Dear all

thanks for taking the time to read my post...

I am about to embark on a CNC router build.

id like to know if I'm thinking along the right track for each aspect of the machine - I know it's hard to picture it without a picture... I'm in the process of designing it and will create a build log in the meantime...

The size I'd like to be able to cut (minimum) is 1200/800/300 -x/y/z respectively

so I'm thinking I'll need approx 1600/950/550 rails (don't ask where I got those numbers from :) they're a guess loosely based on a rough guess of space between bearings)

i want to be able to cut aluminium, but the primary function is to cut PU foam and wood, like MDF or similar...

for the base frame I'm thinking 80x80x3 box-section - similar to designs already posted... I'm used to building heavy duty tables that need to be level, and understand these machines clearly need to be level, namely the long X axis rails need to be spot on parallel in both horizontal and vertical planes. - I heard about using epoxy - didn't really get it if I'm honest - when fabricating the base I would try employ all the usual tricks to ensure accuracy - but any further explanation would be greatly appreciated

the X and Y rails I'd go for profiled rails(square) and for the Z the SBR20 - all with 1x 20mm ball screw (X possibly upgraded later to 2x ball screw) what are the best aspect ratios to go for when setting the bearing blocks under the gantry sides? I've set them 150mm apart (distance between them)

the sides of the Y/Z gantry will be alu plate 20mm over the rails, with series 6 profile (60x120) (rails located top and bottom) spanning the two X-rails.

the Z will be alu plate with the rails on the spindle side of things...

going based on what existing members have already discussed, for the electronics, I'm still not so sure..

what are the best steppers to use? - size and power I can work out I guess , and I'm thinking in the ball park of 3Nm... Readily available, but would need more info with regard to spec-ing the best and what to watch out for... Digital/resonance/racking are all words I've heard... What is racking?

what drivers are going to be the most reliable? Which power source the best...

I did a forum search on this, but I didn't find anything really conclusive - that said, I'm new to the forum game, so it's probably an oversight on my part...

have I missed anything????? what other rules of thumb are there that you guys adopt when building a machine for the purpose of cutting those materials?

thanks in advance