#linuxcnc Logs

Jun 05 2021

#linuxcnc Calendar

12:17 AM veegee: Any recommendations for a surface grinder?
12:24 AM veegee: Brown and Sharpe #2 was what I was looking at but people warned me that it has plain bearings and other potential issues if it hasn't been taken care of properly
12:24 AM veegee: I'm in need for a surface grinder and a tool and cutter grinder
12:24 AM veegee: Cylindrical grinder would be nice but not necessary
12:24 AM veegee: "The machinability rating of AISI 12L14 carbon steel is 190. It can be machined by dispersing lead particles all over the steel." lol what?
12:24 AM veegee: Is it seriously telling me to sprinkle lead powder on my part?
02:02 AM Deejay: moin
04:32 AM Tom_L: veegee, https://blog.mchoneind.com/blog/carbon-steel-grades-chart
04:33 AM Tom_L: morning
04:35 AM Tom_L: veegee, A36 ... i hope not look at the applications
11:47 AM drdoc: veegee_: A36 is wonderful steel
11:49 AM drdoc: Half the world's infrastructure, or more, is made of A36
01:18 PM internut: I love that you can love a thing like A36
02:19 PM roycroft: half the world's infrastructure, or more, is crumbling
02:19 PM roycroft: but correlation is not causality, so that's irrelevant
02:28 PM * Vq has never heard of A36
02:41 PM Tom_L: structural steel
03:27 PM Vq: I'm guessing it's similar to/some kind of S355 steel.
04:28 PM veegee_: Vq 44W in Canada
04:28 PM veegee_: it's the go-to for structural steel
04:29 PM veegee_: I have no problem with it, I'm just wondering why it has such a low yield strength compared to pretty much anything else
04:29 PM Tom_L: cause it doesn't need one?
04:34 PM Vq: veegee_: I believe SS2172 is the swedish equivalent.
04:37 PM Vq: I just looked up the composition for A36 on Wikipedia, and if that article is correct then the carbon contents is outside of the allowed range for SS2172.
05:02 PM drdoc: veegee_: the trade for that yield strength is that you can do almost everything wrong and get away with it
05:04 PM drdoc: you can weld it under awful conditions (and with terrible technique, for that matter), easily correct warpage,
05:05 PM drdoc: it flame-cuts beautifully, is easily ground, and takes a fair finish
05:09 PM veegee_: drdoc the finish on mild steels is the worst of any metal I've ever machined
05:09 PM veegee_: I had to make a "vertical shear tool" for the lathe to get something decent
05:09 PM drdoc: it's not meant to be machined
05:09 PM veegee_: But can you explain "easily correct warpage"?
05:10 PM drdoc: mild steel responds to spot heating/quenching
05:10 PM veegee_: ah ok
05:11 PM veegee_: drdoc what are some of your techniques for welding a box with minimal warping?
05:11 PM veegee_: Let's say I had 1/4" steel plate and had to make a small box
05:11 PM veegee_: keeping it as simple as you can get
05:11 PM drdoc: not welding it, if you want to know the truth
05:11 PM drdoc: TIG gives you the least warpage
05:11 PM veegee_: assume welding is required
05:11 PM drdoc: but you'll get some
05:12 PM veegee_: yeah that's fine, I Just want to know techniques to minimize warping
05:12 PM veegee_: I know you'll get some no matter what, and that's fine
05:12 PM drdoc: when I was building seed chutes, we press-broke parts in an X
05:12 PM veegee_ is now known as veegee
05:13 PM drdoc: if that's available, it stiffens the sheet a lot, and localizes the warpage
05:14 PM drdoc: but a lot of tacks, good design, and preheating all help
05:14 PM veegee: Yeah I have a huge ass press brake that weighs over 6,000kg
05:14 PM veegee: But I still like welding
05:14 PM drdoc: and skip welding, as tedious as it is, helps quite a bit
05:15 PM drdoc: no, I mean you brake a very shallow crease across the sheet
05:15 PM drdoc: you've seen that in ductwork, if you think about it
05:15 PM veegee: Yeah
05:16 PM veegee: Preheating amazes me
05:16 PM drdoc: preheating is pure magic
05:16 PM veegee: It's amazing because it has a make or break difference but you only need to heat to like 300º
05:16 PM drdoc: yup
05:16 PM veegee: that's nowhere near any critical temperature
05:16 PM veegee: so what exactly is going on?
05:17 PM drdoc: you know the temperature for the final heat treat on a knife blade?
05:17 PM veegee: I know you can heat even higher on something like A36 for fun just to reduce warping
05:17 PM drdoc: for carbon steel
05:17 PM veegee: drdoc off the top of my head, something like 500ºC?
05:17 PM drdoc: 432F
05:17 PM veegee: well entirely depending on the hardness you're targeting
05:18 PM drdoc: 60 Rockwell
05:18 PM drdoc: well, 57-60
05:18 PM veegee: Didn't know that
05:18 PM veegee: So you can heat treat in your oven?
05:18 PM drdoc: and that depends some on the alloy
05:18 PM drdoc: yup
05:18 PM drdoc: well, no
05:18 PM veegee: I'm building a custom one because I've been seeing higher temperatures
05:18 PM drdoc: that's the final temper
05:19 PM veegee: Well you do the initial quench
05:19 PM veegee: Then temper in your oven apparently?
05:19 PM veegee: assuming a good temperature controller
05:19 PM drdoc: for 1084 eutectic, for example, the hardening cycle is I think 1700F-ish
05:19 PM drdoc: it's been a few years
05:20 PM drdoc: yeah, I built an oven with a ramping PID
05:20 PM veegee: I bought an oven with a "self cleaning" mode so I know it's built to endure high temperatures for hours and has better insulation
05:21 PM drdoc: anyway, I assume you meant 300C, not 300F, for stress relieving A36?
05:21 PM veegee: yes
05:21 PM veegee: Well not stress relief
05:21 PM veegee: But the higher the temperature, the lower the warping
05:21 PM drdoc: it will, though, if you maintain that temp for awhile
05:22 PM veegee: yeah, that's how I annealed my old brake rotors which were hardened from use
05:22 PM veegee: went from eating my carbide bits to being machined nicely with HSS
05:24 PM drdoc: the short version is that the changes in ferrous alloys from about 350C up to around 800 are much more gradual than the changes from about 150-350C
05:24 PM drdoc: ehh, maybe 250-350
05:24 PM veegee: oh wow didn't know that, I thought it was the other way around
05:24 PM veegee: 250ºC seems pretty low
05:25 PM veegee: and tool steels can endure those temperatures all day
05:25 PM veegee: like M35 and M42 can cut at 250ºC no problem
05:25 PM drdoc: those alloys are designed specifically for high heat
05:28 PM drdoc: here's an example:
05:28 PM drdoc: http://www.cashenblades.com/steel/1095.html
05:29 PM veegee: Medium and high carbon steels are giving me mirror like surface finish on the lathe without even trying
05:29 PM drdoc: yup
05:30 PM drdoc: look at the tempering table at the bottom there
05:30 PM veegee: Ah yeah
05:30 PM drdoc: as far as finish goes, I was referring more to painting/powdercoating
05:31 PM veegee: my bad, I had that chart reversed in my head
05:32 PM veegee: Yeah A36 takes to paint and powder easily after machining I'm guessing especially due to the poor surface finish
05:33 PM veegee: So much pitting and grooving that there's a huge surface area for the powder to cling to
05:33 PM drdoc: there's more to it than that
05:33 PM veegee: But I do like that it's by far the cheapest
05:33 PM drdoc: well, yeah
05:34 PM veegee: I'm going to experiment with 11xx and 12xx series. Need to figure out the difference between resulfurized and resulfurized + rephosphorized
05:34 PM drdoc: and for a lot of applications mass makes up for yield strength
05:34 PM drdoc: what's your application?
05:35 PM veegee: My entire life has no application
05:35 PM drdoc: lol
05:35 PM veegee: entirely learning and experimentation
05:35 PM drdoc: get some grade 90 rebar
05:35 PM veegee: I'm also about to place an order for some steel, just general purpose stock so I'm wondering if it's worth getting 11xx or 12xx or 12L14
05:36 PM veegee: Yeah I was considering the rebar
05:36 PM veegee: strong and cheap
05:36 PM drdoc: In the US the grading requirements are pretty stringent, and enforced
05:37 PM veegee: Same in Canada
05:37 PM drdoc: I expect it's the same there
05:37 PM drdoc: grades 70-90 are effectively 4140
05:37 PM veegee: yeah 4140 machines beautifully
05:37 PM veegee: and it's really strong in the annealed state
05:38 PM veegee: I never tried welding it though
05:38 PM drdoc: also hardens pretty nicely
05:38 PM drdoc: it's weldable, but you *really* need to preheat
05:38 PM drdoc: it's subject to stress voids & cracks
05:39 PM veegee: yeah not a problem for me. I have propane burners of all sizes and oxy acetylene torches
05:39 PM veegee: propane burner should be more than enough
05:39 PM drdoc: and there's a fairly limited range of rods & wire
05:39 PM drdoc: yeah
05:39 PM drdoc: I use grade 90 for punches & drifts
05:40 PM veegee: what's the cost of grade 90 rebar over there?
05:40 PM drdoc: $0/ft
05:41 PM drdoc: I'm nice to a couple of form crews
05:41 PM veegee: I don't know any construction companies or anyone in the concrete pouring business
05:41 PM veegee: so I have to buy it from someone
05:41 PM drdoc: heh
05:41 PM drdoc: I really have no idea
05:42 PM drdoc: last time I needed something bigger than 1/2" was years ago
05:43 PM veegee: I'm placing an order for stock including square bar at least 2.5"
05:43 PM drdoc: that's gonna hurt
05:43 PM veegee: I'm getting good quotes for C1018
05:44 PM veegee: A36 significantly cheaper but for solid bars like this where strength matters a little, I'd rather go for 1018 at least
05:44 PM veegee: Or 12L14/11xx/12xx which I'm researching now
05:45 PM drdoc: I gotta find a good 3" 3-jaw chuck
05:45 PM veegee: surface finish matters a lot more to me than "machinability" in the sense of productivity
05:45 PM veegee: I don't care if it takes a while to cut as long as the surface finish is good
05:45 PM drdoc: there's made in India, then junk, then nosebleed expensive
05:45 PM veegee: what's the size of your lathe?
05:45 PM roycroft: india is the new china, as china was the new taiwan, as taiwan was the new japan
05:46 PM drdoc: maybe Shars has one
05:46 PM roycroft: vietnam is becoming the new india
05:46 PM drdoc: yup
05:46 PM drdoc: but why would you make a chuck out of *zinc*
05:46 PM drdoc: ????
05:46 PM roycroft: and i should imagine that when most of the asians countries start making quality goods, africa will become the new asia
05:46 PM veegee: lol what that's a thing?
05:47 PM roycroft: probably sub-saharan africa
05:47 PM veegee: I'm strongly looking into the bison 3 jaw scroll chucks with the adjustability feature
05:47 PM drdoc: https://www.ebay.com/itm/124502019606
05:47 PM drdoc: veegee: this is for a little Sherline indexing fixture
05:47 PM veegee: Contemplating whether or not that adjustability will compensate for wear over time or if I shouldn't bother and just get 3 jaw chucks and throw them out when they're out of spec
05:48 PM veegee: drdoc oh then anything will work
05:48 PM drdoc: part of a 120lb auction lot
05:48 PM roycroft: i haven't used those adjustable chucks, veegee, but if you're looking at that as a means of being more concentric without having to dial in the jaws every time like a 4 jaw, i think you'll be disappointed
05:48 PM roycroft: unless you use the exact same size parts every time
05:48 PM veegee: roycroft yeah I want to avoid dialing it in every time
05:48 PM veegee: I think you're right
05:48 PM veegee: the scroll wear at the specific location contributes the most to the error
05:48 PM roycroft: the scroll is not going to be precise enough
05:49 PM roycroft: not just wear
05:49 PM roycroft: it's not made precisely enough to begin with
05:49 PM roycroft: but if you dial it in for 12mm rod, and you always use 12mm rod, you'll be fine
05:49 PM veegee: Yeah I hear ya
05:49 PM roycroft: when you stick some 19mm rod in it you might not be
05:50 PM roycroft: consider a collet chuck instead
05:50 PM drdoc: veegee: I maintain that that $19 chuck will NOT work
05:50 PM drdoc: even for an index head
05:50 PM veegee: I didn't know you could get anything for $19
05:50 PM drdoc: I don't think we've proved that you can
05:50 PM veegee: I just got a burrito for dinner and that came to like $19 for a combo
05:51 PM roycroft: you can get a starbucks no fat pumpkin vanilla venti latte for $19
05:51 PM drdoc: the very thought of a canadian burrito makes me shudder
05:51 PM drdoc: :-p
05:51 PM veegee: We have real Mexicans here too
05:51 PM veegee: and they're good
05:51 PM veegee: The burritos I mean
05:51 PM veegee: The Mexicans too, but I wasn't commenting on them
05:51 PM drdoc: right
05:51 PM roycroft: there's a really good oaxacan taco stand in eugene that's great
05:52 PM roycroft: just about everywhere else is tex-mex crap
05:52 PM drdoc: that's just crazy
05:52 PM roycroft: which is what people in the us think is mexican food
05:52 PM drdoc: I lived in Seattle in '78 and there was one place in the county that served real mexican
05:53 PM drdoc: and then there was Taco time
05:53 PM roycroft: there are like 187 regional cuisines in mexico
05:53 PM drdoc: yessir
05:53 PM roycroft: it's hard to say "real mexican"
05:53 PM drdoc: OK
05:53 PM drdoc: "not Taco Time"
05:53 PM roycroft: which is why i mentioned that the good taco stand in eugene serves oaxacan food
05:54 PM roycroft: i didn't say "real mexican" intentionally
05:55 PM roycroft: they make their own tortillas, of course, because the ones from the stores are tex-mex tortillas
05:55 PM roycroft: or should i just say poser-mex?
05:55 PM drdoc: isn't Oaxaca way in the south?
05:55 PM roycroft: it is
05:55 PM drdoc: I grew up with mostly Chihuahuan cooking
05:56 PM drdoc: the Mixican in Austin is mostly ...
05:56 PM drdoc: Coahuilan
05:56 PM drdoc: had to look at a map
05:56 PM drdoc: I no like
05:57 PM roycroft: i just finished boring 16 3-1/8" diameter holes, 6-1/2" deep, in some maple
05:57 PM roycroft: it took me almost four hours
05:57 PM roycroft: time for a break :)
05:57 PM drdoc: that's a lotta sawdust
05:57 PM roycroft: a lot of chips
05:57 PM drdoc: I know
05:57 PM Tom_L: that's what cnc's are for
05:58 PM roycroft: and the drill press has 4" of quill travel
05:58 PM drdoc: ugh
05:58 PM roycroft: so i was able to do the first 4" in a single setup
05:58 PM roycroft: after that i had to lower the table, line up the drill in the hole, raise the table, finish the bore, and repeat 15 times
05:59 PM drdoc: that zinc chuck is just terrifying
06:00 PM drdoc: sorry, I got stuck there
06:01 PM roycroft: a zinc chuck is fine if you're going to drill holes in jello with straws
06:01 PM drdoc: no, it's not
06:01 PM drdoc: my grandkid might find it and try to mount it in a real machine
06:02 PM roycroft: but it would crumble in the process of being mounted
06:02 PM drdoc: one can only hope
06:04 PM drdoc: I need to go try to finish wiring this damn router
06:05 PM drdoc: I've been stuck on the wiring harness for 2 weeks because I keep going in there, looking at it, and coming up with something else to do
06:07 PM roycroft: that's one of my favorite parts of a project
06:07 PM roycroft: making the wiring harnass
06:07 PM drdoc: usually it's no big deal
06:08 PM drdoc: this time I just can't get with the program
06:16 PM veegee: Oh wow that explains why the hydraulic fittings I was turning machined so easily and formed nice chips - I think they were all 12L14
06:17 PM veegee: I was converting some JIC female fittings with 1/4" MNPT ends into hose barbs so they fit directly into 3/8" air hose. Made a custom HSS tool to machine the barbs
06:17 PM veegee: I was expecting it to be a difficult cut but it was so easy compared to the A36
10:04 PM veegee: pcw_home http://www.mesanet.com/software/parallel/6i24.zip returns a 404 error
10:07 PM Tom_L: grab the 5i25
10:07 PM Tom_L: iirc
10:07 PM Tom_L: it's the same
10:08 PM Tom_L: err 5i24
10:09 PM Tom_L: http://store.mesanet.com/index.php?route=product/product&product_id=297&search=5i24
10:21 PM veegee: Tom_L according to the manual, need 6i24-specific stuff to run as native 6i24 mode
10:24 PM Tom_L: guess you'll have to wait for the guru then
10:24 PM Tom_L: i always thought the software was the same
10:26 PM veegee: Doesn't matter anyway, fedex lost my shipment lol
10:26 PM Tom_L: great
10:26 PM veegee: But I just wanted to take a look while I place another order
10:28 PM Tom_L: it should be similar enough