#robotics Logs

Jul 29 2018

12:00 AM weyland|yutani: rue_, you can move your old linux in a VM keeping it there forever so if something breaks you can still use it
01:10 AM rue_shop4: weyland|yutani, yea, I was laughing about doing that on a 2.4GHz celleron
01:10 AM rue_shop3: a machine that really needs to excuses to run slower
01:11 AM rue_shop3: geez, this encoder I'm making is not the king of small
01:13 AM rue_shop3: oh well I can play with size later, proofing an absolute 24 position encoder that only uses 3 bits is the current goal
01:48 AM rue_shop3: ok well, I had to clean the bearing seats with a drill, and I missed, so the shaft sits crookid...
01:48 AM rue_shop3: I suppose that dosn't matter, just proof of concept...
01:53 AM weyland|yutani: rue_shop3, i started with VM on a PII way back in 1998 running windows in it was really a blast :D
01:56 AM Jak_o_Shadows: Hmmm, how is the hip joint going to work
01:58 AM Jak_o_Shadows: Yeah, I definitely think I like having it slightly sprung.
03:14 AM rue_shop4: insane, with a x10 cmos amp, I can get 1Mhz thru an IR link
03:14 AM zhanx_: wait what?
03:15 AM zhanx_: how
03:15 AM zhanx_: IR link is like morse code fast rue_shop4
03:24 AM rue_shop4: well, if you take 3 cmos inverters, chain them, and put a 10M resistor from the first input to the last ouput
03:24 AM rue_shop4: then take a phototransistor with *just* the right pullup resistor, and couple it to that amp with a 0.1uF capacitor
03:25 AM rue_shop4: it can respond easy from 0.1hz to 1Mhz
03:25 AM zhanx_: so black magic
03:25 AM rue_shop4: the two are 3mm apart
03:25 AM zhanx_: oh i need whole house on it
03:25 AM rue_shop4: I'm testing best circuits for the encoder I'm using
03:25 AM rue_shop4: I hit a wall at about 100Khz
03:26 AM rue_shop4: then the cmos blew that all away
03:26 AM rue_shop4: the cmos chip can barely respond at 1Mhz
03:26 AM rue_shop4: just its slew time
03:27 AM zhanx_: other channel rue_shop4
04:09 AM rue_shop4: ok, not 1Mhz, turns out, the <1pf thru the breadboard was activiting it
04:09 AM rue_shop4: so its good up to about 500Khz, still pretty damn good
09:54 AM core7: Anyone here has recommendations for a motor for a boat? Preferably thrusters or pre-built motor+prop combinations? 100lb thrust approximately.
12:59 PM SpeedEvil: I doubt thrustmaster goes that low :)
12:59 PM SpeedEvil: oh - nvm
06:35 PM Tom_itx is now known as Tom_L
09:10 PM rue_shop3: got ht new shop speaker arrangement working, much better distribution
09:43 PM Tom_L: gonna be more productive now ehh?
10:07 PM core7: https://www.amazon.com/exec/obidos/ASIN/B00EYST1L8/ezvid02-20 - anyone knows what kind of motors are used in these?
10:12 PM rue_shop3: probably brushless
10:13 PM rue_shop3: wait, $140? no, not brushless then
10:14 PM core7: rue_shop3: could be brushless if they are mass produced?
10:15 PM rue_shop3: mmmm doubt it
10:15 PM core7: most of the scooters are brushless and they go for < $100 these days?
10:16 PM rue_shop3: smaller motors tho
10:16 PM core7: rue_shop3: yes, indeed they are smaller motors, but two of them
10:20 PM core7: rue_shop3: any ideas how thrust is calculated and how much torque the motor produces?
10:23 PM rue_shop3: you tie a boat to a large fishscale and dial the motor up, read the scale
10:24 PM rue_shop3: you have to tie off the fishscale to something the boat cant move
10:26 PM core7: i see
10:27 PM core7: rue_shop3: what kind of motor do you buy for high torque, low rpm, and reliability for hours of operation?
10:28 PM rue_shop3: depends if I want to pay for having a motor that will outlast me using it
10:28 PM rue_shop3: the old cnc is using a weed eater motor, has for 18 years now
10:29 PM core7: rue_shop3: weed eater motors will propel a boat?
10:29 PM core7: The torque might burn them?
10:29 PM zhanx: core7, i can answer that, yes
10:29 PM rue_shop3: depends on the about of power and how to match it
10:29 PM zhanx: you need the right prop but they do it fine
10:30 PM rue_shop3: on a boat, you can match your power with the right prop
10:30 PM rue_shop3: mostly
10:30 PM rue_shop3: vacuum cleaner motors run 30000 rpm
10:30 PM core7: rue_shop3: probably a drill motor would be better for that?
10:30 PM rue_shop3: vacuum cleaner motors can push 2HP
10:30 PM rue_shop3: but, rpm
10:32 PM core7: are there water tight motors available like this?
10:33 PM rue_shop3: your supposed to put the motor at the top
10:33 PM rue_shop3: and run a stainless shaft down
10:33 PM rue_shop3: "water tight" means that the water that gets in, cant get out
10:33 PM zhanx: rue is right
10:33 PM rue_shop3: WATER WILL ALWAYS GET IN
10:33 PM zhanx: you run a pinion at the bottom to transfer the power
10:34 PM core7: but water can come up as well ? water tight bearings?
10:34 PM zhanx: wax packing
10:34 PM rue_shop3: grease?
10:34 PM zhanx: it will come up part way and then drain back down.
10:34 PM rue_shop3: omnidirectional splash guards
10:34 PM zhanx: grease in water? want to kill more fish rue?
10:35 PM rue_shop3: the gulf is still leaking, whats a little more gonna do?
10:35 PM core7: no grease please
10:35 PM zhanx: all my trolling motors had wax packings in them
10:35 PM rue_shop3: trump said its ok
10:35 PM core7: zhanx: these trolling motors - are they bldc? brushed?
10:35 PM rue_shop3: he says fish fry up better with some oil
10:35 PM zhanx: rue your Canadian
10:36 PM rue_shop3: yea
10:36 PM zhanx: brushed from the ones i have owned
10:36 PM core7: zhanx: https://newportvessels.com/electric-trolling-motor-86lb-thrust-l-series/ - not sure what motor goes into this
10:36 PM rue_shop3: you guys should poke more fun at our PM for being a twitt
10:36 PM rue_shop3: a sellout twitt
10:36 PM zhanx: its canada we feel bad for poking the hat
10:37 PM rue_shop3: should I go to china or come visit you lot next year?
10:37 PM core7: zhanx: if i wanted to replace the brushed motor with brushless motor in a trolling motor setup - how bad is that?
10:37 PM rue_shop3: core7, have a lathe?
10:37 PM core7: rue_shop3: no - but i do have a cnc :)
10:37 PM zhanx: never tried it, but that link is a 3" brush motor
10:37 PM zhanx: not sure what gearbox it has
10:38 PM core7: zhanx: they advertise 86lb thrust. Not sure how much torque that motor can put out...
10:38 PM zhanx: alot
10:39 PM core7: zhanx: what kind of 24v bldc motor would one need to match that?
10:39 PM zhanx: i fish , but rue knows motors better than me
10:39 PM rue_shop3: no, I'm the non-boater of a boating family
10:40 PM zhanx: that motor is 12v fyi
10:41 PM zhanx: i know it says 24v but the wiring in it is for 12v which is funny
10:44 PM rue_shop3: I keep project note paper under my keyboard, I'm trying something new, I have a seperate page for each project
10:44 PM zhanx: i use a log book
10:45 PM zhanx: pages are numbered and dont tear out
10:45 PM core7: rue_shop3: how does one shop for a high torque bldc motor at 24v?
10:50 PM core7: rue_shop3: https://www.alibaba.com/product-detail/high-torque-BLDC-1500W-24v-Brushless_60667846214.html ?
11:11 PM rue_shop3: I forgot the words they use