#robotics Logs

May 14 2014

09:41 rue_more I think I came up with a conveyorbelt design
09:41 rue_more tub chain and picture frames, see how it goes
09:53 GuShH rue_more: conveyor for what?
10:02 Tom_itx thoughts
13:01 f00bar80 Using this code http://pastebin.com/2mWggg3x I have a robot arm with gripper, which should open/close the griupper and moves up/down the arm, but the arm and gripper, move like in here https://www.dropbox.com/s/ghqxu8cuqab962z/2014-05-14%2000.41.28.mp4 , wonder what's wrong in the code?
14:36 GargantuaSauce https://www.gcsurplus.ca/mn-eng.cfm?snc=wfsav&sc=enc-bid&scn=159381&lcn=304656&lct=L&srchtype=&lci=&str=26&ltnf=1&frmsr=1&sf=ferm-clos
14:36 GargantuaSauce 800 bucks.
16:30 GuShH GargantuaSauce: Yes... that would be the minimum bid amount.
16:31 GargantuaSauce yeah and the auction is half over with no bids
16:31 GargantuaSauce it's probably going to sell for the minimum price, if at all
16:31 GuShH that's an open auction?
16:31 GuShH you have 2k in transport I bet :p
16:31 GargantuaSauce yeah
16:31 GargantuaSauce probably still worth it i think
16:32 GuShH If you have the space and ze powah
16:32 GargantuaSauce yeah
16:32 GuShH I have 3 phase service, but no space currently, for instance.
16:32 GuShH says closed bidding on the title
16:32 GuShH so you'll never see other people's bids
16:33 GargantuaSauce hurr
16:33 GuShH highest one wins
16:33 GuShH >_<
16:33 GargantuaSauce it probably needs a new controller to be useful, too
16:33 GuShH I can lend you a pile of floppies
19:44 f00bar80 Using this code http://pastebin.com/2mWggg3x I have a robot arm with gripper, which should open/close the griupper and moves up/down the arm, but the arm and gripper, move like in here https://www.dropbox.com/s/ghqxu8cuqab962z/2014-05-14%2000.41.28.mp4 , wonder what's wrong in the code?
19:45 f00bar80 Started to feel crazy ... don't know what's wrong?
19:45 f00bar80 is it my code or what
21:09 robotustra_ hi
21:19 GargantuaSauce hello
21:20 robotustra_ looks good https://www.kickstarter.com/projects/1650950769/rigidbot-3d-printer?ref=discovery
21:21 GargantuaSauce rigid is a pretty silly name for something with a prismatic frame
21:22 robotustra_ the frame of rhis printer is rigid - and I think it should do good things with precision
21:24 GargantuaSauce i don't see any specifications for motion control precision or repeatability
21:26 robotustra_ I think it's quite standard
21:27 GargantuaSauce yeah the prints look comparable to a mendel i2 or something
21:48 robotustra_ GargantuaSauce: do you have 3D printer?
21:49 GargantuaSauce yes
21:50 robotustra_ what kind of?
21:50 GargantuaSauce mendel
21:51 robotustra_ did you build it yourself?
21:51 GargantuaSauce from a kit
21:51 robotustra_ what is the printing area?
21:51 GargantuaSauce 20x20cm
21:52 robotustra_ and height?
21:53 robotustra_ 10cm?
21:53 GargantuaSauce probably about 15
21:53 robotustra_ and what is a precision?
21:53 robotustra_ finest one?
21:56 GargantuaSauce about 12 microns in theory, closer to 150 in practice
21:57 GargantuaSauce more when it's moving fast and it flops around on the xz plane of course
21:59 robotustra_ so, do you like it or you want better one?
21:59 GargantuaSauce i fucking hate it
21:59 GargantuaSauce and i'm not sure a better one would be ...better
22:00 GargantuaSauce i have not had a lot of success with it lately
22:00 GargantuaSauce it takes a lot of tweaking to get the alignment good enough for the first layer to adhere properly
22:01 GargantuaSauce and then when that's finally right i'll get partway through a print and it'll lose a few steps due to a driver being set to too much or too little current
22:01 GargantuaSauce or the firmware will freeze
22:01 GargantuaSauce or pronterface will crash
22:01 GargantuaSauce or the print will start to warp and pull off the bed
22:01 GargantuaSauce it's always something
22:02 robotustra_ ok
22:02 robotustra_ it seems that it's not so relyable
22:02 GargantuaSauce it is extremely frustrating
22:05 GargantuaSauce i feel like there are some very significant and fundamental issues with the design
22:05 GargantuaSauce the entirely open-loop motion control is one of them
22:05 robotustra_ yeah
22:06 robotustra_ that's what I expect
22:06 robotustra_ that's why I'm thinking to do my own printer
22:06 robotustra_ with stationary table
22:07 robotustra_ and moving carrige in 2 dimensions
22:07 GargantuaSauce you mean 3
22:07 robotustra_ I mean, that table move only along Z axis
22:07 GargantuaSauce that's not stationary :)
22:08 GargantuaSauce i really like the delta designs
22:08 robotustra_ yeah, but motion is slow
22:08 GargantuaSauce slow if you don't want to retract the head for moving
22:08 GargantuaSauce which is not necessarily the best idea
22:08 robotustra_ delta has big size with comparison to the printing volume
22:09 robotustra_ what do you mean retract?
22:09 GargantuaSauce i mean move up in Z, move laterally in XY, move down in Z
22:09 GargantuaSauce so the head doesn't drag through the print
22:09 robotustra_ why do I nid this motion?
22:09 robotustra_ need
22:11 GargantuaSauce it depends really, often people don't use it
22:11 GargantuaSauce but i wouldn't rule it out at the design level
22:11 robotustra_ so, but BotMaker most probably do not use retracking
22:12 robotustra_ and table goes slowl along Z axis
22:12 GargantuaSauce and i would not exactly call it the pinnacle of 3d printing design
22:12 robotustra_ you mean BotMaker?
22:13 GargantuaSauce i am referring to the makerbot replicator, which i assume is also what you are referring to
22:14 robotustra_ yes,
22:14 robotustra_ what is the best model in your humble opinion?
22:17 GargantuaSauce https://www.youtube.com/watch?v=HcnhCNh2Ln4
22:18 GargantuaSauce there really isn't a single one that leaps out as the "best" but this one is pretty far advanced
22:18 GargantuaSauce there are disadvantages to every design though
22:19 robotustra_ delta printer is difficult to make very presize
22:20 GargantuaSauce well it's precise enough to print pla on cold glass
22:20 GargantuaSauce you aren't going to see any cartesian ones doing that.
22:22 GargantuaSauce but yes it is true that it is easier to halfass a cartesian one
22:22 GargantuaSauce not that that is necessarily a good idea
22:23 GargantuaSauce mine is a testament to that
22:23 robotustra_ I hear in the video that it has backlashes
22:24 robotustra_ and what I also see that you have to drive 3 motors all the time
22:24 robotustra_ instead of holding one motor and working with 2 others
22:25 GargantuaSauce http://farm6.staticflickr.com/5510/9119377210_5a090c84a5_o_d.jpg
22:25 GargantuaSauce look at the edges
22:25 GargantuaSauce not a lot of backlash at all.
22:26 GargantuaSauce that is as clean as a well-tuned cartesian bot for sure
22:27 GargantuaSauce and yes ok you have to drive 3 motors instead of 2
22:27 robotustra_ but at the same time it's faster
22:27 GargantuaSauce running without a heated bed makes up the difference in power 10fold
22:28 robotustra_ propaply
22:28 robotustra_ but what about drivers?
22:29 GargantuaSauce a4982 as usual
22:30 robotustra_ and software?
22:30 robotustra_ is it done for delta?
22:30 GargantuaSauce yes it's running marlin
22:33 robotustra_ so, the advantage of delta printer that it can print on cold glass?
22:33 GargantuaSauce well with probing like that uses
22:34 GargantuaSauce and being able to print on cold glass is basically an indication of high 3-axis precision
22:34 GargantuaSauce aside from being an advantage in and of itself
22:35 GargantuaSauce the disadvantages include the bed size you mentioned and also limited mass/volume on the print head, so they pretty much always use bowden tubes instead of direct extrusion
22:35 GargantuaSauce which is ok but add some backlash to filament retraction
22:37 GargantuaSauce anyway if i end up building another it'll be a design like that, a delta bot with a frame made of aluminium extrusions and either a probe or sensors under the bed
22:39 robotustra_ I will think about this design, over night
22:39 robotustra_ so good noght
22:40 GargantuaSauce later