#robotics Logs

Jun 05 2018

12:09 AM rue_shop4: Tom_L, ahve you ever written a cnc program for jeweling metal with a pencil eraser as a tool?
12:13 AM rue_shop4: (not sure of the collette that fits a pencil)
12:13 AM rue_shop4: srrsly? I have no 9.1k resistors?!!?!?!
12:13 AM mrdata: why not
12:13 AM mrdata: rue_shop4, do you have a stack of 10k Rs with 10% tolerance?
12:13 AM mrdata: perhaps you can pick one that's close enough
12:14 AM * rue_shop4 buys another 10k in 1/8w
12:14 AM Triffid_Hunter: rue_shop4: 10k and 100k in parallel will do
12:15 AM rue_shop4: just a sec, let me ask the computer
12:15 AM rue_shop4: hit, error = 0.000000% vals = 18000.000000 and 18000.000000 at 9000.000000
12:15 AM rue_shop4: :P
12:16 AM Triffid_Hunter: that's 9k, not 9.1k :P
12:16 AM rue_shop4: https://paste.debian.net/1028009/
12:16 AM rue_shop4: yes, sorry, there was a subgoal
12:17 AM rue_shop4: I suppose I could speed up the program if I had it just stop if it hits a 0% error solution
12:18 AM rue_shop4: I do have 18k
12:18 AM rue_shop4: and 20000 9.1 on way from china
12:18 AM rue_shop4: :/
12:20 AM mrdata: rue_shop4, what is the tolerance of the stack of resistors you do have?
12:20 AM rue_shop4: mostly 5
12:21 AM rue_shop4: it was kinda more about the fact there is a value I dont and, by record, have never had
12:21 AM mrdata: so you can pick a 100k that's actually 101k to put in parallel with a 10k, perhaps?
12:22 AM Triffid_Hunter: rue_shop4: need to start using surface mount.. those things are ridiculously cheap, $1 per thousand from E14 last time I checked, or get a smd sample book :P
12:22 AM rue_shop4: I might if they made smt protoboard
12:22 AM mrdata: ew
12:23 AM rue_shop4: it'd be like current protoboard, but no thruholes
12:23 AM mrdata: putting SMTs in parallel is gooey but possible if you stack them, often
12:24 AM Triffid_Hunter: rue_shop4: pro tip: 0603 fits perfectly between 0.1" spaced pins
12:24 AM rue_shop4: yes, but
12:24 AM rue_shop4: the thruholes waste half the realestate
12:24 AM rue_shop4: I'm thinking on designing some
12:24 AM rue_shop4: play with ones of a few pitches for setting soic
12:25 AM rue_shop4: bascially just an array of squares
03:02 AM SpeedEvil is now known as Guest51359
05:16 AM BitEvil is now known as SpeedEvil
07:09 AM z64555: mrdata: 1K of a 100K is right on the edge of the 10% tolerance, may be difficult to find
07:10 AM mrdata: z64555, no it isnt
07:10 AM mrdata: 101K is 1%; the stack is 5%
07:10 AM z64555: blah, you're correct
07:10 AM z64555: just woke up
07:11 AM z64555: I shouldn't science at this time
07:11 AM mrdata: sure :)
07:12 AM mrdata: i did this once with capacitors in parallel, each labelled as 20%, and i got it down to within 0.1% with only three of them
05:07 PM durrf is now known as sports`ball`aren
08:52 PM Tom_L: rue_shop3,
08:52 PM Tom_L: would this work as a spindle motor?
08:52 PM Tom_L: https://www.aliexpress.com/item/80mm-220v-750w-2-39NM-3000rpm-17bit-ASD-B2-0721-B-ECMA-C20807RS-Delta-AC-servo/32326080829.html?spm=2114.10010108.1000013.2.55aa6dd28o07V2&scm=1007.13339.99734.0&scm_id=1007.13339.99734.0&scm-url=1007.13339.99734.0&pvid=89957fa5-0471-459d-8d10-62861c3a40d9&_t=pvid:89957fa5-0471-459d-8d10-62861c3a40d9,scm-url:1007.13339.99734.0
10:01 PM zhanx__: quite night
10:01 PM Tom_L: true that
10:02 PM Tom_L: trying to find a somewhat cheap BLDC replacement for my sherline spindle motor with at least 2x power
10:03 PM Tom_L: preferrably 0-10v analog control