Recommendations for Z Axis?

[samsagaz]

I've not used 20mm supported rail only 16mm. I don't know what the price difference is but I'd stay with 16mm or upgrade to profile linear rail (Hiwin etc.)

I don't see a technical problem with combining multiple blocks on one rail. Use whatever fits so single and double would be OK. On my new gantry it will have 4 single blocks per side. Spread them out as you have done so they are at the corners with a gap in the middle.

I meant to ask before - your X axis rails don't appear to be supported on anything. I would not rely on the lower flange which comes with the rail to give you the stiffness. It needs to sit onto a continuous box section or similar running the full length. That would also raise your bearings up and make the gantry sides much smaller, therefore making it very much stiffer for not much effort.

I have the 20mm ones at home, i already ordered hiwin too, but for other machine, mainly aluminium working. This one will be mainly woodworking/MDF.

Yes, im fixing the X axis too, i think that will use an 50mm tubing but will use epoxy to level up and to add a few mm because the tubing that have just have 3mm wall and think that are not enough to insert the bolts. :/