[pete from TN]

But now that I have my Z working without a counterweight I do not currently feel it is necessary. I can get the Z moving at near 150IPM and it changes direction very quickly. Of course I am using some VERY stout 1125 oz inch motors at the max the Geckos will run them.... A counterweigt system is nice and will definitely help but you also have to consider that even tho the weight is now even or close to it you now have to deal with the inertia of that whole mass changing direction... Just a thought....

In reality, barring some serious use of 3d profiling at very high speeds the head never really has to move that quickly. Nor does the table for that matter, I can get rapids of ludicrous speed and I have backed it way down because I am prone to fat fingering stuff on the computer so I gotta be careful, however yesterday night I ran a little engraving program which can and did run at a nice feedrate and even that was nowhere near what it is capable of.... When I was designing this system I was very concerned with max rapid speed and acceleration but in real use at least for me right now and I am sure well into the future I have my max rapids set at 100ipm and even that is probably overkill.... Let's face it the table only travels like 30 inches either way so what do you need stupid fast rapids for? The Z axis is even less important to me, right now I have my toolchange position set 5" above the work zero and it gets there in a hurry.... Maybe if this was a large router table I would worry about it but on this relatively small machine it is PLENTY fast....

The Z axis head is Real heavy especially with the gears and original motor still on there and as one poster said a ballnut will just roll off a vertical ballscrew. If your gibs are so tight that the head does not fall without the screw attatched to the millhead then your gibs are indeed TIGHT!!! If the ballscrew was not there with it's associated pulleys and belt drive atop I am quite sure my millhead would come crashing down onto the table with some serious force.... The gibs would have to be quite near a lock tightness for it to hold up there.... I never weighed the millhead but I am no small fellow and without the cast iron framed motor on there and not including the Z axis slide I carried the millhead across the shop one time and let me tell ya I could not wait to put it down!!!! What is that saying if you plan to lift an elephant you had better have a place to put it down ready, well that goes double for an RF45 millhead!! peace