Interesting discussion but the economics of this discussion are escaping me ....
I work with a manufacturer that runs a large waterjet system 1-2 shifts per day at least 5 days per week. Their biggest costs related to the waterjet are water and electricity. The amount of water they use and the sewage charges they pay to dispose of it are significant. Electicity costs are at least $1000 per month. It isn't difficult to pay $50,000 for a decent water jet pump.... I believe the waterjet system that they have (gantry, conveyor, pump, water handling system, and controls installed ) was about $250K when it was new 10 years ago. Waterjet swivel joints are expensive, but they are incidental to the cost of operating the machine. Sheetcam is very inexpensive compared to anything related to waterjet cutting. It does cost more than EMC2 but not that much. ;-) Dave On 4/20/2010 10:42 AM, Viesturs Lācis wrote: >>> I would like to do it without any additional cost and in EMC >>> so that i can use my current CAM application, so that is why i was >>> asking, if someone has managed to implement preprocessor for EMC that >>> does tangential control. >>> >> I fully understand. Apart from the monetary cost of buying another >> package you then need to spend time and effort learning how to use it. >> > Yes, You got the point very precisely. Plus i would like to mention, > that my programm - Wrykrys - is made specifically for > waterjet/plasma/laser cutting and has some very cool features; for > example - cutting only piercing points, which is crucial for cutting > brittle materials, easy switching the side of compensation (side of > the line, on which the tool goes and the amount of tool (width of > water jet kerf in this case) compensation) and few more, about which i > am not sure that they are present in SheetCAM. SheetCAM seems to be > first of all CAM for milling, which is adapted for > waterjet/plasma/laser cutting - it seems to have limited options with > lead-in/lead-out moves, which are very well-developed in my software. > > >>> No, that point will move, if the head rotates around C and the head is >>> tilted around B axis. >>> I believe that some additional work with kinematics module will solve >>> this issue and EMC will calculate all the necessary compensating moves >>> >>> >> Theoretically you should be able to do it all with kinematics but it >> could be tricky to implement. You would have two options: >> 1) As you suggested, set B to the kerf angle then rotate C to be >> tangential to the cut path >> 2) Have A as tilt left/right and B as tilt front/back then use >> kinematics to operate both axes as you cut. The kinematics would have to >> offset X and Y as it tilts A and B. This would be a variation on the >> standard 5 axis kinematics. >> >> > I certainly would choose second option, because it would not rotate > cutting head and thus does not require any kind of solution, how to > deal with the rotating movement in high pressure tubing. cheapest > swivel i have found cost 970 EUR, KMT swivels cost 1300 EUR. I am left > only with bulky spirals of the tubing which also would cost me more > than all the remaining parts of the project together, because inviting > technicians, that can create them, would cost me at least 600-700 EUR > plus cost of tube itself, which is ~40 EUR/m. driving myself to them > would be cheaper, but still costly. > there are 3 reasons, why i have not chosen the second option: > 1) by the time i was starting this project, i had no idea, how the > mechanical solution should be created - how it should be built. > now i have understood, that i can simple turn this assembly itself > around B axis so that C becomes A and i have, what i needed. > 2) first option allow tilting angles close to 70-80 degrees, so all > the potential of 5 axis waterjet cutting can be realised on the > machine side, affordable CAM programm is the biggest problem, second > option limits tilting angle to 20-25 degrees, but, if i give up all > the spirals in high pressure tubing and stay with traditional tubing > solution, i have 10-12 degrees of tilt available. fortunately, it is > still completely sufficient for taper compensation > 3) i do not understand, how can i make the second option work from > g-code and CAM software side :) with first option i have 2 theoretical > solutions - either preprocessor in EMC or postprocessor in SheetCAM or > even my existing CAM programm (today i wrote them to ask, if that is > possible, they did not say "no", i have to provide more details). > Is it possible to have G-code for B-C setup and have A-B setup on > machine and have the custom kinematics module to "connect" them > together? > > >> >>> My apologies, i do not completely understand, what did You mean by >>> this question :) >>> >>> >> If you are using scheme 1 above you need a joint on the nozzle that can >> handle rotation as the C axis rotates. A rotary joint then can handle >> waterjet pressures is likely to be very expensive. I suppose you could >> mount the nozzle assembly in a bearing so the nozzle itself does not rotate. >> >> > I have already built cutting head assembly with B and C axes. total > cost for materials - few small metal sheets, profiles and conical > bearings - as well as milling and lathing shafts has been around 100 > LVL, which is approximately 140 EUR or 210 USD. > This is exclusively DIY project on mechanical part, because it goes > together with switching from DOS-based controls to EMC :)) > > So i have started thinking that i would like to rebuild the assembly > to a A-B setup, if only i can get a working solution for G-code > generation and/or transformation for this setup to work. actually it > would save me a lot of money. > > Actually i have one more question - can anyone share a sample g-code > before and after inserting C rotation for tangential tool > control? > > Viesturs > > >> ------------------------------------------------------------------------------ >> Download Intel® Parallel Studio Eval >> Try the new software tools for yourself. Speed compiling, find bugs >> proactively, and fine-tune applications for parallel performance. >> See why Intel Parallel Studio got high marks during beta. >> http://p.sf.net/sfu/intel-sw-dev >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> >> > ------------------------------------------------------------------------------ > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. 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