Opps! Fumble fingers or fading brain. Only a 20” planer. Have ordered parts. May need a bit of help with programming. It may be awhile before the parts arrive.
> On Jun 6, 2025, at 6:02 PM, gene heskett <ghesk...@shentel.net> wrote: > > On 6/6/25 16:36, Chris Albertson wrote: >>> On Jun 6, 2025, at 12:46 PM, gene heskett <ghesk...@shentel.net> wrote: >>> .. >>> >>> I'm assuming you meant a woodworking planer? Single n. A 25" is a pretty >>> large machine & may use V-belts & std multi-hp induction motors. Most >>> planers used by us hobbyists are half that width and use cogged timing >>> belts. Which would be destroyed by /any/ slippage. The duplicate encoder >>> setup sounds good, until a prolonged run overruns one of the encoders. The >>> only thing I can suggest would involved a single hall device to give a once >>> per rotation trigger, driving a one shot, measure that period and feed it >>> to another one shot set to trigger if the first one slows by 5%, to drive >>> an another much longer period one shot showing on an LED from the second >>> one when it fires. It will also flash at power up until its up to speed, >>> giving the user a visual clue to start the feed. If it comes on in the >>> middle of a board, tell the user to reduce the depth of cut for the next >>> pass. Or cut the power at the same time. Except for the led, that is all >>> in the arduino file. Minimal cost. A $10 arduino could do that. Or a >>> multicore arm64 could do it easier but that's higher cost. >> Why would a prolongeed run over load the sensors. The sensors are >> measuring either speed or shaft angle not accumulated rotation. One shots >> and triggers? Why to complex. Just compare the speeds. You don’t need a >> once per rotation index, you don’t care about shaft angles, only speed >> matters. >> >> Actualy the dual core ARM process is cheaper then Arduino. Look at the >> Raspberry Pi Pico. It is a dual core ARM that costs $4 and you can program >> in in Micro Python. The Pico can easly handle reading two quadrature >> encoders at the MHz speed level. Just get two $2 magnetic encoders. these >> are fast and have 1024 line encoders in them. Read them Using I2C about 25 >> times per second and when the speeds are a few percent or so apart, the >> belt is slipping. >> >> Don’t spend motr the $2 on the encoder, 0.1% accuracy is good enough and you >> can have that at the $2 price point. Somthing like this: >> https://www.aliexpress.us/item/3256805971765108.html?src=google&pdp_npi=4%40dis%21USD%2110.15%215.53%21%21%21%21%21%40%2112000036033485665%21ppc%21%21%21&src=google&albch=shopping&acnt=708-803-3821&isdl=y&slnk=&plac=&mtctp=&albbt=Google_7_shopping&aff_platform=google&aff_short_key=UneMJZVf&gclsrc=aw.ds&albagn=888888&ds_e_adid=&ds_e_matchtype=&ds_e_device=c&ds_e_network=x&ds_e_product_group_id=&ds_e_product_id=en3256805971765108&ds_e_product_merchant_id=5071463479&ds_e_product_country=US&ds_e_product_language=en&ds_e_product_channel=online&ds_e_product_store_id=&ds_url_v=2&albcp=20123152476&albag=&isSmbAutoCall=false&needSmbHouyi=false&gad_source=1&gad_campaignid=20127768206&gbraid=0AAAAAD6I-hGTFVe80aKnm_qXISwfO1_L7&gatewayAdapt=glo2usa >> Then the computer can be this: >> https://www.seeedstudio.com/Raspberry-Pi-Pico-2-p-5940.html?gad_source=1&gad_campaignid=12740071602&gbraid=0AAAAACiAB466mzmjSu4q9jtCxQXrJQljL >> Raspberry Pi Pico 2 >> seeedstudio.com > Now we are getting someplace, I hadn't tangled with a rpi pico, yet. . . > Thanks Chris. >> Poswe can come in via the USB port from a phone charger or maybe there is >> already 5 volts available some place else. >> >> >> >> Magnetic encoders are very easy to use. If the shaft is steel the magnet >> can stick to the shaft end and then the encoder mounts to a peice of plastic >> or aluminum and has about a 1mm air gap from the magnet. There is room for >> some imprecision, getting within 2 mm is “good enough”. The magnet need not >> be exactly concentric with the chip-sensor. You can super glue the magnet >> if you like. >> >> All the software has to do it raise a pin to high if the speed ratio is >> wrong. It can check a few dozen times per second and wait untill it has >> been wrong for maybe a 10 times in a row and still shut the motor down a >> half second after it starts to slip. >> >> >> >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users > > Cheers, Gene Heskett, CET. > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author, 1940) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net <mailto:Emc-users@lists.sourceforge.net> > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
