A non-trivial kinematics can be used to square up a machine or compensate for rotaries being a bit out of perpendicular with each other. If I remember right we did a bit of this for a home built mill for a student who was able to borrow a Renishaw Ball Bar for testing.
Rayh On Sat, 2007-10-06 at 13:27 -0400, Dale wrote: > I see this idea come up every now and then. If the Machine is not square > then you square up the machine. If the ways are worn then you refinish > them, and If the lead screws ar worn you replace them. You're right it > is impossible to build a perfect tilting rotary table, or anything else > no matter how small the error may be. I have used tilting rotary tables > to inspect parts and you'd need to look damn hard to find the > inaccuracies in those tables. I know from working with machinery fo 34 > years that unless you have some instrument that can measure in micro > inches you can't acheive micro inch precision. In order to compensate > more all the machine and tooling inaccuracies you first have to be able > to measure them. In manufacturing every dimension has a tolerance > appropriate for each and every feature of the part to be machined. Not > everything needs to be perfect. It's not difficult to align tooling of > any kind on a machine including a tilting rotary table. Besides the > ability to measure accurately there are thermal factors. Rigidity of the > machine and tool holders is not constant. The longer you have to reach > the more deflection you will encounter. The amount of deflection also > changes as the cutting tool wears as well as with feeds and speeds. You > are talking about a huge battle to get software to compensate for what > is part of a machinsts job. If the machine is not up to the task I would > consider it a loosing battle. Before taking on such a challenge I'd > strongly suggest that the machine and tooling is up to specs in order to > even have a chance at a successfull implemantation. Like it's been > said, "You can't make a silk purse out of a sow's ear". > > I wish you the best of luck and do hope you keep us all informed as to > your progress and successes/failures. To have EMC compensate for > inaccuracies in the machine alignment would be a great asset. If I > should ever find the room to contine building my second (larger) > machine. It sure would be nice, there are limits as to just how accurate > I can build and align a machine in my garage. > > Dale > > > Stuart Stevenson wrote: > > Gentlemen, > > I want to start a dialog concerning how best to implement geometry > > compensation. At this point I am not thinking about roll, pitch and > > yaw. These may be included but my main concern is the manufacturing > > inaccuracies of multiple rotary motion components. > > It is impossible to build a perfect tilting rotary table. The > > intersection of the axes will not be perfect. > > I would like to have registers to hold compensation values > > representing the determined manufacturing inaccuracies. This would > > allow the control to compensate the linear motion positions to > > 'perfect' the tilting rotary table. > > I have just requested three items. This is the fourth. If I am > > successful in the implementation the the three items I should be much > > more able to address this myself. > > > > Any and all suggestions and comments are welcome. > > > > thanks > > Stuart > > > > ------------------------------------------------------------------------- > > This SF.net email is sponsored by: Splunk Inc. > > Still grepping through log files to find problems? Stop. > > Now Search log events and configuration files using AJAX and a browser. > > Download your FREE copy of Splunk now >> http://get.splunk.com/ > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Splunk Inc. > Still grepping through log files to find problems? Stop. > Now Search log events and configuration files using AJAX and a browser. > Download your FREE copy of Splunk now >> http://get.splunk.com/ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
