Fixed Gantry small precision begineer project advice

[Wal]

Hi Yasu,

Sounds like a cool build. I made something similar, but you're starting from a better place by opting for the profile rails (I used the TBR20 supported rails). Here's a 3D vis of what mine looks like:



...and a pic of how the stages looked before the build was finished:



As you can see, I used 20mm eco-cast plate (this means that it was machined flat and the surfaces were parallel) which was bolted to a welded box section (60x60x5mm) frame and yep, the 'squareness' was shimmed in. Compared to some of the master-pieces that have been built by folks on here my build's a bit agricultural, but hey, I had to start somewhere!

What I will say to you at this early stage (and it might not matter to you) is that you could buy yourself a slightly larger work-space by swapping your machine table (the bit that you fix the work-piece to) with your Y-axis stage. ie. make the machine table the long plate and mount the rails and the ball-screw supports to its underside and fix the pillow blocks it rides on to the Y-axis along with the ball-screw housing. I dearly wish I'd done this with mine for the extra travel/work area..! One possible disadvantage here is that it could be a more complex assembly and the motor will be mounted to the underside of the machine table which may introduce extra unwanted resonance (could be an issue for a lighter machine). I say extra resonance because with a machine this size/weight you will already have some resonance which could potentially create ridges on your surface finish that exceed the magical .01mm resolution you have in mind... A good way to combat resonance is to increase machine mass, although at this scale I doubt it's all that beneficial and I appreciate that you're trying to keep the weight of the machine down for the sake of portability, which leads me to my next bit of advice...

I built a bench for my machine and included adjustable feet and castors on each corner (see pics below), when the bench is in position all the weight is borne by the feet (the loaded bench is IMPOSSIBLE to lift) if I need to move it I retract the feet so the castors take the weight and let me move it to where it needs to go.



Good luck with your build, ask plenty of questions - there's a wealth of knowledge and experience to tap into here! Looking forward to seeing it come together.

Wal.