Laser cutter, Take 3:


(Ryan Mitchell) #21

I’m looking up airkits now, it’d be temping to hook the thing up to our compressor, on one hand you gotta worry about moisture, on the other, for a cutter this cheap, would the moisture really be that much of an issue?
That said, you’d also have to spin up the air compressor for every cutting session, perhaps not something people would want to do due to the maintenance.

…Just my luck, turns out something that I hoped would exist, does.

Perhaps pic related would be the best option?
Hook it right up to the cutters main power switch.

I’m curious what everyone uses for their (hobbyist) systems.
I mean, sure, the big commercial systems where you can just break out the facilities compressed air, run it through thousands of dollars of moisture traps, then into the cutter are COOL and all, but I’m looking for solutions that won’t cost us the earth and back (Preferably with whatever’s left from $700 minus the new K40 minus a new lid for the old one, if there is anything left after that).

$55 USD for a dedicated compressor plus a $8 lens assembly sounds pretty good to me.


(Max Bainrot) #22

What’s cool with the brewery/aquarium hobbies, is they’ve already done this stuff for us :slight_smile:

https://www.keg-king.com.au/aquarium-regulator-co2-with-magnetic-solenoid-valve.html

Only issue with continous discharging of CO2 is it building up in the room the laser is at (I am assuming it’ll be in with the 3D printers to keep the dust bunnies at bay?


(Max Bainrot) #23

Dedicated air pump like that would be perfect, I haven’t gotten around to replacing this with one of those yet, my hearing probably wants me to do so soon (it’s very loud)

Pros of this

  • Cheap

Cons

  • Very very very noisy

  • Limited cycle time of about 12 minutes

My exhaust system (needs 12v psu) Tis is a 3 inch bilge blower fan, cork sheet to dull out the noise it makes from transferring into the desk

And my air assist system


(Ryan Mitchell) #24

Looks perfect.
I take it the time limit is from the pump heating up too much from the load?
Anyway, that should make everything nice and cheap, should be sufficient.


(Max Bainrot) #25

Thanks :slightly_smiling_face:

Yup motor gets really hot, I had a long list of improvements to make the laser cutter more maker space friendly/resilient floating around somewhere on iCloud, some are overkill, some are probably only needed if there are issues and some are important (interlocks for doors, big ass e-stop button)

One thing I want to try is cutting under gas, like nitrogen or co2 to see if we can make the burny stuff not burn so well.

Apparently the tubes have to be kept cool, sub 20*C for optimal life apparently. They also apparently degrade overtime with or without use as apparently oxygen migrates through the seals and messes up the gas mix or something.


(Ryan Mitchell) #26

Laser’s arrived, installed, and tested, and does exactly what you’d expect from a laser that arrived with its tube full of water.
Still trying to work out some good configs, the 3D printer’s roaring away with interlocks, air assists and drag chains, to be installed tomorrow.
Rather than say it’s not perfect, let’s say it’s “nuanced”, that said, half of the time I sped working on laser cutters a few jobs back was just cutting material samples over and over to come up with the perfect presets.
3mm acrylic and 1.5-3mm laser ply really shouldn’t be that much of a tough nut to crack.


(Max Bainrot) #27

Hah my tube was full of water too :grin:

I have some spare 3mm acrylic if you’d like

Keep an eye on power output, over time on long jobs you will find that the power level will drop off

Great work on the interlocks and chains, holler if you need help, my 3D printer is hungry for work

What do we want to do in terms of swatches? From talking to the guys at plastic creations in Fyshwick, they said it’s nearly impossible to get swatches so I might be able to provide a few swatches from my offcuts I have.


(Steve Kennedy) #28

Hey Ryan i will be bringing that 120mm fan to 4" exhaust tube adapter saturday


(Max Bainrot) #29

https://hackaday.com/2019/01/31/k40-gets-a-leg-up-with-open-source-z-table/

Idea for the future?


(Stephen Davies) #30

Nice one Max.

This video falls into the “must watch” category https://www.youtube.com/watch?v=zF9nQHlvGkc


(Max Bainrot) #31

Thanks :slight_smile:

So for mine I have a problem, at the moment I cool it with ice bricks, which drastically limits my cutting times, and isn’t terribly effecient/effective as once the bricks melt a bit they airgap and become less effective.

I have a g1/4 water cooling block pair with a peltier jammed inbetween them and it works great, question is, how best do I incorporate it into my cooling system?

I ordered a g1/4 to 6mm barb but it never arrived as my original plan was to just plug it inline with the tube’s waste water and be done with it.

My options I can think of are

  1. Build a lid for my esky that is my resevior and have two pumps, one is for the laser and the other is the peltier loop

  2. obtain somehow a g1/4 to 6mm barb and carry on as planned

  3. do something completely different

What are peoples thoughts?


(Ryan Mitchell) #32

I’ve had to cool liquids like this in the past, for various non-laser related projects, using either an aircooled radiator or a peltier for cooling, and my usual approach is to make a closed loop full of my coolant of choice, usually pure isopropyl alcohol (if you wanna get REAL cold, and if algae wants to try living in that, well, good luck to it), run it to the cooling mechanism of choice, then attach a spool of copper wire acting as a heat exchange, to be submerged in the bucket of whatever it is you wanna cool.

I usually do this because whatever’s being cooled isn’t bio-critical, and it doesn’t matter if anything builds up in it.
In this case, because you don’t want algae going through your tube, it doesn’t make much of a difference, but if you do wanna hit those cryonic temperatures, two loops is the way to go.
(I’m not sure about the minimum operating temp of the tubes, but this is Australia, on a 40ºc day you probably want as cool as you can get. I doubt you’ll be freezing your 10l of water, even if you used a cryocooler)

I’m curious about what times you are getting so far, from reading online people tend to be giving wildly different statements about how long they can cut/engrave for before things start giving out.
Right now I’ve just got a temp probe in the cutter at the space, to monitor how much everything goes up by on each cut, how do you handle things?
(Sorry for not replying for so long, for some reason your post slipped past me)


(Max Bainrot) #33

So a bit after writing the email I had a brainwave and went to officeworks :stuck_out_tongue: I bought a compressor based water cooler :'D, About $160 for a 88 watt compressor (actual is not known and haven’t benchmarked it’s cooling ability but looks promising), takes about 15-20ish minutes to cool 1L of water from 23.8C to 6C. More testing is needed once I’ve gotten through my rental inspection this week. 1L mark is the point at which the water is above the evaporator coil, you can put more in but need to have a circulation pump to keep it consistent. Needs an external thermostat so I can run it 15-19C as opposed to it’s normal cycle of about 6C to 9C which is too cold (below dew point, therefor is risking condensation)

Seems to run way better with a fan blowing on the condensor ““coil””, atleast the coil isn’t getting stupid hot (> 60C)

Mmmm interesting, didn’t think of IPA, I’ve heard of acetone (applied science on youtube uses it iirc), both would be cyrogenic napalm if you got them cold enough lol. I am probably going to run vegetable glycerine in my loop, about 40% (good to -30C iirc), apparently concentrations > 30% is biocidal and overal isn’t terribly toxic (compared to proplyene glycol and ethelene glycol). Only caveat with IPA is that if the loop gets too hot you start getting vapours which could ignite from the piece being cut flashing over momenterially.

So it’s about 15-30 minutes of continuous use before the power starts to drop off appreciably, doesn’t take much to get to the point where it causes thin whispy pieces in acrylic that like to catch fire on the second pass :open_mouth:

I do the same, I have a random sealed thermistor thermonitor in the reserviour and try to keep it < 20C because I’ve read somewhere that’s what keeps the tube happy for longer thus putting off the fun order of ordering a tube from China via aliexpress.

Hopefully this weekend I’ll fire up the laser so I can 'ava go at cutting various hobby materials such as balsa and balsa ply and also see whether the water cooler ““cuts”” it hehehe #dadjokeoftheday


(Ryan Mitchell) #34

I hadn’t considered a good old compressor, most of the water coolers I’ve seen just have an internal cold block that water runs through before being dispensed, rather than cooling an entire reservoir, I guess you could just use it as a heat exchange in that case; anyway I’d like to see some pics of your system just to see how you’ve set things up/am curious how it’s built.

As per dew point/isopropyl flash vaporising: as I’d be using two loops, you wouldn’t get the Iso in the tube itself, it’d just be cooling the reservoir.
I say “Cooling”, I’m more thinking of it as trying to bring something over ambient back down to ambient, rather than pre-cooling in advance, to me getting a system that could actually get the reservoir below dew point is such a far-off idea I hardly even considered it.

I just use IPA as an all purpose “Not water”, I doubt, say, a litre of it in a cooling loop, to cool down 10l of water, would get cold enough for it to start getting “Sticky”, it all depends on how fast you’re circulating it through your cooling system, but unless you’re trying to, say, flash-chill cans of soft drink, it’s not really necessary to get them that cold, so long as you’re displacing as much heat as possible.

Anyway, I’d love to see some pics of your water cooler once you’re happy with it, it’s such a good idea I’m almost tempted to try it at the space.


(Ben Paton) #35

I am just sticking the link to this controller here, not so much to say we should buy one (though it may be food for thought) but more so I can come back and find it later on. Plus I thought it was worth sharing


(Max Bainrot) #36

I haven’t gotten around to replacing the controller in mine, would be nice because I can then use laserweb to prepare the cuts to avoid the shenanigans i’ve been experiencing with dodgy dxf files and k40 whisperer

Also something I noticed, if you are having dxf files that cut the outside edge instead of the inside edge inspite of you selecting that option in k40 whisperer, check that the drawing isn’t doubled up, I’ve noticed some files exported from Fusion 360 tend to be doubled up. This is easily fixed by opening the file in say librecad and then deleting the drawing until it actually deletes :slight_smile: then ctrl + z and #profile :stuck_out_tongue: then performs properly :slight_smile: