Thank you, guys, for the ideas. I will try to answer the questions: 1) encoder in the pivot point is something I like, it would make mechanical design simplier, but that will require high-cpr encoder or there has to be some timing belt reducer; There will be no HAL, because using LinuxCNC for this task is serious overkill and I certainly do not want to maintain whole PC, where Arduino can handle the task; 2) boards are expected to move at 8m/min approximately - this is not the high tech production line, where AFAIK standard speed is 32 m/min and more; this machine will be combined with a simple planer, boards will be fed manually, so the distance between the boards is up to me as long is it reasonable; based on hardware design, time to measure the width is around 1 second; Time between boards will be 5-6 seconds due to fact that there is a sole plate on the movable size, so I have to wait before the board completely passes along it before repositioning the head - if the next one is wider, it will hit the plate; 3) electrical or mechanical - I actually do not really much care, if it "just works" and is easy on maintenance :)) 4) thanks, I did not think about the hydraulic door dampers - it could do both tasks - pull the lever back and limit the speed at the same time; 5) that proximity sensor idea also looks really good; the delta measuring range (difference between closest and furthest edges) is about 220 mm, so any sensor with 250 mm delta will do; Arduinos have analog input, so it could be forced to do some math to calculate width and position the head accordingly. I am looking at something like 0,2-0,5 mm positioning accuracy. I like the sensor idea, because that would keep the head from moving to start point after each board, it would move just by the difference of board widths instead. Are there any other possible sensors that could do the trick? That particular is out of stock, but it seemed that it had pretty good slope in 100-350 mm range on the graph of outputs volts vs sensing distance.
Viesturs 2014-05-13 18:47 GMT+03:00 Les Newell <[email protected]>: > Depending on the required accuracy one possibility would be the Sharp > GP2Y0A21YK IR distance sensor <https://www.sparkfun.com/products/242>. > > It would give you a pretty good idea of the board width then refine on > that using the stalled stepper/ servo current idea. > > Les > > On 13/05/2014 16:37, andy pugh wrote: > > On 13 May 2014 13:55, Viesturs Lācis <[email protected]> wrote: > >> The problem with this is that once the board passes through, the spring > >> will return that lever to starting position very quickly and the motor > >> might not manage to follow, so I cannot think of a nice way to adjust, > how > >> fast it returns back. > > You could use http://www.slamproof.co.uk/Rotary-Dampers > > > > But, actually, replacing the whole spring/arm with a hydraulically > > damped door closer would probably work rather well. > > > > > > ------------------------------------------------------------------------------ > "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE > Instantly run your Selenium tests across 300+ browser/OS combos. > Get unparalleled scalability from the best Selenium testing platform > available > Simple to use. Nothing to install. Get started now for free." > http://p.sf.net/sfu/SauceLabs > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE Instantly run your Selenium tests across 300+ browser/OS combos. Get unparalleled scalability from the best Selenium testing platform available Simple to use. Nothing to install. Get started now for free." http://p.sf.net/sfu/SauceLabs _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
