If its to cut wood and occasionally aluminum its perfectly fine.

But apart from deflection, there is ringing, vibration, when cutting metal. Ideally when an engineer is designing a machine he will know frequency of the tool - material and space bearings of Z and all other parts so it does not synchronize so all starts ringing like a bell. And i suspect use much more weight than needed just to be sure .


I remember what Dean said about one commercial machine , an expensive one, that if you hit it with a hummer it would "thump" not ring. So thats also important especially with metal machining.


In a DIY situation after designing a couple of machines as light as possible and as rigid as possible / blamed to be OTT even / i believe using 10mm plate as an additional steel bracing here and there we could imitate at least 5-8 times heavier machine properties.


For example my machine /1300x2600x200/ weighs 700kg all included and is at least as strong as 4 ton commercial one, if not more. You could lift it and hold it from one side, other side in air and deflection will be less than 0.05mm if not less than 0.01/


So remember the magic word- " bracing" with thick 10mm steel in all possible directions to imitate solid shape properties and at the same time keep things light. If you are making a machine to work aluminum. For wood your problem always will be not this but the spindle KW and how fast the machine could move.