with that stage.

So if you mean all day doing precision aluminum milling is one thing, other thing is if you do all day wood.

Even so, the bigger the machine the difficulty to achieve precision multiplies. It not only the epoxy, it how many times you check all and if you take your time to repair all that you have found.

Its difficult to explain but at the end the precision of the machine depends how precise are you or how precise you want it to be. All else is means and ability to achieve it.