Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet

[Zeeflyboy]

To fix the squareness the easiest way I found was to drill two holes for precision dowels in the Y-axis, then using a precision edge run a dial indicator along the X-axis with the precision edge clamped against the dowels. I then loosen bolts on the gantry and gently tap it in the direction required before re-tightening the bolts and re-checking. Repeat a few times and you will get it fairly close to square (although you will come to realise that your gantry is probably not flat, but bowed slightly leading to it being impossible to square out completely - I just tweak until the dial indicator reads the same at 1/4 and 3/4 travel).

I ended up just having it as square as I could get it over the centre of the bed where I do most of my work, the squareness varies a little as you move around the bed due to the lack of straightness inherent in extrusions. I found it generally holds the square ok-ish after messing with it, but if you move it then you'll have to re-do.

Ultimately I do think its good for the money as an entry point, but for really precise work you have to work within the limitations of the machine and spend a lot of time tweaking. The best option in terms of value for money is to take what you've learned from the machine (plus all your tooling and associated equipment) and use it when designing/following a design on here for building your own machine. The conclusion I came to is that while I've managed to make some really good stuff on it, it simply isn't worth fixing up or modding extensively as you end up chasing your own tail.

That said I have managed to make some pretty precise parts with it, and it is still leagues ahead of the unsupported rail type 6040 machines.