It has been a long time but I just wanted to let everyone know what the outcome of very lengthy and thorough tests has shown. Well I tied and measured all the suggested solutions - than you for everyone that helped. In the end we discovered that due to the beams being clamped by means of hydraulic clamps and ram rollers, we get a very uneven loading on the X axis as well as a very jerky (not so noticeable when the piece weighs 1 ton) movement. Our test showed that we cannot get a repeatable result and so we have to redesign the X axis mechanics.
On 2013/05/08 01:07 PM, Marius Liebenberg wrote: > 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 <[email protected]> >>> Reply-To: "Enhanced Machine Controller (EMC)" >>> <[email protected]> >>> To: "Enhanced Machine Controller (EMC)" >>> <[email protected]> >>> Subject: [Emc-users] Creep in X axis >>> >>> On 7 May 2013 07:17, Marius Liebenberg <[email protected]> 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 >>> [email protected] >>> 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 --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 130610-2, 2013/06/10 Tested on: 2013/06/11 06:58:06 AM avast! - copyright (c) 1988-2013 AVAST Software. http://www.avast.com ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
