#linuxcnc Logs

Oct 08 2021

#linuxcnc Calendar

12:20 AM miss0r: morning
12:28 AM XXCoder: o/
03:14 AM solarwind: Does an oxy acetylene flame emit any UV radiation?
03:14 AM solarwind: I'm wondering if I can get away with sunglasses
03:14 AM solarwind: At least for brazing with a reducing flame
03:17 AM solarwind: All the oxy acetylene goggles I have are fully sealed around the eyes and just get foggy and sweaty
03:20 AM solarwind: I was also contemplating switching to oxy-propane. The only problem is propane uses a lot more oxygen than acetylene
03:20 AM solarwind: So then I was thinking I could buy an oxygen compressor
03:22 AM solarwind: Apparently there are those medical oxygen concentrator devices
03:23 AM solarwind: 90% oxygen is still pretty damn good for making a very hot flame with propane
05:00 AM JT-Cave: morning
06:23 AM Loetmichel_ is now known as Loetmichel
06:38 AM -!- #linuxcnc mode set to +v by ChanServ
06:47 AM CloudEvil: solarwind: the human thermal output those are designed for is about 100W, they have a surplus, often, and can do around 200W IIRC.
06:48 AM CloudEvil: So you need to add a buffer for other than very small flames.
06:49 AM Loetmichel: CloudEvil: 100W is human rest output. Working out can be in excess of 1kW of heat
06:50 AM CloudEvil: yes.
06:50 AM CloudEvil: Oxygen generators used in healthcare settings are not designed to support heavy workouts.
06:50 AM Loetmichel: IIRC you'll have to have a/c in the winter if you design a tent for 1000 ppl dancing.
06:51 AM Loetmichel: i think thouse generators are designed to take the bad efficiency of the human hungs into account though
06:51 AM Loetmichel: lungs
06:52 AM Loetmichel: but if you want a hot flame its easier to make an HHO generator
06:52 AM CloudEvil: Well.
06:52 AM CloudEvil: One of the above generators, and several trashbags as buffer storage works just fine.
06:53 AM Loetmichel: I dont know if trashbags filled with pure oxygen is a good idea ;)
06:53 AM CloudEvil: (being aware that if there is any significant static, the trashbags may completely combust)
06:53 AM Loetmichel: but what i meant is that a hydrogen/oxy flame is MUCH hotter than propane and oxy
06:54 AM CloudEvil: yeah
06:54 AM CloudEvil: Though you don't care probably for brazing
06:55 AM Loetmichel: not for brazing, no. But for welding you do.
06:57 AM CloudEvil: I have idly wondered about electrically boosting.
06:57 AM CloudEvil: Preheat gas/air to 500C with 3kW of heat, and you can do a 12kW or so burner that is 500C hotter.
06:58 AM CloudEvil: just doing air with a hot-air gun is probably easiest
06:59 AM Loetmichel: IIRC thats not how it works
07:00 AM CloudEvil: You could not quite get 500C, it's going to be close to that.
07:00 AM Loetmichel: the temperature in a flame is a constant with fuel and oxygen concentration defining the amount of energy per volume
07:01 AM Loetmichel: and heating up one of the components will do not that much
07:01 AM Loetmichel: but i may be wrong
07:01 AM CloudEvil: Right, now what happens if you put the fuel and oxygen together at the nominal flame temp?
07:01 AM CloudEvil: Do they not react?
07:02 AM Loetmichel: i think they do, but less violent because at that temp the gasses are much thinner
07:02 AM Loetmichel: IIRC it counteracts the added heat nearly completely
07:03 AM enleth: CloudEvil: some jet engines do preheat input air using waste exhaust heat, it increases efficiency but doesn't do much for performance
07:03 AM Loetmichel: its the reason why turbochargers need intercoolers so you get actually more oxygen into the cylinder instead of the same amount at molecules just at a higher pressure
07:04 AM enleth: might actually hurt performance?
07:04 AM CloudEvil: Air propne temp is 1900C peak.
07:04 AM enleth: but they're all about efficiency anyway
07:04 AM CloudEvil: Incresing that to 2400 will only increase volume by a quarter
07:07 AM Loetmichel: as i said: IIRC. but i have a dim recollection that it dosent work well to preheat the reaction air.
07:07 AM CloudEvil: Fair enough.
08:53 AM Tom_L: partly cloudy 89F today
09:24 AM Vq: Fog and 11C here
11:27 AM roycroft: it's friday here
11:27 AM roycroft: that's all that matters :)
12:06 PM Tom_L: 42" water main break. no water to be had in the store
12:09 PM * roycroft finds it irritating when vendors list circuit breakers for sale and do not include the trip curve in the specifications
02:47 PM unterhaus: I suppose telling someone they need a differential encoder probably wouldn't be too helpful
02:50 PM unterhaus: PPMC doesn't take differential signals, that's not great
02:58 PM roycroft: i just got a quote for modifying that timing gear - they want a minimum of 2 hours @$45/hour, plus the cost of the gear
02:58 PM roycroft: that seems rather excessive
02:58 PM roycroft: but i also just found the 1" boring bar that i knew i bought years ago but could not locate
02:59 PM roycroft: so i'll be doing the work myself, it appears
03:44 PM Tom_L: roycroft, how much would you do it for?
03:45 PM Tom_L: it seems like alot for the gear but machine time isn't cheap
03:59 PM satiowadahc[m]: Life of a trucker... you better "grind them gears!"
04:00 PM roycroft: it's for my own shop, so the cost of the time is not of paramount importance
04:01 PM roycroft: it does not seem like a 2 hour job to me, though, if one has the proper equipment and skills
04:01 PM roycroft: it's more like a 1 hour job
04:01 PM Tom_L: maybe
04:01 PM roycroft: make a hole bigger and machine a keyway
04:01 PM roycroft: that's all there is to it
04:02 PM Tom_L: yeah
04:02 PM roycroft: it might take me 4 hours
04:02 PM Tom_L: 2 setups and 10 min per op
04:02 PM Tom_L: and having the broach
04:02 PM roycroft: the real factor in this equation is their 6-10 week lead time
04:03 PM roycroft: that means 6-10 weeks without my mill
04:03 PM Tom_L: how long have you waited so far?
04:03 PM roycroft: i don't have a broach, and won't have one for this
04:03 PM roycroft: the machine died over the weekend, so less than a week
04:03 PM roycroft: actually, i think it was monday when it died
04:04 PM Tom_L: i got one because i don't have the right equipment to do it another way
04:04 PM roycroft: anyway, it's just been a few days
04:04 PM roycroft: that's why i found the boring bar
04:04 PM Tom_L: you already have a vfd for the new motor right?
04:04 PM roycroft: not dedicated for it
04:04 PM roycroft: but i can get one quickly
04:04 PM roycroft: and have one i can use initially
04:05 PM roycroft: anyway, with the boring bar i can make a broach and use my lathe like a shaper
04:05 PM roycroft: that will take a while, but it should work
04:05 PM roycroft: and since the gear is ductile iron, it should cut like butter
04:07 PM Tom_L: it should work
04:08 PM Tom_L: my cutter wasn't ideal so the results were less than stellar
04:08 PM roycroft: i'm hoping to get the lathe and mill moved this weekend, after which i need to measure and make a drawing for the new motor mount, and then i can calculate the length of the belt i need and order the belt and the gears
04:09 PM roycroft: so hopefully monday or tuesday i'll be able to place the order
04:12 PM Tom_L: sdp-si has a nice center distance calculator
04:12 PM roycroft: the place where i'm ordering the gears do too
04:12 PM Tom_L: you enter the type of belt (if they stock that series) and the center distance
04:12 PM roycroft: it's not a difficult calculation, but online plugin configurators are easier
04:12 PM Tom_L: ok
04:13 PM roycroft: https://www.bbman.com/belt-length-calculator/
04:13 PM roycroft: pretty much the same thing
04:14 PM roycroft: i just need to determine the center distance, and i won't be able to do that until i design the motor mount
04:14 PM Tom_L: yeah i had to wait on mine too
04:14 PM roycroft: sadly, i have to use a 1/2"belt
04:14 PM roycroft: i'd like to use a wider one, but a 3/4" won't fit
04:14 PM roycroft: the current belt is 14mm
04:14 PM Tom_L: mine was a tight fit but it did work
04:14 PM Tom_L: 15mm
04:15 PM Tom_L: mine was 9mm
04:15 PM Tom_L: 14 should be ok
04:15 PM roycroft: yeah, but i'll be getting a 12.7mm belt
04:16 PM roycroft: and i'm increasing the horsepower of the motor by a factor of 2.6
04:16 PM roycroft: i hope the belt holds up
04:16 PM roycroft: otherwise i have a much bigger project
04:16 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/Mill_Steel/Spindle/Pulley2.jpg
04:17 PM Tom_L: takes the whole spindle shaft
04:17 PM Tom_L: and that's after i pocketed the bottom: http://tom-itx.no-ip.biz:81/~webpage/cnc/Mill_Steel/Spindle/Pulley1.jpg
04:20 PM roycroft: i'd really rather use a wider belt, but offhand i can't see how it would work
04:21 PM roycroft: when i get the mill moved and can access it from all sides easily i'll spend some more time trying to get that sorted
04:21 PM Tom_L: my previous belt was 2mm? pitch too
04:21 PM Tom_L: 2 or 3
04:23 PM roycroft: i'll be getting a type l belt, which is 3/8" pitch
04:23 PM -!- #linuxcnc mode set to +v by ChanServ
04:24 PM Tom_L: that's pretty coarse
04:26 PM roycroft: yes, but it's not for positioning, just power transfer
04:27 PM Tom_L: yeah
04:27 PM roycroft: i wanted something with a smaller pitch, but finding anything that can work on my mill has proven difficult
04:28 PM roycroft: ideally i'd make my own timing pulleys, but i don't have the equipment to do that
04:56 PM CaptHindsight[m]: solarwind: science says https://rkdmb.home.xs4all.nl/rkd/flame/spectrum.html
04:58 PM CaptHindsight[m]: CaptHindsight: The most important radiating molecule in the outer flame is OH. Its emission lies between 260 and 350 nm and is so strong it causes actinic conjunctivitis ("welding blindness") if the human eye is not protected.
04:59 PM XXCoder: I just follow this simple rule
04:59 PM XXCoder: all equipment, all time
04:59 PM XXCoder: never skimp or skip safety stuff like goggles etc
05:00 PM CaptHindsight[m]: solarwind: science says https://rkdmb.home.xs4all.nl/rkd/flame/spectrum.html
05:00 PM JT-Shop: we just got back from Kentucky for lunch
05:00 PM CaptHindsight[m]: and also "The most important radiating molecule in the outer flame is OH. Its emission lies between 260 and 350 nm and is so strong it causes actinic conjunctivitis ("welding blindness") if the human eye is not protected."
05:01 PM CaptHindsight[m]: XXCoder: beware of beer goggles
05:01 PM XXCoder: yup, never wear that