Reliability is important. How much trouble does the cutting dust cause? When I first thought about it, I saw bellows in my mind. Then I saw some more photos and it seems linear rail/carriage with build in wipers is "good enough". Is that really good enough? How much lubrication is needed?
I saw some in factory working in glass dust, running dry and getting some abuse, that was not very reliable but it worked for quite long time getting more and more play.
Should I make some shield above and around the torch to protect the rail from piercing products?
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, however it means the motor has to be mobile too which means more mass to accelerate. I found some T type (with the notches) belt with steel reinforcement, looped and probably long enough the whole rail. I can run the return side through the "tunnel" on the back of the beam, but what about the front? Should I worry about the dust? I plan to use the water table.
All of this "openness" means it's quite easy to upgrade if you start right. This is why the first few post of this topic have so much value, they are based on a lot of experience. A machine with shitty 40A plasma will cut faster and more precise than you can trace the material for manual cutting unless you fail seriously. Problems that pop up during build can be addressed earlier if they are expected. This is why I am not so sure about the dust issue, but hey, drawer slides do work well.
I put some pancake photos here:
Part of the message is hidden for the guests. Please log in or register to see it. The smaller one is 300W with resolver on some kind of test stand connected to 400W DC motor with coils instead of stator magnets. the CEM model M19 is quite comparable to Axem MC19S - I found crazy priced spares here:
inverterdrive.com/group/Armature-Discs/P...ring-Brush-Set-AXEM/
The oldest polish one is from 1971. I think the original patent is US3090880A from 1950s. I have some extra brushes and rotors, they show very little wear. As the articles state, there is little arcing and wear on the brushes - I believe the bearing failure is similarly possible as brush failure. Dismantling requires demagnetizing of the magnets - there are two wire loops with ends hidden under one plate. Maybe one day I will check the field strength with gaussmeter and attempt to change the noisy bearings in the worst of them and see if I can put it back together and remagnetize. Theres four of them, I will try to get them running. I think I could swap a good one for a decent straight plasma torch:P
@Tommylight: How often do You meet a bad bearing in an AC drive? I saw its quite possible to replace them with lots of caution and ducktape, and Andy even managed to turn the shaft and not end with hairy cylinder of swarf.
Thanks!