Looking into a ballscrew, not sure if I should buy. Help

[irving2008]

Just found your other posts. That is a monster of a machine. What are you planning to machine in steel that size?

With that amount of z travel you're going to have real problems with rigidity. All the effort in worrying about screw tolerances is pointless, the gantry will deflect one or two orders of magnitude more.

I think you need to take a step back and explain why the machine needs to be this big.

[oldmam4m80s]

Thank you for chiming on this irving. Well I am building the machine to be able to handle a wide variety of things. I had one gentleman who approached me to machine some 500-800 lb steel pressure housings. I am unsure what machine they belonged to but they were pretty massive pieces of metal. They had been machined wrong at the factory and they were looking for someone to fix the error. They may have been something like 4'x3'x1.5' in size. just a rough estimate. That is not my main goal though. I basically just wanted to build a machine where I could turn down a minimal amount of jobs as possible. I also would like to make quiet a few custom parts (about 40%) for a personal project that will be large. perhaps not as large as the work area. But it will definitely come in handy. Some parts (about 15%) I want to make will need the majority of the work area. I would not mind making smaller CNC machine parts such as kits that I can put on the market locally to help people get into CNC building. The kit is more of a hopeful venture but the parts are a definite MUST have. I called many machine shops and in order to make the parts I would want I could pay for a CNC machine twice over so I decided to just build one and be done with it.

The only reason I am looking into this specific ballscrew is that it fits the budget better than most others I have found. It would be nice to find one that is a tad bit longer and smaller diameter as well as price tag but this has been the find that fits the build closest for now. I plan to use what I can get to increase income so I can buy new from Manufacturer and sell the used one to recoup some costs. Until that happens though I am left scrounging around for surplus and cheaper stuff that will get the job done.

I think for the pitch size though it may be too high. Would it be better to have a lower pitch such as 10mm or there about, when using weaker servo's? I guess the real question is what type of servos work best with high/low pitch ballscrews? Will it be best to go with a higher speed/torque servo with higher pitch ballscrews? or what is the relationship there, if any?