Peter, Thanks for the info. It might just be the problem. I am waiting to get access to the machine and then I will test all the advise I received here. I will give feedback on my findings.
On 2013/05/07 04:11 PM, Peter C. Wallace wrote: > On Tue, 7 May 2013, Roland Jollivet wrote: > >> Date: Tue, 7 May 2013 15:41:39 +0200 >> From: Roland Jollivet <roland.jolli...@gmail.com> >> Reply-To: "Enhanced Machine Controller (EMC)" >> <emc-users@lists.sourceforge.net> >> To: "Enhanced Machine Controller (EMC)" >> <emc-users@lists.sourceforge.net> >> Subject: [Emc-users] Creep in X axis >> >> On 7 May 2013 07:17, Marius Liebenberg <mar...@mastercut.co.za> wrote: >> >>> New machine Stuart. It is a custom machine that processes structural >>> beams. the machine is 30m long with 5 axis and many pneumatic controls. >>> The x axis is the material that is moved and not the machine. >>> >> >> Hi Marius >> >> Have you tried doing a very slow movement, like at 50mm/min or even >> slower. >> >> Place a ruler on the table and compare the DRO to physical movement. >> Check >> again at the halfway mark, then again at the end. You can then determine >> whether the error is at start, or at end, or in scaling. >> >> Also, if the output, possibly, from the encoder is not exactly 50/50, it >> could accumulate an error at anything faster than slow stepping. >> And maybe this is not applicable, but is the index pulse >> mathematically, or >> logically involved in the distance calculation. It could be being >> subtracted? in the computation of position. >> >> Regards >> Roland >> ------------------------------------------------------------------------------ >> >> > > > > If the drives encoder output cable was wired wrong so that index and > one of the A, /A, B, /B lines were swapped, It might cause strange > behaviour like this. > > Also with a 3500 count/mm scale and 20000 mm/m the count rate is 1.16 > MHz. Can the drive actually generate good quadrature at that rate? If > the Drive has quadrature output hardware hardware or a FPGA this > should be easy, but if this is being done by a DSP, its quadrature is > probably pretty lumpy at this rate. > > This should be testable by doing a motion at say 1/2 the maximum speed. > If the error goes away, you might try lowering the drives quadrature > output resolution. > > > > >> Learn Graph Databases - Download FREE O'Reilly Book >> "Graph Databases" is the definitive new guide to graph databases and >> their applications. This 200-page book is written by three acclaimed >> leaders in the field. The early access version is available now. >> Download your free book today! http://p.sf.net/sfu/neotech_d2d_may >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > > Peter Wallace > Mesa Electronics > > (\__/) > (='.'=) This is Bunny. Copy and paste bunny into your > (")_(") signature to help him gain world domination. > > > -- Regards / Groete Marius D. Liebenberg MasterCut cc Cel: +27 82 698 3251 Tel: +27 12 743 6064 Fax: +27 86 551 8029 Skype: marius_d.liebenberg Skype Me^(TM)! <skype:marius_d.liebenberg?call> Get Skype <http://www.skype.com/go/download> and call me for free. --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 130507-2, 2013/05/08 Tested on: 2013/05/08 01:07:44 PM avast! - copyright (c) 1988-2013 AVAST Software. http://www.avast.com ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. This 200-page book is written by three acclaimed leaders in the field. The early access version is available now. Download your free book today! http://p.sf.net/sfu/neotech_d2d_may _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
