Re: [Emc-users] DRO input?
[EMAIL PROTECTED] wrote: I do wonder how accurate the positioning is for a 50 foot table and how repeatable the positioning would be after a long move. That would still be one impressive machine. Well, this machine was supposed to have a 50 foot glass scale. Depending on the architecture of the machine's frame, and how close the scales were to the spindle, it could vary a lot. For instance, if the home position was at one end of the 50' scale, and you were way out in the middle of the table, then you'd be doing your cutting 25 feet from the home, and any differential thermal expansion between glass and iron would shift everything around. If the scale was constrained to the iron table, then there's be less quirky shifting of coordinates. Also, on a 50' machine, there is an opportunity for orthogonality errors to be magnified to a huge amount. The bottom line is you don't make swiss wristwatch parts on a machine with a 50 foot table. You make wing spars, or boat keels, or hatches for space shuttles, and the tolerances on these parts take into account the limits of precision such a large part can be made to. Jon - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input
What I would like to try someday is to connect linear encoders while still using rotary encoders. For example, if you have linear encoder resolution of 0.0005, and rotary encoder resolution of perhaps 0.0001, you could position from your rotary encoders just like normal but update the position with linear encoder position. Sort of use the linear encoder to know the position to the nearest half thou and use the rotary encoder for tenth positioning. Or heck with it, just get scales that you can set up to 1 micron resolution :-) But I think the motor needs to be controlled using its own feedback. - Original Message - From: Kirk Wallace [EMAIL PROTECTED] To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Sent: Saturday, February 02, 2008 5:29 PM Subject: Re: [Emc-users] DRO input On Sat, 2008-02-02 at 15:05 -0500, John Kasunich wrote: I like that allot can be done with EMC, HAL, and pyVCP without having to make the substantial cost jump for controllers, drivers and motors. Allot of value can be realized with an EMC enhanced manual machine. -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending) - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Emc-users DRO input?
Kirk, That's not my website on the DRO's I just built a couple from there and they work well. John On 1 Feb 2008 at 16:34, [EMAIL PROTECTED] wrote: That's a nice setup DRO system and website you have. I was fishing for a reason to have a serial micrometer connected to EMC for a reason other than as motion feed back or axis position. For instance, to automate offset adjustments, or something like Will Ferrell said in Old School, Maybe she's wearing something I haven't even thought of yet. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] DRO input
Send Emc-users mailing list submissions to emc-users@lists.sourceforge.net To subscribe or unsubscribe via the World Wide Web, visit https://lists.sourceforge.net/lists/listinfo/emc-users or, via email, send a message with subject or body 'help' to [EMAIL PROTECTED] You can reach the person managing the list at [EMAIL PROTECTED] When replying, please edit your Subject line so it is more specific than Re: Contents of Emc-users digest... Today's Topics: 1. Re: DRO input? (John Thornton) 2. Re: Emc-users DRO input? (Kirk Wallace) 3. Re: DRO input? (Jon Elson) 4. Re: DRO Input? (Jon Elson) 5. Re: DRO Input? (Jon Elson) 6. Re: DRO Input? (Jon Elson) 7. Re: DRO input? ([EMAIL PROTECTED]) 8. Re: DRO Input? (Anders Blix) 9. Re: DRO Input? (Kirk Wallace) -- Message: 1 Date: Fri, 01 Feb 2008 06:24:24 -0600 From: John Thornton [EMAIL PROTECTED] Subject: Re: [Emc-users] DRO input? That would depend on the accuracy of your scales... .4 precision (.001mm)is not cheap... In my case mine are not nearly that accurate... I guess it depends on how much accuracy is needed and the future of the machine. EMC does have screw mapping... The cheapo (relatively) DRO I'm looking at is accurate to 0.005 mm / 0.00019 which is good enough to be getting into the realms of temperature compensation for thermal expansion of the work. I accept the comments about DROs generally not liking rapids, but it has to be said rapid is a relative term, the rapid on my mill isn't going to be that rapid. I accept the points about home made DRO with the chinese non glass scales, just not robust enough, scale reader wise, against contaminants, and just not accurate enough, for what I want. I also accept the comments about modern NC servo systems never being at rest, this is a feature that I would always program out, WAIT 100 style, in g-code, I understand the benefits of this in a cut throat commercial production environment, but again, my mill won't be operating in one, so adding a whole 0.5 seconds here and there isn't going to have any downsides and will have plenty of upsides. I also accept the comments such as those above about screw mapping, but again, this is all adding an extra layer of fudge tables, whereas the DRO is measuring ACTUAL X Y Z positions. I also have to convert my mill to NC, it is currently all manual. SO it looks like (please comment) the story so far is... a/ DRO (with pukka glass scales) is a huge boon to any manual mill. b/ A DRO could almost pay for itself in calibrating the screw etc mapping in emc, both initial set up and then monthly re-calibration, unless of course your time is valueless. c/ A DRO beats EMC as a fake dro ONLY, sans servo/steppers, see point b/ re time. d/ a DRO can enhance the functionality of EMC considerably, injecting trustworthy positioning data into EMC to re-calibrate screw etc mapping on the fly. e/ For NC then EMC is obviously the answer, since EMC is likely to be part of a DIY installation, a DRO makes making all those NC conversion parts that much easier and faster... the rule of thumb is between 50% for simple parts and 90% for complex parts, for time setting up vs actual making chips time, see point b/ re time again. f/ A DRO + EMC / NC system means redundancy, *lots* of things have to go wrong before you're knocked back to a pure manual machine. g/ So the trick here is getting that electronic feedback loop, either from the DRO or from the glass scales themselves, into EMC, lacking that electronic feedback loop, putting operator pauses into the gcode of a dual system still allows periodic operator visual checking of agreement on position. h/ lacking a DRO, the answer is to retrofit my machine with precision ballscrews and to scrape the ways etc, a prospect that will take about ten time the time of fitting a DRO and cost at least five times as much in money. i/ I guess this is going to come down to a philosophical choice, do you pursue the DRO first, or the EMC + NC first? vi vs emacs anyone? cheers - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input?
I just wonder why you want to put such a nice DRO on a worn out old manual mill that needs the ways scraped and the screws are worn out? You will not be able to make an accurate part to the abilities of your DRO if the table won't stay where you put it and your Z is always changing because your table moves up and down as you move X and Y because the ways are worn... It's the silk purse/sows ear thing. And if cost is an issue then a cheaper DRO would be more fitting for an old manual mill and more suited to the jobs one might do on that type of equipment. Do you really expect to make parts with a +- 0.005mm tolerance on an old manual mill just because you add a DRO? John On 2 Feb 2008 at 3:57, [EMAIL PROTECTED] wrote: The cheapo (relatively) DRO I'm looking at is accurate to 0.005 mm / 0.00019 which is good enough to be getting into the realms of temperature compensation for thermal expansion of the work. h/ lacking a DRO, the answer is to retrofit my machine with precision ballscrews and to scrape the ways etc, a prospect that will take about ten time the time of fitting a DRO and cost at least five times as much in money. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input?
drivers are free to (and probably should) keep encoder counts in 'long long's. This way, the exported count may wrap at 2^31-1 (limit of signed 32-bit ints) but the exported position can continue to increase to 2^63-1 counts. Jeff - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input
[EMAIL PROTECTED] wrote: i/ I guess this is going to come down to a philosophical choice, do you pursue the DRO first, or the EMC + NC first? vi vs emacs anyone? If you are going to the trouble and expense of embarking on one of these paths, then the CNC path is the most reward for your efforts. You need some kind of encoder either way, and you need some kind of box (DRO or PC). With a DRO, you can position precisely. That is IT. You can't MOVE any more precisely than your hands can turn the handles. You can't cut angles and arcs by hand. Using a rotary table to do angles and arcs has so many limitations, I don't want to waste bandwidth on it. The first time you design a part with free-flowing angles and arcs, and watch the machine cut it as easily as a straight line parallel to the ways, you will be kicking yourself and saying I should have done this YEARS ago! I know, I was there about a decade ago. I retrofitted two axes on my Bridgeport, and immediately designed a piece for the Z-axis retrofit with all sorts of stuff I never would have attempted with a rotary table. It took minutes to cut, instead of a WHOLE DAY fooling around with a RT. Heh heh, yes, I'm an emacs guy, but I only know how to use 5% of emacs. But, that 5% is a great boon. Jon - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input?
John Thornton wrote: I just wonder why you want to put such a nice DRO on a worn out old manual mill that needs the ways scraped and the screws are worn out? Hate to argue, but the differential wear in the screws makes it totally impossible to make anything with better than 1/8 accuracy using the dials on the handwheels. With a DRO or any other direct measuring scheme, you CAN make FAR more accurate parts. Even a dial caliper bolted to the slides will work. The differential wear on the screws can easily be more than one order of magnitude worse than any worn spot in the ways. You will not be able to make an accurate part to the abilities of your DRO if the table won't stay where you put it and your Z is always changing because your table moves up and down as you move X and Y because the ways are worn. I have a 1938 Bridgeport with all this sort of way wear, but I can make parts of substantial size to within .001 tolerance with little difficulty. With the original Acme screws, I was lucky to get within .025 of where I wanted to be. I put an ancient Bridgeport optical measuring system (glass reflective scales and rear-projection magnifier boxes) on it in 1995 or so, and suddenly I could make a box with holes and a cover with matching holes, and didn;t have to spend a day filing out the holes to match! Wow! Jon - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input
Jon Elson wrote: [EMAIL PROTECTED] wrote: i/ I guess this is going to come down to a philosophical choice, do you pursue the DRO first, or the EMC + NC first? vi vs emacs anyone? If you are going to the trouble and expense of embarking on one of these paths, then the CNC path is the most reward for your efforts. The first time you design a part with free-flowing angles and arcs, and watch the machine cut it as easily as a straight line parallel to the ways, you will be kicking yourself and saying I should have done this YEARS ago! I second that. I've only had my machine working for a month, and I'm already changing the way I look at machining. For example, this part: http://jmkasunich.com/cgi-bin/blosxom/shoptask/spindle-encoder-bracket-01-07-08.html Because I was fitting an odd shaped part into a odd-shaped blank with oddly located holes in it, there was no cut in the entire part that was parallel to a machine axis. The blank was mounted at an angle too... The only things that were aligned to the machine are the two 3/8 holes that I clamped it down with. Regards, John Kasunich - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input
On Sat, 2008-02-02 at 15:05 -0500, John Kasunich wrote: Jon Elson wrote: [EMAIL PROTECTED] wrote: i/ I guess this is going to come down to a philosophical choice, do you pursue the DRO first, or the EMC + NC first? vi vs emacs anyone? If you are going to the trouble and expense of embarking on one of these paths, then the CNC path is the most reward for your efforts. The first time you design a part with free-flowing angles and arcs, and watch the machine cut it as easily as a straight line parallel to the ways, you will be kicking yourself and saying I should have done this YEARS ago! I second that. I've only had my machine working for a month, and I'm already changing the way I look at machining. For example, this part: http://jmkasunich.com/cgi-bin/blosxom/shoptask/spindle-encoder-bracket-01-07-08.html Because I was fitting an odd shaped part into a odd-shaped blank with oddly located holes in it, there was no cut in the entire part that was parallel to a machine axis. The blank was mounted at an angle too... The only things that were aligned to the machine are the two 3/8 holes that I clamped it down with. Regards, John Kasunich I like that allot can be done with EMC, HAL, and pyVCP without having to make the substantial cost jump for controllers, drivers and motors. Allot of value can be realized with an EMC enhanced manual machine. -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending) - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input
On Sat, 2008-02-02 at 11:57 +, [EMAIL PROTECTED] wrote: ... snip a/ DRO (with pukka glass scales) is a huge boon to any manual mill. Agreed. I write all my way-points with a sharpie on the vise or table before hand so, I don't know what I would do without a DRO of some sort. b/ A DRO could almost pay for itself in calibrating the screw etc mapping in emc, both initial set up and then monthly re-calibration, unless of course your time is valueless. My ex-DRO was too complicated to use other than as a straight position display making any features it has useless. c/ A DRO beats EMC as a fake dro ONLY, sans servo/steppers, see point b/ re time. From my point of view, an EMC based DRO will beat a standard DRO because I have plenty of free PC's with color displays and printer ports. Why pay for something you don't need? Just buy some scales, sprinkle on some HAL and pyVCP and you're done. Plus, with minor additions you can control the spindle, mist, whatever. But wait, there's more, you also have a migration path to EMC. d/ a DRO can enhance the functionality of EMC considerably, injecting trustworthy positioning data into EMC to re-calibrate screw etc mapping on the fly. No, EMC an the DRO get the same information from the scales. The only time the DRO might be necessary is if the parallel port can't keep up with the the data rate. In which case you could go with an interface card with hardware counters, like the Pluto(?) and others. Otherwise, you would have to filter the scale data through the DRO which won't add anything to the data and will impose restrictions due to how the DRO would interface to EMC. e/ For NC then EMC is obviously the answer, since EMC is likely to be part of a DIY installation, a DRO makes making all those NC conversion parts that much easier and faster... the rule of thumb is between 50% for simple parts and 90% for complex parts, for time setting up vs actual making chips time, see point b/ re time again. There is less waste with having an EMC based DRO from the start. f/ A DRO + EMC / NC system means redundancy, *lots* of things have to go wrong before you're knocked back to a pure manual machine. I don't think redundancy is that important. If you have a good e-stop system and something breaks, you're just not machining until you get it fixed. If what is broken happens to be a PC, you probably have a spare one loaded and ready to go. g/ So the trick here is getting that electronic feedback loop, either from the DRO or from the glass scales themselves, into EMC, lacking that electronic feedback loop, putting operator pauses into the gcode of a dual system still allows periodic operator visual checking of agreement on position. h/ lacking a DRO, the answer is to retrofit my machine with precision ballscrews and to scrape the ways etc, a prospect that will take about ten time the time of fitting a DRO and cost at least five times as much in money. I agree. I think an EMC based DRO is a good way to enhance a manual machine, changing or spending as little as possible. i/ I guess this is going to come down to a philosophical choice, do you pursue the DRO first, or the EMC + NC first? vi vs emacs anyone? cheers I realize I may have missed something along the thread which would change everything I have said here. I also failed to consider fitting rotary encoders to your hand wheels, sparing the expense of linear scales. An argument for linear scales is, they give you your actual position without having to guess at things like backlash. My counter is, that you still need to use good manual machining practices to deal with backlash and positional stability problems. Coming up to a dimension from the same direction for each pass, is needed to take up backlash and preload the system against the cutting force. Backlash elimination and preload beats a sloppy, but accurate initial position. Linear scales can mask the need to pay attention to real world machine dynamics. -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending) - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO Input?
Message: 9 Date: Thu, 31 Jan 2008 13:36:51 -0800 From: Dave Engvall [EMAIL PROTECTED] Subject: Re: [Emc-users] DRO input? Hi Dave, It all depends on what you want to do. If you just want manual position then the glass scales will do your job. However, if you ever intend to control the axes then encoders mounted on the end of the ball screws would be my choice. USdigital or Automation Direct (Koyo) encoders are reasonably priced and should do the job. With respect to you all, I know about encoders, and I know any CNC control software is going to need positional input many, many times per second. but... sticking an encoder on an axis is not measuring the position of anything except the leadscrew, it takes no account whatsoever of backlash, uneven wear or pitch errors. To a certain extent you can map out backlash and areas of wear on a leadscrew, but leadscrew pitch errors are going to be tough. The DRO is, quite differently, measuring the *actual* X Y Z position, if the DRO says you are 100.000 mm from point A then you can take it to the bank. My leadscrews are ten turns to the inch, I can compensate for backlash etc manually, second nature, and even with less than theoretically perfect accuracy I can still trust feeding a leadscrew in a few thou and know and measure that the error on that movement is very small. We appear to be confusing two things. Encoding leadscrew rotational angles and feeding this back to the human brain or CNC software, and factoring in mental or electronic fudge tables for backlash and wear, can give us fairly good accuracy of MOVEMENT. A DRO with proper glass scales gives us fairly good accuracy of POSITION. 5 times a second is *plenty* for an accurate positional measurement system to update an accurate movement system, and produce a system with true accuracy. While leadscrew encoders and a copy of emc and no stepper or servo motors will indeed give me a system that will display X Y Z co-ordinates on a screen, the accuracy of these readings is going to be just as suspect as it is sans emc and encoders, only the DRO and pukka glass scales will give true positional accuracy. As someone who couldn't code hello world (except maybe in BASIC) writing the code isn't an option, so unless emc has this facility on the roadmap then being free as in beer isn't enough. Many thanks to all, hopefully there is some more meat in this subject yet. end - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO Input?
Dave. I would say all the advice given to you is sort of a shot in the dark- until you tell us your intentions with your equipment. Of course what you do with the advice is up to you. As far EMC and serial input from a DRO goes - there is no driver currently to do what you ask, but it could be written. One would need some information about the DRO first. Another idea is you could feed the scales output to EMC then Get EMC to output a signal to your DRO (assuming the scales output square wave signals) The question is why? Cheers Chris Morley Date: Fri, 1 Feb 2008 10:07:32 + From: [EMAIL PROTECTED] To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] DRO Input? Message: 9 Date: Thu, 31 Jan 2008 13:36:51 -0800 From: Dave Engvall Subject: Re: [Emc-users] DRO input? Hi Dave, It all depends on what you want to do. If you just want manual position then the glass scales will do your job. However, if you ever intend to control the axes then encoders mounted on the end of the ball screws would be my choice. USdigital or Automation Direct (Koyo) encoders are reasonably priced and should do the job. With respect to you all, I know about encoders, and I know any CNC control software is going to need positional input many, many times per second. but... sticking an encoder on an axis is not measuring the position of anything except the leadscrew, it takes no account whatsoever of backlash, uneven wear or pitch errors. To a certain extent you can map out backlash and areas of wear on a leadscrew, but leadscrew pitch errors are going to be tough. The DRO is, quite differently, measuring the *actual* X Y Z position, if the DRO says you are 100.000 mm from point A then you can take it to the bank. My leadscrews are ten turns to the inch, I can compensate for backlash etc manually, second nature, and even with less than theoretically perfect accuracy I can still trust feeding a leadscrew in a few thou and know and measure that the error on that movement is very small. We appear to be confusing two things. Encoding leadscrew rotational angles and feeding this back to the human brain or CNC software, and factoring in mental or electronic fudge tables for backlash and wear, can give us fairly good accuracy of MOVEMENT. A DRO with proper glass scales gives us fairly good accuracy of POSITION. 5 times a second is *plenty* for an accurate positional measurement system to update an accurate movement system, and produce a system with true accuracy. While leadscrew encoders and a copy of emc and no stepper or servo motors will indeed give me a system that will display X Y Z co-ordinates on a screen, the accuracy of these readings is going to be just as suspect as it is sans emc and encoders, only the DRO and pukka glass scales will give true positional accuracy. As someone who couldn't code hello world (except maybe in BASIC) writing the code isn't an option, so unless emc has this facility on the roadmap then being free as in beer isn't enough. Many thanks to all, hopefully there is some more meat in this subject yet. end - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users _ - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Emc-users DRO input?
That is how my DRO's work that I built for my mill and lathe. http://www.shumatech.com/ John On 31 Jan 2008 at 18:04, [EMAIL PROTECTED] wrote: Another thought, is there any value in having an RS-232 connection with serial calipers or micrometers? - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input?
That would depend on the accuracy of your scales... .4 precision (.001mm)is not cheap... In my case mine are not nearly that accurate... I guess it depends on how much accuracy is needed and the future of the machine. EMC does have screw mapping... John On 1 Feb 2008 at 4:04, [EMAIL PROTECTED] wrote: The DRO is, quite differently, measuring the *actual* X Y Z position, if the DRO says you are 100.000 mm from point A then you can take it to the bank. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Emc-users DRO input?
On Fri, 2008-02-01 at 06:03 -0600, John Thornton wrote: That is how my DRO's work that I built for my mill and lathe. http://www.shumatech.com/ John On 31 Jan 2008 at 18:04, [EMAIL PROTECTED] wrote: Another thought, is there any value in having an RS-232 connection with serial calipers or micrometers? That's a nice setup DRO system and website you have. I was fishing for a reason to have a serial micrometer connected to EMC for a reason other than as motion feed back or axis position. For instance, to automate offset adjustments, or something like Will Ferrell said in Old School, Maybe she's wearing something I haven't even thought of yet. -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending) - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO Input?
RogerN wrote: Would it be difficult to update the actual position with the position from the linear encoders? The DRO position would just stomp on the actual position. Hopefully most of the time the error would be small and it would require real time DRO position... or perhaps only assign the DRO value when the axis is moving very slow or stopped. How about when moving at 60 IPM? What is the time delay in the DRO software? I've seen a number of good DROs that have SIGNIFICANT delays in the update, and settle once you slow down. If the serial output from the DRO box has a 1/4 second delay, and the servo is running at 1000 updates a second, you can only re-sync when you KNOW the machine is dead still. A true servo is NEVER dead-still, it is always bouncing between adjacent encoder counts. Jon - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input?
Yep! Wilson machine bought a 50' x 4' CMM at a Boeing auction. Got it cheap and spent a million moving it and getting it set up again. And that was only a few miles. Holy COW! a 50 FOOT CMM? There must only be 2 or 3 in the entire US that big. (I can understand why Boeing would need such a machine.) 50 foot at .0001 / Inch resolution would almost be at the limit for a 32 bit unsigned integer! I could see some really strange software bugs begin to show up. (Signed vs unsigned integers). Would a double precision float handle that? Yikes! 0xD693A400 - or something like that. Jim Combs - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO Input?
I have a different idea. Why not tap in to the signal from the encoders themselves? If this is glass scales with proper quadrature output it should be simple to read this signals by a cheap card? There is nothing that says the quadrature signals can't be read by both EMC and the DRO main unit. I plan to do this myself. I also bought a far eastern DRO with glass scales and hope to be able to tap in to the signals being transmitted by the scales. I have a Universal Stepper Card with quadrature inputs. At the same time it is quite nice to have the DRO for manual milling. Does anyone have a good reason for not doing this? I should possibly use optoisolators though, right? Anders -Original Message- From: [EMAIL PROTECTED] [mailto:emc-users- [EMAIL PROTECTED] On Behalf Of Chris Morley Sent: 1. februar 2008 12:02 To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] DRO Input? Dave. I would say all the advice given to you is sort of a shot in the dark- until you tell us your intentions with your equipment. Of course what you do with the advice is up to you. As far EMC and serial input from a DRO goes - there is no driver currently to do what you ask, but it could be written. One would need some information about the DRO first. Another idea is you could feed the scales output to EMC then Get EMC to output a signal to your DRO (assuming the scales output square wave signals) The question is why? Cheers Chris Morley Date: Fri, 1 Feb 2008 10:07:32 + From: [EMAIL PROTECTED] To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] DRO Input? Message: 9 Date: Thu, 31 Jan 2008 13:36:51 -0800 From: Dave Engvall Subject: Re: [Emc-users] DRO input? Hi Dave, It all depends on what you want to do. If you just want manual position then the glass scales will do your job. However, if you ever intend to control the axes then encoders mounted on the end of the ball screws would be my choice. USdigital or Automation Direct (Koyo) encoders are reasonably priced and should do the job. With respect to you all, I know about encoders, and I know any CNC control software is going to need positional input many, many times per second. but... sticking an encoder on an axis is not measuring the position of anything except the leadscrew, it takes no account whatsoever of backlash, uneven wear or pitch errors. To a certain extent you can map out backlash and areas of wear on a leadscrew, but leadscrew pitch errors are going to be tough. The DRO is, quite differently, measuring the *actual* X Y Z position, if the DRO says you are 100.000 mm from point A then you can take it to the bank. My leadscrews are ten turns to the inch, I can compensate for backlash etc manually, second nature, and even with less than theoretically perfect accuracy I can still trust feeding a leadscrew in a few thou and know and measure that the error on that movement is very small. We appear to be confusing two things. Encoding leadscrew rotational angles and feeding this back to the human brain or CNC software, and factoring in mental or electronic fudge tables for backlash and wear, can give us fairly good accuracy of MOVEMENT. A DRO with proper glass scales gives us fairly good accuracy of POSITION. 5 times a second is *plenty* for an accurate positional measurement system to update an accurate movement system, and produce a system with true accuracy. While leadscrew encoders and a copy of emc and no stepper or servo motors will indeed give me a system that will display X Y Z co-ordinates on a screen, the accuracy of these readings is going to be just as suspect as it is sans emc and encoders, only the DRO and pukka glass scales will give true positional accuracy. As someone who couldn't code hello world (except maybe in BASIC) writing the code isn't an option, so unless emc has this facility on the roadmap then being free as in beer isn't enough. Many thanks to all, hopefully there is some more meat in this subject yet. end - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users _ - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users
Re: [Emc-users] DRO input?
[EMAIL PROTECTED] wrote: Yep! Wilson machine bought a 50' x 4' CMM at a Boeing auction. Got it cheap and spent a million moving it and getting it set up again. And that was only a few miles. Holy COW! a 50 FOOT CMM? There must only be 2 or 3 in the entire US that big. (I can understand why Boeing would need such a machine.) 50 foot at .0001 / Inch resolution would almost be at the limit for a 32 bit unsigned integer! I could see some really strange software bugs begin to show up. (Signed vs unsigned integers). Would a double precision float handle that? That's a good point. I vaguely seem to recall the OLD EMC(1) overflowed the 32-bit raw encoder count into a double float. The current version just goes to a 32-bit signed value (unless this has been changed recently). I was wondering if that would ever be a problem. Hmm, calculating it, I get 50 * 12 * 1 = 6 million, which is not anywhere near 4 billion, or even +/- 2 billion, which is what the numerical limits of a 32-bit integer are. I calculate that 2^31 / ( 1 * 12) = 17896.xxx FEET, which sounds like it is a lot less of a problem. Jon - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] DRO input?
Sorry, haven't RTFM, downloading as I type. I'm considering buying a Far Eastern made 3 axis DRO for my Pinnacle universal mill, DRO + 3 glass scales (to 1/5thou) and all cabling etc etc for under 400 UK Pounds. This DRO has an RS232 output. So, does EMC have the facility to take absolute X Y Z positioning data from the RS232 on the DRO, rather than the traditional method of counting leadscrew revolutions and subtracting backlash and wear? TIA GF - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input?
emc2 doesn't include any serial protocol drivers. You would have to write the driver to do this yourself. The most important thing to know is that emc2 requires a new feedback position at the servo rate (typically 1ms) and emc (not external hardware) has to control when the feedback position is retrieved. The first DRO-with-rs232-output I looked at (http://www.newall.com/DROs/c80_rs232.htm) has a maximum report rate of 0.5 seconds per report, and the timing is controlled by the DRO, not by the PC. I don't think that this source of position feedback is a good one for emc. Jeff - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input?
[EMAIL PROTECTED] wrote: Sorry, haven't RTFM, downloading as I type. I'm considering buying a Far Eastern made 3 axis DRO for my Pinnacle universal mill, DRO + 3 glass scales (to 1/5thou) and all cabling etc etc for under 400 UK Pounds. This DRO has an RS232 output. So, does EMC have the facility to take absolute X Y Z positioning data from the RS232 on the DRO, rather than the traditional method of counting leadscrew revolutions and subtracting backlash and wear? If you mean to control the position of a machine as a closed-loop servo system, using the RS232 output, the answer is no. EMC by default reads encoder position 1000 times a second. It is highly unlikely the RS232 output of your DRO updates more than a couple times a second. Depending on the type of signals coming from the scales directly, they may be usable. The position resolution os fairly low, however. I assume 1/5thou means ~.0002, which is actually 0.005mm Servo control works a lot better with a higher resolution. Jon - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input?
On Thu, 2008-01-31 at 11:04 -0600, Jeff Epler wrote: emc2 doesn't include any serial protocol drivers. You would have to write the driver to do this yourself. The most important thing to know is that emc2 requires a new feedback position at the servo rate (typically 1ms) and emc (not external hardware) has to control when the feedback position is retrieved. The first DRO-with-rs232-output I looked at (http://www.newall.com/DROs/c80_rs232.htm) has a maximum report rate of 0.5 seconds per report, and the timing is controlled by the DRO, not by the PC. I don't think that this source of position feedback is a good one for emc. Jeff Besides EMC or HAL would make a perfectly good, and less expensive machine controller or DRO with the scales alone. In thinking about scales again, one thought that came to mind is, EMC might make a good CMM (manual or powered). But I guess the real magic is in the granite slides, though errors could be mapped out. Which brings me back to the issue of accurate standards. Another thought, is there any value in having an RS-232 connection with serial calipers or micrometers? -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending) - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input?
On Thu, 2008-01-31 at 12:54 -0800, Kirk Wallace wrote: ... snip In thinking about scales again, one thought that came to mind is, EMC might make a good CMM (manual or powered). But I guess the real magic is in the granite slides, though errors could be mapped out. Which brings me back to the issue of accurate standards. Another thought, is there any value in having an RS-232 connection with serial calipers or micrometers? FYI on eBay: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItemitem=290200642943 EMC CMM? -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending) - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input?
Hi Dave, It all depends on what you want to do. If you just want manual position then the glass scales will do your job. However, if you ever intend to control the axes then encoders mounted on the end of the ball screws would be my choice. USdigital or Automation Direct (Koyo) encoders are reasonably priced and should do the job. Both my Mazak and my Cincinnati are configured that way. I use the highest resolution I can buy ... 2500 ppr which gives me 10K counts/rev. This, of course, assumes you are going to use servo's not steppers. Using this approach with emc should get you a DRO at less than the 400 UK for the scales and give you an upgrade path into machine control. http://automationdirect.com http://usdigital.com HTH Dave On Jan 31, 2008, at 9:11 AM, Jon Elson wrote: [EMAIL PROTECTED] wrote: Sorry, haven't RTFM, downloading as I type. I'm considering buying a Far Eastern made 3 axis DRO for my Pinnacle universal mill, DRO + 3 glass scales (to 1/5thou) and all cabling etc etc for under 400 UK Pounds. This DRO has an RS232 output. So, does EMC have the facility to take absolute X Y Z positioning data from the RS232 on the DRO, rather than the traditional method of counting leadscrew revolutions and subtracting backlash and wear? If you mean to control the position of a machine as a closed-loop servo system, using the RS232 output, the answer is no. EMC by default reads encoder position 1000 times a second. It is highly unlikely the RS232 output of your DRO updates more than a couple times a second. Depending on the type of signals coming from the scales directly, they may be usable. The position resolution os fairly low, however. I assume 1/5thou means ~.0002, which is actually 0.005mm Servo control works a lot better with a higher resolution. Jon -- --- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input?
Kirk Wallace wrote: On Thu, 2008-01-31 at 12:54 -0800, Kirk Wallace wrote: ... snip In thinking about scales again, one thought that came to mind is, EMC might make a good CMM (manual or powered). But I guess the real magic is in the granite slides, though errors could be mapped out. Which brings me back to the issue of accurate standards. Another thought, is there any value in having an RS-232 connection with serial calipers or micrometers? FYI on eBay: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItemitem=290200642943 EMC CMM? Good Gourd! $99 for the machine, $9900 to move it to your shop, and that's if you are pretty close! That thing must weigh 15 tons, maybe a lot more. Jon - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DRO input?
On Jan 31, 2008, at 6:01 PM, Jon Elson wrote: Kirk Wallace wrote: On Thu, 2008-01-31 at 12:54 -0800, Kirk Wallace wrote: ... snip In thinking about scales again, one thought that came to mind is, EMC might make a good CMM (manual or powered). But I guess the real magic is in the granite slides, though errors could be mapped out. Which brings me back to the issue of accurate standards. Another thought, is there any value in having an RS-232 connection with serial calipers or micrometers? FYI on eBay: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItemitem=290200642943 EMC CMM? Good Gourd! $99 for the machine, $9900 to move it to your shop, and that's if you are pretty close! That thing must weigh 15 tons, maybe a lot more. Yep! Wilson machine bought a 50' x 4' CMM at a Boeing auction. Got it cheap and spent a million moving it and getting it set up again. And that was only a few miles. Dave Jon -- --- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
