#linuxcnc | Logs for 2012-12-29

[02:10:38] <DJ9DJ> moin
[10:00:11] <IchGuckLive> hi all B)
[10:03:04] <bpuk> Random question of the day: Has anyone used absolute (serial) glass scales with lcnc? For some reason the absolute scales I'm looking at are roughly 1/8th the price of the A/B/Z quadrature scales...
[10:06:07] <awallin> are you sure the serial scales are fast enough for cnc use? those meant for DRO on a manual machine might be too slow..
[10:08:11] <bpuk> that was one of my concerns - 52 bit packet at 19.2 kHz - which is managable for the fairly low speeds that machine runs at - but it's apparently been done by US Motion.
[10:09:31] <bpuk> and yeah, not really designed for NC feedback - hence the curiosity
[10:10:00] <bpuk> (also, the three grand difference in price is enough to make me rather curious about whether stuff would work ;))
[10:10:13] <awallin> for in-loop use you would want to read all axis in real-time at 1ms interval
[10:10:36] <awallin> if you just had them out-of-loop you could do screw-compensation and update that once in a while
[10:12:15] <bpuk> assuming 1 bit per cycle thats around 3 ms - which is just a bit on the slow side.
[10:12:22] <archivist> I used a vernier type cheapo on a manual lathe once and the update was just too slow for my eyes never mind cnc
[10:17:45] <bpuk> yeah - cheap verniers aren't the most pleasant to use. Although, the digimatic verniers I have aren't exactly the fastest to update
[10:18:22] <IchGuckLive> bpuk: what is your leadscrew pitch
[10:19:00] <bpuk> 5mm, 2:1 reduction from the motor to the screw - motor caps out at around 1k rpm
[10:22:33] <IchGuckLive> bpuk: where are you from europ usa ...
[10:22:45] <bpuk> UK
[10:27:08] <bpuk> thanks awallin - that loop time has confirmed it for me - no go. Darn. I'll try and drag a quote out of mitutoyo UK in the new year.
[10:32:38] <IchGuckLive> http://www.ebay.co.uk/itm/OPTICAL-SHAFT-ENCODER-9-24VDC-400-P-REV-FREE-UK-POSTAGE-/150959899229?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item2325e9425d
[10:32:57] <IchGuckLive> bpuk: did you see the lowprice endcoders
[10:34:25] <bpuk> I did, I have a box full of the US Digital HEDS ones - as well as a few (currently) unused resolvers. Can't easily fit them to the motor (sealed, no through shaft), and there isn't room to fit them to the ballscrew shaft.
[10:34:55] <bpuk> While they're very handy - they won't help on this particular machine
[10:35:44] * archivist wonders what the beast is
[10:36:10] <bpuk> tiny little lathe - but one which is giving me no end of grief at the minute
[10:37:35] <IchGuckLive> im retrofitting also a little lathe with the same problems
[10:37:41] <archivist> what is your definition of little mine is Denford Starturn
[10:38:23] <bpuk> slightly bigger - Denford Easiturn 3
[10:39:35] <bpuk> I've done the retrofit - and it works... mostly. The problem now is with repeatability, and it's coming in from a few different sources - correct use of scales should ease most of those.
[10:40:11] <bpuk> and cause an E-Stop on the ones it can detect but can't fix - which is at least better than cutting a part 4 thou undersize
[10:40:13] <archivist> I kept the steppers and the drivers on mine
[10:40:55] <IchGuckLive> archivist i do also like this
[10:41:02] <bpuk> all the electronics on mine were fried (water+electric = escaped magic smoke) - so pretty much a complete rebuild - the motors are the same atm, but may get replaced with servos if I find any that fit (and can afford)
[10:41:35] <IchGuckLive> bpuk: i use omron Servos R7m
[10:41:51] <IchGuckLive> bpuk: they are tiny and good for this
[10:42:10] <bpuk> also, both inductive sensors were dead (and those were *horrible* to rethread), all bar one limit switch was dead, the optical sensors on the spindle encoder were dead
[10:42:23] <bpuk> IchGuckLive: Let me have a look at those
[10:43:42] <archivist> one of my stepper drivers died a few hours after getting it running, I just fixed it although I had got some new drivers ready to use
[10:43:42] <IchGuckLive> http://www.tortlex2.com/ebay7.php?image=plc7077.jpg
[10:45:16] <bpuk> hmm, I'll bookmark that and have a look later on - those do look quite tiny
[10:45:18] <IchGuckLive> bpuk: you can get this size from 30W to 500W
[10:45:54] <IchGuckLive> bpuk: yust ebay search omron r7m
[10:46:02] <bpuk> the ones I can see (ebay) seem to be around the £500 mark
[10:46:36] <IchGuckLive> they are used for cammera supports
[10:48:03] <IchGuckLive> bpuk: servo systems are very expensive
[10:48:23] <bpuk> indeed - just wanted to check I was looking at the same motor range :)
[10:48:30] <IchGuckLive> therfor at your space best is to go for 3NM at 5/4 pulley
[10:48:51] <IchGuckLive> you can get 5m/min out of this at 0.01mm
[10:50:23] <IchGuckLive> ok im off till 19:00 Berlin time
[10:54:48] <archivist> is the stepper inline with your leadscrew, mine is not so an encoder could be coupled to the leadscrew on the starturn
[10:57:00] <bpuk> nope, its beneath it - but theres only about 1/4" between the back of the pulley housing and the back of the machine - it'd be a bit tight trying to get an encoder in there
[10:59:13] <archivist> I am reminded of "go faster bump" so you can hang it outside
[10:59:36] <archivist> I never refitted my end cover
[10:59:56] <bpuk> could do that on the table travel, not on the cross-slide (well, not easily)
[11:00:32] <bpuk> and once I start doing stuff like that I might as well just throw servos on there with inbuilt encoders anyhoo :P
[11:01:11] <archivist> most of my lathe work is one off, cnc often gets in the way :)
[11:01:30] <bpuk> that's what the manual lathe is for :P
[11:02:03] <bpuk> it's when I'm doing 5 and 10 offs that it really kicks in (also, wierd threads)
[11:03:04] <bpuk> I have to admit though - theres days when I'm tempted to ask if I can 'borrow' one of the spare 4kW servos from work - that'd make a lovely spindle drive
[11:03:59] <archivist> put a u/s label on one
[11:06:30] <bpuk> failing that theres an unused (not spare) 125 kW DC motor sitting in the corner - don't think I could power it though
[11:07:34] <bpuk> or... you know, fit in in the workshop
[11:09:44] <archivist> keep the tool still and rotate the workshop
[11:09:56] <bpuk> heh
[11:10:39] <bpuk> hmm, looks like I can *just* fit a 50W R7M in the space available
[12:06:44] <IchGuckLive> hi all Back B)
[12:31:44] <IchGuckLive> cncbasher: the build from this morning is it in master buildbot available
[12:36:48] <cncbasher> IchGuckLive: hi
[12:36:56] <IchGuckLive> hi
[12:37:09] <cncbasher> it should be available from buildbot
[12:37:24] <IchGuckLive> if seen on devels log that there wahere a new build this morning from seb
[12:38:35] <IchGuckLive> http://www.youtube.com/watch?v=HvuEFafFhBA for some nice laufth
[12:38:45] <cncbasher> buildbot usualy keeps track of the latest build that compiles clean
[13:10:35] <IchGuckLive> by for today :D
[14:41:48] <AR_> anyone build anything with those chinese SBR16 rails?
[14:43:33] <andypugh> Has this been posted before? I love it: http://www.linuxcnc.org/index.php/english/forum/30-cnc-machines/25986-boxed-cnc--steampunk-pendant-usb
[14:44:29] <frysteev> cool
[14:44:30] <AR_> sexy
[14:44:40] <frysteev> AR_: railing it up?
[14:44:52] <frysteev> i just got a bunch of odd rails from the surplus store
[14:44:55] <AR_> yep
[14:45:21] <AR_> about 1.5 years ago I collected some parts and produced a very bastardized cnc
[14:45:22] <frysteev> that steampunk bendant looks like an old wired vcr remotte
[14:45:51] <AR_> now decided to buy some half decent things, but dont want to spend as much money as I would need to for profile rails
[14:45:52] <frysteev> anyone ever use hollow rails?
[14:46:01] <AR_> hollow rails? o_0
[14:46:03] <AR_> sounds horrible
[14:46:06] <frysteev> im thinking about scaing up my 40 watt laser cutter,
[14:46:27] <andypugh> Makes less difference to stiffness than you might think. But do you really care about weight?
[14:46:35] <frysteev> debating about mouting the laser tub on the gantry,
[14:47:00] <frysteev> if i mount it on the gantry all use solid ones, if not i was thinking about hollow ones to keep the moving weight down
[14:47:15] <andypugh> You could play interesting games with using tubes full of ball-bearings as both the encoder and the support...
[14:47:34] <Jymmm> solid what?
[14:47:59] <Jymmm> oh
[14:48:15] <Jymmm> why do you need rails for a laser?
[14:48:20] <Jymmm> why do you need rails for a 40W laser?
[14:48:23] <frysteev> i have some hollow stainless tubes i was contimplaying usiong as rails, IF i cared about weight
[14:49:50] <Jymmm> frysteev: as in round tubes, or hollow profiles?
[14:50:04] <frysteev> i wanna scale up the laserr to do 4'x4'
[14:50:12] <frysteev> roung tubes
[14:50:36] <Jymmm> are they rigid? Do they flex at all?
[14:50:41] <frysteev> i cant type today either, its too cold in here
[14:50:58] <Jymmm> frysteev: That's ok, I speak typo
[14:51:13] <andypugh> The correct way to do this is to calculate the second moment of your tubes, and find out what solid rod that would be equivalent to.
[14:51:23] <frysteev> they are pretty rigied, and been stored carefully, if i used them they would only have a small mear and lens mounted on it
[14:52:09] <frysteev> i guess the first question is, how much of a concern is it to keep weight off the moving parts
[14:52:15] <Jymmm> frysteev: Not "PRETTY" rigid, I mean stiffer than a 14yo boy that got kidnapped by a group of nyphos
[14:52:49] <frysteev> lol,
[14:53:04] <frysteev> ill use the solid ones then :P
[14:53:14] <andypugh> frysteev: Do the maths here: http://www.engineeringtoolbox.com/area-moment-inertia-d_1328.html
[14:53:28] <bpuk> The more important question (assuming the tubes are of a reasonable size and wall thickness) is probably: is the surface ground? - if it's not then you'll probably get bounce as you travel along - which will alter your focus.
[14:53:36] <Jymmm> frysteev: It doesnt have to be solid, just rigid. Mine uses aluminum profiles.
[14:54:10] <andypugh> I = (pi)d^4/64
[14:54:26] <frysteev> but should i try and keep a lightweight moving gantry? or just use uber rigisd stuff and not care
[14:54:44] <Jymmm> frysteev: You're just moving a mirror around, it just needs to be rigid so ther'es no flex
[14:55:04] <andypugh> And for a tube it is (pi)(d1^4 - d2^4)/64
[14:55:17] <Jymmm> frysteev: You're not placing a force against material here
[14:55:26] <frysteev> Jymmm: agreed,
[14:55:29] <andypugh> Those 4th-powers mean that you don't need to be very much bigger than the solid bar to be just as stiff.
[14:55:40] <Jymmm> frysteev: you could use square aluminum tubing
[14:56:01] <frysteev> Jymmm: my question moreso is about moving weight,
[14:56:03] <Jymmm> frysteev: Just round seems to like to bow
[14:56:12] <bpuk> Also: with a 40W laser you're probably not going to be cutting at super-high feedrates - guessing 250mm/min max?
[14:56:21] <frysteev> not the force of the cutting material, but of the momentum of the machine itself
[14:56:35] <andypugh> Jymmm: Enough of the misinformation already
[14:56:42] <frysteev> i mainly use it for cutting acrylic
[14:56:46] <Jymmm> andypugh: ?
[14:56:59] <Jymmm> andypugh: I'm going off what MY laser does.
[14:57:19] <andypugh> You don't seem to "get" stiffness calcs.
[14:57:47] <andypugh> This is very much related to the "hot spring" discussion.
[14:57:53] <frysteev> Jymmm: what kind of laser you have?
[14:58:10] <Jymmm> andypugh: And i dont try to either. Hold the end of a 5ft hollow round tube and see if it stays flat.
[14:58:15] <Jymmm> frysteev: ULS M-300
[14:58:39] <andypugh> Jymmm: But the same is true of a square tube.
[14:58:57] <frysteev> im debating mounting the laser tube at the back of the cabinet, or to just but the tube on the gantry, which would mean less distance for the optic path
[14:59:02] <Jymmm> andypugh: Not that i have ever seen.
[14:59:11] <andypugh> And then if you chose a 6" diameter carbon-fibre tube....
[14:59:38] <andypugh> The round tube would deflect a whole lot less than a solid bar of the same mass.
[14:59:49] <Jymmm> andypugh: 6" diam? For moving a 1" mirror around?
[15:00:01] <andypugh> I am talking about generic mechanics here.
[15:00:41] <andypugh> It is not very difficult to compare the stiffness of various cross-sections. I posted a URL just moments ago.
[15:02:14] <andypugh> A square tube is somewhat stiffer in bending than a round tube of the same material with a diameter equal to the flat length. It is somewhat less stiff than a tube with a diameter equal to the diagonal length.
[15:02:30] <andypugh> The round tube is rather stiffer torsionally.
[15:02:44] <frysteev> im sorry to have started something here
[15:03:01] <bpuk> but somewhat more prone to buckling? (sorry, I'll shush)
[15:03:08] <Jymmm> frysteev: Nah, it's all good =)
[15:03:41] <andypugh> frysteev: I am just saying that your tubes might be OK. You might be surprised what size solid bar they are equivalent to in stiffness.
[15:04:18] <Jymmm> frysteev: https://www.youtube.com/watch?v=YBJ9yhUQt4E&NR=1&feature=endscreen
[15:04:24] <frysteev> im going to try them out, its the same dia and the solid stock i have
[15:04:34] <Jymmm> Man, no good videos overall view
[15:05:30] <frysteev> i stocked up on the linear bearings and rails and leadscrews today,
[15:07:25] <Jymmm> frysteev: Leadscrew????
[15:07:31] <Jymmm> frysteev: BELTS!!!!
[15:07:41] <frysteev> ya
[15:07:44] <Jymmm> frysteev: 48x96 =)
[15:08:02] <Jymmm> well 50x 98
[15:08:13] <frysteev> Jymmm: i already have a 48x96, its a slow job getting it operational
[15:08:27] <Jymmm> how so?
[15:08:46] <frysteev> lack of documentaion, i just oncly recently got some missing docs,
[15:08:48] <andypugh> My pulley-hob arrived today. Soon I will be able to make arbitrarily large timing belt pulleys.
[15:09:22] <Jymmm> frysteev: docs for what specifically?
[15:09:30] <frysteev> Jymmm: i have the 4x8' 1.5kw laser cutter if you recall
[15:09:44] <frysteev> Jymmm: missing the programing docs only now,
[15:10:00] <Jymmm> oh, forgot
[15:10:04] <frysteev> had some life issues pop up and sidetrack me for months,
[15:10:13] <jpratt3000> hello
[15:10:26] <andypugh> Hi
[15:10:36] <Jymmm> frysteev: Heh, I know that one. My car won't start and just ordered the Frod Manuals for it
[15:10:38] <Jymmm> Ford
[15:11:03] <jpratt3000> andy thanks for the help on the forum, i got my xyuv working this morning
[15:11:20] <andypugh> Great
[15:11:35] <frysteev> i just got ther service manuals for my robot arm
[15:11:48] <Jymmm> frysteev: and the left dash entirely disassembled atm, cluster on the workbench too
[15:11:49] <frysteev> has all the usefull info i need to get emc to contyrol it
[15:12:08] <frysteev> Jymmm: i swapped out 2 engines in my last truck i know the pain,
[15:12:11] <bpuk> Jymmm: I take it thats the 1.5kW laser in the video you linked?
[15:12:31] <Jymmm> bpuk: probalbly 30W
[15:13:03] <bpuk> Ah, so that's *not* the 1.5kW laser :D
[15:13:07] <frysteev> i have one of these in my shop http://www.youtube.com/watch?v=PUY32GEUCpU
[15:13:19] <frysteev> without the extra pallet loader
[15:13:26] <frysteev> also i WISH my shop was that clean
[15:14:01] <bpuk> pah, anyone with a shop that clean clearly isn't working hard enough ;)
[15:14:25] <frysteev> take care guys ill be back later
[15:14:30] <Jymmm> frysteev: http://i50.tinypic.com/11816qt.jpg
[15:15:13] <Jymmm> frysteev: 5" wide =)
[15:16:26] <bpuk> my only issue with (metal cutting) laser cutters is that the laser and optics cost too darn much - one day....
[15:17:12] <bpuk> andypugh: I have a vague recollection that you made a custom (plated?) spindle encoder for a lathe a while back - I don't suppose you have any more info than the video you posted (if it was you?)
[15:18:06] <andypugh> I have made so many encoders I have lost track :-)
[15:18:40] <bpuk> think this one used an AEDS chip - quadrature output, milled then plated
[15:19:45] <andypugh> Ah, no, that one was laser-cut from stainless by a local company who generally make solder stencils
[15:20:03] <bpuk> ah-ha! did it work? :P
[15:20:33] <andypugh> You mean these? https://picasaweb.google.com/lh/photo/izs9EehSiBmY_omIxaSJBtMTjNZETYmyPJy0liipFm0?feat=directlink
[15:21:18] <andypugh> One works, one doesn't. I need to get back to it, I _think_ that the detector is not properly soldered.
[15:21:45] <bpuk> nope, that wasn't the one I was thinking of - but that does look interesting
[15:22:00] <andypugh> https://picasaweb.google.com/lh/photo/iHKPEhyEJB1_zbvUYLQ6JNMTjNZETYmyPJy0liipFm0?feat=directlink
[15:22:16] <andypugh> https://picasaweb.google.com/lh/photo/AID8-fbxSbaQjuMm-riTAtMTjNZETYmyPJy0liipFm0?feat=directlink
[15:22:18] <andypugh> ?
[15:22:28] <bpuk> that last one :D
[15:22:51] <andypugh> That didn't work, the line pitch was too coarse for the sensor.
[15:23:07] <bpuk> well, that's clarified one thing for me
[15:23:31] <andypugh> It might work with two individual sensors, but that tiny AEDS chip is differential and fussy about line pitch, hence the laser-cut ones
[15:24:40] <bpuk> to put in in context, my current spindle encoder is... not the best. 100 holes (ish) in a plasticy material that I can't remember the name of. two optosensors which are noisy as heck.
[15:24:41] <andypugh> The last one was just overhead-projector pen (very fine marker pen) and an FeCl etch of polished aluminium. Very easy to try with whatever detectors you have.
[15:24:55] <andypugh> Slot detectors will always be less trouble though.
[15:24:57] <bpuk> and was hoping to try and improve it a bit (along with fixing other issues)
[15:25:22] <andypugh> Quadrature is really rather good at rejecting noise.
[15:25:36] <andypugh> Does your spindle have any gears?
[15:25:39] <bpuk> I was hoping that I'd be able to hit 6k ppr - which *should* be enough for basic live tooling
[15:26:00] <bpuk> nope, belt driven - currently off an old VFD which is due for replacement (as is the motor)
[15:27:21] <andypugh> More options: http://www.cnczone.com/forums/1212335-post21.html
[15:27:51] <bpuk> tbh, pretty much every major component of that lathe will be getting upgraded as time/money allows - the basic structure is pretty good, but the electronics side is somewhat antiquated
[15:29:00] <bpuk> detecting off fear teeth, interesting - seen it in crank sensors, not so much in anything else
[15:29:19] <andypugh> A crank sensor is a rather interesting idea for a lathe.
[15:29:52] <andypugh> I happen to have a few, with a 3" through-bore. Magenetic ones using missing-tooth index.
[15:30:49] <bpuk> I can see them working well for threading, rigid tapping - I can see problems with resolution for live tooling though. I'm guessing they're all 2-wire?
[15:31:13] <andypugh> (Traditional crank sensors worked off the starter ring-gear, and had one short tooth. Many cars now use a dedicated pulse wheel on the other end of the crank, and some of those use a magnetic track and hall sensors)
[15:31:55] <bpuk> Also, I've got ready access to (free) V-belt material in pretty much any size I want - so I tend to use belts+pulleys rather than geartrains for most simple applications
[15:32:05] <andypugh> The latest generation are bidirectional (to keep synch through start-stop events and pistons falling back)
[15:32:23] <bpuk> eeek. Not quadrature though? or... hmmm
[15:32:45] <andypugh> But they don't use quadrature, they use long pulses for one direction and short pulses for the other....
[15:33:03] <bpuk> gotcha, keeping it down to 1 or 2 wires
[15:33:22] <andypugh> _some_ may be quadrature. But good luck finding which
[15:33:44] <bpuk> heh. I take it automotive aren't the best for providing datasheets?
[15:33:59] <bpuk> or is it just that theres thousands of seemingly identical sensors
[15:34:05] <andypugh> The latter.
[15:34:31] <andypugh> How do you work out which cars are using quadrature? I doubt that even the manufacturers know.
[15:35:19] <andypugh> The cam-sensor engineer on each engine and car-line will know, but I doubt that it is collated anywhere.
[15:35:56] <andypugh> I thought my engine was quadrature until I asked someone in electrical for the datasheet.
[15:36:10] <bpuk> Probably not - but the drive to keep costs down is so intense in automotive that the extra cost of a third wire will probably rule it out for 99% of manufacturers
[15:37:18] <andypugh> Well, Allegro only launched the wire-reduced bidirectional sensor last year, so I suspect that start-stop applications 2 years ago would have been using quadrature.
[15:37:47] <andypugh> But I don't _know_ that, and I wouldn't know how to tell without counting pins in the connectors.
[15:39:28] <bpuk> hmmm... did JLR or Bentley have start-stop before last year? I'd guess so...
[15:39:51] <bpuk> I might know someone who knows the right person to ask. Probably a dead end though
[15:42:32] <bpuk> http://www.sensoronix.com/products:quadrature-sensors
[15:43:17] <andypugh> I think Ford 1.6 diesel econetic would be my first port of call.
[15:43:31] <bpuk> no index pulse on that one, but that's not a huge issue (inductive proxy on a ground down tooth)
[15:44:11] <andypugh> I keep intending to add missing-tooth index to the HAL component. But it's not high on the list.
[15:45:07] <andypugh> What you really want is a resolver on the spindle.
[15:45:47] <bpuk> Mmmm... I have a couple of spare resolvers - but they're 1/4" shaft or less. Haven't really come across any in the region of 1 1/2"
[15:46:12] <andypugh> http://www.ebay.co.uk/itm/LTN-Resolver-RE-15-4-D01-LTN-Servotechnik-GmbH-/150646241254?pt=LH_DefaultDomain_0&hash=item23133737e6
[15:46:13] <bpuk> Erm, 6.35mm, 38mm ish
[15:46:16] <andypugh> Is also too small
[15:47:44] <bpuk> I'm not actually sure of the spindle O.D without going out to the workshop and checking, but it's in that general region I think
[15:48:07] <andypugh> This is how I put a Resolver on my spindle recently: http://www.cnczone.com/forums/1212353-post22.html
[15:48:09] <bpuk> hence trying to replace the existing ~6" (125mm) disc
[15:49:23] <bpuk> hmm, gear drive of a known ratio. backlash?
[15:49:41] <bpuk> shouldn't be too much of a problem, so long as the index is on the spindle itself, not off the driven gear
[15:51:12] <andypugh> Most resolvers are gear driven. They typically use an anti-backlash gear (two gears sprung so that they "pinch" the driver)
[15:51:29] <bpuk> Off current topic: Why the heck do so many people (especially on cnczone) suggest getting rid of resolvers in favour of encoders with (typically) much lower resolutions?
[15:51:31] <andypugh> In my application I can adjust the centres for almost zero backlash.
[15:51:46] <bpuk> Hmm... ok, you've got me thinking :D
[15:51:58] <andypugh> Because Resolvers are a pig to interface to parallel ports..
[15:52:50] <bpuk> heh, true - but once you've spent the cash on a mesa system that's less of an issue - unless all your resolvers are 11uA :D
[15:53:58] <bpuk> ok, last request of the night :D don't suppose you have a dxf of the laser-cut wheel?
[15:55:46] <andypugh> I have, but to be honest you would be better designing one to suit your machine
[15:56:13] <bpuk> ok, what grating spacing do the AEDS chips like? (which is the key point)
[15:57:02] <andypugh> Best see what chip you can get, and design accordingly
[15:57:41] <bpuk> :D
[15:57:47] <andypugh> I think mine was 75 lines per inch, but there are several variants.
[16:00:06] <bpuk> Hmm. The laser cut one would require a transmissive sensor? I think the think I liked about the etched design was that it was reflective (i.e could use the AEDR)
[16:00:42] <bpuk> or is it as simple as blocking the slots with paint then repolishing?
[16:02:12] <andypugh> A hole is about as non-reflective as a thing can be
[16:02:56] <bpuk> thats a good point...
[16:02:57] <andypugh> Those sensors see shiny-black just as well as shiny-silver. They basically _need_ a hole to detect zero.
[16:04:18] <bpuk> In that case, time to pester my local laser-cutting firm :D 180 to 318 LPI readily available
[16:08:47] <ReadError> anyone here do any 4 axis milling?
[16:08:52] <ReadError> on a rotary table
[16:09:42] <andypugh> A bit
[16:09:58] <ReadError> what do you use for CAM software?
[16:11:10] <andypugh> gedit. Not a very helpful answer for you, I suspect.
[16:21:05] <ReadError> ya not really :)
[16:24:10] <bpuk> What are you looking to machine? decorative? simple parts? complex ones? Since I tend to use vi I suspect my 'cam' software won't be helpful either - but may be able to suggest something else
[16:28:40] <JT-Shop> yuck! I think the BP head is not trammed... I drilled some holes then dropped the knee for a longer set up and the center is off by 0.015"
[16:29:09] <bpuk> ouch!
[16:29:19] <JT-Shop> times 9
[16:30:14] <bpuk> better get that head trammed then :D
[16:31:27] <pcw_home> Andy: is it possible Viesturs problem is something with the lead angle? Sort of sounds like it
[16:33:22] <ReadError> bpuk: mostly some simple stuff
[16:33:37] <JT-Shop> must be 5:00 somewhere
[16:34:07] <skunkworks> 35 too here...
[16:35:37] <pcw_home> I dont have a 8 pole motor but I can test sometime in the following week
[16:36:37] <bpuk> if it's fairly simple stuff then doing it by hand is entirely doable. for *slighly* more complex stuff laying it out in 3d in your cam-program of choice then using a wrapping script may do the job. I'm told Bobcad has a pretty good 4th axis wrap. I also know theres a python script to do so - but can't find it at the second, will keep looking
[16:39:56] <skunkworks> I have some 3 phase ones from keling... they are 4 pole it looks like.
[16:40:37] <bpuk> ReadError: failing that CNCWrapper ($25) may be of interest - carry on using your current cam, and wrap the flat code to round. I have a vague recollection artcam ha a feature to do so as well, but it was a bit expensive for my taste
[16:40:47] <pcw_home> 4 pole is by far the most common
[16:41:26] <skunkworks> I have some brushless amc drives that I have played with them.
[16:41:33] <pcw_home> more poles for slower and higher torque usually
[16:42:20] <skunkworks> I thought there was something wrong with them as the ticked while they rotated.. figured out it was the commutation noise...
[16:42:25] <skunkworks> they
[16:42:59] <pcw_home> Thats what you get with Hall commutation
[16:43:03] <skunkworks> yes
[16:43:09] <skunkworks> I know that now.. ;)
[16:46:04] <ReadError> thanks bpuk
[16:50:04] <bpuk> andypugh: I'm getting a slot width of ~70 micron - which seems a bit on the fine side to be lasercut - right region or...?
[16:51:36] <andypugh> How many lpi?
[16:52:06] <andypugh> Or is that just from diameter and required encoder count?
[16:52:11] <bpuk> 180 - the 75 seem to be out of stock
[16:53:27] <bpuk> ah, rs have the 75 lpi one - farnell have nothing below 180
[16:53:41] <andypugh> I got mine from RS
[16:53:49] <andypugh> Where are you?
[16:54:02] <bpuk> which is .338 micron - more reasonable
[16:54:05] <bpuk> UK
[16:54:30] <bpuk> so readily available from them
[16:54:30] <andypugh> I used http://www.sparkslaser.com/Sparks_Laser_Services.html
[16:55:02] <bpuk> * .338 mm - and bookmarked
[16:55:48] <bpuk> and now wondering if I can wirecut it directly... using .25 wire I get about .35 width of cut
[16:55:50] <andypugh> I do have a spare disc, but I don't know that it will always be spare.
[16:56:23] <andypugh> I would worry that an open-slot design might turn wiggly
[16:56:28] <bpuk> better to get my own cut
[16:56:57] <bpuk> and yeah - heat distorsion on such a thin disk could be interesting :D
[16:59:17] <andypugh> I have PCBs spare: This design https://picasaweb.google.com/lh/photo/Of6lsgdXzIDmIRxQI0WZONMTjNZETYmyPJy0liipFm0?feat=directlink or this one https://picasaweb.google.com/lh/photo/JTR29Tkv4zcmFph_DvNYRdMTjNZETYmyPJy0liipFm0?feat=directlink
[16:59:54] <andypugh> Though those are for 2 of the AEDS chips plus Hall sensors, so may not be appropriate
[17:00:08] <bpuk> was going to say, seems like a pretty complex pcb :D
[17:01:05] <bpuk> (for the chip we're talking about anyway) the chip (with extended ground land), plus one/two SMT resistors and output pins should be enough
[17:01:22] <jpratt3000> is it possible to have a manual A axis? meaning have a hard pause in the gcode to turn an object by hand
[17:02:10] <cradek> there's certainly an M code for pause, if that's what you're asking
[17:02:29] <cradek> I can definitely imagine using a manual rotary table in that way
[17:02:48] <cradek> if you don't need rotary/linear coordinated motion, why not
[17:04:29] <bpuk> simply adding an M01 code should be enough to pause it ready for the move?
[17:05:24] <jpratt3000> sweet
[17:06:13] <bpuk> As long as the optional stop switch is on. Then just hit start again to continue after moving
[17:06:41] * JT-Shop doesn't remember doing anything to the BP to knock the head out of tram... good thing scrap prices are high
[17:06:45] <bpuk> Or M0 without the switch - again, just hit start
[17:07:00] <jpratt3000> will give that a go and see. i imagine using the M01 with the A gcode as a comment would be a good way
[17:12:55] <skunkworks> I have used a manual rotory table on the K&T - worked great
[17:15:55] <skunkworks> http://electronicsam.com/images/KandT/conversion/rotorytable.JPG
[17:16:46] <DJ9DJ> gn8
[17:18:12] <jpratt3000> doing it on the cheap side. maybe a lazy-susan with a few holes and bolts ;-)
[17:19:39] <skunkworks> JT-Shop: throwing it out?
[17:21:14] <skunkworks> JT-Shop: if the gibs on the knee are not that tight - the table may 'rock' as you lower it..
[17:24:57] <JT-Shop> yea, I always lock the knee before using
[17:25:18] <JT-Shop> I must have been a bit too aggressive drilling some holes at some point
[17:25:26] <JT-Shop> the head was pushed up a tad
[17:25:54] <JT-Shop> the parts are scrap, not the mill :)
[17:27:34] <JT-Shop> I should have picked up on the problem when the first hole was off and like a dumb ass I just indicated the vise jaw again...
[17:29:34] <cradek> the cnc boss machines were "rigid ram" which you couldn't knock out of alignment unless you managed to do it permanently
[17:30:11] <cradek> your factory cnc tilts like a manual?
[17:31:27] <JT-Shop> it's a BP Series 1 with an Anilam 1100M 3 axis CNC conversion on it... so yes it started life as a manual BP
[17:32:13] <JT-Shop> now the controls are much easier to use...
[17:32:37] <JT-Shop> http://gnipsel.com/shop/bp1/bp1-01.xhtml
[17:37:30] <MercuryRising> im trying to use linux cnc with an extruder attached to my A axis for 3d printing, but i'm having some trouble making my Z axis work correctly
[17:38:20] <MercuryRising> i have 4" of travel on my Z, and i'm not sure what the 'normal' setup is, is home at the height of travel, and then you put an offset it in?
[17:39:38] <MercuryRising> i have been 'homing' on my 0 point (touching the table), but I feel like something is not right with that
[17:40:38] <cradek> JT-Shop: oh I thought you had a bridgeport small vmc
[17:41:00] <cradek> nice location for the jogwheel!
[17:41:31] <cradek> it'd be neat to have one on the end too, and have them always do X/Y
[17:46:49] <andypugh> jpratt3000: Still there?
[17:47:16] <JT-Shop> cradek: yes, I have a BP Discovery 308 VMC with a picky Siemens drive
[17:47:30] <skunkworks> JT-Shop: is that a mesa manual on your chair?
[17:47:46] <JT-Shop> the jogwheel is even more handy with the axis selection switches
[17:48:13] <andypugh> This is a manual A-axis doing coordinated moves with the X and Z. My spindle wasn't slow enough, so I am cranking with a handle :-) http://youtu.be/T4q8gCpeY1A
[17:48:28] <JT-Shop> skunkworks: yes you are very observant
[17:48:39] <skunkworks> looked right...
[17:48:59] <JT-Shop> 7i77 manual to be exact
[17:49:49] <andypugh> MercuryRising: You can touch-off anywhere convenient, and call that position anything you like
[17:50:45] <andypugh> MercuryRising: Normally in subtractive machining the top of the work is zero and all cuts are in negative Z. For additive work table = 0 and work all at positive Z seems entirely logical.
[17:53:25] <andypugh> I just watched a recorded Big Bang Theory. I was most amused that they get Steven Hawking in as a guest star on the telephone, when any computer would be perfectly convincing.
[17:55:56] <skunkworks> heh
[17:56:28] <skunkworks> That is the only show right now that the mythtv is recording every episode of.
[17:57:09] <skunkworks> (so far the wife and I have not seen one we have missed.)
[17:59:26] <andypugh> I was a physicist, I did a PhD. I am one of them. Not sure which.
[17:59:33] <skunkworks> http://www.youtube.com/watch?v=9H86iNWPYds
[17:59:40] <skunkworks> heh
[18:00:03] <andypugh> Probably Kuthripali, despite the lack of tan.
[18:00:34] <skunkworks> heh
[18:02:12] <skunkworks> I like how they make fun of wolowitz for 'just' having a masters...
[18:02:17] <JT-Shop> also when I run the BP Series 1 it doesn't seem to scare Woody
[18:02:46] <skunkworks> 'I have a masters degree!' - 'don't we all?'
[18:02:57] <andypugh> I don't have a Masters.
[18:03:23] <andypugh> At least, I don't _think_ I have.
[18:03:48] <jdh> you just forgot to pick it up.
[18:03:59] <skunkworks> I sure you can get one onliine...
[18:04:34] <andypugh> It's possible. I was (as I recall) enrolled on a Masters then had to write a report to upgrade.
[18:08:06] <andypugh> It's got me off at least one speeding fine, so must have been worth it.
[18:18:01] <MercuryRising> @andpugh: thanks.
[18:18:25] <MercuryRising> table is now 0. is there any way to throw an offset in from where I am homed? For some reason, my print wants to start at 0.1, but that's floating 0.1" in the air.
[18:22:39] <JT-Shop> just touch off and call it what you need
[18:23:37] <MercuryRising> what does touching off actually do? does it change my coordinates at all?
[18:24:11] <JT-Shop> well you can touch off to any coordinate system and if you have a tool loaded the tool table
[18:25:04] <JT-Shop> touch off doesn't change the machine origin
[18:25:38] <MercuryRising> okay, so i won't risk crashing my print head into the table if i touch off?
[18:26:11] <JT-Shop> if you have your soft limits set correctly...
[18:26:17] <andypugh> MercuryRising: Not if the top of the table matches the soft limit. Otherwise, yes, you are quite at liberty to crash the head.
[18:26:44] <JT-Shop> MercuryRising: some tutorials here http://gnipsel.com/linuxcnc/g-code/index.html
[18:27:19] <MercuryRising> awesome, thanks!
[18:32:01] <andypugh> Isn't this pretty? http://www.ebay.co.uk/itm/Miniture-Twin-Headed-Pillar-Drill-Watchmakers-/181048412838
[18:34:59] <JT-Shop> what do you think it did?
[18:37:25] <pcw_home> wonder if those pegs in the back are for a missing motor
[18:49:42] <Nick001-Shop> got a 5i20 and 7i30 and have something weird going on. Have a motor and encoder plugged into x axis plug and it homes good and travels good and have a motion program that runs good. Move the plug to Y axis and it wont home and movement is erratic - goes to following error. Move it to Z and motion kinds of coasts to a stop after I release the + or - key and wont home. All the axis info is the...
[18:49:43] <Nick001-Shop> ...same for all axes. Do I have a card problem or am I doing something wrong with switching plug positions?
[18:52:09] <JT-Shop> well this round of parts came out much better with the head in tram
[18:52:11] <andypugh> Are you plugging different physical axes into the same plug, or the same motor into different sockets?
[18:53:26] <Nick001-Shop> same motor and encoder into different sockets
[18:53:56] <andypugh> I suspect that not all the enables are equally effective.
[18:54:14] <andypugh> or that there are differences between the setups of the various axes
[18:54:54] <Nick001-Shop> the ini info is the same for all the axes 0,1,2
[18:56:21] <andypugh> Is all the HAL wiring the same too?
[18:57:31] <Nick001-Shop> yes ,as far as I can tell.
[18:57:38] <andypugh> Do all axes have the same homing sequence number?
[18:58:36] <andypugh> (How are you homing?)
[18:58:38] <Nick001-Shop> search vel and latch is the same
[18:59:07] <Nick001-Shop> to an index signal
[18:59:25] <andypugh> If Z home is moving the X motor onto the X limit, then I can't see that working
[19:01:00] <andypugh> Is this a trivial-kinematics machine?
[19:01:07] <Nick001-Shop> no limit switches - just goes to the index and calls it home. Works for X plug but not the rest of them
[19:01:55] <pcw_home> With the correct FPGA and 7I30 current limit settings all 4 axis should be the same
[19:02:20] <Nick001-Shop> Just doing 3 axes for now.
[19:03:26] <Nick001-Shop> and only X is working properly. Moving the plug assembly to Y and Z is giving me a problem
[19:03:30] <pcw_home> also all axis should be set for slow deacy
[19:03:57] <pcw_home> different HAL setup maybe
[19:04:03] <Nick001-Shop> is that a jumper?
[19:04:49] <pcw_home> theres a per axis current limit jumper (1A,3A)and a per axis fast/slow decay mode jumper
[19:06:26] <Nick001-Shop> is that the h and L?
[19:07:49] <Nick001-Shop> I notice X is set to H and the rest is set to L - need to try it out
[19:14:04] <Nick001-Shop> switched jumpers and somethings different - dinner bell went off and II'll have to come back to this tomorrow. Thanks for the help.
[20:05:43] <ReadError> it would be cool to have 3 MPG on a box
[20:05:57] <ReadError> for manual control of all axis easily
[20:10:51] <alex4nder> yoh
[20:13:46] <ReadError> sup
[20:29:31] <jpratt3000> andypugh: still here doing some work
[20:30:26] <jpratt3000> andypugh: watched the video, makes sense
[21:13:42] <r00t4rd3d> http://imgur.com/a/mskl7
[21:13:47] <r00t4rd3d> that is pretty cool
[21:15:40] <ReadError> lathing is hard ;(
[22:17:15] <r00t4rd3d> nah, just rotate some wood and shove something in its path.