#robotics Logs

Jun 03 2014

01:51 GuShH rue_more: alright I managed to improve surface finish on the lathe, you know how the crosslide clamps with a relatively small piece of iron and 3 allen screws on the back?, the surface finish on that was terrible, and that's what makes the entire saddle track and remain horizontal, well it turns out it was somehow "copying" all those imperfections and also causing drag in the process... so I lapped the hell out of it until it wa
01:51 GuShH s almost perfectly flat, brought it up to 600 grit (started at 80 or so and it took a while, it was, like most cast iron parts from china, slightly higher in all corners)
01:52 GuShH well not "somehow" it was making it tilt ever so slightly degrading the surface finish, that's my theory.
01:53 GuShH also, with the reduced drag, it's a lot nicer to manually feed it, previously it had a lot of stiction
01:54 GuShH so if yours feels like it should be smoother, remove it... just 3 screws, maybe 4 in yours, blue the part... rub it against some 400 grit or similar sandpaper on glass, or better surface and see what you get... I only got 2 thin stripes on the corners making contact initially.
01:54 GuShH make sure you support the saddle with some wood, so it doesn't rest on the leadscrew though, while the part is out.
01:55 GuShH soon I'll lap the cross feed, as that has a bit of stiction and it's not the "oh god it's so flat it's sticking" kind, it's the rough surface grinding kind, mostly I suspect from the gib not being polished nor brass.
01:56 GuShH anyway, saddle clamp, inspect that and lap it to a nice shine.
01:56 GuShH it's amazing how such a small thing makes a huge difference, in feel and finish.
01:57 GuShH I suspect a bronze "clamp" would be even better.
01:58 GuShH the iron has it's graphite for lubrication, but the bed is also iron, although at different hardness - in theory - I just think bronze would be a better choice, but you really need a mill to machine that part, or a shaper. it has a slight angle so it can clamp properly...
01:58 GuShH I'm not sure how the saddle clamps on older lathes
01:59 GuShH I know they clamp on a wider region though, that could be a neat mod for rigidity.
02:01 rue_more that might explain my experience today
02:04 GuShH which is?
02:04 GuShH just try it, believe me I wouldn't talk about it if I didn't think it was damn worth doing.
02:04 GuShH it feeds so much nicer now, and moves a lot nicer.
02:05 GuShH and when you adjust the screws back, take your indicator and try to pull the entire saddle up, you should see no movement on the needle, any further adjustment is just going to be detrimental (drag)
02:06 GuShH I'll make a video later showing the new results.
02:07 GuShH given the machining marks on the block, I'd say it was made using a shaper.
02:07 GuShH which is fine for me, but cast iron has to "age" before you can machine it, otherwise it distorts.
02:08 GuShH I see it in every cast iron part I've blued, and it's not my surface I tried many different surfaces.
02:22 Curious plays with his punchthrough
04:14 X-Scale https://www.youtube.com/watch?v=iuc0lkQqzkc
04:17 SlaveToTheSauce_ neat
04:17 SlaveToTheSauce_ don't think the structure will work long term though
04:18 SlaveToTheSauce_ needs to be plastic with flexible joints and wire actuation i think
04:19 SlaveToTheSauce_ instead of aluminium pivots that will get all gummed up with vegetation or corrosion
05:41 shelving hay
10:16 rue_more GuShH, I see what your talking about
10:16 rue_more I'll pull that off later and take a look
13:34 GuShH rue_more: yeah, big improvement.
13:35 GuShH I think I already spent more time tweaking it than they did manufacturing it
14:11 Hyratel GuShH, care to say more on what you mean about pre-aging cast iron?
14:30 Hyratel *pokes GuShH with a blunt sprewdriver
14:45 GuShH Hyratel: iron has to age to relieve all strain before it's actually machined, otherwise the stress is relieved after the operations, leaving distorted parts as a result
14:45 Hyratel aha
14:45 GuShH the cooling rate of cast iron is also important
14:46 ShH wonders how to remove this tiny metal chip off his t
14:46 Hyratel strong magnet, if it's iron
14:46 GuShH non ferrous
14:46 GuShH could be brass or stainless...
14:47 GuShH they're so tiny you only become aware once the skin turns red.
14:47 ShH ponders investing in a precision tweezer
14:47 GuShH latex gloves serve no protection
14:48 GuShH Hyratel: if you look into the big manufacturers you'll see they age the iron, such as you would age wood for a rifle stock or a pool cue
14:49 Hyratel ahhh
14:49 GuShH in case of the wood you also want a specific humidity and to reduce warping
14:49 Hyratel is there any special process to aging iron, or "just let it sit for a while" after casting?
14:49 GuShH I don't know the specifics!
14:49 GuShH I believe it sits on a controlled environment...
14:50 Hyratel I have to wonder though -
14:50 GuShH mhh cheese.
14:50 Hyratel if it'd be possible to buy un-machined castings
14:50 uirrelCZECH believed that proper way is to put it under ground for a long time
14:50 GuShH likewise precision machines are actually still hand-scraped.
14:50 Hyratel and then shape them yourself
14:50 GuShH for some things yeah they sell castings for kits
14:50 GuShH I've seen them for model engines and such
14:50 GuShH including magnesium castings
14:51 Hyratel I'd doubt they would for cheap drill vises
14:51 ShH never machined magne
14:51 GuShH it's best if you start with big lumps of quality steel for that
14:51 GuShH and, they do sell cast iron ingots and other stock
14:51 Hyratel just cut it from straight billet?
14:51 GuShH I'm not sure if the square stock comes from round stock.
14:52 GuShH because there's a specific process for continous cast iron billets
14:52 GuShH SquirrelCZECH: could be
14:52 SquirrelCZECH :)
14:53 GuShH where can I read more about it?
14:53 GuShH the potting process is also something only the big manufacturers do
14:53 GuShH to reduce resonant chatter
14:54 SquirrelCZECH Dunno, friend of mine which worked in big factory told me :)
14:54 GuShH fancy granite epoxy mix
14:54 GuShH with specific grits
14:54 GuShH to obtain a certain epoxy to filler ratio
14:55 GuShH SquirrelCZECH: I think in China it gets machined while it's still warm...
14:55 GuShH But I do know they're cast by a separate company
14:55 GuShH So probably that's just an exaggeration.
14:55 GuShH there's an awesome pic out there, showing a massive cast... can't find it now
14:55 SquirrelCZECH Maybe?
14:58 GuShH the annealing and final hardening have to be just as important.
14:58 GuShH some manufacturers claim natural or artificial aging of at least 2 to 3 years heh
14:58 GuShH but for non precision stuff, that's not the case. unknown alloy, unknown hardness, unknown age
15:01 SquirrelCZECH Yeah :-)
17:44 magicpacman any of you guys know how to attenuate microphone amplifier signals?
18:08 magicpacman I have a microphone amplifier that outputs a signal from 0-5V. I need to connect it to an ADC on my Beaglebone Black but that can only handle 0-1.8V. What is the best way to attenuate the signal so that all the frequencies will be preserved but the signal will be adjusted to fit in the 0-18V range?
18:12 GargantuaSauce voltage divider?
18:16 magicpacman as in have my Vin = 5 and my voltage divider to divide it down to 1.8?
18:38 GargantuaSauce_ ya
19:09 GuShH mulvane: fix your client
19:20 blank___ Devices that deliver sensations to the skin surface of their users (i.e.--tight body suits and gloves) are also sometimes used in virtual reality to complete the experience. "Virtual sex"�in which two people are able to have sex with each other through virtual reality, or in which a human can have sex with a "simulated" partner that only exists on a computer�becomes a reality.
19:20 blank___ http://en.wikipedia.org/wiki/Predictions_made_by_Ray_Kurzweil#Early_2000s
19:24 GargantuaSauce_ kurzweil is full of shit
19:24 GargantuaSauce_ teledildonics IS the pinnacle of our field though
19:24 blank___ http://www.kurzweilai.net/images/How-My-Predictions-Are-Faring.pdf
19:25 blank___ could you imagine how big teledildonics would be? at least a $100 billion a year industry!
19:25 Tom_itx wish me luck.. i may never be back.
19:25 Tom_itx configuring my router :)
19:25 blank___ good luck Tom_itx
19:26 GargantuaSauce_ threats of violence always facilitate that process i find
19:27 Tom_itx i'm trying to configure 2 inbound port forwards
19:27 Tom_itx and learning the router's 'language' at the same time
19:32 Tom_itx well at least i didn't blow this connection
19:33 Tom_itx could one of you verify if you can see this page? http://tom-itx.no-ip.biz:81/~webpage/index.php
19:33 GargantuaSauce_ yup
19:34 Tom_itx well the 2nd part worked then
19:34 GargantuaSauce_ fyi some services block links to the .biz tld automatically
19:35 Tom_itx i'm trying to configure a DVR
19:35 Tom_itx i'm having to change from port forwarding to using NAT rules
20:30 GargantuaSauce_ http://xn--d-bga.su/dlink/6.jpg plan B
20:32 Tom_itx i'm missing one rule i think
20:32 Tom_itx http://tom-itx.no-ip.biz:81/~webpage/index.php
20:32 Tom_itx is that still visible?
20:32 GargantuaSauce_ no
20:36 Tom_itx hmm
20:36 Tom_itx you sure?
20:39 GargantuaSauce_ yes
20:40 Tom_itx odd. that's the config i tested a bit ago when it was working
20:41 GargantuaSauce_ Nmap scan report for tom-itx.no-ip.biz (24.255.188.115)
20:41 GargantuaSauce_ Host is up.
20:41 GargantuaSauce_ PORT STATE SERVICE
20:41 GargantuaSauce_ 81/tcp filtered hosts2-ns
20:42 Tom_itx that's the right ip
20:43 Tom_itx i need to figure out a firewall rule to allow that local ip
20:44 Tom_itx but i don't understand why it worked the first time
21:33 GuShH Tom_itx: it's visible now
21:34 GuShH reverted?
21:34 Tom_itx it is?
21:35 Tom_itx i didn't change anything since GargantuaSauce_ checked
21:35 Tom_itx try refresh or a different page on the site...
21:35 ShH stares at the death
21:35 Tom_itx mkay
21:35 Tom_itx thanks
21:36 GuShH mini itx (epia MII) watching no
21:36 GuShH now
21:36 Tom_itx i just wish i could get the rules for my dvr working
21:38 Tom_itx i am slowly learning though
21:39 GuShH you could always use my hammer
21:39 GuShH to learn faster
21:39 GuShH or unlearn, depending.
21:40 Tom_itx it's poorly documented
21:40 Tom_itx but the help community is quite responsive
21:41 Tom_itx i posted a question and had a reply within minutes