#robotics Logs

Sep 25 2015

01:58 ferdna like these:
01:58 ferdna http://www.ebay.com/itm/2-Curved-Round-Linear-Bearing-Guide-Rails-Curved-THK-HSR35-Circular-Motion-/151310014482
02:00 Snert I picture a big robotic arm sitting on those to swivel.
02:03 Hyratel the large one has a "rack" gear on the outside
02:14 peepsalot oooh, fancy
19:51 ace4016 weather-proofing/resisting my burner is going to be fun...
19:54 ace4016 rue_mohr, how cheap do you think one could build a fairly accurate "engraving-sized" 5-axis CNC machine? less than $2k USD?
19:54 Tom_itx https://www.youtube.com/watch?v=g99lUtjLfMU&feature=youtu.be
19:54 Tom_itx ace4016 why not and why 5 axis?
19:54 Tom_itx rotary?
19:55 ace4016 making shapes that a 3-axis (isn't it technically 4?) CNC isn't quite capable of
19:56 Tom_itx linuxcnc will do 9 axis
19:56 Hyratel you could make an indexing spindle for a 3 Axis
19:57 Tom_itx full 5 axis is just cooler to watch though
19:57 ace4016 hehe
19:58 ace4016 whatever gets me the shape complexity
19:58 ace4016 as much as i like cool, i will cast it to the wind for practicality
19:58 Tom_itx what do you want to make?
19:59 ace4016 many things, but one of the main ones i want to toy with are centrifugal impellers
20:05 ace4016 hrm...
20:22 ace4016 maybe the indexing spindle will work
20:23 Tom_itx or just an index head
20:27 Hyratel a spinedl will allow for undercuts on the Chord axis
20:27 Hyratel spindle
20:31 ace4016 hrm...
20:34 ace4016 are indexing spindles/index heads meant for lathe type CNCs?
20:41 Tom_itx not necessarily
20:44 ace4016 hrm, i wonder if 3/4 axis CNCs aren't used for centrifugal impellers due to time
20:44 ace4016 also, is there a difference between the index CNCs and a 4-axis CNC or are they analogous?
20:45 Tom_itx yes, no
20:45 Tom_itx there are indexers and there are full control rotary axis
20:45 Tom_itx with synchronous motion
20:45 ace4016 ah
20:45 Tom_itx the vid i posted was an example of synchronous motion
20:46 Tom_itx really cool feature of linuxcnc
20:48 newradio how do you guys buy nuts and bolts (6-32 + length, 8-32 + ...) ? :)
20:49 Jak_o_Shadows in metric :P
20:49 Jak_o_Shadows More seriously, local bolt shop
20:49 ace4016 hrm, i might have missed the synchronous motion; is that the fact that multiple "platforms" are used in conjunction to get the full motion (e.g the drill/router bit goes up and down and the table provides the other 2 axes? )
20:50 ace4016 also, your own build Tom_itx?
20:50 newradio Jak_o_Shadows: It seems like i've to go there too often :) washers, bolts, nuts, ....
20:50 Tom_itx ace4016, Z is following the spindle rotations to run the rigid tap in: https://www.youtube.com/watch?v=g99lUtjLfMU&feature=youtu.be
20:50 Tom_itx it's a sherline but i did quite a few mods to it
20:51 Hyratel Tom_itx, that's different than what I was using Indexing to mean
20:51 Jak_o_Shadows My place has decent (for australia) shipping, so that's how I'd do it.
20:51 Tom_itx Hyratel i'm aware of that
20:51 Tom_itx but the motion is quite similar
20:51 Tom_itx you move one axis and the other moves in step with it
20:51 Tom_itx be it a cutter path or a tap
20:52 Tom_itx or a helix gear
20:52 Tom_itx etc
20:53 Hyratel http://cnckingdom.com/shopbots-cnc-indexing-tool/
20:53 ace4016 or even this without 5-axis? https://d2t1xqejof9utc.cloudfront.net/screenshots/pics/18cf657ed76da161eb412482f16be9c5/medium.JPG
20:54 Hyratel ace4016, chord
20:54 Hyratel chord of the circle on the indexing drum
20:57 ace4016 chord...could you explain that bit a little more?
20:57 Hyratel if you draw a straight line through a circle without intersecting the center, it's a chord
20:57 Tom_itx https://www.youtube.com/watch?v=CqePrbeAQoM
20:57 Hyratel keep it paarallel with your diameter reference
20:59 ace4016 that's what i thought it was, but wasn't sure how that necessarily helped, but i don't know much about machining :P
20:59 Hyratel so, if at any location, you have chord line of sight onto all surfaces of the finished item, you can use an indexing drum for your 4th axis
21:00 Hyratel clarifying
21:00 Hyratel if you have line of sight by diameter or chord through the circular section of the part by z axis
21:02 ace4016 z-axis being up and down? (i've had to deal with a lot of different coordinate systems :P)
21:02 Hyratel X axis is left right, Y is near/far, Z is up/down (tool), R is Drum
21:03 Tom_itx A B C
21:04 Tom_itx R is an undefined axis
21:04 Hyratel fiiiine
21:04 ace4016 lol
21:05 Tom_itx X Y Z A B C U V W
21:05 ace4016 so either way, you're saying the CNC in that CNC Kingdom link would be able to produce https://d2t1xqejof9utc.cloudfront.net/screenshots/pics/18cf657ed76da161eb412482f16be9c5/medium.JPG (looks like it to me)
21:05 Tom_itx are defined axis
21:06 Tom_itx you would want a live rotary for that
21:06 Hyratel ace4016, no, I'm saying a 4 axis such as a shopbot would be able to
21:06 Hyratel I don't see any geometry that'd be blind on the indexing drum
21:07 Hyratel if you take the center hole as "pre-existing" or 'added after"
21:07 Tom_itx in order to cut the tight radius at the base of the large vein you would need to tilt the axis which you can't do on an indexer
21:08 Hyratel vane
21:08 Tom_itx that's what i said... vein!
21:08 ace4016 lol
21:08 ratel stabs Tom_itx in the
21:08 Tom_itx you're so vain
21:08 ace4016 a live rotary?
21:09 Tom_itx or a live tooling head
21:09 Tom_itx where the head tilts
21:09 Hyratel ace4016, are you handy with fabrication?
21:09 Hyratel you could build an offset Z axis
21:09 Tom_itx just buy a friggin 3d printer
21:09 Hyratel with manual angle set
21:10 Hyratel could get you up to ... 45 degrees
21:10 ace4016 no, this is my first foray into building things more complicated than what i can build with a drill and bandsaw :P
21:10 Hyratel a bandsaw? you're already ahead of the game then
21:10 ace4016 Tom_itx, the ones that can touch ceramics are 3pricey5me
21:11 ace4016 lol Hyratel
21:12 ace4016 so based off of the suggestions, 5-axis is ideal; can be done with 3 and 4 if you get the 5th through stationary means
21:13 ace4016 hrm...
21:13 Hyratel so what I'm seeing in my head here
21:14 Hyratel is a 3 axis, but the Z axis gan be rotated where it meeds the X axis
21:14 Hyratel and either a turret or drum indexer
21:15 ace4016 lowest cost solution eh?
21:15 ace4016 should be find as i won't be mass producing
21:18 Tom_itx 2k might be a low bid for such an animal
21:18 Hyratel nice thing is you could start with a 3 Axis mill with a removable Z axis
21:19 Hyratel and then build up your parts
21:19 ace4016 removable z?
21:19 Hyratel an incremented swivel for the Z, a turret bracket
21:19 Hyratel yeah
21:19 ace4016 you mean to rotate it about the Y-axis?
21:19 Hyratel the Z frame bolted to the X slide
21:22 Hyratel http://www.anchoragemakerspace.com/wp-content/uploads/2014/05/shopbot5.jpg
21:23 Hyratel one thing that'll be a limiting factor is rigidity
21:26 ace4016 hrm...
21:26 Tom_itx ace4016, about the X axis
21:26 Tom_itx is the norm
21:26 Tom_itx X usually has more room for it
21:27 ace4016 hrm, that seems redundant as the indexer in Hyratel's example link seems to handle that by moving the part
21:28 ace4016 unless i missed something
21:28 ace4016 which is definitely possible
21:28 Hyratel ace4016, you're pivoting the Z axis attach point where it meets the X axis
21:28 Hyratel so it scissors
21:30 ace4016 and the X axis is the one going left and right, correct? (assuming you're facing the machine)
21:30 ace4016 (standing up...)
21:31 Hyratel yes
21:32 ace4016 hrm...and that's different than just rotating on A?
21:32 Hyratel what's A
21:33 Tom_itx usually about the X axis
21:35 Hyratel <Hyratel> it's A, but the pivot point is at the meeting of X and Z
21:35 Hyratel <Hyratel> er
21:35 Hyratel <Hyratel> http://www.turkcadcam.net/rapor/cam-terimleri/01.jpg
21:35 Hyratel <Hyratel> per this diagram, where Y-Z meet
21:35 Hyratel <Hyratel> your C would be on a turret
21:35 Hyratel <Hyratel> woops
21:35 Hyratel so a manual A axis, a turret C
21:38 ace4016 ah, that's what you meant by meeting of X and Z; essentially having the tooling head rotate in it's "cradle" in fixed positions to reach certain parts
21:38 ace4016 also, what do you mean by turret C?
21:41 Hyratel ok i was misusing the twerm
21:41 Hyratel term
21:41 Hyratel I had in mind an indexing platform
21:47 Hyratel ace4016, make more sense?
21:47 Hyratel with the combination of a manual A axis and a rotating platform for C
21:49 ace4016 C being about Z, A being about X
21:50 Hyratel per the diagram there, it's X>Y>Z>C>A as far as parenting of axis
21:50 Hyratel you'd have X>Y>mA>Z
21:50 Hyratel and C
21:51 Tom_itx http://www.ebay.com/itm/CNC-Rotary-Table-Rotational-Axis-A-B-4th-5th-Axis-Self-Centering-Manual-Chuck-/261854394644?hash=item3cf7bcf914
21:51 Tom_itx like that?
21:51 Hyratel C would be a "root level" axis
21:51 Hyratel yes, that's a B>C table
21:54 e4016 chuc
21:55 ace4016 it almost seems like you're suggesting something like this (tom linked previously): https://www.youtube.com/watch?v=CqePrbeAQoM
21:55 ace4016 except not that machine because that probably cost more than my house
21:57 Hyratel you haven't been listening
21:57 Hyratel I say you'd need a manual A axis and an indexing C axis
21:58 ace4016 manual A being that I set the tool bit to rotate on A manually?
21:58 Hyratel yes
21:58 Hyratel you have an approch angle
21:58 Hyratel A
21:59 ace4016 indexing C i didn't quite get
21:59 ace4016 oh wait, nevermind
21:59 Hyratel because there's a locking swivel between the Z and either Tool or Y
22:00 Hyratel it's a platform in your platform bet that you attach the work to, and it rotates
22:04 ace4016 so part sits on platform that rotates on C; and the tool can be manually set to different set A angles; and the translation axes in almost any configuration (tooling XYZ, table XY/tooling Z, table XYZ, etc.)
22:05 Hyratel yes
22:05 Hyratel Rigidity will always be the issue though
22:06 ace4016 rigidity of what? the tool and being able to hold the angle?
22:06 Hyratel the A connection
22:06 Hyratel depending on how it's built
22:06 ace4016 ah
22:06 Hyratel you want to always approach with the tool on-axis
22:07 Hyratel this requires synchronous Y-Z operation, or an angled Z
22:07 ace4016 hrm
22:07 Hyratel (Y>C>Z>Tool)
22:07 Hyratel er
22:08 Hyratel Y>A>Z>Tool
22:09 ace4016 hrm, if rigidity is the issue there, is that why say that industrial machine did a XYZBC instead of an XYZAC?
22:09 Hyratel buah
22:10 Hyratel I don't understand the question
22:10 ace4016 heh
22:12 ace4016 nevermind; wasn't an important question. and i think i figured it out either way
22:25 at^ attaches a crank to the channel wall and begins slowly crankin
22:29 e_house pop
22:29 ^kat^ !ACK!
22:30 at^ re-reads the crank instruct
22:30 Hyratel ace4016, I'm movking up what I was trying to describe in CAD
22:32 rue_house Hyratel, excellent
22:43 ace4016 ahoy ^kat^
22:43 ^kat^ yey ace
22:43 ace4016 Hyratel, cool. i think i understand what you meant; appreciate it. same to you Tom_itx
22:43 Hyratel ace4016, hold sec, still sketching
22:44 ace4016 while i was letting my dogs out i was thinking about kinematics since we were talking about CNCs, and then i was thinking about efficient walkers
22:45 ace4016 for walking, bipedal may be the most efficient; then i was trying to think of other bipedal walking animals than humans...and all i can think of are birds
22:46 Jak_o_Shadows dinosaurs?
22:46 ^kat^ lemurs
22:46 Jak_o_Shadows meerkats
22:46 ace4016 lemurs hop it seems more so than walk
22:46 Hyratel https://dl.dropboxusercontent.com/u/33593534/images/5%20axis%20CNC%20mockup%201.png
22:47 ^kat^ ok
22:47 ace4016 dinos are birds now Jak_o_Shadows :P
22:47 Jak_o_Shadows kangaroos, but they hop. In a very cool way
22:47 ace4016 hehe
22:48 Hyratel ace4016, does that diagram make it make more sense?
22:48 Hyratel proportions not to scale
22:48 ace4016 Hyratel, so you were thinking of rotation at the beam supporting the Z axis actuators and tooling? thought you just meant tooling head
22:49 ace4016 i more or less thought that was what you meant though
22:49 Hyratel that was one option. let me rearrange it
22:51 Hyratel https://dl.dropboxusercontent.com/u/33593534/images/5%20axis%20CNC%20mockup%202.png
22:51 Hyratel here's X>Y>Z>A
22:52 Hyratel the previous was X>Y>A>Z
22:54 Hyratel with this one you'd have to synchronise Y/Z for linearity of movement on the tool
22:54 Hyratel so you don't wind up with transverse stresses killing it
22:56 ace4016 hrm...
22:56 Hyratel rue_house,
22:58 ace4016 ooh, the motors don't look too expensive
22:59 ace4016 i guess they go up in price according to accuracy and power though
23:01 Hyratel rue_mohr, beep boop
23:04 ace4016 also, are UVW axis just the accomodation of automated tooling change in a CNC?
23:04 Hyratel I don't know
23:10 ace4016 more of a curiosity think; no worries
23:10 ace4016 thing*
23:16 ace4016 hrm...now you have me thinking Hyratel...would the A rotation at the top or tool be better. seems like at tool would be
23:24 rue_house yes?
23:25 Hyratel you expressed interest in the mockup of the CNC 5 axis design
23:25 Hyratel https://dl.dropboxusercontent.com/u/33593534/images/5%20axis%20CNC%20mockup%201.png
23:25 Hyratel https://dl.dropboxusercontent.com/u/33593534/images/5%20axis%20CNC%20mockup%202.png
23:25 ace4016 oh, i never finished my thought on bipedals. seems like simply being bipedal isn't enough; efficiently falling seems to be the best means to walk bipedally. anything more controlled uses a lot more energy
23:27 ^kat^ yeas, because walking isn't statically balanced, it takes control to do well, it's a constant fall recovery act
23:28 rue_house Hyratel, hmm, not quite as ridgit a design as I'd aim for
23:28 Hyratel that's just slapping together CAD primitives
23:28 rue_house yup
23:29 at^ shows ace the bruise and large gash on her arm because she didn't perform walk() properly the other
23:29 rue_house :/
23:29 ace4016 aww
23:30 rue_house did you pull a rue and walk into a door before the open() was finished?
23:30 Hyratel ace4016, http://www.ebay.com/itm/6-CNC-Rotary-Indexer-and-Accessories-/111780075899?hash=item1a069c997b
23:30 rue_house damn, thats a give-away
23:30 ^kat^ no i attempted to pass speed and placement parameters that were refused
23:30 ace4016 maybe bipedal walking isn't worth it; quadraped seems simpler. must be why the quads can walk in days/weeks/hours/minutes
23:31 Jak_o_Shadows I know of some people who are making a nice kangaroo robot
23:31 ^kat^ quadruped
23:31 Jak_o_Shadows better than festo's hopping rat
23:31 ace4016 woops, thanks ^kat^ :P
23:31 rue_house http://www.harborfreight.com/6-inch-cross-slide-vise-32997.html
23:31 rue_house even thats $80
23:32 ^kat^ and you can prolly make a better one
23:33 ace4016 Jak_o_Shadows, is it the kangaroo robot with a spinning tail?
23:33 Hyratel rue_house, only good for drill press
23:33 Hyratel and they probably don't relax the iron before shaping
23:34 Hyratel but if you just need the cross-slide action and aren't too worried about precision, it's fine
23:34 Jak_o_Shadows Nah. I don't think there's anything on the net about it. They're using elastic material (in the place of tendons?), so it actually hops
23:34 ace4016 ah
23:34 Jak_o_Shadows So it's actually similar in mechanics to a real kangaroo
23:34 ace4016 neat
23:35 Hyratel rue_house, what were you saying about rigidity?
23:39 ace4016 hrm...should get to work drafting up a mount for my motor and pump...and figure out my fan situation.