#homecmos IRC log for Thursday, 2013-03-21

glowplugI've made some more progress in the motor control department.02:11
glowplugThe design that I am going to use is controlling steppers directly with the parallel port and LinuxCNC.  Encoder data feeds directly into the parallel port.  And two L298N for the powerstages.02:13
glowplugTotal closed loop stepper motor control hardware cost.  $10.02:15
glowplugHello.  =)02:43
B0101sigh, if there only was a piece a software to simulate sub atomic particle collisions...03:36
glowplugI'm sure they have that at CERN.03:47
glowplugWe should ask for them to GPL it.  8)03:47
B0101It would be good they did so, and could be useful in testing transmutation reactions03:53
glowplugSo why does your name show up as B0101 half the time? Hah03:59
B0101huh? my nickname is always B0101!04:00
glowplugOh.  Fair enough.04:36
azonenbergThat feeling when you open up the Edmund Optics catalog and drool over all of the stuff you can't afford...21:08
Sync_I used to work in the quantum optics lab21:11
Sync_we used to order stuff from EO, coherent or thorlabs daily21:12
glowplugSpeaking of optics I'm updating the litho section of the wiki.  Work in progress!21:22
Sync_we also had the lab snacks stacked on a wall21:53
glowplugI think I found a suitable webcam for the microscope.21:55
glowplugWould 1000x magnification be too much?22:17
glowplugNot for inspecting parts.  Just for the direct-write.22:19
glowplugNevermind.  The digital scope they used in that PDF is way underpowered for 1 micron detail.22:21
glowplugI can't believe they paid $150 for that thing.  O_O22:22
glowplugI'm new to the microscope stuff.  =)22:25
glowplugA WF10 eyepiece and 100x achromatic objective is reasonable for the direct-write?22:27
Sync_is it really just one page or is the firefox pdf viwer acting up on it?22:28
glowplugIt really is just one page.  Those bastards.22:28
glowplugCrap I think this channel is logged!22:28
glowplugI mean... amazing individuals!22:28
glowplugI realize that you are going to shut down this idea.22:29
glowplugBut here goes anyways.22:29
glowplugI was researching micrometers and apparently within their range most micrometers have some amount of error.  Even if their zero mark is calibrated.22:30
glowplugThey are basically .5mm pitch leadscrews with a dial and some writing.22:30
glowplugIf we assume there is going to be error anyways (and that error is probably constant throughout the usage of that leadscrew).22:31
glowplugWe can assemble an x,y stage for $5.  Measure its absolute position with a interferometer throughout its movement range.  Use that data for controlling the stage with nearperfect accuracy.22:32
glowplugThe result will probably be more accurate than a set of micrometers for $200.22:33
glowplugThe same could be accomplished in realtime also.  But I think it would be more reliable to categorize the stage beforehand in software then the PID loop can be less aggressive.22:35
Sync_I cannot find the paper anymore22:35
glowplugWhich one?22:35
Sync_the one paper thing22:36
glowplugI put it here.22:36
Sync_what the hell22:38
Sync_it really is just a page22:38
glowplugYeah it really is...22:38
glowplugTheir microscope is a Celestron 4434022:38
glowplugI finally figured that out22:38
glowplugIt is max 400x.  =(22:40
Sync_400x is fine22:41
glowplug1000x will only cost $80 including hd webcam with nice optics (significantly better than the Celestron unit but still not amazing).22:41
Sync_hmm, actually, it'd be pretty easy to make the spindles oneself, 8x0.5 is a standard die size22:42
glowplugOh!  The micrometers?22:42
glowplugYou can get a meter of the stuff for $8.22:42
glowplugPack of 50 hex nuts for $2.5022:43
glowplugYou could probably build an x,y stage for $5 using acrylic realistically.22:43
glowplugThats my current plan at least.22:44
Sync_the error in a regular threaded rod is awful22:44
glowplugThats what I was reffering to earlier.22:44
Sync_I don't really see fine ones there22:44
glowplugDid you get those messages?22:44
glowplugOn mcmaster they have .5mm pitch stainless steel.  Same as micrometers.22:45
Sync_oh haha they have fine pitch stainless22:46
Sync_I did not expect the fine ones there22:46
glowplugThe only way to eliminate the error in any threaded rod, mcmaster or micrometer either one is to characterize the rod in software with absolute data throughout its range measured with an interferometer.22:46
Sync_yeah lol it is m322:46
glowplugThat should work fine. =)22:47
glowplugMy strategy will be to laser cut the acrylic to shape with m3 sized rectangular holes for the nuts.  Then I can lower them in and epoxy into place.22:49
Sync_nice. just looked into my tap and die drawer and found a complete M8 set22:49
Sync_so I also have M8x0.522:49
glowplugVery cool.  =)22:50
glowplugI'm ok with the m3 given the cost ($8 per meter).22:50
glowplugI haven't figured out the linear slides yet.  Given the slow speeds kapton tape could be used.22:51
Sync_well it is only a chinese set but I'll make a micrometer tomorrow22:53
glowplugSounds good.  =)22:53
glowplugI'm thinking a design like this.22:56
glowplugTwo smooth rods as guides should be the easiest way to do it.22:57
Sync_yes, a challenging thing is how to make the thrust bearing assembly22:57
Sync_because it has to be preloaded22:57
Sync_two rods is easy but you need pay close attention to the fit of the bushings22:58
Sync_and it will be a pain to get everything aligned perfectly22:58
glowplugThat design is fantastic.22:59
glowplugHe has every detail in a PDF.23:00
glowplugJust has to be miniaturized and I'll be using acrylic just because its a ton easier to work with.23:01
Sync_yes just don't expect micron precision23:04
glowplugWhy not?23:04
Sync_because it is unrealistic23:04
glowplugWhich component is the bottleneck?23:05
glowplugThis design is a clone of the pdf design with .5mm pitch leadscrews instead of .5mm leadscrews inside of a retail micrometer (chinese).23:06
glowplugWouldn't the closed loop control and interferometer feedback make it more accurate?23:06
Sync_there still is the problem, that the x and y need to aligned very very perfectly23:07
Sync_which is not that easy to do23:07
Sync_and also the play in the bushings needs to be very low which is not going to happen23:08
Sync_oh haha wow23:13
Sync_more or less it comes down to the problem that 1┬Ám is not a lot :D23:17
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