#robotics Logs

Jan 25 2018

01:21 AM SolG is now known as Solgriffin
02:11 AM rue_bed: PI has a good camera for he price
02:17 AM veverak: DIRT: ORB has awesome aluorithm
02:17 AM veverak: but the implementation sucks hard
04:13 AM Sol is now known as Guest54176
04:26 AM diego_: hello everybody, I am not sure if this is the correct place for my question, but I would try to ask: what could be the impact of using a 4 pole rotor in a bldc motor designed to use a 8 pole rotor? thanks a lot
05:32 AM SpeedEvil: From not working at all, to going twice as fast, to exploding.
05:33 AM SpeedEvil: Or do you mean actually replacing the rotor
05:33 AM SpeedEvil: In that case it's unlikely to do much more than buzz and melt.
05:33 AM SpeedEvil: Because torque will approach zero
06:32 AM Snert: buzz and melt...lol.
06:32 AM Snert: people come up with the weirdest things to do.
07:22 AM diego_: SpeedEvil: the idea would be to actually replace the rotor (and redesign all of the needed parts), could you please let me understand better your previous points?
07:23 AM diego_: SpeedEvil: for sure the commutation logic will be re-designed
07:23 AM SpeedEvil: You can't replace the rotor without replacing the stator and windings, and at that point all you have left is the can
07:23 AM SpeedEvil: what are you actually trying to do that you think you need to do this.
07:26 AM diego_: SpeedEvil: actually we have a 8 pole motor with a characteristic curve that fullfills our requirements, but because of project constraints we need to have a 4 pole rotor, so we are wondering what would be the impact of this change (of course we will re-design the windings, commutation logic and so on...), in the end I would expect to have a lower stall torque
07:27 AM veverak: lower torque, more RPM with same wattage
07:29 AM diego_: veverak: if we then magnetize the magnets stronger, could we achieve a similar curve? From what I've seen around it seems that 4 poles motor have lower performances (considering nominal power) than the same 8 pole counterparts
08:35 AM diego_: SpeedEvil: could I please ask you why you said that when you replace the rotor, you also need to replace the stator? Our idea would be to design a rotor that fits correctly in the stator
08:44 AM SpeedEvil: Because the stator poles are too long circumferentially
08:45 AM SpeedEvil: If you're asking this sort of basic question, you should not remotely be considering designing motors.
09:13 AM Sol is now known as Guest66511
09:29 AM SolG is now known as Solgriffin
10:07 AM diego_: SpeedEvil: thanks for your feedback, I am not motor designer, but I am trying to understand the possibilities, so this means that the stator poles are "smaller" (circumference related) in 8 pole rotor motors than in 4 poles?
10:12 AM Sol is now known as Guest60119
10:16 AM Guest60119 is now known as Solgriffin
10:21 AM Sol is now known as Guest96543
10:24 AM Guest96543 is now known as Solgriffin
03:11 PM Sol is now known as Guest65850
03:18 PM Guest65850 is now known as Solgriffin
06:38 PM mrdata-- is now known as mrdata-
08:45 PM renl: hi anyone used sabertooth motor drivers with the kangaroo motor controller before?
09:11 PM Tom_L: rue_shop3, got the column squared to the table now
09:11 PM Tom_L: working on the actual spindle part now
09:12 PM rue_shop3: how far was it out?
09:29 PM Tom_L: umm, i think i put about .050" shim near the rear of it
09:30 PM Tom_L: a little past center
09:31 PM Tom_L: if you don't true each piece in the chain though, it will mess with you later
09:31 PM Tom_L: moving up to the spindle next, maybe tomorrow
09:31 PM Tom_L: i worked on it a while but ran out of time
09:31 PM rue_: yup, cool
09:32 PM Tom_L: i had a precision valenite holder i put in the spindle to use to check it
09:32 PM Tom_L: just a round tube but it's spot on dimension wise
09:33 PM Tom_L: and if i can get that square left to right and front to rear, i'll be happy with it
09:33 PM rue_: I'm starting to lean towards "too far gone" with my old cnc
09:33 PM Tom_L: it's done you well
09:33 PM rue_: need to make a new spindle controller I think
09:33 PM rue_: still dont want to
09:34 PM rue_: I'd like to make anohter optic speed regulator tho
09:35 PM rue_: I'm just in one of those ruts I cant get myself to do anything before I'm too exhausted
09:46 PM Tom_L: so walk away from it for a while