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

[oldmam4m80s]

Thank you irving and bikepete. Very good viewpoints and insights. This is exactly the information I need to make sure what I have envisioned will actually work. I have only done a few calculations on the project and I know doing the math is the blueprint for getting it done right. So I will be calculating more of what is needed very soon.

I had done some calculations in regard to steel flex of the table and gantry to make sure it would be within acceptable tolerances. I came up with some safe numbers but I do not have them handy at the moment. It was a green light for me to continue searching for the next item I needed though. I lost the deal I had setup with the 4"x8"x.25" steel tubing I had setup and I believe my design came in at about 3800lbs. Definitely not light! As far as speeds go I am in no hurry to manufacture parts fast. I would baby this machine to increase longevity of components as well as tools. Perhaps once it produced enough income to build a heavier duty one, not within such a small budget, I would consider building it to maximize speeds and getting better resolution and accuracy. For this build I will be satisfied to get in the .00X's inch. maybe a very low .0X's but I would rather it be more precise and accurate than not.

In response to the second/thirdhand machine option I have looked into it but I did not feel confident I would be able to find one within my budget. If by chance I did happened to come across one I would then have to learn that machine and troubleshoot any issues with it. I felt as though I would be much more prepared to troubleshoot and deal with a machine I designed and put together so that I would know every nook and cranny. This build to me is much more than just getting a machine to do a job. It is more of a Build it to learn it, troubleshoot along the way to fine tune it and watch it go! :) if that makes any sense.

I did think about the two screw option on an axis and if I had to the shorter of the axes would be ideal. An Engineer at a manufacturer I spoke to advised I go with only one screw per axis. I called them to ask about pricing on parts and WOW! they were very proud of their parts. I am considering a design with single screws at every axis but if I see the design benefits from two screws at any point I will go with that option.

As far as drives I have looked into them just briefly because I figure that there would need to be a lot of time involved in choosing the correct one once the other parts have been selected. I will give them another once over now though.

It is an ambitious project and I would like to become more aware of how this all comes to be. Every detail that has to be accounted for to achieve this build I would like to learn about. It is interesting to me to be involved in a from every aspect inception to reality.

Assembly of the table to maintain projected machinability was one thing I wrestled with. I have come up with a few ideas. I asked a couple of machine shops to Face mill the table top where all rail and screw mounting would take place but they wanted ALOT of money for just this simple operation. I know its not the easiest thing to do but not difficult enough to warrant the amount they wanted to charge. So for this issue I am currently designing an easy to make setup that will allow me to achieve the operation at home. It really is not as bad as I anticipated. So that issue has a cost effective solution to implement.

I just recently purchased a welder that I have yet to try out. It is a Lincoln Invertec 275s. I will TIG weld the assembly together to reduce warping. I will take the utmost care in making and designing the tools I will need to help me accomplish this build and they will be used for the next more precise build I spoke about earlier.

Thank you for the Link bikepete. I did not know it was one till I read over it a second ago to make sure I was responding to everything. I have read a few things on the subject, my eyes are still good so I should read some more :) I am looking into the link as I type. As far as resonance goes, I don't believe I will attain the speeds required in the current design but they are still something I should apply calculations on before buying a part just to be sure. I had not gotten that far since I am shopping around for economically available parts. Resonance changes per available ballscrew. :( This one I am considering is probably a good buy but I do not know it yet. I have contacted the person selling it and they advised they sell the large ones fast so I guess I should make up my mind on it. I just have not decided for sure since I am in hopes of finding one closer to my design.

The deciding factor on this particular ballscrew is strength of the Servo I am going to put it on. Let me find the link of the servo kit I am looking to buy to post that here. Well the link is a strict PDF. The website is not allowing me to view since I do not have a PDF reader on this PC. Here is the link from my other post: http://dmm-tech.com/Files/dmmmaxs14a_p.pdf I believe Irving already read this one and the torque of the motor seems to be just enough. When I posted my choice I had not anticipated the thickness of the ball screw to be as large so I would likely chose differenlt once I acquire the screw if necessary.