H & J Johnson wrote: > The Backlash is very small on the R/P [I can't measure it] but it does wear > out over time [I'm on my second set of rack and third set of pinions] I've > decided that it would be a better system if I moved to the ballscrew or a > super hard helical R/P. The ballscrew came out cheaper so.. that's where I'm > headed.. The R/P starts to get rough after it's worn in for a while and > finally at some point you just have to replace it.. It's not SUPER high > quality stuff either so the overall accuracy suffers a bit [It's very > repeatable, just not super accurate over linear length] > > Not sure I follow you on the bidirectional lead screw comp? > > J. Johnson > > > >> J. Johnson >> If the rack drive has no backlash and is strong enough to >> handle the >> cutting forces there is no reason to go to a ball screw. >> The bidirectional lead screw compensation works very well. >> Stuart >> >> On Fri, Sep 4, 2009 at 12:46 PM, H & J Johnson >> <hjjohn...@sasktel.net>wrote: >> >>> Thanks Steve, this was infact my plan. I've got a bunch of >>> >> G202's and >> >>> steppers sitting around. It would >>> be fairly simple to load it up and start playing and get my feet >>> >> wet that >> >>> way.. we'll see how things progress >>> from there. I'm several months away from any major changes on my >>> machine..just want to start >>> mapping out the process and seeing if I can make it work. :) >>> >>> Thanks again! >>> >>> J. Johnson >>> >>> >>>> H & J Johnson wrote: >>>> >>>> >>>>> Steven, thanks for taking the time to reply. I'm by no means a >>>>> >>>> programer>nor do I expect that I'd get proficient at it in the >>>> time frame needed [or to >>>> >>>>> the level that would be required]. I'm more interested in being >>>>> >>>> able to >>>> >>>>> 'look up' stuff and learn to read code a little.. to >>>>> >> understand what >> >>>>> is be asked where etc. >>>>> >>>>> >>>>> >>>> Actually, I think I might have been wrong about where to start. >>>> Get >>>> yourself an old throwaway PC, and install Linux using the EMC2 >>>> liveCD >>>> from linuxcnc.org. You will find that it's very similar to what >>>> you're >>>> used to, just some of the details are different. (The "program >>>> menu" is >>>> at the top left of the screen, and is labeled "Applications" >>>> instead of >>>> being at the bottom left and labelled "start" ...) >>>> >>>> Play around, and don't expect to save anything from this install. >>>> You >>>> can always intsall again if you do something that you can't fix. >>>> (Note: you can do a lot of experimentation just by booting from >>>> the CD >>>> - it's a fully functional system - but you may be nervous about >>>> destroying data, that's why I suggest doing an install on a PC >>>> that has >>>> no useful data on it) >>>> >>>> >>>>> On the motion controler I should have called it a step generator. >>>>> >>>> I've>used the G100 and have [haven't installed it yet] a Smooth >>>> Stepper>for Mach3. >>>> >>>> OK, I wasn't sure. There are several similar units for EMC2, but >>>> none >>>> use ethernet or USB for communications - they're either PCI or >>>> parallel >>>> port connected. >>>> >>>> >>>>> I've been satisfied w/ how Mach3 has run the only >>>>> thing that is driving my switch to EMC is the ability to do >>>>> >>>> proper tool >>>> >>>>> offsets while in 5 axis. Brian [from Artsoft] has advised me >>>>> >> that he >> >>>>> doesn't currently have plans to add this functionality. He's a >>>>> >>>> busy guy >>>> >>>>> and my move is in no way a slight against him. >>>>> >>>>> >>>>> >>>> None taken :) >>>> >>>> >>>>> I'm sure that a switch to EMC is more daunting in the initial >>>>> >>>> stages >>>> >>>>> than it is once one jumps in. However I'm at a bit of a loss >>>>> >>>> since I've >>>> >>>>> no experiance w/ Linux or EMC. >>>>> >>>>> >>>>> >>>> It's more in your head than anywhere else :) >>>> >>>> The differences between Linux and Windows today are a bit like the >>>> differences between cars. Some have the headlight switch on the >>>> dash, >>>> others on a stick on the steering column. Some need you to press >>>> a >>>> button to switch high/low beam, others need to be pulled to >>>> toggle, >>>> others are push-pull ... They all do more or less the same thing, >>>> but >>>> the controls are slightly different. You probably don't have much >>>> trepidation about jumping into an unfamiliar rental car - try >>>> adopting >>>> the same attitude toward a new operating system. (note: I'm not >>>> saying >>>> that there are no differences, or that it will never be >>>> frustrating to >>>> figure out how to do something on Linux that you already know how >>>> to do >>>> on Windows, it's just that most of the differences in day to day >>>> use are >>>> small details) >>>> >>>> >>>>> I've down loaded the manuals and will start reading them this >>>>> >>>> weekend.> >>>> >>>>> Has there been configurations created for a 5 axis system >>>>> >> where a >> >>>> person>can just add the head dimensions to allow the software to >>>> compute the tool >>>> >>>>> offsets? >>>>> >>>>> >>>> Yes, maybe. >>>> >>>> It depends on the construction of the head. There are two >>>> versions that >>>> I know of, one of which is included with EMC2 (5axiskins). Stuart >>>> Stevenson has also made a kinematics file for one of his >>>> Cincinatti >>>> 5-axis machines, which takes many things into account, including >>>> certain >>>> build errors. I don't know if that's finished yet. >>>> >>>> >>>>> I'm hoping I can put a auto tool length system in as well so the >>>>> machine automatically measures the tool length on each ATC. >>>>> >>>>> >>>>> >>>> Fully automatic measurement needs some G-code support at the >>>> moment (you >>>> can call a subroutine to measure and apply the length) >>>> >>>> >>>>> Just had a look at the Motec stuff, I see the 100 series has 8 >>>>> >>>> axis which >>>> >>>>> would suffice [I need min of 6, prefer 7] for my setup. I'm not >>>>> >>>> seeing >>>> >>>>> anywhere, where it states that it will output step/dir, as I >>>>> >> re- >> >>>> read your >>>> >>>>> reply I believe that is infact the case. >>>>> >>>>> >>>>> >>>> No, the Motenc hardware outptus analog control voltages. >>>> >>>> >>>>> Are the Mesa cards 'stackable' in that I can add as many as I >>>>> >>>> need [IIRC >>>> >>>>> they have 4 axis cards so I'd need two?] Does Mesa provide >>>>> >> some form >> >>>>> of a configuration file w/ their cards to help a user get to >>>>> >>>> [almost] plug >>>> >>>>> and play, or does one have to manually configure the card etc? >>>>> >>>>> >>>>> >>>> You can mix and match anything you want. You can use parallel- >>>> port >>>> software PWM to control spindle speed, while using a Mesa card for >>>> some >>>> motors and a Pico Systems card (connected via a separate parallel >>>> port) >>>> for some other motors. They can be any mix of velocity control, >>>> torque >>>> control, PWM, and step/dir motors. >>>> >>>> A single Mesa 5i22 card can handle as many as 16 servos, though >>>> I'm not >>>> sure there's an FPGA configuration for that. The cards are >>>> reprogrammable, and you can select different "firmware" for the >>>> cards as >>>> you see fit, even using different firmware for each card when you >>>> have >>>> more than one. The Mesa cards have from 2 to 4 "IO Connectors". >>>> Each >>>> connector can support up to 4 motors, or 24 I/O lines, and in some >>>> cases >>>> you can use motor controls and I/O on the same connector. >>>> >>>> >>>>> Also on alot of this hardware I'm seeing the closed loop of the >>>>> >>>> encoders >>>> >>>>> coming back in. How does this play w/ a closed loop drive where >>>>> >>>> it requires >>>> >>>>> the encoder connection back to it's self, to be able to accuratly >>>>> >>>> drive the >>>> >>>>> motors? [ie; my Granite drives] >>>>> >>>>> >>>>> >>>> You can run the encoder back to EMC as well as to the drive. It >>>> shouldn't be too much of a load on the encoder line drivers. For >>>> the >>>> Fanuc Yellow Caps, you may want to look into an analog velocity >>>> mode >>>> servo amp. I don't know how well the Granite drives are matched >>>> to >>>> those relatively large motors. I wouldn't choose step/dir >>>> controlled >>>> drives unless I had to (for example, because that's all my >>>> software >>>> supports ... :) ), I'd much prefer to close the loop in the >>>> >> PC. I >> >>>> think >>>> you get snoother motion (which can translate to better surface >>>> finish), >>>> and you also have more advanced alogrithms available. The PID >>>> software >>>> in EMC2 is actually PIDFF - it has feed-forward terms that can be >>>> used >>>> to get better performance under acceleration. >>>> >>>> >>>>> Thanks VERY much for your help and advice.. >>>>> >>>>> >>>>> >>>> Sure. I just hope I'm right :) >>>> >>>> - Steve >>>> >>>> >>>> --------------------------------------------------------------- >>>> >> ---- >> >>>> ----------- >>>> Let Crystal Reports handle the reporting - Free Crystal Reports >>>> 2008 30-Day >>>> trial. Simplify your report design, integration and deployment >>>> >> - >> >>>> and focus on >>>> what you do best, core application coding. Discover what's new >>>> with >>>> Crystal Reports now. http://p.sf.net/sfu/bobj-july >>>> _______________________________________________ >>>> Emc-users mailing list >>>> Emc-users@lists.sourceforge.net >>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>>> >>>> >>> >>> ----------------------------------------------------------------- >>> >> ------------- >> >>> Let Crystal Reports handle the reporting - Free Crystal Reports >>> >> 2008 30-Day >> >>> trial. Simplify your report design, integration and deployment - >>> >> and focus >> >>> on >>> what you do best, core application coding. Discover what's new with >>> Crystal Reports now. http://p.sf.net/sfu/bobj-july >>> _______________________________________________ >>> Emc-users mailing list >>> Emc-users@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/emc-users >>> >>> >>> >> -- >> you can lead a person to knowledge >> but you cannot make him think >> ------------------------------------------------------------------- >> ----------- >> Let Crystal Reports handle the reporting - Free Crystal Reports >> 2008 30-Day >> trial. Simplify your report design, integration and deployment - >> and focus on >> what you do best, core application coding. Discover what's new >> with >> Crystal Reports now. http://p.sf.net/sfu/bobj-july >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> >> > > > ------------------------------------------------------------------------------ > Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day > trial. Simplify your report design, integration and deployment - and focus on > what you do best, core application coding. Discover what's new with > Crystal Reports now. http://p.sf.net/sfu/bobj-july > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > My suggestion is to just replace the pinion as most of the wear is there. At some point it maybe necessary to replace the rack as well. Of course if the amount of engagement is adjustable there may well be a lot more service gotten out of the pinions as well. Doug
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