2014-12-04 11:35 GMT-03:00 Dave Cole <linuxcncro...@gmail.com>: > I know you are not in the USA so shipping cost may be an issue, but I > would rewire them as normal resolvers and tie them into a Mesa > resolver interface and be done with it since you have other Mesa hardware. > > A drop in replacement for those encoders in a similar housing will not > be cheap. > > These are likely the proper frame size and they start at $240 x 3 .... > > http://www.automationdirect.com/adc/Shopping/Catalog/Sensors_-z-_Encoders/Optical_Rotary_Encoders/Heavy_Duty_Incremental_Encoders_%28Quadrature%29 > > And then you need to replace cables and connectors, make adapter plates, > replace couplings, etc. > > If you leave the resolvers alone you only need to deal with the Mesa > boards and getting the excitation right to the resolvers which is really > pretty easy. > > Rewiring in the control box is a lot easier than replacing the resolvers. > > Resolvers are pretty much bullet proof other than the bearings. > > I've replaced several encoders that were broken from shock. >
Hello Dave and thanks for your advice! Well, you're pretty much encouraging me to keep the resolvers and use a 7i49 to drive them. I'm a little bit concerned about using them backwards, just because I read on this site just on the end of the article ( http://www.amci.com/tutorials/tutorials-what-is-resolver.asp) that although they can be used backwards performance cannot be guaranteed. Anyway I know they are just rotary transformers so I guess it's not a big deal to make them work. The main concern is the transformation ratio, and the 7i49 has the option 1:1 or 2:1, I don't know if these have one of those ratios (The labels are not legible anymore). Is it possible to excite the rotor and measure the voltages on the SIN and COS outputs? Originally the machine has increments of 0.001 mm and the ballscrews have a thread lead of 10 mm. Just by guessing I'm thinking that the encoders, in case of using them would have to be 5000 PPR at least and ideally 10000 PPR, I don't trust the PID using only 1000 PPR because I think I will be compromising the accuracy since I tend to use increments of 0.01 mm on this machine. There are some 5000 PPR encoders on ebay at USD 160 plus USD 50 for shipping, but yes.. I'm spending a lot more just for one axis. -- *Leonardo Marsaglia*. ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
