3 ms·

I wasn't going to read it as I skimmed through, but I recognized the lathe (minus the computer and shield) and am glad I read through. Having worked metal with

by wwortiz 16y ago

I wasn't going to read it as I skimmed through, but I recognized the lathe (minus the computer and shield) and am glad I read through. Having worked metal with these things and mills you can easily understand why cnc machines are so damn expensive. There is so much to deal with and I think if you would have chosen a mill instead this would have ended in more headaches more quickly. One question that has more to do with the tech than the hell part I have is: did you have to deal with the excess strips of metal (which I've seen build up to dangerous length of spinning razor metal when people were being stupid) in the computer or was it under manual inspection? (There's plenty more that I thought about but that was my first)

jacquesm 16y ago
There was a 'swarf breaker' option, especially useful for working with plastics but also when working with stainless steel. During rough-cutting this would modulate the toolbit by pausing it just long enough that the swarf would break and would fall away from the toolbit. If you don't do that in some materials it will build up to the point where it will form a giant mess which can cause the whole thing to stall out, cause toolbreakage or even machine damage. Swarf control is a very tricky sub problem of the whole machining thing. I left out the milling program that was developed in parallel, when I compare the two I'd say the mill was (in spite of being one dimension more) the easier one of the two.
- wwortiz 16y ago
  I can understand how you worked so many hours on this, this should have been a huge project for a bigger team with expertise in the field and knowledge of controls. I must say I would have given up much more early, although you probably would have too knowing what you know. Another question I had was if these machines required a large amount of manual interaction (though lubrication probably was at least provided by the machines at this time).
  - jacquesm 16y ago
    > I had was if these machines required a large amount of manual interaction Because they were 'retrofits' rather than machines designed from the ground up things like tool exchange, zeroing, tool breakage and so on caused quite a bit of operator interaction. If you look closely on the photo there is a little switch above the big red STOP button that we called the 'softstop', it was polled every few milliseconds in all situations except for thread cutting, and when engaged the machine will pull the tool away from the work (in all operations, including drilling, inside work, outside work and cut-off) so that you could stop the spindle. Later versions had a tool changer driven by a third stepper motor, this was mechanically a very weak device and caused tons of trouble. Lubrication on most manual lathes is either done by a hand pump that you operate ever so often, on more advanced machines it is timer driven, or coupled to the amount of movement on the carriage. There also is the coolant to take care of, we had a relay box hooked up so that the various functions of the machine could be switched on or off under programmatic control. All these mods together meant that installing the kit on an existing lathe was quite a bit of work, it wasn't unusual that more than one day went in to mating the x-y table to the machine (this is a very precise job), running tests, hooking up all the auxiliary stuff and so on.
    - wwortiz 16y ago
      Thanks for answering my questions, theres just so much work involved with these kinds of things and I'm sure it was just one thing after another. But it is rather interesting how you handled all of it especially for the time when cncs had only been out for like less than a decade and you were modifying existing machines.
  - mirkules 16y ago
    "I must say I would have given up much more early" In my experience, it's really easy to fall into the smooth-talking salesman trap, especially if you aren't fully aware of the scope of work. When you're already committed to the project, things like "let's just make a big push to get out feature X" don't sound so unreasonable until you realize that all you have been doing is making big pushes.

by wwortiz 16y ago

jacquesm 16y ago

There was a 'swarf breaker' option, especially useful for working with plastics but also when working with stainless steel. During rough-cutting this would modulate the toolbit by pausing it just long enough that the swarf would break and would fall away from the toolbit. If you don't do that in some materials it will build up to the point where it will form a giant mess which can cause the whole thing to stall out, cause toolbreakage or even machine damage. Swarf control is a very tricky sub problem of the whole machining thing. I left out the milling program that was developed in parallel, when I compare the two I'd say the mill was (in spite of being one dimension more) the easier one of the two.

wwortiz 16y ago
I can understand how you worked so many hours on this, this should have been a huge project for a bigger team with expertise in the field and knowledge of controls. I must say I would have given up much more early, although you probably would have too knowing what you know. Another question I had was if these machines required a large amount of manual interaction (though lubrication probably was at least provided by the machines at this time).
- jacquesm 16y ago
  > I had was if these machines required a large amount of manual interaction Because they were 'retrofits' rather than machines designed from the ground up things like tool exchange, zeroing, tool breakage and so on caused quite a bit of operator interaction. If you look closely on the photo there is a little switch above the big red STOP button that we called the 'softstop', it was polled every few milliseconds in all situations except for thread cutting, and when engaged the machine will pull the tool away from the work (in all operations, including drilling, inside work, outside work and cut-off) so that you could stop the spindle. Later versions had a tool changer driven by a third stepper motor, this was mechanically a very weak device and caused tons of trouble. Lubrication on most manual lathes is either done by a hand pump that you operate ever so often, on more advanced machines it is timer driven, or coupled to the amount of movement on the carriage. There also is the coolant to take care of, we had a relay box hooked up so that the various functions of the machine could be switched on or off under programmatic control. All these mods together meant that installing the kit on an existing lathe was quite a bit of work, it wasn't unusual that more than one day went in to mating the x-y table to the machine (this is a very precise job), running tests, hooking up all the auxiliary stuff and so on.
  - wwortiz 16y ago
    Thanks for answering my questions, theres just so much work involved with these kinds of things and I'm sure it was just one thing after another. But it is rather interesting how you handled all of it especially for the time when cncs had only been out for like less than a decade and you were modifying existing machines.
- mirkules 16y ago
  "I must say I would have given up much more early" In my experience, it's really easy to fall into the smooth-talking salesman trap, especially if you aren't fully aware of the scope of work. When you're already committed to the project, things like "let's just make a big push to get out feature X" don't sound so unreasonable until you realize that all you have been doing is making big pushes.