I was reading an article recently about mitigation concepts that are known to be successful in mitigating the effects of earthquakes on buildings. The functional takeaway concept that I gleaned from the article (that applies to other construction also obviously....CNCs?? ) is active correction of forces that are (whether we like them or not) acting to knock THINGS out of alignment). Here is the idea that is by no means new except in the application to CNCs..... Friction Pendulum BearingsA modified version of friction pendulum bearings with some sort of dampener medium. I envision something like a "Non-Newtonian" fluid of some sort (for instance cornstarch and water; shown in the following picture...also known as "magic-mud", "Ooze" or similar) which works as a shear thickening fluid, or dilatant fluid, in which liquid the 'stickiness' (viscosity/thickness) increases when the shear rate increases (in water alone, shear is constant no matter how fast you move your fingers through it). Corn starch, "....when stirred slowly it looks milky, when stirred vigorously it feels like a very viscous liquid." The bearing on which the table sits would (I envision) be suspended in such a solid to keep vibrations from getting 'out of control' (resonance). Also gravity and a curved seat for the bearing (see picture that follows), would necessarily keep everything level with gravity (which is very good for building with pseudo liquid materials like fluid ABS or PLA or what not because then the balance of the part, the bed, AND the nozzle are all simultaneously balanced perpendicular to gravitational pull (which means the part is not pulled harder on one side then the other while it is still pliable and susceptible to having its shape messed up by gravity and a bed that may be sitting cock-eyed. Any ideas or thoughts. This is an open brainstorming session. Thanks to those that contribute, (PS....in brainstorming there are no ideas or thoughts too ridiculous to be shared. Any thoughts could be the one that directly works, or jogs a thought in someone else that would directly work.
True, stability while working is extremely essential. My thought is that there will always be a certain amount of instability. The key idea in my mind is to minimize such instabilities to whatever the 'acceptable' threshold of instability is. To that end what I am suggesting is a couple key points. Design constraints and specifications must necessarily be 'close-enough' to whatever the agreed upon tolerance is. My thought is that even though something is easy, it still takes time to do (even if only a minute or so) everytime one prints. Time spent preparing (even if only 15 seconds) adds up. The more things that affect the quality of print that you can automate mean the following; less mistakes less time correcting mistakes less worry less time spent in setup more time to do other tasks better overall quality of prints over time (assuming that, for instance...like many people....one allows the bed to get more and more out of tolerance until it reaches the threshold.....causing the prints to be more and more off. Although admittedly within the 'accepted tolerance', the print quality would necessarily degrade. and more With that general idea in mind, and the realization that there are always better ways of doing things my thought on a more specific visualization of how earthquake mitigated design could be applied to a CNC bed would look something like what follows. Hopefully this gives you enough to go on (coupled with the photos that I included earlier in this post). The core idea is to have four self stabilizing connections on the bed (similar to the one on which the building in the picture sits....which is placed on top of a foundation pier (I would assume). One would be placed at each corner. Oil could be all that is needed for the dampener, but I thought that a non-newtonian or Bingham plastic type liquid could be very effective as the substances become more thick and even brittle in nature as energy is introduced into the liquid. This would lend itself to helping to minimize vibration induced movement and or oscillation more and more as more energy is introduced (I.E. vibrations from the machining process itself....). Also, perhaps the tool assembly could have a ball hinge, which allows gravity to level the tool with the bed. Then all of them would conceivably have a screw mechanism (or something else) that serves the function of tightens down / stabilizing each respective self-leveling mechanism/ball hinge (whatever the final system happens to be) after an 'automatic' / quality assurance function of the program operates (perhaps set to run just prior to a print job....similar to the use of limit switches for boundary checking). Any other ideas!? Thanks for participating by the way. Sometimes people are afraid of giving ideas because the tendency is for people to find the reasons they don't work (which CONSTRUCTIVE criticism obviously has its place), but just not in the initial phases of coming up with new and innovative ideas. I am very adamant about the power of questioning the the status quo in order to come up with better, more effective and or even just different ways of doing the same thing....because doing such opens up countless possibilities.
Also a huge benefit of such a system is that they would be much more portable in nature....(YOU would not need a "level" surface to place the printer on). You could (perhaps if so desired..) design it such that you could even set the apparatus on the side of a hill in a park or some other place obviously and print stuff wheresoever the need presented itself?!
