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List question
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On Thu, 17 Jun 1999 01:50:07 -0500, mike grady <mgrady@...> wrote:
why cant all emc posts have emc at the beginning of the subjectThat would work, but requires voluntarism from just the opposite folks, than are being annoyed by a barnburner. Still, I've seen that used effectively to shield tangential stuff from the general listener. One minute problem, BTW, with making use of this "diplomacy" step, is that the current prefix [CAD_CAM_EDM_DRO] is sooooo bloody long to begin with, that adding another further filtering suffix like EMC: just makes it even HARDER to read the subject lines in any reasonable length field. Now that the group's at "cruise altitude", how hard would it be, ObieWan, to shorten that some? Maybe to "CNC+" or something short. Gar |
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Pete Jarman
As a lurker I would say keep the list as one. I have a home workshop with a
Taiwanese mill/drill which I am slowly improving as time allows. I also have a cupboard with some steppers and driver boxes which I rescued from the scrap bin about 10 years ago and one of these days I will have enough of my other projects out of the way to start fitting the steppers to the mill drill and thinking about a control system. Till then I'm lurking and watching developments so that when the time does come to start I will be some way up the learning curve. Pete Jarman IMLEC 99 at Northampton North of Bedford, England 3-4th July 1999 |
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Fred Proctor
There is an EMC mailing list proper that I set up a few months ago to
alert EMC users of new releases, etc. To subscribe to this, send mail to: listproc@... with subscribe emc in the body of the message. To unsubscribe, do the same, with "unsubscribe emc" instead. The list itself is "emc@...". Anyone can post; only subscribers will get the postings. The problem with emc@... is that you already need to know about the EMC to benefit from it. That's why the EMC postings started popping up on the CAD_CAM_EDM_DRO mail list. I was surprised at the amount of EMC postings, which dwarf those on the emc@... list. Of course, if you aren't interested in the EMC, it's a pain to have to hop through all the related messages. One way to reduce traffic on this list is for EMC users to post most of the discussion to the emc@... list, especially if it's something that's not likely to elicit new interest from anyone on the CAD/CAM list. I myself sort email by subject, and then trash anything in a subject I don't have the time to read. You can also filter messages by subject, so if [CAD_CAM_EDM_DRO] and EMC appear in the subject line, you can trash it or move it to a folder that you may only read and trash periodically. --Fred |
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Dan Mauch
You may run into a problem using the pic servo stuff with a step and
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direction software. They have the pic step but it executes rather slowly even on a 486-33 whereas on the serial port it screams. You may also run into a problem with having enough power. You may need external amps. Dan -----Original Message-----
From: Andy Olney <aolney@...> To: CAD_CAM_EDM_DRO@... <CAD_CAM_EDM_DRO@...> Date: Wednesday, June 16, 1999 8:00 PM Subject: Re: [CAD_CAM_EDM_DRO] List question From: "Andy Olney" <aolney@...>discussion of shop built systems in the above catagories. To Unsubscribe: |
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Dan Mauch
The pic handles the encoders and had the PID filter. You need the PIC step
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with the servo board and the rs serial board. You need to d/l the setup info via a serial port to set the PID filter and the other parameters. Then you can switch to the pic step and run your dos based parallel port programs from there. I experimented with the PIC Servo and found that under serial operations it was blazing fast. Under the pic step is was incredibly slow where I was unable to get 250 RPMS out oif it. But I see that he is coming out with a rate multiplier which should speed it up significantly. I was going to design a servo system around the pic servo chip because it was so low cost. JRKerr even gave me the gerbers but the top layer gerber file was corrupted. For some strange reason he would not send me another copy of the top layer gerbers. I also don't have the time to reverse design the top layer. Other wise I could make a low cost servo system kit available . -----Original Message-----
From: Tim Goldstein <timg@...> To: CAD_CAM_EDM_DRO@... <CAD_CAM_EDM_DRO@...> Date: Wednesday, June 16, 1999 9:04 PM Subject: Re: [CAD_CAM_EDM_DRO] List question From: "Tim Goldstein" <timg@...>to use for your servo motors?boards discussion of shop built systems in the above catagories.from www.jrkerr.com that I am intending to use to move my table. To Unsubscribe: |
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Dan Mauch
see www.jrkerr.com
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It is a programmable controller chip call the PIC servo that does the intelligence for a low cost servo system. Dan -----Original Message-----
From: TADGUNINC@... m <TADGUNINC@...> To: CAD_CAM_EDM_DRO@... <CAD_CAM_EDM_DRO@...> Date: Thursday, June 17, 1999 6:40 AM Subject: Re: [CAD_CAM_EDM_DRO] List question From: TADGUNINC@...discussion of shop built systems in the above catagories. To Unsubscribe: |
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I vote to keep the list intact. Yes, there are things I don't
understand, and am not interested in, but if I filtered everything I _thought_ I didn't need, I probably would never have considered either Linux or EMC, and I'd still be dreading Big Bad Bill's copyrighted "Blue Screen." Linux/EMC looks like a better bet. I imagine there will be other topics that seem boring at first, but become interesting with a bit of effort. Geoff |
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Ron Ginger
Well, I sure drew out the lurkers with that one :-)
and it seems to have opened up a couple new threads as well, so great, lets forget splitting and keep talking. The question of coordinating 2 (or even 3) PIC servos- or for that matter any servo is one that has bothered me. There are several servo boards Ive sen that are single axis, with serial port control. Can these be used for coordinated movements? I notice the PIC has a command to set the time of a movement, so I asume you could calculate the longest time and program both boards to that time. I would really like to hear from someone that has done this ron |
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Ted
rtr@...
maybe I'm missing something, but integrating the movements of a couple of axes is what Bresham's Algorithms in linear and circular motion is about. It breaks down the motion into a lot of very small motions and steps the control through these small motions. It never allows the axes to loose synchronization by more than the resoplution of the machine, if you choose to limit the small motions to that size. Ted Robbins ---------- From: Ron Ginger <ginger@...>discussion of shop built systems in the above catagories. To Unsubscribe: |
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Ward Merkouris
I guess I'm one of the one hundred ninety that are saying nothing, so to change that I'd like to say, NO don't split the list. I
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enjoy learning about all the topics discussed here. I currently have a Grizzly bed mill that I'm converting to CNC using AHHA software and PacSci motors. I am ordering ballscrews from Nook Industries (precision rolled) and have put a 3 HP DC motor on the spindle. I plan to pick up Linux 5.2 this weekend and try to get EMC going also and compare the two (AHHA and EMC). I also have a couple of really big BostonMatic CNC mills (about 13,000 LBS each) to upgrade the controls on. I'm sure that what I learn from the discussions on this list will help me decide which software and hardware to use in this project also. Thanks, everyone !! Ward M. WAnliker@... wrote: From: WAnliker@... |
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Jon Elson
Ron Ginger wrote:
From: Ron Ginger <ginger@...>Well, I really haven't DONE it, but I've worked with several systems that do it, and I have picked some of the intricate code apart. Clearly, one processor that can do it all makes it easiest. That's what EMC does now. Since a single routine generates all waypoints on the toolpath, and then passes the positions it expects all axes to be at, at every tick of the trajectory generator's clock, the axes should stay well in sync under normal conditions. Anything where the separate axes have their own system clocks could get out of sync, and at least could be 1/2 a tick out at any moment. If the servo loop runs fast enough, this error will be small. HP makes a real neat servo chip, not too different from the LM628, but much cheaper. BUT, it doesn't have fractions in the velocity, meaning that, say, X can move at 1/2, 1/3, 1/4, etc. the speed of Y. But, X can't move at .53725 times the speed of Y! Well, that's unusable for multi-axis work. You couldn't even do a decent circle with it. Most of these things don't use time, they use velocity. So, the main program computes velocity such that all the moves take the same time. An easy computation, although you also need to scale the acceleration, so all axes accelerate for the same time before coming to their respective constant velocities. Jon |
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Jon Elson
Ted wrote:
From: "Ted" <rtr@...>Oh, yes, of course. But, that is to be run on a single processor. You can't have two separate processors each running part of the Bresenham algorithms. So, a distributed system would run the Bresenham circle generator, for instance, and send a stream of small, incremental moves to 2 axis control processors. What if those axis processors get out of sync by a few of those incremental moves? How does the central computer keep them in sync? It can be done, but it is a lot more complicated than just throwing the move commands down a blind pipeline, and hoping everyone is on the corresponding move simultaneously. As for resolution, my machine has resolution of .00005" in the X and Y, and .000025" in the Z. If I was moving X at 120 IPM (= 2 IPS), that is 20,000 incremental moves per second, which is beyond the capability of most systems to handle giving 3 (or more) axes their marching instructions that fast. So, this sceme is really not practical for systems that have a relatively fast motion capability. Jon |
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Jim Register
At 09:14 PM 6/16/99 -0400, you wrote:
From: Ron Ginger <ginger@...>I just joined the list - the big reason was the good feed of Linux/EMC info - the other was the EDM content. I vote for not splitting the list, although I think putting EMC in the subject line of related posts might make it easier to sort through the messages for archiving and stuff. Of course, as I wrote this, I though of several other methods that should work equally as well for me, though not as automatic as a filter. Just my two cents worth, as I resume lurking until I can actually contribute something. |
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