CNC milling machine assembly

Hello,

with all the quarantine stuff going on right now I was not able to mill the rest of the parts on my university's milling machine. Thankfully my friend is a cnc operator, milling mostly in plastics and plywood. I asked him to mill a few plywood plates for me so I can continue the assembly. This way I could learn operating the machine on plywood parts and then replace them with aluminium sheets.

I like to show a lot of photos so here you go:

Plywood parts 

Assembly of the machine under a watchful eye of the cat-supervisor

assembled frame without Z axis

For not the milling machine is located on my desk

Currently the machine is partially assembled and is able to mill. I'm still not sure about the housing and protection for linear rails and ball screws. During the build I used the dial indicator with a resolution of 0.01mm and I was able to set the rails paralel to each other with a +-0.02mm error. I find it a quite resonable error considering that the rails were mounted on regular aluminium profiles. All the measurements were made relative to these big 90x45mm aluminum profiles side planes, so this could introduce some error too. I had to put a a couple of paper sheets under one side of Y axis linear rail, as it was about 0.1 mm lower than the other rail. For now it seems to work, but I will inspect the heights after some time as the paper can be compressed to some extent.When I checked the table height the indicator showed about 0.05mm difference in X axis and about 0.03 in Y axis. That's quite acceptable, especially when the table is made of plywood.

The biggest issue is the Z axis which has about +/- 0.15 mm of play in Y direction. However I kind of saw that coming and ordered additional two 300mm long 20mm wide linear rails. These are going to be mounted on a new plywood plates and only when it works I will mill the final parts from aluminium sheet.

Milling the first piece of laminate was very satisfying. After taking it off the table my calipers showed that the hole is perfectly 10mm, while the contour was about 0.07 off. For a first run it was fine, but when I mount new Z axis I expect to achieve better accuracy :). Milling in aluminum wasn't very demanding, but the dimensions were off by 0.15mm. It turned out that the machine was settling down and all the screw connections got a bit loose. After screwing them once again the dimensions are off only by 0.05mm in Y axis (due to Z axis play) and about 0.02 - 0.01mm in X axis. Hopefully I will get down to 0.02 in both axes when I mount new Z rails.

So far I've tried milling laminate, PA9 aluminum and a soft unknown aluminum. I'm really happy with the PCBs. Compared to the traditional thermo or photo methods this one is the fastest and most predictable. Even two sided PCBs are easy :). After getting the machine to work I milled a LED lamp for the spindle:

Milled traces and outline

Assembled lamp

Working setup (actually it could be mounted on the spindle itself, because when the spindle is too low it causes a shadow to appear just in the place where the milling bit is mounted) 

assembled double sided PCB for USB<->CAN converter

 I think that's all I wanted to show for now. Next I'm going to try milling some plastics and try a bit more aggressive aluminum milling.