Quote Originally Posted by Mattia View Post
Do you guys lubricate the carriages before putting them into operation? They feel like they're a little 'dry' out of the box, but not sure if that's the ZA preload I'm feeling?
Grease them when your ready to use the machine, there is enough grease inside them for setup etc but not enough for running.
The stiff and notchy feel is quite normal, when greased and in use under weight they run smooth.

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Quote Originally Posted by Mattia View Post
ow it's down to selecting the ballscrew for the X axis. Some folks on a Dutch forum suggested going for dual ball screw to prevent the gantry from racking. Gantry width is 800mm, and as mentioned I plan to mount a 2.2kw Teknomotor spindle. This machine was originally designed with steppers in mind. Will adding servos (with their potential for greater acceleration/rapids) make a duals screw with individual drive a more stable solution? If so, 2020 or 2010 for both, or downsize to 16mm screws?

Also, is there any significant upside to getting a C5 ground ballscrew (e.g. a TBI from Tuli) vs a C7 screw from Fred here?
At 800mm your at the limit of a single screw and personally I would use twin screws, esp if using servos.
Regards the screw size then it depends on the length, if over 1100mm then I would use 2020 with a 2:1 ratio, again even more so if using servos because of the higher RPM's servos run at. The ratio will half the screw speed but bring the resolution and federate back inline with 10mm pitch.
If between 1000-1200mm You could use 1616 and do the same but the difference in cost isn't worth taking the trouble, and if over 1200mm then 20mm is the best choice.

Just getting C5 rolled screws over C7 is worth it and ground goes a step higher but so does the cost. End of the day it's down to how a good a machine you want and your budget. BUT.!! . . .Just remember the machine is only as good as it's weakest link so even if you fit C1 ground screws they won't take up any slack in other weak areas so it could easily become wasted money. The goal and secret to a great machine is a balanced machine, if your going to fit C5 level then the rest of the machine needs to be built to C5 level.