CNC Plasma cutters, DIY, building info and guide

Dust from plasma cutting is very fine and very sharp so it can do quite some damage to rails and bearings. Having a water table diminishes that problem a lot, but not totally, so daily cleaning of rails is a good practice.
Not seen any failed bearing on AC servo motors yet, same goes for DC motors and steppers.
Have seen what the dust from the brushes gathered at the motor commutator can do on DC brushed motors, from messing up the tuning during work to getting very hot with very little use and heating the drives to the point of shutting off.

I do need some opinions here,
I am thinking of doing a small machine with simple bearings, since i used that over 10 years ago i really did not like them for linear movement at all. What do you guys think?
Usually up to 2 meters in length ( 80 inches ) i use round rails, 30 or 35 mm diameter with corresponding linear bearings, the problem with them is that with no support they do sag a bit and i can not find bearing holders here so i have to improvise.
If used with a THC, the sagging problem is non existent as the THC takes care of that difference easily. Without a THC they are usable only up to 1 meter in length.
The main issue right now is i am out of stock on long linear rails, got some THK 45mm left and some short 35mm and 30mm.

jmr wrote:

There are claims of belt drive being a good way. I know it can be used as a rack, this way teeth can be facing the bottom and would not collect the dust deposit,

The Bell-Everman "Servobelt" arrangement is good this way, the belt teeth are protected by the "counterbelt"

community.carbide3d.com/t/bell-everman-s...belt-system/10923/11 has a nice diagram.

Seen that when they started, it is a very nice way of removing belt flexing on machines and with light loads it can do some very fast moves. Planning to do that for a long time now, but time is not on my side.

The thing with plasma CNC machines is, you have to know what you need from it. There is no "one size fits all" deal with plasma ( or any other cnc machine ).
The first and main question is: what do you want to cut with if ?
Now that is not addressed at the material you want to cut as plasma does not care much if it is cutting Alu, mild steel or extremely hard metals, that makes little difference.
Thickness makes a lot of difference as that is mainly dependant on speed, and speed is directly linked to profit i.e. less time to cut=more parts=more profit.
There are a lot of other things that will determine the speed of cut, but for us right now we are dealing with thickness.
Cutting from 1 to 3mm thick plates requires the machine to move fast, even with a 50A plasma source, so the machine needs to be light and agile and have very fast acceleration. At the other end of the spectrum, cutting 20mm thick plates goes slowly even with a 150A source, so the machine can move slowly, be heavy and have sluggish accelerations.
Then we to get to rapids. Rapids are not important for making one off's or doing large parts, say 2 to5 parts per plate. They are very important when you have to do 280 cuts in a single 2x1 meter plate and they are extremely important when doing 400 to 500 cuts on a 6x2 meter plate. This is very important for decorations and art.
Rapids greatly reduce the time it takes to do serial parts, and that in turn is good for profits.