#linuxcnc Logs

Jan 17 2022

#linuxcnc Calendar

01:58 AM randy: morning
02:33 AM Loetmichel: ah well... Boss had a scanner "exercising" for the whole weekend to test for the shielding on the FFC to unravel. Every three seconds one scan... now it says "scan head stuck"... maybe even high performance flatbed scanners are NOT meant to do THAT many scans back to back? (I will out a few drops of oil on the linear ways and try again...)
02:54 AM roycroft: many folks use epoxy granite to fill casting voids in their milling machines for vibration dampening and rigidity
02:55 AM roycroft: is that something one might sensibly consider for filling 80/20 extrusions that are used to build a cnc router?
02:55 AM XXCoder: ehh too small effect I think
02:55 AM XXCoder: unless youre using beefy ones with large void in center
02:56 AM roycroft: i actually am, for the x axis
02:57 AM roycroft: roycroft.us/CNC-Router/X-Z-Axis-Preliminary.jpeg
02:57 AM XXCoder: hmm
02:57 AM XXCoder: can be done I suppose, though I guess you'd have to be careful not to finish ends till you fill it
02:58 AM XXCoder: leaving gaps at ends then mill off for nice clean finish
02:58 AM XXCoder: in least thats what im picturing, probably is not best
02:59 AM roycroft: i would probably cnc print a thin filler plug for one end
02:59 AM XXCoder: thats an idea yeahj
02:59 AM roycroft: insert that then stand the extrusion on end
02:59 AM XXCoder: make for other end too
02:59 AM roycroft: and fill it from the top
02:59 AM roycroft: until it almost reaches the other end
03:02 AM XXCoder: yeah. having other end cap would tell you if you have reached equal fill approx
03:02 AM roycroft: https://roycroft.us/CNC-Router/X-Z-Axis-End-View-Preliminary.jpeg
03:02 AM roycroft: you can see how big the voids are really well in that view
03:03 AM roycroft: that's what made me think that epoxy granite might help
03:03 AM XXCoder: indeed.
03:03 AM roycroft: i'd probably just fill the two big voids
03:04 AM roycroft: but i don't know, maybe i'd do the smaller ones as well
03:04 AM XXCoder: different vibration freq range damping mixtures for smaller?
03:08 AM roycroft: the folks on cnc zone who talk about epoxy granite have formulae with mixtures of different size aggregate materials
03:08 AM XXCoder: yeah. I remember that nice video where guy makes mixtures from cheap path filling rotten grinite
03:08 AM roycroft: i think if i used a mix of aggregates i could use the same mix in all the voids
03:09 AM XXCoder: he washes it in bathtub. Id not do that, since sand and such can clog pipes
03:09 AM XXCoder: otherwise nice
03:09 AM roycroft: yeah, i would not do that
03:09 AM roycroft: also, i have a bunch of glass bead
03:09 AM roycroft: i bought it for media blasting, but i hardly ever used it
03:09 AM XXCoder: anyway thats an odea for you. after all, clean rotted grinite is very expensive
03:09 AM roycroft: i have like 90 lbs in sealed buckets
03:09 AM XXCoder: wow
03:09 AM roycroft: never used
03:10 AM roycroft: so this would be a good way to use some of that up
03:10 AM roycroft: it's something to think about
03:10 AM roycroft: it could make the x axis crossmember a lot stiffer
03:11 AM roycroft: and i shouldn't think it would add much expense to the project
03:11 AM roycroft: if the mix is 10-15% epoxy, i would not need all that much epoxy
03:11 AM XXCoder: dunno on percentage
03:12 AM roycroft: from what i've read, to make it the way hardinge did it it should be <10% epoxy
03:12 AM XXCoder: do keep in mind yard shop rotted grinate. save a lot of money compared to some other places
03:12 AM roycroft: commonly, folks make it with 20% epoxy so that it pours well
03:13 AM roycroft: so i'm thinking 10-15% is probably about right
03:13 AM XXCoder: cool
03:13 AM XXCoder: theres couple projects I want to try
03:13 AM XXCoder: but meh
03:13 AM roycroft: i have a vibratory tumbler
03:13 AM roycroft: if i fill that half full of sand
03:14 AM roycroft: i could set the extrusion in it and run it while i'm filling the extrusion with the epoxy granite
03:14 AM roycroft: that would help flow it down, and get rid of air bubbles
03:14 AM XXCoder: indeed
03:15 AM XXCoder: have hot air torch too, to de-bubble top too
03:15 AM roycroft: that won't really matter
03:15 AM XXCoder: quick fly over it and thats gone.
03:15 AM roycroft: the ends will not show
03:15 AM roycroft: but if the air bubbles accumulate on the top and it makes it hard to fill completely, i can do that
03:16 AM roycroft: i don't think i'd need to, but it's easy enough to set a propane torch next to me while i'm filling it, just in case
03:16 AM roycroft: anyway, it's something to ponder
03:17 AM roycroft: one drawback is that if ever rebuild the router to change the size, it would be harder to repurpose the extrusions i remove
03:17 AM roycroft: and those extrusions are pretty expensive
05:00 AM JT-Cave: morning
05:05 AM Tom_L: morning
05:11 AM Tom_L: roycroft, get a kiddy pool for the neighbor kids as a token of goodness and clean the rock in it instead of the tub
06:15 AM unterhausen: we got 6" of snow, not really feeling the urge to go out and shovel
06:15 AM XXCoder: pay me plane ticket, food and board, and $100 per work minute and ill go
06:16 AM XXCoder: note plane ride counts as work
06:16 AM unterhausen: I only pay half rate for travel
06:17 AM XXCoder: meh thats fine
06:17 AM unterhausen: I was always surprised when clients didn't blink about that
06:18 AM XXCoder: interestin
06:22 AM Loetmichel: unterhausen: if you're worht it you're worth it ;)
06:22 AM Loetmichel: worth#
07:02 AM JT-Cave: hmm looks like my uspace tutorials text files are long gone
07:06 AM CloudEvil: archive.org ?
07:07 AM JT-Cave: the text files were never online only the generated html files
07:17 AM Tom_L: be a chore but you can recover it from that
10:01 AM roycroft: if i needed to clean granite dust or whatever, the amount i'd be dealing with is small enough that i could just use a gold pan and a nearby creek to do it
10:03 AM roycroft: i'm not conviced yet that the benefits of filling my extrucions with epoxy granite would justify the amount of work it would take to do it
10:04 AM roycroft: it was just an idea that popped into my head when i looked at an end view of a 15 series 3060 extrusion
10:15 AM Alicrow-phone: Wooo!! My 60V variable power supply arrived!
10:23 AM roycroft: no deliveries today - it's a holiday
10:27 AM * JT-Shop just ordered a Robert Sorby chuck and the crap chuck is going in the scrap bin
10:28 AM CloudEvil: crap chucks are ideal for fixturing round stuff for approximate work
10:28 AM roycroft: i love my sorby chuck
10:28 AM roycroft: i spent a lot of time comparing chucks before i ordered it
10:30 AM roycroft: i finally got my lathe extension bed last week - it was backordered for quite a while
10:30 AM roycroft: i can turn pieces up to 40" long now
10:31 AM CloudEvil: :)
10:55 AM Alicrow-phone: Yeah, I didn't think it would come today, because the delivery estimate said tomorrow, even though it was already at my local post office. Figured no deliveries today, but here it is.
10:56 AM Alicrow-phone: Haven't powered it up yet; had to clear slush from the flat roof over the garage and now I need some food.
10:56 AM roycroft: i'm starting to design my gantry sides
10:57 AM Alicrow-phone: We're trying to save up money to rip out that roof (and joists) and put in a proper sloped roof that won't rot and leak like a sieve.
10:58 AM roycroft: if you don't need the overhead clearance you can just build the pitched roof on top of the existing one
10:59 AM roycroft: that might save some cost, as you would not have to replace the joists
11:03 AM Alicrow-phone: I guess that could work, but it's kinda like just slapping a Band Aid over it. The structural integrity is very much compromised at this point, and the joists and stuff all should be replaced.
11:04 AM Alicrow-phone: Our idea is actually to extend the regular roof (one story above the garage) over the garage, and then we get some additional storage space, too.
11:04 AM roycroft: i've obviously not seen it, so i can't properly evaluate the options
11:05 AM roycroft: but i have built pitched roofs on top of existing flat or slightly sloped roofs before
11:05 AM roycroft: it can work fine in some circumstances
11:06 AM JT-Shop: roycroft, what jaws do you have for your sorby?
11:08 AM Alicrow-phone: I think building the pitched roof right on top would be fine if the joists and plywood and stuff weren't already so far gone.
11:09 AM JT-Shop: on second thought I'll clean up the PSI set and sell it for 1/2 price on craigslist
11:10 AM JT-Shop: hmm the set sells for $200 so I'll list it for $100
11:10 AM Alicrow-phone: The "flat" roof is about as flat as a baking pan you used as an anvil.
11:10 AM JT-Shop: might just help someone out
11:14 AM roycroft: so far i have the stock jaws and the pen jaws
11:15 AM roycroft: i plan on getting pretty much the complete set over time
11:15 AM JT-Shop: I ordered the 3 1/2 jaws and the outside jaws
11:15 AM roycroft: one of the main reasons i went with the sorby is that it's the only chuck that has a complete overlapping set of jaws - all the other brands have gaps
11:16 AM JT-Shop: I found that out about my PSI set yesterday
11:16 AM roycroft: i want to make some wooden hinges, which involves center drilling small dowels
11:16 AM roycroft: the pen jaws are perfect for that
11:17 AM Alicrow-phone: I have the PSI cheapo chuck. Recently upgraded to a Nova Supernova 2, but need to get my wife to make an adapter insert for it before I can use it.
11:17 AM JT-Shop: hmm it's lunch time
11:17 AM roycroft: the sorby chuck has a big, thick rubber band that is wrapped around the chuck body
11:17 AM roycroft: it's supposed to be a safety feature - it won't injure your knuckles if you bump them into the rubber band vs. the chuck body itself
11:18 AM roycroft: i've found that the rubber band starts stretching and sticking out from the chuck body at high speed
11:18 AM roycroft: i've removed it from my chuck, but i may reinstall it, attaching it with contact cement or the like
11:19 AM roycroft: that's a bit odd, but other than that it's a great chuck
11:20 AM roycroft: the wooden hinge thing is the main reason i bought my lathe when i did, btw
11:20 AM roycroft: i'd been meaning to buy a smaller lathe and get rid of my old, way too big, crappy one
11:21 AM roycroft: rob cosman sells a wooden hinge drilling jig, and when i saw it costs well over $100, i decided that i could invest that money in a new lathe instead
11:22 AM roycroft: there's also an incra wooden hinge jig, but it's also expensive and very limited in what it can do
11:25 AM JT-Cave: I don't think I've seen a wooden hinge...
11:25 AM Alicrow-phone: Power supply puts out the right voltage (slight 0.1V discrepancy between what it displays and what my multimeter says, but that's fine and could be the multimeter or voltage drop from the leads)
11:27 AM Alicrow-phone: Also, not as loud as I had feared, at least not with no load.
11:28 AM roycroft: https://www.youtube.com/watch?v=87vbqCQUigE
11:29 AM roycroft: allocate some time to watch that - it's over an hour long
11:29 AM roycroft: but rob really explains it well, and he makes really nice wooden hinge boxes
11:29 AM JT-Cave: yeah I saw that, I'll download that in the morning
11:30 AM JT-Cave: thanks
11:38 AM roycroft: i see most folks center their spindle axis between the gantry bearings
11:39 AM roycroft: is the axis what should be centered, or the center of the z axis mass?
11:39 AM roycroft: or the center of the x+z axis mass?
11:40 AM roycroft: the center of the x+z axis mass seems like the correct alignment to me
11:57 AM roycroft: the average density of granite is almost identical to the density of aluminium - that makes mass calculations easy
11:59 AM roycroft: epoxy is much less dense, but it would also be a small percentage of the epoxy granite, so i can ignore the difference and still come out close enough in my calculation
12:29 PM JT-Shop: hmm for $40 I'm not going to try and straighten the HR1000 receiver tube and it seems to be the only thing bent
01:18 PM Alicrow: Just powered up one of the motors with that power supply. Seems to work fine, though it wasn't in the machine; just free spinning.
01:35 PM t4nk_freenode: that's always a rugged test ;)
01:36 PM t4nk_freenode: I thought my diy supply was excellent too..
01:36 PM t4nk_freenode: until all the motors were connected and under load
01:36 PM t4nk_freenode: *sigh*
01:37 PM t4nk_freenode: well, not even under load too.. just had to hit the home button
01:43 PM Alicrow:  This is an old Sorensen rack mount variable power supply. Can do 60V at 18 Amps. Not quite the 22.5 Amps combined between the servos in the original schematics (7.5 A fuses for each servo; no idea how much power they actually used), but it should at least get things running.
01:43 PM Alicrow: Just opened it up for a cleanout, remove all the dust and stuff.
01:45 PM roycroft: you can always augment it with a second power supply later if it isn't providing enough current to run all your motors
02:07 PM -!- #linuxcnc mode set to +v by ChanServ
02:12 PM Alicrow: contactors just arrived, too. Will check those out later
02:17 PM roycroft: i have devised a new rule to weed out spam calls
02:17 PM roycroft: when the phone rings i pick it up and say "hello"
02:17 PM roycroft: if there is no response in 2 seconds i hang up
02:18 PM JT-Shop: being a big sport I see giving them a whole 2 seconds
02:18 PM roycroft: i may tweak that
02:18 PM roycroft: but my experience that most auto-dialers take more than 2 seconds to connect to the live spammer
02:19 PM roycroft: i could see myself cutting that down to 1.5 seconds, though
02:19 PM roycroft: i think i'll probably always give folks at least a second to respond
02:23 PM JT-Shop: hmm I should have finished my inspection of the bike rack before ordering... I needed a few small parts to finish fixing it good as new
02:34 PM roycroft: i've done exactly that many times - order what i think i need, then immediately dig in deeper and realise i need more parts
02:40 PM JT-Shop: Hollywood Racks canceled both orders and I put all the parts in one order
02:58 PM unterhausen: I stopped answering the phone years ago. Most of the numbers are so obviously spam calls that there wouldn't be a point
02:59 PM unterhausen: if it's a real call they will start to leave a message and I will pick up
03:00 PM roycroft: i can't do that
03:01 PM unterhausen: doesn't matter anyway, since they didn't give us antennas with our new cell/land box and the land line doesn't work
03:01 PM roycroft: once it goes to voicemail i have to wait for it to finish, then i get an email
03:01 PM unterhausen: we have an answering machine hooked up so it grabs it before AT&T
03:02 PM roycroft: i have a pbx at home
03:02 PM roycroft: it's all voip, except a single land line, which is managed by the pbx
03:02 PM unterhausen: if you have a pbx, you could just transfer it to your secretary
03:03 PM roycroft: yeah
03:03 PM roycroft: and that would be me
03:04 PM unterhausen: you should fire yourself
03:04 PM roycroft: now i not only have to deal with the spam call, i have to put on a different hat while i'm doing so
03:04 PM roycroft: one that does not fit very well
03:04 PM roycroft: i've almost fired myself many times
03:04 PM roycroft: but i'm too much of a softie at heart
03:04 PM unterhausen: I did think about getting a high gain antenna, because other than the spam calls it's nice to have a good phone line
03:05 PM unterhausen: we used to run to get calls, if you just let the phone ring you were a sociopath
03:06 PM unterhausen: but less than 10% of calls were not fully legit. Now it's the other way around, we almost never get a legit call
03:06 PM roycroft: back in the '80s i had a housemate like that
03:07 PM roycroft: i could be sitting right next to the phone, but if it rang, he would run from the far end of the house and grab the phone before i could reach over and pick it up myself
03:07 PM unterhausen: probably from a big family with bullies as older siblings
03:08 PM roycroft: i never understood it
03:08 PM roycroft: i don't ignore the phone
03:08 PM roycroft: but i do dislike telephony, generally, and don't panic if i cannot pick it up on the first ring
03:08 PM roycroft: i've always been that way
03:09 PM roycroft: unless i'm either far away from the phone or busy doing somthing else, i usually pick up by the 3rd or 4th ring
03:38 PM perry_j1987: got me a set of 123 blocks and a 4in machinist square
03:39 PM XXCoder: nice. those is nice to have.
03:39 PM XXCoder: i suggest indicate the machinist square
03:39 PM XXCoder: be sure its nice
03:39 PM perry_j1987: i put the square on the 123 blocks
03:40 PM perry_j1987: the inside of the square is not square at all
03:40 PM perry_j1987: but if i set the 122 block on eachother and then set the square up against it i cant see light through it
03:40 PM perry_j1987: so the outside of the square looks to be good but inside of it is atrocious
03:40 PM XXCoder: :(
03:42 PM perry_j1987: luckily the outside surface is all i need the square for
03:51 PM perry_j1987: going to get this new z axis all trammed in
04:09 PM -!- #linuxcnc mode set to +v by ChanServ
04:33 PM _unreal_: FINALLY I got my new stickers/reg for my boat trailer
04:43 PM t4nk_freenode: hurray!
04:43 PM t4nk_freenode: ;)
04:44 PM t4nk_freenode: what's a floridian without a boat trailer... nothing I say
04:46 PM _unreal_: t4nk_freenode, https://drive.google.com/file/d/123aBDcIolrc4Mdoj5bWxp4P3MLXUyfA8/view?usp=sharing https://drive.google.com/file/d/0B3vL4RqyNgQAUGZYcjM1WWpJVWc/view?usp=sharing&resourcekey=0-xbD-CEhTbMF1mXkzgdwb_w
04:47 PM _unreal_: t4nk_freenode, 100% hand made https://drive.google.com/file/d/0B3vL4RqyNgQANzVBc3BiT0pobHM/view?usp=sharing&resourcekey=0-NPHObsBYBI_uST7ZznrX_Q
04:47 PM t4nk_freenode: I didn't want to upset you by not clicking
04:47 PM t4nk_freenode: but
04:48 PM t4nk_freenode: I clicked them, against every fiber in my soul
04:48 PM t4nk_freenode: and I'm still looking at the first link, and it won't show
04:49 PM t4nk_freenode: 20181231_161622.jpg that's the most I get
04:50 PM t4nk_freenode: the name that is
04:50 PM _unreal_: no idea
04:51 PM t4nk_freenode: :(
04:52 PM t4nk_freenode: tell me what ever came from the grblhal adventure then
04:52 PM _unreal_: I have not touched it
04:52 PM _unreal_: to much going on
04:53 PM t4nk_freenode: to mych too do
04:53 PM t4nk_freenode: to much too doo
04:54 PM t4nk_freenode: well, thats okay than,
04:54 PM t4nk_freenode: can I offer you a syrup waffle perhaps?
04:56 PM t4nk_freenode: (don't mind if I get one myself!)
05:02 PM t4nk_freenode: so... I wanted to print the rest of the bearings overnight
05:03 PM t4nk_freenode: started the print, but when I was heading for bed... I noticed the prints literally hadn't gotten off the ground
05:03 PM t4nk_freenode: pffff... put a new nozzle on and had to level my bed
05:04 PM t4nk_freenode: I was fortunate enough to be able to lift the rods with everything still in place
05:04 PM t4nk_freenode: heh
05:04 PM t4nk_freenode: but my heart sank a bit when I tried the first bearing and noticed a lot of play :|
05:05 PM t4nk_freenode: but that one was off too, because of the bed
05:05 PM t4nk_freenode: anyhow
05:05 PM t4nk_freenode: tried the new ones and they are just perfect
05:06 PM t4nk_freenode: no play whatsoever, yet they go on very easily, no pressure
05:07 PM t4nk_freenode: though there is stil play.. well, not play, but backlash I guess
05:07 PM t4nk_freenode: this is the first time I'm able to feel it so clearly
05:09 PM t4nk_freenode: or at all, even ;)
05:10 PM t4nk_freenode: so the axis moves nice now when I turn the screw
05:10 PM _unreal_: so you go tthe bearings setup installed?
05:10 PM t4nk_freenode: but if I push it up.. I can feel the spring in the nut, and then a little play
05:11 PM t4nk_freenode: and if I let go I can feel the spring pushing it back
05:11 PM t4nk_freenode: so I guess this anti-backlash thing is a bit of a scam
05:12 PM t4nk_freenode: I mean...all fina and dandy if you run a 3d printer of a laser thingy
05:12 PM t4nk_freenode: but milling 3' thick steel will have you facing the backlash again
05:13 PM t4nk_freenode: I gather it might still be ok for milling pcbs though
05:13 PM t4nk_freenode: with the weight of the spindle and clamp helping to pull it down
05:14 PM _unreal_: t4nk_freenode, I've been to all of these places https://youtu.be/znTpJazXzdY
05:22 PM t4nk_freenode: impressive
05:23 PM t4nk_freenode: good thing I don't live there.. all I'd want to do is eat, lay on the beach and impregnate females
06:25 PM roycroft: i've been working on my gantry sides, and i'm ready to start designing my y axis (on which the gantry will move)
06:26 PM roycroft: i see most folks mounting their linear rails on the sides, but it seems to me that mounting on the top would be better
06:26 PM CaptHindsight[m]: near infinite possibilities, all about the same give or take
06:26 PM roycroft: if i mount them on the sides, then the entire weight of the gantry will be pressing down on the upper row bearings (i'm using hiwin style rails/trucks)
06:26 PM CaptHindsight[m]: the devil is in the deatils
06:27 PM roycroft: if i mount them on the top then the weight will be evenly distributed on both rows of bearings
06:27 PM CaptHindsight[m]: details even
06:27 PM CaptHindsight[m]: also bottom mount
06:27 PM roycroft: bottom mount would have some advantages, but would require the machine to be wider
06:28 PM roycroft: or maybe not
06:28 PM CaptHindsight[m]: keeps the chips out of the bearings
06:28 PM roycroft: it's something i can consider
06:28 PM roycroft: sawdust, in this case
06:28 PM roycroft: but that can be worse than chips
06:28 PM CaptHindsight[m]: mounting on the side may require bigger bearings
06:29 PM roycroft: it would be easier to design it with the bearings mounted on the sides
06:29 PM CaptHindsight[m]: depends on you numbers
06:29 PM roycroft: but is my concern about uneven loading realistic?
06:29 PM roycroft: or is it so minor that it doesn't matter?
06:30 PM CaptHindsight[m]: there are calculators for given bearings and rails
06:30 PM * roycroft is asking the general voice of experience, but is not sure that said voice is present here at the moment :)
06:31 PM CaptHindsight[m]: you should have this in your calculations
06:31 PM roycroft: yes, i'll do some calculations
06:32 PM CaptHindsight[m]: but since you seem to be winging it
06:32 PM CaptHindsight[m]: Splunge!
06:32 PM roycroft: although finding reasonable values for imported clone bearings/rails may prove difficult
06:32 PM roycroft: i'll probably find the values for the genuine articles, and guess at a proper derating factor
06:32 PM CaptHindsight[m]: you're a gambler
06:33 PM CaptHindsight[m]: good luck
06:33 PM roycroft: i think i'm doing a lot more thinking/calculating than the average cnc router builder who does not do it for a living
06:33 PM roycroft: i try not to gamble too much
06:34 PM roycroft: my approach has been to try to figure out a good design, modeling it, and then using the derived data from the model to calculate whether it will work or not
06:35 PM roycroft: for some components i'm just using what similar-size commercial units use
06:35 PM roycroft: that's the gambling bit, i suppose
06:36 PM CaptHindsight[m]: just a suggestion, mount the bearings in way that is easily serviced and replaced
06:36 PM roycroft: no matter what configuration, i'll likely have to disassemble the gantry to service the bearings
06:37 PM roycroft: they will have grease fittings, so i can lubricate them while installed, but if they need to be disassembled/cleaned/replaced, i'll have to remove the gantry
06:38 PM roycroft: and i am getting bearings with wipers on the ends of the blocks, so that should help keep some of the dust and debris out
06:48 PM roycroft: but if i spend $100 on a pair of rails and four bearing blocks that would cost me $400 for the same thing but high end, and i end up sending $50 for higher quality ball bearings to make them work,i'm still a lot of money ahead
06:53 PM Tom_itx: roycroft, mount them on the top and add accordion dust covers on each side
07:01 PM Tom_itx is now known as Tom_L
07:01 PM roycroft: it's a looooooooooong axis - those would be some pretty big accordians
07:01 PM Tom_L: my kid just did a prototype and landed a good run of parts 257 x 60 x 6" alum block
07:01 PM Tom_L: that's a long axis :)
07:01 PM roycroft: the correct thing to do is design and build a proper extractin system, so that the chips/dust never get to the gantry bearings :)
07:01 PM Tom_L: but they will
07:03 PM roycroft: and that i'l have to figure out then whether it's good enough as is or whether i need to do something else
07:03 PM roycroft: and keep in mind that this is a router, not a mill, and the primary materials that are machined on it will be wood products, not metals
07:04 PM roycroft: the loads will be nowhere near what they are on a milling machine
07:04 PM roycroft: and the part tolerances nowhere near what they can be for metal parts
07:07 PM Tom_L: so where are you exactly on the design?
07:07 PM Tom_L: pics...
07:08 PM roycroft: roycroft.us/CNC-Router
07:08 PM roycroft: i'm working on the gantry sides right now
07:09 PM roycroft: so no pics of that yet
07:10 PM Tom_L: do those rails use T slot nuts on the 80 20?
07:11 PM roycroft: they use the 80/20 t slot nuts
07:11 PM Tom_L: i've never used the stuff personally
07:11 PM roycroft: it's expensive, but it will save a lot of time
07:12 PM Tom_L: a good method for mounting rails is to have one in a slot and the other one 'float'
07:12 PM roycroft: i'm not going to use it everywhere
07:13 PM Tom_L: your design has them both floating
07:13 PM Tom_L: not saying it's bad but the other will hold one true
07:14 PM roycroft: i've seen several videos where folks align one with the edge of the extrusion, and then align the other one to the first one, and they can dial it in to 0.001" or less
07:14 PM roycroft: using the 80/20 nuts
07:15 PM roycroft: the clone stuff uses the same hole sizing/spacing as the genuine hiwin products
07:16 PM roycroft: i figure if i start with the clone rails, if they are too sloppy or wear out too soon, i can replace them with hiwin down the road
07:21 PM XXCoder: id do deep maintance right away
07:21 PM XXCoder: besides that they should be pretty good.
07:21 PM roycroft: i absolutely shall do that, xxcoder
07:22 PM roycroft: my plan is to take them out of the box, gently push the bearings along the rail to see how bad they are
07:22 PM roycroft: then immediately disassemble the bearing blocks and clean everything, lubricate, and reassemble
07:23 PM Tom_L: i can't remember now but i think my trucks were not mounted to the rail during shipping
07:23 PM roycroft: if they're initially stiff that's fine
07:23 PM Tom_L: plastic retainers inside for the bearings
07:23 PM roycroft: if they initially wiggle on the rails then i'll need new bearings immediately
07:24 PM XXCoder: might need to clean up mold flash too
07:25 PM roycroft: yes
07:25 PM roycroft: i've seen some reports that mold flash can cause the retainer clips to bend and press against the bearings
07:27 PM XXCoder: yeah
07:28 PM Tom_L: sonic blast from the eruption heard 2500 miles away...
07:28 PM Tom_L: visible
07:29 PM roycroft: we still don't know what's going on in tonga
07:29 PM roycroft: almost all communication with the outside world has been cut off
07:34 PM Tom_L: yeah, my rails shipped with the trucks off http://tom-itx.no-ip.biz:81/~webpage/cnc/Rail_Goodies.jpg
07:34 PM roycroft: it makes sense that they would
07:34 PM roycroft: and when i said i'll slide the bearings along the rails to see how they do right away, i'll actually clean up the rails, and do some light honing if they seem to be a bit rough where the bearings run, before i install and test the bearings
10:31 PM Tom_itx is now known as Tom_L
10:51 PM skunkworks: pcw-home: stupid question - the transistor h-bridges that drive the coil have a diode between the top and bottom transistors. Is this just to just make it so there is no chance the both top and bottom tranistors are on at the same time. (the bottom transistor can only come on when the top transistor is off?
10:51 PM skunkworks: https://electronicsam.com/images/KandT/conversion/accu.pdf
11:38 PM CaptHindsight[m]: skunkworks: flyback diodes
11:38 PM * flyback bites CaptHindsight[m]
11:38 PM CaptHindsight[m]: https://www.build-electronic-circuits.com/h-bridge/
11:38 PM flyback: skunkworks, imagine putting a 1 ton safe on a very long pole
11:39 PM flyback: skunkworks, now imagine standing under it and kicking out the pole
11:39 PM flyback: that's what the diode is for
11:39 PM flyback: discharges the spike from the collapsing magnetic field every time you switch off
11:39 PM flyback: so it doesn't shoot up th etransistor's asshole
11:47 PM JoseIgnacioRome4: Is the asshole the collector or the emmiter?
11:47 PM flyback: that I dunno sorry
11:48 PM flyback: but it's a common mistake some new ee people make
11:48 PM flyback: and their chip or transistor stops working very shortly after they start using it
11:48 PM flyback: you need the flyback diode
11:49 PM flyback: cause the voltage will keep building up till it punches thru whatever was driving it
11:53 PM CaptHindsight[m]: https://www.robotroom.com/BipolarHBridge.html
11:54 PM CaptHindsight[m]: Jose Ignacio Romero: i thought it was the mosfets that were a-holes