#robotics Logs

Dec 12 2014

00:05 rue_shop3 erp, problem
02:49 rue_more heh, there is a windstorm and I'm leaving the reprap to finsih a jab
02:58 rue_bed its printing houses
09:57 mumptai so, where can i see the 3d printed psycho arudino robots?
10:00 uirrelCZECH is in
10:02 SquirrelCZECH more like mine is in too
10:02 SquirrelCZECH *todo
10:03 SquirrelCZECH https://cloud.veverak.org/public.php?service=files&t=69a4aa63c65affa60b10bfc8d5746eac designing fase so far
10:03 mumptai what armament?
10:04 SquirrelCZECH not decided yet
10:04 SquirrelCZECH missiless like thingie would be awesome
10:04 SquirrelCZECH but I suppose I will have to stick with an airsoft gun
10:04 SquirrelCZECH mumptai: but figured out it would be awesome to build quadracopter with abillity to lift this thing up and move it around
10:06 mumptai make it light enough, and that should'nt be a problem at all
10:06 mumptai is that in openscad?
10:06 SquirrelCZECH yep
10:07 SquirrelCZECH and no
10:08 SquirrelCZECH mumptai: got my own library in python that allows me to do what you can do in scad with python
10:08 SquirrelCZECH and that library just exports scad code :)
10:08 mumptai and i guess you want to have double idlerwheels at first and last positon
10:09 mumptai yep, openscad is rather limited as an language
10:09 SquirrelCZECH well
10:09 SquirrelCZECH "first" is geared wheel :D
10:09 SquirrelCZECH but yeah, two printed parts making one wheel
10:09 SquirrelCZECH afk, exam
10:09 mumptai okay, then the second
10:09 mumptai good luck
10:55 SquirrelCZECH back
10:55 SquirrelCZECH mumptai: geared wheel is made out of 3 parts
10:55 SquirrelCZECH fron wheel out of 2
11:06 mumptai but if the first lower idlerwheel take some preasure from climbing some obstace, the trace will twist as the point of contact of of center
11:11 SquirrelCZECH what? :D
11:11 SquirrelCZECH mumptai: a. there are three types of wheels -> geared, idler and normal wheel
11:12 SquirrelCZECH I assume you think normal wheel nearest the idler wheel which is in front of the machine?
11:12 mumptai the ones actually bearing the machines weight
11:13 SquirrelCZECH yeah
11:13 SquirrelCZECH well the idea is that they are close enough to prevent this
11:14 SquirrelCZECH I just suppose that with the distance between each other, the fact that tracks by itself doesn't want to twist a much and the fact that fron wheel will prevent this a little...
11:14 SquirrelCZECH it shoudln't be problem ;)
11:14 mumptai if the bearings in the track can take it
11:15 SquirrelCZECH there are no bearings in the tracks...
11:16 mumptai there are joints, there is _some_ kind of bearing
11:16 SquirrelCZECH oh, yeah
11:17 SquirrelCZECH metal wires... didn't picket the right ones, but idea is that you take wire trought that and bend it at the ends
11:18 SquirrelCZECH mumptai: the surface when two pieces touches that is orthogonal to axis of the join is quite big
11:18 SquirrelCZECH hmm
11:18 SquirrelCZECH on the other hand, it should be possible for me to decrease the chance it will slip with "smarter" design
11:27 mumptai just let the printer run some more hours ;)
12:04 SquirrelCZECH mumptai: https://cloud.veverak.org/public.php?service=files&t=cbd452aa67c84bc8d4e37802549d47e8
12:04 SquirrelCZECH upgrade :)
12:16 mumptai nice :)
13:40 SolarNRG can anyone recommend a really powerful awesome hand powered drill?
13:40 SolarNRG like geared, hi torque hand crank long lever that sorta thing
13:47 GuShH SolarNRG: yeah, go back to the 70s and buy the first one you see
17:45 Hyratel https://www.sparkfun.com/products/13204
17:53 SquirrelCZECH nah, dc
18:53 GuShH rue_more: finally ordered a geometric die head and a tapping head!
18:54 rue_shop3 geometrix?
18:54 rue_shop3 the hex ones?
18:54 GuShH what do you mean?
18:54 GuShH it uses 3 dies and it moves them in or out
18:54 GuShH has a fine and coarse mode
18:54 GuShH automatically pulls the dies out when it disengages
18:54 GuShH so you can quickly thread bar stock with them
18:55 GuShH this one is limited to like 5/16 but it has 4 die sets.... so I can't complain
18:55 GuShH bigger ones are really expensive
18:55 GuShH cool thing is that you can adjust the thread fit very finely
18:55 GuShH more so than with an adjustable button die
18:56 arko anyone here familiar with IMUs?
18:56 GuShH this style http://www.ebay.com/itm/GEOMETRIC-5-16-DIE-HEAD-W-5-8-SHANK-CHASERS-/121492454488
18:57 GuShH I believe the chasers/dies can be honed back to a sharp edge, but we'll see once I get them here.
18:58 GuShH oh heh, 4 chasers not 3
19:00 GuShH can't believe they still hold their value after so much time
19:01 Tom_itx whasssup?
19:01 GuShH they had rolling die heads but yakno' the dies are non-existent for them
19:02 GuShH kinda neat how they form the thread and you have to start with a smaller OD
19:02 Tom_itx are so
19:02 GuShH wat
19:02 Tom_itx i've done thousands of em
19:02 Tom_itx rolled threads
19:02 GuShH no, for these small heads they don't make the dies anymore "here"
19:02 GuShH not available "for me"
19:03 GuShH the flat big dies for the big machines are available
19:03 Tom_itx aaaahhh yeah
19:03 Tom_itx ur in a 3rd world country...
19:03 GuShH wa wa wa
19:03 Tom_itx :)
19:03 GuShH this type http://www.ebay.com/itm/Thread-Rolling-Die-Head-M3x0-5-rod-spoke-threading-head-Gewinderollkopf/181428609802?_trksid=p2047675.c100010.m2109&_trkparms=aid%3D555012%26algo%3DPW.MBE%26ao%3D1%26asc%3D27538%26meid%3D4762443beb44412d908444dc067420f2%26pid%3D100010%26prg%3D11353%26rk%3D3%26rkt%3D24%26sd%3D231399617151
19:04 GuShH the local manufacturer closed shop a long time ago.
19:04 choonway arko: imu = inertial measurement units?
19:04 Tom_itx for od thread?
19:04 GuShH yeah
19:04 arko choonway: yes
19:04 Tom_itx yep, i've done many of them
19:04 Tom_itx are those geared together?
19:04 Tom_itx the ones i used were 2 thread dies
19:04 Tom_itx geared
19:04 Tom_itx and single bump thread
19:05 arko i'm wondering, can modern IC IMUs get gimbal locked?
19:05 GuShH I'm not sure if they are
19:05 choonway arko: no
19:05 arko ok i thought so
19:05 arko gimbal lock is a mechanical issue
19:05 GuShH typically they have gearing... and speaking of which, I'm worried about the tapping head gears and clutch
19:05 choonway arko: only mechanical imus can get locked
19:05 arko cool
19:06 GuShH if it has a fiber clutch, you think I could refurbish it?
19:06 choonway arko: and only if they have gimbal on 3 axes
19:06 arko right
19:06 choonway arko: mechanical gimbals can overcome gimbal lock if they have 4 axes
19:06 GuShH it has an MT2 arbor and it comes with an MT3 adapter, which is great
19:06 arko if you have 4 you go quaternion
19:06 choonway arko: but then you need to actively drive the 4th axis to avoid gimbal lock
19:07 arko really?
19:07 arko ohh
19:07 GuShH rue_more: here's a vid https://www.youtube.com/watch?v=mUFYhaSxvkY
19:07 arko right
19:07 arko in case 3 of them lock
19:08 GuShH Tom_itx: are brass threaded rods / all-thread also rolled?
19:08 choonway arko: there's a story about the 4th gimbal on the original apollo missions to the moon lol
19:08 arko yeah
19:08 Tom_itx idk
19:08 arko collins wishing one for christmas
19:08 arko :P
19:08 GuShH I guess
19:09 arko choonway: your control code would need to handle gimbal lock though no?
19:09 choonway arko: but the modern ones are based on MEMs and based on some kind of vibrating beam
19:09 arko right, you get axial measurements
19:09 GuShH Tom_itx: are the dies made out of carbide? they roll stainless and all kinds of materials, they seem to last a very long time with lubrication
19:10 arko but to apply a transformation/command
19:10 Tom_itx why do you need a thread roll?
19:10 choonway arko: no you just don't get gimbal lock with modern mems
19:10 GuShH oh I don't
19:10 Tom_itx tool steel
19:10 arko hm
19:10 GuShH I'm not even buying any of that
19:10 GuShH just the heads
19:10 Tom_itx not carbide
19:10 arko wonder why video games can have gimbal lock
19:10 choonway arko: gimbal lock is the nature of the gyro mechanism. it doesnt exist for mems accelerometers
19:11 choonway arko: lousy algorithms
19:11 Tom_itx we did alot of knurls too
19:11 GuShH Tom_itx: I don't plan to roll any threads at all, not my thing
19:11 Tom_itx alum brass and steel
19:11 choonway arko: they rely on RPY transformation matrices instead of quaternions
19:11 GuShH but I'm dying for the tapping head
19:11 Tom_itx they're pretty when they're done right
19:11 arko choonway: ahh
19:11 Tom_itx look better than cut threads
19:11 choonway arko: the phenomenon mirrors that of the mechanical gimbal lock so the term stuck
19:12 GuShH should be stronger also
19:13 arko that makes sense now
19:13 arko thanks choonway
19:13 choonway arko: np :)
19:13 ShH wonders why the torque bar is mis
19:38 GuShH wth I didn't know SKF used to make taps
19:43 Tom_itx why not?
19:43 GuShH I didn't know.
19:44 GuShH They still make taps?
19:44 GuShH oh DORMER bought the division?
19:44 GuShH or was it always part of SKF
19:44 Tom_itx dunno
20:06 armyofevilrobots rue_more: You win, I'll take on of those PSUs if you can spare one.
20:06 armyofevilrobots Trying to print large objects without a heated bed.... _pain_.
20:07 armyofevilrobots OTOH, Entire bottom end of the power printer is now printed.
20:08 armyofevilrobots Which means instead of working in the shop, I have to fire up lein repl, CGAL, and start working on the custom slicer for the bitmap strips for the inkjet. :(
20:11 armyofevilrobots er.... _powDer_ printer.
20:13 Tom_itx what gage wire is run to the steppers on a reprap?
20:14 Tom_itx 18?
20:14 Tom_itx 20?
20:14 Tom_itx 20 may be a little thin..
20:15 Tom_itx err.. maybe not, i rean 18 to my cnc steppers
20:27 armyofevilrobots 20 is fine for 1.5A or so. Beyond that 18 is a better choice. Repraps might run more than that continuous if you crank the current up on your drivers.