First CNC Project - 3 Axis - Large table format

[Xavi]

Hi all,

I am embarking on a CNC project to build a large format CNC Router, mainly for drilling and milling plywood, MDF, and wooden doors. I suspect I would like to mill aluminium in the future too.

I have a budget of around 2-3k (though preferably closer to 2k) and would like to get as accurate as possible. I was looking at industrial strength models which are accurate to .02. Realise this is unlikely from a DIY job but would be interested to know what can be achieved.

I have a fairly good idea on the electronics and software factors. I was software engineer and have a fairly good grasp of electronics. The main concern for me at this early stage is the table/frame design. After reading a number of threads on this subject I have decided on steel due to its rigidity and stability and price (whats not to love) and may be bolting it to the floor. Woefully lacking in welding skills though, and have some concerns over the shear amount of drilling of steel required.

I would like to keep rails beneath the surface of the table for easy access, also flexibility to put a vacuum table on in the future if it works well in the first iteration. If the machine works well I may be using it for short furniture production runs.

Posted some pictures below. The length of the table is 2500mm. The main structure from 50mm x 100mm 3mm steel tube. Looking at rack and pinion for the X Axis and Lead screw for the Y. No detail on hardware yet just looking at getting the overall form right. In particular how best to attach the X Axis rail and pinion rack to the main structure. Considering bolting the rail and rack onto an angle profile, then bolting onto the sides of the main structure. Comments especially welcome on this. I read on this forum welding the steel surface of the rails is a bad idea due to warping. Attaching on a plate separately would allow for a fair but of shim. Look forward to any comments/concerns/suggestions anyone has. Many thanks in advance.

Xavi.