Re: [Emc-users] calibrating stepper motor cnc
2011/9/29 Martin Patton mart...@gmail.com: The part looked right but the caliper says every dimension cut a little small. What is the range of deviances? What I mean, how consistent is the deviance in dimensions? Is it very close in all directions, is the error along one of the joints or is it completely random? I think that each of these cases will lead to different potential causes of the problem. Is there a good post on calibrating for a stepper motor machine? I think that cause of problem should be eliminated rather than trying to adjust g-code to it. Even more - if You do not know the cause, You will not be able to treat it in g-code anyway, because You need to know, what should be adjusted to workaround those deviances in dimensions. I think that first thing for stepper machine to try is playing with acceleration and velocity parameters. And next thing is actually testing the machine and understand those deviances - is there particular direction, where they occur etc. Viesturs -- All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2dcopy1 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] calibrating stepper motor cnc
Martin; For what it's worth - I'm playing with a new machine of mine (Sieg KX1 with Gecko G540) and am looking at the backlash in the x-y table. To do this, I put a dial indicator on an axis; move +1mm, +1mm, +1mm, all show accurate moves; move +1mm +1mm -1mm shows the backlash. What if you did the same? At least it would show if you can move each axis as you expect. From a newbie; JohnS. -- All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2dcopy1 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] calibrating stepper motor cnc
One recommendation is to put a Vee cutter in your spindle and run a program where the Vee bit just touches the material in a uniform grid pattern. Take your part and measure all the positions from the 0,0. You may have your machine set up in such a manner that it is not just perfect. When I did this, I ended up adjusting the ini file slightly to correct for a 1/8 undershot over my 4' X axis and 1/16 on my 2' Y axis. On Thu, Sep 29, 2011 at 1:10 AM, Martin Patton mart...@gmail.com wrote: Hi EMC users, I have EMC running on an old pc, latency number about 25000. I got an occasional real time error with latency number set at 22000. I drew a part in CamBam, generated some g-code and cut a part. The part looked right but the caliper says every dimension cut a little small. A circle pocket drawn 1.50 diameter cut about 1.42 in diameter, The tool diameter matched the tool specified in the cad program. Is there a good post on calibrating for a stepper motor machine? Thanks, Marty -- All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2dcopy1 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2dcopy1 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] calibrating stepper motor cnc
Hi Marty, As other people pointed out, it might be better not to jump to conclusions the cause of the error may not be stepper calibration. How long have you been using CamBam and what do you think of it? Martin Date: Thu, 29 Sep 2011 01:10:10 -0400 From: marty To: emc-users@lists.sourceforge.net Subject: [Emc-users] calibrating stepper motor cnc Hi EMC users, I have EMC running on an old pc, latency number about 25000. I got an occasional real time error with latency number set at 22000. I drew a part in CamBam, generated some g-code and cut a part. The part looked right but the caliper says every dimension cut a little small. A circle pocket drawn 1.50 diameter cut about 1.42 in diameter, The tool diameter matched the tool specified in the cad program. Is there a good post on calibrating for a stepper motor machine? Thanks, Marty -- All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2dcopy1 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2dcopy1 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] calibrating stepper motor cnc
Martin Patton wrote: Hi EMC users, I have EMC running on an old pc, latency number about 25000. I got an occasional real time error with latency number set at 22000. I drew a part in CamBam, generated some g-code and cut a part. The part looked right but the caliper says every dimension cut a little small. A circle pocket drawn 1.50 diameter cut about 1.42 in diameter, The tool diameter matched the tool specified in the cad program. Is there a good post on calibrating for a stepper motor machine? First, you need to measure the actual movements with some kind of measuring tool, even if it is just using a dial caliper. You need to separate linear movement error, backlash and tool deflection. Without separating these different error mechanisms, you will not make the right correction. Linear error is pretty easy, put a pin in the spindle and measure between it and a block fixed to the table. If you move in the same direction, backlash will not alter the reading. Moving a number of inches so as to use nearly the full range of the caliper will give the most informative result. Then, approach the same coordinate from both directions and measure position. This may be harder to do with a caliper, as hopefully your backlash is relatively small. It is best to do this with a tenth-reading dial test indicator, if you have or can borrow one. Backlash alone could cause the error you report above. It will also leave 4 steps in the walls of a circular pocket, at those places where the axis needs to reverse, but takes a moment before the linear motion picks up on the other side of the backlash. If your problem is backlash, these steps should be really obvious on the part you mention above. Finally, it could be tool deflection, which will cause milled pockets to come out small. (Your measurement above seems to big to be tool deflection, however.) But, tool deflection will NOT leave bumps in the wall like backlash. Jon -- All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2dcopy1 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] calibrating stepper motor cnc
On 29 September 2011 06:10, Martin Patton mart...@gmail.com wrote: A circle pocket drawn 1.50 diameter cut about 1.42 in diameter, 1.5 / 1.42 = 1.0563 2mm / 12tpi = 1.0583 Just a thought, do you have metric leadscrews calibrated in TPI? -- atp Torque wrenches are for the obedience of fools and the guidance of wise men -- All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2dcopy1 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] calibrating stepper motor cnc
?A circle pocket drawn 1.50 diameter cut about 1.42 in diameter, 1.5 / 1.42 = 1.0563 2mm / 12tpi = 1.0583 Just a thought, do you have metric leadscrews calibrated in TPI? -- atp Torque wrenches are for the obedience of fools and the guidance of wise men Nope. They are 20 tpi. Thanks, Marty -- All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2dcopy2 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
