#robotics Logs

Nov 26 2017

12:03 AM anonnumberanon: maybe in ##artsandcrafts
01:38 AM rue_shop3: awe damnit
01:38 AM rue_shop3: I forgot that the dc-dc modules have a resistor on the ouput - for the current detection/limiting
01:39 AM rue_shop3: so I cant just common them all
01:41 AM rue_shop3: oh maybe I'm ok, only the charger does
10:32 AM robotustra: finally I made it working
10:32 AM robotustra: not it speeds up correctly
11:07 AM robotustra: MrCurious, wow, flatfab might be cool to make toys
11:10 AM SpeedEvil: https://newatlas.com/robby-robot-2nd-most-expensive-movie-prop-forbidden-planet/52298/
11:11 AM robotustra: SpeedEvil, who need this trash?
11:20 AM Tom_L: robotustra what was wrong?
11:21 AM robotustra: voltage(frequency) torque ramp was set up for 220 v motor
11:21 AM Tom_L: probably about 2x improvement :)
11:23 AM SpeedEvil: 8* more fire.
11:23 AM robotustra: what are you talking about?
11:23 AM Tom_L: i'd probably rather had Marilyn Monroe's dress
11:24 AM Tom_L: what for? no clue
11:24 AM robotustra: to wear it on halloween?
11:24 AM Tom_L: neither one has value to me
11:25 AM Tom_L: think of the cnc shop i could have for that
11:25 AM SpeedEvil: The alien cargolifter would be nice
11:37 AM HumanSheeple: What is a good source of bronze/brass/copper wormwheels worm gears worm pinions?
11:42 AM Tom_L: HumanSheeple stp-si.com
11:42 AM Tom_L: maybe mcmaster
11:47 AM HumanSheeple: thanks
08:10 PM Tom_L: rue_shop3, i'm wondering how to make the column adjustable but still rigid
08:13 PM robotustra: make a leaf spring in the base
08:14 PM robotustra: hmm did some scraping today
08:15 PM robotustra: made a rough scraping and came to fine scraping
08:30 PM Tom_L: rue_shop3, any thoughts on how to mount it?
08:31 PM rue_shop3: I liked the method you had set up
08:31 PM Tom_L: i need to consider how to attach the column to the base though
08:31 PM Tom_L: just weld it in place?
08:32 PM rue_shop3: with the bolt
08:32 PM Tom_L: then if it's off, i'll have to fix it another way
08:32 PM rue_shop3: and the plates
08:32 PM Tom_L: plates?
08:32 PM rue_shop3: with the slots
08:32 PM Tom_L: oh i have that for the back support yes
08:32 PM rue_shop3: oh wait, then what are ya on about?
08:32 PM Tom_L: but i'm talking about the cross brace between the base
08:32 PM rue_shop3: the middle bottom spacer?
08:32 PM Tom_L: yes
08:32 PM rue_shop3: oh just weld it
08:32 PM Tom_L: where the column rises
08:33 PM rue_shop3: made corrections on the shimming and position of the rails
08:33 PM Tom_L: what if it's not perp though?
08:33 PM rue_shop3: oh, the two rails, then shim them
08:33 PM Tom_L: yeah i thought about that
08:33 PM rue_shop3: I have about 1/8" of shims on the right half of my upright for the x axis
08:34 PM Tom_L: what did you use for shim?
08:34 PM rue_shop3: washers
08:34 PM rue_shop3: but its not continious
08:34 PM Tom_L: mine would have to taper off as it went along the rail
08:34 PM rue_shop3: yup
08:35 PM Tom_L: lots of bolts
08:35 PM rue_shop3: your going to use lots onyhow
08:35 PM Tom_L: i should figure a way to make shims then
08:36 PM rue_shop3: start drinking pop out of aluminum cans
08:36 PM Tom_L: i'm thinking brass
08:37 PM orlock: aluminum
08:37 PM orlock: i thought you were canadian
08:37 PM rue_shop3: close to the border,
08:37 PM rue_shop3: call it aluminium if you want
08:37 PM orlock: or do you lot use the american name for aluminium too?
08:38 PM MrCurious: alu mini uhm?
08:38 PM Snert: aloonimum.
08:38 PM rue_shop3: https://removeandreplace.com/wp-content/uploads/2015/09/The-Periodic-Table-Of-The-Elements.jpg
08:38 PM orlock: MrCurious: thats what we call it here
08:40 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/Mill_Stepper_mounts.jpg
08:40 PM Tom_L: i plan on using that rear brace
08:41 PM Tom_L: i'll probably weld that mount in place first then square up the column and let it be the last piece to weld
08:41 PM AchiestDragon: cant use aluminium washers or copper for shims , as its too soft , and will crush to a different thickness when in use if theres any stress on it , if you want it to be stable you need a strong metal like brass
08:41 PM Tom_L: that's what i said
08:42 PM Tom_L: that or steel sheet
08:42 PM rue_shop3: what parts are needed for a 12' mecha that can be bought from china and are going to cost more or not be available later?
08:42 PM rue_shop3: I think steel sheet would be your beer cans over there
08:42 PM rue_shop3: you an alcoholic yet?
08:42 PM Tom_L: naw, they're aluminum too
08:43 PM Tom_L: canned vegtable cans
08:43 PM rue_shop3: no ripples?
08:44 PM rue_shop3: how thick is aluminum foil?
08:44 PM rue_shop3: I'd check, but I'm too lazy to get off my ass at this exact moment
08:48 PM AchiestDragon: idealy you should weld the upright to a plate with and have a matching plate on the base with holes to mount them together , that way you can place shims between the two plates to get the requierd alignments , as if you have multiple holes along the lenght of the rail to mount things trying to put shims allong the lenth of a rail to make it "ramp" a small fraction is a lot more work and you may get rail flexing or bending making
08:48 PM AchiestDragon: it uneaven over its lenth
08:48 PM Tom_L: i may consider modding it with a plate
08:48 PM Tom_L: i was looking a some designs earlier
08:49 PM AchiestDragon: making an adjustmant point at one end, saves making 20 or so shims at points over the lenght
08:49 PM Tom_L: it would be easy if i had a full blown shop full of tools to build it with
08:50 PM Tom_L: either way i think i'll leave the rear brace
08:52 PM Tom_L: i could mount the plate to the top of the bottom rails
08:56 PM AchiestDragon: https://drive.google.com/file/d/1VK2HVKvYFvmoDi_VtZq2-hQpyE0S5Nn2/view?usp=sharing i built this welded and given the fact that it was thown together with about +-2deg on angles and +- 3mm on holes all hand drilled and cut the fact i added ajustments made getting it to give about 0.1mm acuracy was not that bad
08:56 PM AchiestDragon: wrong pic
08:56 PM AchiestDragon: https://drive.google.com/file/d/1SqUGTJsSM8M0vqXknLTC2gE4Z3xbKq7D/view?usp=sharing
08:57 PM AchiestDragon: tools i had was , vice (not actualy attached to a bench ) hacksaw , hand drill , welder , spaners and a mig welder
08:58 PM Tom_L: that's about what we're looking at here
08:58 PM Tom_L: i've got an angle grinder and used a diamond blade in a table saw to cut the tubes
08:59 PM Tom_L: what's the screw pitch on your Z?
09:00 PM AchiestDragon: i used threaded bar it had 1turn per mm , made doing the stepper maths easy
09:01 PM Tom_L: fine thread then
09:01 PM AchiestDragon: m8 or m10 cant remeber
09:01 PM Tom_L: what's the stepper torque?
09:01 PM AchiestDragon: 110nm
09:02 PM Tom_L: i just got some triple stack nema23
09:02 PM Tom_L: 570 in/oz
09:06 PM MrCurious: i wonder if the lead screw or the end mill will die first for you with over aggressive cuts :)
09:06 PM MrCurious: scratch that, probably the screw coupler
09:06 PM rue_shop3: I made my second machine in 1998, and the threaded rods are still fine
09:07 PM Tom_L: to mount it like that i may have to swap ends with the Y stepper
09:09 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/Mill_Steel/StepperMount2.jpg
09:09 PM Tom_L: ok so i think i'll weld that brace in solid
09:09 PM Tom_L: and put a plate on top of it
09:10 PM Tom_L: and add another cross brace to the vertical column near the bottom
09:10 PM AchiestDragon: threaded rods are fine if you use 2 leadscrew nuts in an antibacklash araingement , the disadvantages are there slow and even when oiled tend to have more friction that means you need slightly stronger steppers than if your using proper lead screws
09:10 PM Tom_L: mine is just to be a step up from my sherline
09:11 PM * rue_shop3 takes a hilighter and hilights SLOW MORE FRICTION
09:11 PM AchiestDragon: :)
09:11 PM rue_shop3: these are important points, over 50% of your motors torque goes into the FRICTION
09:11 PM Tom_L: it uses acme thread but it still wears the nuts
09:11 PM Tom_L: yeah
09:11 PM Tom_L: that's another reason i'm doing it this way
09:12 PM Tom_L: so i'll add pads to the bottoms of the legs and bolt them to the bottom rails and shim if necessary
09:13 PM Tom_L: maybe put an extra plate on the bottom rails
09:13 PM Tom_L: that will least interfere with the current layout and make a workable solution
09:14 PM AchiestDragon: i did see a tip somware that was saying if you put the threaded bar in a drill and run a suare file to give a 45% chamfer accross the top edge of the thread it would reduce some of that friction but not tried that mod
09:19 PM AchiestDragon: ho and the x rails on that machine where 20mm dia solid stainless steel bar , supported by some 20,*3mm steel angle welded into some unistrut , and there was still about .5mm of flex noticable when the machine was under load drilling
09:22 PM MrCurious: with 20mm hardened steel rods (30") length, i found the machine i made would deform them at mid point, and as such could not make a strait cut, just from teh weight of the machine
09:22 PM rue_shop3: from what I can tell, usually the threaded rod is a 'loose fit' in the nuts, it can move sideways a bit, so I dont think modifying the tips would help
09:22 PM AchiestDragon: well drilling 15 mm dia holes though 20mm of aluminium block with a not so sharp drill bit , at least it did not skip steps
09:23 PM MrCurious: if you have not tried freecad (devel daily) for doing cnc/pathing, give it a try, it is now a completely usable viable tool!
09:25 PM AchiestDragon: you only need to take a fraction off the tip so the tip of the tread is rounded , the sideways movment on the threaded bar should not be an issue as the rails should be what matters
09:26 PM rue_shop3: I was not able to get freecad to not crash
09:26 PM MrCurious: that sounds like a problem with the host computer/os
09:27 PM MrCurious: grab a daily and test again
09:27 PM AchiestDragon: it stops dirt and stuff from cloging it up also and as most stock treaded rod is rough anyway stips the tread cutting into the bolt over time
09:27 PM AchiestDragon: stips /stops
09:31 PM AchiestDragon: it gives it more of a "gear " profile and can make them run smoother
09:37 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/Z_Upright_Support.jpg
09:37 PM Tom_L: that should work
09:38 PM Tom_L: and i can adjust it for plum and parallel to X
09:47 PM AchiestDragon: k i would tend to do the support brace on the back the same way having a gap and using a bolt->plate->nut->(space on thread)->nut(1)->plate->nut(2) arangement to hold it rather than the slot , why , because under force the slot mount will creap out of line over time , adjust by nut(2) loose turn nut(1) to allign tighten nut(2) to hold once set they dont slip , unless the force is strong enough to deform the bolts
09:48 PM AchiestDragon: also saves making shims
09:49 PM Tom_L: i thought about putting a turnbuckle there too
09:50 PM Tom_L: also adding a tube spacer inside the upright to prevent crush
10:00 PM AchiestDragon: i did try freecad couple of years back , cant remeber the reason i stoped using it , i ended up using openscad , just find its easyer to do some things in
10:03 PM AchiestDragon: and thats saying something , since i have qualifications in 3d on autocad , the only 2 i seem to use now are blender and openscad and both are free
10:12 PM MrCurious: but the freecad perk now is it does CNC pathing and spits out workable gcode
10:16 PM AchiestDragon: blender has a gui that takes a few weeks to get to know , but once you get the hang of it ,its not so bad and the mesh editing options giving free from sculpting are like no other , the bad points is its more aimed at video than cad , but you can inport /export stl and if you create a referance stl to imptr you can get the size right quite easy
10:17 PM AchiestDragon: and scad does stl also , both import to slic3er for 3d printing gcode gen
10:19 PM Tom_L: i use several
10:19 PM Tom_L: trained on catia i also use solidworks and an old cad cam i have, smartcam
10:20 PM Tom_L: i tried openscad and hated it
10:21 PM orlock: wtf
10:21 PM orlock: What's _WRONG_ with you??
10:21 PM Tom_L: also tried bobcad
10:23 PM AchiestDragon: openscad is basicaly a 3d scripting language , guess it comes from doing povray scripting years back but its just as easy for me to do it that way as is second nature and quicker for me
10:23 PM Tom_L: and i've got a student copy of acad but i haven't used it much
10:24 PM Tom_L: my kid is taking it
10:24 PM AchiestDragon: autocad used to be a pain having to enter 3 sets of xyz cordinates to define a rectangle
10:25 PM Tom_L: you can get/use fustion 360 free
10:25 PM Tom_L: yeah i didn't ever use acad much
10:25 PM Tom_L: not for cnc anyway
10:26 PM Tom_L: i still have the dos version of smartcam
10:26 PM AchiestDragon: solidworks well yea and autocads new fusion360 but there still propietory code and licencable in some way
10:27 PM Tom_L: both dos and windows
10:28 PM Tom_L: f360 has a ways to go
10:28 PM AchiestDragon: as i do it for hobby now i tend to stick to gpl /opensource stuff and i dont use windows , i still have a xp laptop someware but have not had need to run any windoew only software for over 5 years now
10:28 PM Tom_L: this is hobby for me now too
10:28 PM orlock: we also use a thing called NX11 here
10:29 PM Tom_L: but i have a few decent tools leftover
10:29 PM orlock: but i think thats one of the Big Boys Toys
10:30 PM AchiestDragon: also seems kicad seems better than the older geda pcb package , looks quite usable but not done a pcb for ages
10:30 PM Tom_L: i used eagle for that
10:31 PM AchiestDragon: well have to say i used altium for that last time i did one
10:31 PM Tom_L: i tried pads but actually like eagle better for hobby stuff
10:31 PM orlock: we have that one too!
10:31 PM * orlock doesnt actually use any of them
10:31 PM orlock: i just install the licence servers
10:32 PM Tom_L: NX11 looks like it originated in the robotics world
10:33 PM orlock: Tom_L: its history dates back to the 70's
10:34 PM orlock: http://www.plmworld.org/index.php?mo=cm&op=ld&fid=220
10:35 PM AchiestDragon: 1972
10:42 PM AchiestDragon: the other is brlcad , now opensource , been a couple of years since i used it but they where working on a beter user interface for it , but its still like 70's software
10:46 PM rue_mohr: were still using engies designed in the 1700's why is 70s software so bad?
10:46 PM rue_mohr: talk to me when evryone has an electric car
10:47 PM rue_mohr: that flies
10:47 PM AchiestDragon: because i nolonger have space for papertape
10:48 PM AchiestDragon: and punch cards take ages to sort if you drop them
10:51 PM AchiestDragon: i used to repair computervison cad systems , they where rebadged datagenaral eclipce series minicomputers with vector graphics terminal , bitslice cpus and most of them at least had 5mb fixed 5mb removable 12" hdds
10:53 PM orlock: AchiestDragon: Tektronix displays?
10:53 PM AchiestDragon: yea
10:55 PM AchiestDragon: 99% of all problems was eather adjusting the display focus on the monitor or finding the optical limit sensor in the plotter that had got a bit of paper jamed in it
10:59 PM AchiestDragon: also some pdp11's and sun kit , i had a pdp11/03 and an 11/23 at home many years back
11:00 PM AchiestDragon: but did not get into cad miself till i got a 286 machine , remeber it costing me small fortune to get the needed 287 maths co processor
11:03 PM AchiestDragon: my first home computer was a nascom1 back in 1979
11:10 PM AchiestDragon: in some ways i miss the old systems , mainly documentation , the manula set for the 2 pdp11/s was a 2 6foot tall stacks of a4 ring bound folders full with the schimatics and assembly drawings a stack of about 3" high of a3 sheets right down to every last nut and bolt
11:12 PM AchiestDragon: every link setting explained every register and logic gate , and every o/s function call etc
11:13 PM AchiestDragon: althoug hsaying that it would prob amount to more than my house full for one modern pc if they did the manuals that detailed today
11:15 PM rue_mohr: so your saying you have the source for all the floating point trig functions
11:15 PM AchiestDragon: the souce code for the os for one , how many cubic miles of printout for the source code for 4Gb of object files take ?
11:18 PM AchiestDragon: download the linux source, you should find the trig functions in the maths lib for the generic c compiler or one of the other copiler libs
11:18 PM rue_mohr: I want the source for the ones sthat run so quick on a 1Mhz computer
11:19 PM rue_mohr: that said,t he last time I did complex floating point on a 16Mhz avr, I was REALLY impressed with the speed
11:20 PM AchiestDragon: the amd29000 data sheets used to have the asembly code for the multiply divide , sin and cos functions , as examples in there
11:21 PM rue_mohr: floating point in 8 bits?
11:22 PM rue_mohr: cause I thought the 29000 was 16 bit
11:22 PM AchiestDragon: although emulationg a soft fpu sould be in the linux libs also someare , no the 29000 was 32 bit risc
11:22 PM rue_mohr: right
11:23 PM AchiestDragon: soft fpu on eraly arm chips , but it takes a lot of cycles 32bit fp mult on a 32bit risc (one cycle per instuction) cpu is 64 cyles
11:24 PM AchiestDragon: and cos is something like (1/n)+(1/n*n)+(....... ... type maths
11:29 PM AchiestDragon: http://www2.clarku.edu/~djoyce/trig/compute.html cosx=1-(x2/2!)+(x4/4!)-(x6/6!)+( ....
11:32 PM AchiestDragon: if you need to do a lot of math its worth having a micro with a fpu
11:37 PM AchiestDragon: if i recall correctly the 68000 fpu data sheets covered soft emulation of maths co processor functions also but are usualy in the prewritten maths libs that come with the copiler /assembler
11:37 PM AchiestDragon: and sadly only in some c compilers for 8 bit microcontrolers
11:39 PM AchiestDragon: with 8bit you could prob get a robot arem to draw them in graphics format using a pencil and compas quicker than you can get the cpu to do it
11:53 PM AchiestDragon: rue https://www.quinapalus.com/qfplib.html < 16 bit float ing point lib arm source
11:56 PM AchiestDragon: they also quote benchmarks for Microchip PIC18F242 and Atmel ATmega8 so theres prob a port of it for them also