#homecmos IRC log for Saturday, 2013-03-16

--- Sat Mar 16 201300:00
glowplugHello.  =)00:37
glowplugI'm not the only one in here!  Thats fantastic.  =)00:42
glowplugIs this project still active?00:42
azonenbergIt's slow, i've been the main one working on it and i've been busy with my "real" research00:43
azonenbergThe evaporator on campus that i had been using was down for repairs for a while but is up again00:43
azonenbergthen i need to find time to upgrade my spin coater00:44
glowplugI must say that you are amazing sir.  This is very important research and work and I want to thank you personally for what you have accomplished and shared.  8)00:46
glowplugAre you familiar with the OpenCores / OpenRisc projects?00:47
azonenbergI am00:49
azonenbergThough homebrew fab is a LONG way from being able to do that00:49
azonenbergthe current state of the art is Jeri's millimeter-sized CMOS inverter and my 20-micron lithography without any working transistors (thoguh i haven't tried, been focusing on the litho)00:50
glowplugI was very impressed by the 20-micron lines.  I couldn't believe it.00:51
azonenbergI think i can get a lot better than that with some time and effort00:51
glowplugWithout this technology progressing OpenCores will stagnate on proprietary FPGA chips running at 50mhz.  Not a good place to be.00:52
azonenbergA paper from SDSU demonstrates a UV direct write laser lithography system for under $1K00:52
azonenbergwith better than 5um resolution across a large area00:52
glowplugI was just going to ask if you had tried direct laser yet.  8)00:52
azonenbergbasically a blu-ray diode with a blanking circuit, a preciison x-y stage, and some control hardware/software00:53
azonenbergIt's very high on my list of things to build00:53
azonenbergBut i have other stuff going on so it hasn't happened yet00:53
glowplugA cartesian blu-ray machine.  Thats trivial.  How much better than 20 microns do you think such a setup can achieve?00:54
azonenbergThat paper quoted 2um "easily"00:55
azonenbergI was thinking you could then do a second shrink step00:55
glowplugThats almost an Intel 386.00:55
azonenbergMake a 2um mask and then use it in a reducing stepper00:55
azonenbergwith say another 4x reduction00:55
azonenbergso direct write for photomask making at 4x your desired feature size00:55
azonenbergthen projection litho through the mask00:55
glowplugDo you have a link to the PDF?00:56
azonenbergSadly no00:56
azonenbergi printed it out and the title was messed up00:56
azonenbergit's by Kassegne and Khosla00:56
azonenbergautomated maskless photolithography using UV laser diodes00:56
azonenbergshould be able to google it00:56
glowplugI will try to track it down.  I have a CNC, its homebuilt but decently accurate.  I don't think it would complain about having a blu-ray diode strapped on.00:56
azonenbergIt looks like the limitation in their system is twofold00:57
azonenbergfirst, x-y positioning00:57
azonenbergsecond, spot size00:57
glowplugI am extremely surprised that there aren't more contributing.  I'm sure many more people understand how incredibly important this is.00:57
azonenbergmechanical and optical respectively00:57
azonenbergI would like to get most of the equipment scaled to glove-box size00:57
azonenbergto avoid needing a full cleanroom00:57
glowplugBoth are difficult problems to solve.00:57
azonenbergor alternatively, sealed cassettes of some sort to move wafers between machines00:58
azonenbergThe nice thing about larger features is that you're less sensitive to particles00:58
glowplugAn accurate cartesian robot in a glovebox is non-trivial.  Really servos should be used not steppers, accurate encoders are big, servos are big.00:58
azonenbergOne idea i had for positioning was interferometry00:59
glowplugI think that sealed cassettes is more realistic.00:59
glowplugBut still that doesn't answer why there aren't more people helping you.  Haha00:59
azonenbergYou forget, the majority of hobbyists are scared of soldering BGAs01:00
azonenbergor even writing HDL01:00
azonenbergif you tried to show them CMOS layout they'd run away and scream01:00
glowplugI'm trying to learn Verilog right now to contribute to the mor1kx core that Stefan and Julius are working on.01:00
soul-dor able to fix a fancy lab in their backyard01:00
azonenbergwhereas i'm the kind of guy who has nude photos of MCUs on his bedroom wall (PIC12F683 metal 3 in particular)01:00
azonenbergglowplug: in case you haven't checked out siliconpr0n.org01:01
azonenbergdo so01:01
azonenbergi'm one of the two main people behind the group01:01
azonenbergthe project*01:01
soul-dis there pic of higgs boson already ?01:01
azonenbergsoul-d: http://i.imgur.com/esVwLlK.jpg01:01
soul-di want to paint that one on the wall :P01:01
glowplugI'll check it out.  =)01:01
azonenbergXC6SLX4 x1 metal layer01:01
azonenbergi think this is M5 and M6 but the polishing was a little uneven so i can't be sure01:02
azonenbergI do know it's the smallest pitch on the device by comparing it to cross sections from chipworks, it's a lot smaller than the top two or three layers01:02
glowplugSo let me get this strait.  If we have a very accurate cartesian robot wth a blu-ray diode we can build 2um semiconductor devices using techniques that you already know?01:02
azonenbergglowplug: Jeri Ellsworth has a FEOL process for doing transistors working at macro-scale without lithography01:02
azonenbergIf you can do direct-write exposure, you can buy standard photoresist and developer solutions and do lithography01:03
azonenbergThe last remaining problem is interconnect01:03
soul-dwhat am i looking at azonenberg   looks like egyptians beat you to nano scale to01:03
azonenbergsoul-d: that's a spartan-601:03
azonenbergrandom logic area01:03
azonenbergLower mag view http://i.imgur.com/wm4W3Xz.jpg01:03
azonenbergI have no idea what this circuitry does, i did no analysis - the point was to see if the SEM had the resolution for a modern deep submicron process01:04
glowplugHow much work needs to be done from a design perspective to get functional logic gates?01:04
azonenbergApparently it does, this is Samsung 45nm01:04
azonenbergglowplug: Alliance etc have standard cell libraries if we can figure out how to build them01:04
azonenbergJeri has the transistor angle mostly figured out01:04
azonenbergI've made good progress on litho but it's not done01:04
azonenbergThe last remaining problem is interconnect01:04
glowplugShould we ignore the direct laser methods due to their limitations in process accuracy?01:05
azonenbergJeri's stuff used conductive epoxy and regular fine-gauge hookup wire01:05
azonenbergDefinitely not01:05
azonenbergI think that's the way to go01:05
glowplugThe theoretical smallest device is at the wavelength of the laser itself correct?01:05
azonenbergFor direct write, approximately yes01:06
glowplugWhich is determined by the photoresist we can acquire.01:06
azonenbergWell, it's going to be probably mercury vapor H-line (405nm)01:07
glowplug~250nm might be possible with direct laser assuming photoresist at those wavelengths is avialable.01:07
azonenbergwhich is what most UV diodes use01:07
glowplug405nm.  Thats not bad at all either.01:07
azonenbergDeep UV photoresists are not sold to the general public01:07
azonenberg193nm is the standard wavelength for most mass production afaik01:07
azonenbergYou can buy them if you're Intel01:07
azonenbergBy the 55 gallon drum01:07
soul-dk cool ,( forgot i was  cooking for a bit :P )01:08
glowplugExactly.  Thats the main problem with direct laser.01:08
glowplugAvailability of the resist.01:08
azonenbergbut regular resists are relatively easy to get hold of01:08
glowplugWIth 405nm we are looking at theoretical devices with frequencies 10x higher than FPGA's.  I think OpenCores expirimentors would be quite happy with that.01:09
azonenbergShipley 1813 can be bought by the quart from fisher scientific for $372 for example01:09
azonenbergIf a bunch of us split a bottle that's quite reasonable01:09
glowplugYou have really done your research.  =)01:09
azonenbergThen you can get HMDS from SPI supplies for $12 for 30ml01:10
azonenbergor $15 for 100ml but the larger volume needs hazmat shipping01:10
azonenbergWhich is why they offer the small option01:10
azonenbergMTI sells single wafers01:10
azonenbergincluding with oxide/nitride films01:10
azonenberg(though you're limitd by what they have in stock)01:10
soul-dchemical sharing you will hit stuff like shipping  :P  probably need to live close/same country01:10
azonenbergMost other wafer sellers wont touch you if you buy less than a boat of 2501:10
azonenbergSame country would be nice01:11
glowplugSo what is immediately necessary to progress is a CNC with ~405nm stepping accuracy.01:11
azonenbergNot even that01:11
azonenberg1um is plenty for a lot of stuff01:11
azonenbergI want to put the initial focus on MEMS01:11
azonenbergGet the lithography down01:11
azonenbergBut forget about trace metal contamination01:11
azonenbergYou can use much less pure chemicals for MEMS01:11
azonenbergyou care about particles but not ions01:12
glowplugTrue.  For research and progress it's not necesary to be at the theoretical smallest.  We could have football field sized devices as long as we are figuring these things out.01:12
azonenberginjectorall.com sells photoresist in small volumes intended for PCBs01:12
glowplugMy CNC has 1um accuracy as do most.01:12
azonenbergIt's probably not CMOS grade01:12
azonenbergBut for MEMS it'll do just fine01:12
azonenbergThat's what i did all of my testing with01:12
glowplugHave you had any interest from hackerspaces or other organizations like that to help with the research?01:13
azonenbergI haven't had the time to push too hard on recruitment01:13
azonenbergOnce I graduate I'll "only" be working 40-50 hour weeks01:13
glowplugIt's disturbing to me that people aren't throwing equipment and money at you.01:13
azonenbergand thus have weekends etc to play on stuff01:14
azonenbergBut i've been funding my operations out of a grad student's stipend01:14
glowplugIf you don't mind me asking where are you located?  I'm in Michigan.01:14
azonenbergWorking on my PhD (in computer science, go figure)01:14
glowplugAhh New York.01:15
azonenbergThen some of the folks here are in europe i think01:15
azonenbergwolfspraul, whenever he shows up, is in china01:15
glowplugDoes anyone else except you have physical equipment?01:15
azonenbergoh, and B0101 is in Singapore01:15
azonenbergShe's done some minimal lab work01:15
azonenbergBut not much01:16
azonenbergMost of the others just talk01:16
azonenbergSync__:  is a grad student somewhere and has equipment but idk how much he's done toward home fab01:16
azonenbergIn my case I have a home lab plus i'm on good terms with the manager of the electron microscopy lab on campus01:16
azonenbergI did all of my metal coating in their evaporator01:16
azonenbergsince i don't have vacuum gear at home yet01:16
azonenbergSo like the nyan cat on the website01:17
glowplugHow much is the evaporator?01:17
azonenbergthat was evaporated copper using their system01:17
soul-dlast time i posted a pic of my "lab"  azonenberg  had to cry :S01:17
glowplugHaha.  Yeah my "lab" is a color laser printer and DIY cnc.  :/01:17
soul-dcnc can build things01:17
azonenbergglowplug: Upper bound? A commercial small-sample sputter coater01:18
azonenbergIf you homebrewed, you could likely make it a LOT cheaper01:18
glowplugHomebrew is more what I was thinking.01:18
glowplugIf its $13k retail then I'm going to assume $500 for DIY.01:18
azonenbergI'd budget more like $1K but we'll see01:18
azonenbergIf you want to get serious about this kind of stuff, i'll set you up with wiki access01:19
azonenbergPM me your google code email address01:19
azonenbergand i'll add you as an editor01:19
azonenbergyou can start making pages with hardware designs01:19
azonenbergwe also need wiki pages with collections of relevant papers01:20
glowplugI try to stay away from google technology whenever possible.  But documentation is something that I can contribute.01:20
glowplugHave you considered a github page?01:20
azonenbergI was planning to make a dedicated website for it at some point with a mediawiki01:20
azonenbergIf you bug me in a week or so i might get to it01:20
glowplugHow about this.  Let me toss up a site on gitpages then email you a link then tell me what you think about it.  If its not garbage I can fork it to a shared repo (not my personal one) that way more people can add content ect.01:22
azonenbergWhat about mediawiki?01:22
azonenbergdo you have something against that?01:22
azonenbergI just want to move to my own domain at some point rather than bouncing between third-party services and having content scattered around01:22
glowplugUnfortunately it has an SQL backend.  I can design a quick HTML5 page that can survive without any special database and host for free on github.01:23
azonenbergI have several VPSes01:23
glowplugIf you have a server with SQL and everything setup that would work too I suppose.  =)01:23
azonenbergand i own a couple of domains01:23
azonenbergit'd be the work of an hour or two on the weekend to set up a dedicated domain for it and put up a wiki01:24
azonenbergThat way i can move the stuff around and as long as i own the domain the content will still be reachable01:24
glowplugThe wiki is likely sufficient anyways.  What if I designed the page anyways then we can link to the wiki.  Thats a fairly common way of doing things now adays I think.  =)01:25
azonenbergI just want there to be one central place for all of the info01:25
glowplugPretty front page.  Then link to the wiki for community documentation ect.01:25
azonenbergi dont want a collection of a dozen different websites01:25
azonenbergDesign it, but don't put it anywhere public just yet01:25
glowplugIt wont be that bad!  O_O01:25
azonenbergI just mean i dont want it showing up in search results before we have anything on the back end01:26
glowplugThe mediawiki page is actually a great idea.  It's relatively easy to add content to a regular HTML5 page but the wiki format is a LOT easier.  Also easier to keep track of permissions ect.01:26
azonenbergThen we can have a github or something for CAD files and stuff01:27
glowplugI was actually mad for a second when I noticed the google page wasn't updated since 2011.  I literally said outloud.  "There is no fucking way that they gave up, its too important!"  Haha01:27
azonenbergI did not give up, i just got really busy01:27
azonenberggrad school happened :p01:27
glowplugBiggest relief ever...01:28
azonenbergSo it's been back-burnered but is very high on my "things i want to do" list01:28
glowplugAlmost had a heart attack at 26.01:28
azonenbergI just want to be able to build a board with an ASIC of my own design on it :D01:28
azonenbergAlso, re packaging01:28
glowplugAnd even though they don't know it yet.01:28
glowplugThat's what everyone else on Earth needs.01:28
azonenbergMy tentative thought is to solder-bump the bare die and make a flip-chip CSBGA01:28
azonenbergWire bonding is a huge pain in the neck01:28
Sync__oh haha azonenberg they use sparkplugs. m)11:54
glowplugMolecular beam epitaxy?  Do we need such a thing for +405nm sized devices?16:49
Sync__no but it is nice to have16:50
glowplugThank goodness.  Haha16:50
Sync__most of my work has to do with mbe16:50
glowplugI see.16:50
Sync__but it wouldn't be too hard to make a system16:51
glowplugI think that if we do get DIY MBE it will also come with superior litho/optics together as a package.  That is probably very far in the future.16:51
Sync__if you are lucky maybe 10k for everything16:51
glowplugI would say mostly for cost reasons.16:51
glowplug^Exactly.  Haha16:51
Sync__10k is not a lot16:51
Sync__the more annoying things then is the analysis hardware16:52
Sync__I mean, it's a hobby, that's where you spend your money16:52
glowplugI agree.  But people are still trying to get CNC's and 3d printers down below $400 each.  I built my CNC for only $400.  I think sub $1k for all equipment for an entire lab is the pricepoint we need to get a true DIY following.16:53
Sync__I don't get why people even bother with those shabby 3d printers16:53
Sync__or those clapped out cncs16:53
glowplugThat pricepoint isn't necessary for progress.  Obviously not.  But it will get a real massive following of people to explode research and resources.16:54
glowplugMy CNC is fairly accurate (50 microns).  The 3D printers I mostly agree with your point.  The usefulness of plastic parts of that accuracy is not super great.16:55
Sync__50 microns is not accurate imho16:55
Sync__I expect a cnc mill to be able to produce bores tolerated close enough for bearings ~j5-616:56
glowplugIn the grand scheme of things no its not.  But its accurate enough to make 50um masks for the litho process.  Yes 50 micron semicunductors are not super useful.  But its good enough for research and to prove concepts before scaling down.16:56
glowplugBasically I agree with you on all points in the grand scheme.  But there are some major consessions that have to be made in the name of DIY, cost, and getting the word out to expirimentors.16:57
glowplugThen when the resources and peoplepower allow.  We can get "real" equipment.  =)16:58
glowplugBe right back have to go to the post.16:58
Sync__I'm probably spoiled by having too much money to spend16:59
Sync__but yeah it's an interesting problem to get sub µm positioning accuracy when you have a mechanical stage and piezos are out of question17:02
Sync__I guess one could try preloaded ballscrews and two interferometers17:02
Sync__even 5 micron positioning would be easy enough to do for a hobby machine17:05
soul-d3d printer could be handy if the parts are acurate enough to be used as mold   for say aluminum /metal  or alloy17:07
Sync__yes, professional 3d printers are able to do that17:07
Sync__or at least provide good enough finish to be used to laminate off them17:08
soul-dalthough bit redundant might as well cnc them directly  ( i assumed most home cnc's don't have the strengt or accuracy for metal ) but still some parts might be better off with a mold17:11
azonenbergSync__: i was thinking of making ~5um features photomasks with direct write litho17:15
azonenbergfollowed by ~5x optical shrinking17:15
azonenbergfor ~1um features17:15
Sync__that'd be easy17:20
Sync__the only issue would be the cumulative error if you do not have an interferometer or linear encoder17:20
azonenbergYeah, you'd need feedback for sure17:21
azonenbergYou can get encoder strips on plastic film from laserlab at 12.5um half-pitch (25um pitch)17:21
azonenbergthen use interferometry for reading the position between lines17:22
Sync__that's too much hassle17:22
Sync__you'd need to develop all that17:22
azonenbergOther option is a rotary encoder geared down17:22
Sync__I'd just get chines scales17:22
Sync__well that does not help the cumulative error17:23
Sync__which you will always have17:23
azonenbergWhat do you suggest for that?17:23
Sync__because of pitch error17:23
Sync__well, for the closed loop an encoder on the screw and to get the pitch error out cheap linear scales17:24
azonenbergPItch error is probably fine17:25
azonenbergas long as you dont have backlash and it's repeatable17:25
Sync__the regular positioning scheme for everything cnc17:26
Sync__well, usually screws are specced for 1/100mm per 300mm17:26
azonenberg10um absolute error17:26
azonenbergthat's not 10um of jitter17:27
Sync__that's not even accounted for17:27
azonenbergalso, 300mm is HUGE unless you're making something like a full 8" wafer17:27
Sync__because it could jitter around in the 300mm17:27
azonenberglet's say you're using a 40mm wafer17:27
azonenbergso positioning accuracy of 1.3 microns across the entire wafer?17:28
azonenbergWith repeatability quite a bit better than that>17:28
azonenbergI'd take that17:28
Sync__if you trust the screw in the range you use17:28
Sync__but you could just check that with an indicator17:28
glowplugOk theres a lot of information here.17:38
glowplugFirstly this page has everything you need to know about making accurate plastic parts.17:39
glowplugSecondly the CNC / encoder accuracy.  It's not something I have physically at the moment but something that I've solved and am working on.17:40
glowplugMy next CNC will have closed loop 200,000 steps per revolution bldc motors (you could call them servos).17:41
glowplugIt is possible to position the machine very accurately using a conductor the diameter of a hair and a conductor around the perimeter of the part.  When they make contact you get a zero position.  That obviously has limitations but its probably good enough.  Inteferometry is easy to build but hard to measure.17:43
glowplugAlso I don't think that I can get better than 10 microns on my next machine.  I hope that is accurate enough.  :/18:16
glowplugActually I may have spoke too soon.  I found someone just now with a DIY CNC who is getting 1 micron accuracy engraving with a diamond tip.  Interesting.18:22
Sync__encoder resolution is not really everything :D18:30
Sync__because mostly the mechanical accuracy is far inferior18:38
glowplugAgreed.  I have been researching this problem over the last month or so.  Unfortunately it did turn out that encoder/motor accuracy was the easiest problem to solve.18:59
glowplugThat machine is what I need to aproximate.  Unfortunately it costs $20k.19:00
glowplugRepeat accuracy .05mm under no load (blu-ray laser in my case).19:01
glowplugWait thats 50 microns not 5.  Hmm.19:01
glowplugMichal (the google employee who wrote the article I linked above) gets ~2 micron accuracy with that mill.  I wonder how.19:02
glowplugIt has a state mechanical resolution of .001mm but that is not repeat accuracy (clearly).19:03
Sync__wow they actually want 20k for that19:04
glowplugThat repeat accuracy is probably for very large parts.19:06
glowplugHere is a qoute from Michal.19:06
glowplug""But in the end, I ended up with accuracy routinely in the vicinity of 0.002 mm for small parts."19:06
Sync__in the material that is not a problem19:06
glowplugAlso he is milling at .002mm.  I will be using a laser.19:07
Sync__milling is just fine19:07
glowplugIt just means that in theory I should have an easier time getting the same repeat accuracy.19:08
Sync__I'd just get a few surplus linear slides preferrably preloaded ones and new hiwin preloaded ballscrews19:09
Sync__then it should be no issue at all to get that level of positioning accuracy19:09
glowplugAlso his machine has a massive work area.  I only need 2 micron accuracy in a square inch workspace at most.19:09
glowplugI'm researching the chinese ballscrews/nuts right now.  They may be accurate enough at $77 per axis.20:13
azonenbergglowplug: yeah, it gets much easier to get accuracy across a small area20:15
azonenbergEspecially if you restrict the prototype to single dies rather than a full wafer20:15
azonenbergin industry people are trying to work with 18" wafers20:15
azonenbergrather hard by comparison :p20:15
glowplugAbsolutely.  And that kind of scaling is an economical consideration for production.  That is very very very far in the future.20:19
glowplugI think some transistors and logic gates would be a massive feat.  =)20:19
glowplugIt looks like I'm going to go with chinese ballscrews and a double ballnut per axis configuration.20:20
Sync__azonenberg: interestingly those large wafers rely on impurities from the melt for stability20:20
glowplugShould be ~$300 per axis.20:20
Sync__huh double ballnut is eh20:20
azonenbergglowplug: for hobbyist volume 2" wafers is more than enough20:20
Sync__get real preloaded ballscrews20:21
glowplugI had a very strong feeling you were going to say that.20:21
Sync__the cost of the double nut is not worth it20:21
glowplugI'm on a pretty limited budget.  If I can get 2 micron repeatable accuracy with a $500 CNC I will be happy.  If we need more accuracy than that then I need a grant / donation.  Haha20:22
Sync__I'm not even suggesting planetary screws!20:23
glowplugThe ballscrew/nut sets you are suggesting cost per axis the same as my entire planned machine.  =P20:24
glowplugDo you have any links?20:26
Sync__price out some hiwin spindles20:27
glowplugThose are the sets I'm talking about.20:27
glowplugThey are $300+20:27
glowplugVersus $100.20:27
glowplugHiwin KK10020P40238 is $460 per axis.20:29
Sync__well no shit20:29
Sync__you are looking at ground ones20:29
Sync__also much too large ones20:29
glowplugThats why I asked if you had links.20:30
glowplugHiwin Tech 9812963004 are $490 each.20:30
Sync__I wrote them an email a few years ago20:31
Sync__and requested some pricing20:31
Sync__and it was way less20:31
glowplugAlright I did find something.20:33
glowplugNevermind those are also chinese.20:34
glowplugYeah I don't know.  All I can find are surplus Hiwin and those are still $400+20:36
Sync__if you use only positive approaches backlash does not matter20:38
Sync__so you could just use acme screws20:38
glowplugYou mean never changing direction while running the laser?20:40
Sync__you you only laser while moving forward20:42
glowplugWhat happens when the machine changes direction after passing over the part to make another pass?20:42
glowplugWouldn't it lose absolute accuracy there?20:42
Sync__you get backlash20:43
glowplugBut its known backlash that does not damage the part.  So you compensate in software?20:49
Sync__well if it is always the same you can compensate it in software20:51
glowplugIs it common for the backlash to be always the same?  Are there digital tools for measuring backlash during operation?  I have never even researched that.21:03
Sync__you can use a dti for measuring backlash21:20
glowplugLooks like indicators with USB are ~$300.21:30
glowplugI will try to track down something cheaper.21:30
Sync__why do you want usb21:30
Sync__just read it21:30
glowplugBecause EMC2 has to make the adjustments.  I'm not making them by hand every pass screw that.  Haha21:31
Sync__I do have an extramess with a resolution of 200nm21:31
Sync__you did not understand me21:31
Sync__you can just measure it one time and set it21:31
Sync__backlash will be the same21:32
Sync__if you want that get linear encoders21:32
Sync__linuxcnc can do rs42221:32
glowplugBacklash will be the same every time no matter what?21:33
Sync__but you can measure that21:33
glowplugSo I would have to measure every pass?21:34
Sync__just let the spindle run a few passes measure average backlash and put that value in emc21:35
glowplugAnd you think that average backlash is sufficient for 2 micron accuracy?21:36
Sync__you gotta try21:36
glowplugThat is deffinately the easiest way.  If it fails however.21:37
glowplugCouldn't I take constant measurements with a digital indicator and apply that in realtime for backlash compensation?21:37
Sync__there are linear encoders for that21:38
glowplugWhat do you think about using a combination of rotary and linear encoders?21:41
Sync__that ist the standard solution for cnc drives21:41
Sync__gah -t21:41
glowplugAlrighty.  Looks like thats what I'll do then.21:44
Sync__well 1µ glass slides are not exactly cheap21:45
Sync__still affordable21:45
glowplugYeah around $350.  I'm going to see if I can DIY something.21:47
Sync__that's not worth the effort21:48
Sync__those are things that are just not worth making21:51
glowplugUnless it works.  Then it was worth it.  Haha21:51
Sync__there is just too much hassle involved21:52
Sync__if one calculates the hours you put in it just does not make sense21:54
glowplugThat device has 15 micron accuracy.21:59
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