Laser in the house...

... on the floor. Haven't figured out where to put it yet. It's one of the cheapest cheezy chinese (C3?) laser cutters - 3020 style; 8"x12" cutting area. Bigger cabinet than I thought it would be. I expect it to be the starting point for a lot of modifications and eventual morfitication into a larger, more capable cutter. I suppose it must go in the garage, but I wasn't thinking about the cold - can't freeze the water cooling. Must investigate use of anti-freeze. Sub-problem is that there are no windows in the garage - might have to cut a vent hole in the side door. Got it off ebay and they shipped fast - ordered Friday, arrived Tuesday. No apparent damage but we'll see at first light.

Unless the coolant is being exposed/ sprayed you might be able to replace the water with a RV antifreeze for potable water systems.

rharshberger said:

Unless the coolant is being exposed/ sprayed you might be able to replace the water with a RV antifreeze for potable water systems.

Click to expand...

Yep, got it figured, I think. Propylene Glycol for the antifreeze, and for the suspenders, heat tape around the cooling bucket with the tape and pump on a thermostat. Going to the store Saturday to get a couple of recycled doors, one to replace the (nice) side door so I can poke a vent hole in it, and one to build a bench for the setup.

vcp said:

... on the floor. Haven't figured out where to put it yet. It's one of the cheapest cheezy chinese (C3?) laser cutters - 3020 style; 8"x12" cutting area. Bigger cabinet than I thought it would be. I expect it to be the starting point for a lot of modifications and eventual morfitication into a larger, more capable cutter. I suppose it must go in the garage, but I wasn't thinking about the cold - can't freeze the water cooling. Must investigate use of anti-freeze. Sub-problem is that there are no windows in the garage - might have to cut a vent hole in the side door. Got it off ebay and they shipped fast - ordered Friday, arrived Tuesday. No apparent damage but we'll see at first light.

Click to expand...

On that very topic:

Cooling laser tube with antifreeze

https://www.cnczone.com/forums/gene...sion/50904-cooling-laser-tube-antifreeze.html

Optimal CO2 laser temperature?

https://www.photonlexicon.com/forums/showthread.php/18320-Optimal-CO2-laser-temperature

Note that lower laser tube operating temps usually equal more laser output power for these Chinese tubes, at least when using chilled distilled water. I don't own one myself, but I was reading a great deal about them when I was considering buying a cheap Chinese model until the local library system opened up two free-use maker spaces with $5K (and larger) commercial laser cutters.

Gas discharge CO2 lasers require cooling water to carry away the excess heat produced by the current in the gas discharge. For example if the laser has a 40 watt output and is 20% efficient, it is consuming 200 watts and you have to remove 160 watts of waste heat. If the efficiency is 10% then it is consuming 400 Watts so you have to remove 360 watts of waste heat. If you don't remove the heat the laser output will continuously drop as the laser head heats up. The laser will stop lasing and eventually the vacuum seals will fail and the laser is dead.

Depending on laser head design, the high voltage electrodes may be directly in contact with the cooling water. If this is the case you must use distilled water or the laser heat can be shorted out by ions in the water. You can probably use a pure glycol based antifreeze added to the distilled to lower the freezing point. You will probably need 40-50% glycol to provide antifreeze protection. Ethylene glycol solutions have a lower viscosity than propylene glycol so they are easier to pump, but ethylene glycol is extremely toxic to humans and pets if swallowed.

Be careful if you choose to use a commercial antifreeze. Check the wiki article and the coolant matrix references on what type of antifreeze has what additives.

https://www.eetcorp.com/antifreeze/Coolants_matrix.pdf

https://www.ttequip.com/knowledgelibrary/Proper Use Of Inhibited Propylene Glycol.pdf

https://www.engineeringtoolbox.com/propylene-glycol-d_363.html

https://www.engineeringtoolbox.com/ethylene-propylene-glycol-d_904.html

https://www.engineeringtoolbox.com/ethylene-glycol-d_146.html

https://msdssearch.dow.com/Publishe...rans/pdfs/noreg/180-01314.pdf&fromPage=GetDoc

https://en.wikipedia.org/wiki/Antifreeze

Bob

Excellent collection of information.

The Dowfrost sounds cool, but it's pretty expensive, and with only a cheap pump to worry about, I don't think the rust inhibitors will be necessary. In the garage, in typical winter weather here, I doubt it will get below 20F. I can always drain it if we're getting really cold weather. So I think a couple of quarts of straight prop g will do. Now I'm thinking about something a little better than the cheap aquarium pump, perhaps this, which would also get away from a submersible.

Posts in other threads also warn that ethylene glycol can be susceptible to algae growth, where a >15% prop g will inhibit it.

This weekend I at least got it unboxed and cleared a table in the garage for it. Hope to get a chance to fire it up this next weekend.

You don't want to use pure PG. Pure water is the best coolant and has a higher heat capacity than either PG or EG. Adding PG or EG to water lowers the heat capacity and raises the viscosity which makes it harder to pump. 2 volumes of distilled water and 1 volume of pure PG (about 35% w/w) should drop the freezing point to ~0F without raising the viscosity too much and provide adequate margin when you expect the the garage temperature not to go below 20F.

Bob

Oh yeah, I meant a couple quarts of prop g in a water bucket to an appropriate percentage. 35% sounds good.

Should get to fire it up this Saturday. Then I've got to think about upgrades, which will outpace the base cost of the cutter by about 2X. But I'll be buying upgrades with the intent of building a larger cutter. This one is just my 'training wheels'.

This thing is a remarkable value for under $400, and a remarkable piece of crap at the same time. The aquarium pump included is ok, though you might want something better. The blower is a piece of crap that must be replaced (looking at a 4" bilge blower). Looking inside before powering it up, we found the wiring neat and tight, but also a rusty allen wrench, stuck underneath a flange, where it had been accidentally bolted in place! The XY motion appears good; at least it moves smoothly by hand and it homes properly. The laser test fire switch is stuck down, so that it fires 'automatically' when the laser power is turned on; ...no safety problem there. But, it did put a nice, tiny, hole in a piece of cardboard when it fired. After I replace that switch, I'll be able to check its alignment.

Do you have any links or photos?

I use the heck out of my cheapo K40 laser and love it to bits. I've upgraded mine with a Light Object DSP controller and a few other bits and pieces and it works really well.

Something to think about with cooling is that you don't necessarily want the laser tube to be cold, it should operate within an optimum temperature range and introducing active cooling can cause a differential that could crack the glass if you're not careful. Who wants high voltage dc current connected to a leaking water pump? Not me. I realized over time that my jobs and duty cycle are rarely hard enough to heat up the tube if I simply use a five gallon water volume as my heat sink.

Exhaust is another huge deal to sort out. I placed mine directly in front of a window at the right level so I'd get maximum extraction without a bunch of bends in the duct. I used a 6" vent fan (like $28 on amazon) and a 6 to 4" reducer and a single 90 degree bend to extract it:



Lasers are the best tool for rocket building. sleds, bulkheads, and fin alignment guides are easy as heck now:

I think I got it from this source on ebay: https://www.ebay.com/itm/High-Preci...065645?hash=item3cba62a8ad:g:nVUAAOSwqu9U0J0b

Ordered on a Friday, delivered on next Tuesday. Packed well, no shipping damage. There are dozens of these on ebay (tho most appear to be from the same few vendors). AFIK they all are known as k40 lasers, also perhaps 3020 lasers (300x200mm cutting area). They all appear about the same, though there may be some differences in the control panels, probably depending on when/where it was produced. Doesn't much matter since one of the first things you do is replace the controller and panel.

Last time I tried, photos wouldn't upload, though there's not much to see yet, just the basic cutter you can see in the ebay photos.

smapdiage9 said:

I use the heck out of my cheapo K40 laser and love it to bits. I've upgraded mine with a Light Object DSP controller and a few other bits and pieces and it works really well.
...
Exhaust is another huge deal to sort out. I placed mine directly in front of a window at the right level so I'd get maximum extraction without a bunch of bends in the duct. I used a 6" vent fan (like $28 on amazon) and a 6 to 4" reducer and a single 90 degree bend to extract it:

Click to expand...

Which LO controller did you use? I'm having a heck of a time figuring out the differences.

Thanks for pointer to Ventech blower. So now I'm wondering whether to run the Ventech off 110, or the bilge blower off of 12V (about the same price and CFM).

Have you added air assist?

I have a harbor freight airbrush compressor hooked up to an LO air assist head, it works pretty well. I am using the X7 controller, which is their branding of an AWC-708c lite. The handful of CNC laser controllers from China are all the same basic design manufactured by a different company with a different software workflow; light object's are good because they have an active support forum, though it is pretty obvious that their CAM product (called LaserCAD) is a program being written and updated by one guy. It works fine and I use it happily, but there are a few foibles to get used to. Right now I do complicated designs as sketches in Autodesk Fusion 360, export as DXF, import the DXF into LaserCAD to set my power/feedrates/etc and save that file to run on the machine.

I would do the 110v blower because if you ever move off the stock power supply (mine fried out during an arduino upgrade) the replacement LPSU may or may not have 24v/5v/12v coming from it. Right now I'm running a 40-60W supply that only powers the laser and using a separate PSU to run my electronics.

I am interested in how this works out for you. I have looked at these to cut my own av bay parts.

I cut my own bulkplates and sleds constantly, it's really handy. Be prepared to generate a tremendous amount of garbage, as everything you cut will create scraps. Also do not let it run alone ever, not even for a minute. Things catch fire unexpectedly sometimes.

smapdiage9 said:

I have a harbor freight airbrush compressor hooked up to an LO air assist head, it works pretty well. I am using the X7 controller, which is their branding of an AWC-708c lite. The handful of CNC laser controllers from China are all the same basic design manufactured by a different company with a different software workflow; light object's are good because they have an active support forum, though it is pretty obvious that their CAM product (called LaserCAD) is a program being written and updated by one guy. It works fine and I use it happily, but there are a few foibles to get used to. Right now I do complicated designs as sketches in Autodesk Fusion 360, export as DXF, import the DXF into LaserCAD to set my power/feedrates/etc and save that file to run on the machine.

I would do the 110v blower because if you ever move off the stock power supply (mine fried out during an arduino upgrade) the replacement LPSU may or may not have 24v/5v/12v coming from it. Right now I'm running a 40-60W supply that only powers the laser and using a separate PSU to run my electronics.

Click to expand...

The HF airbrush compressor is one I was looking at; is it quiet/loud? Also the 7 lite. Sounds good.

I was planning to add an extra 12V supply for accessories, like I did for my printer - cheap.

What stepper drivers did you use for the 7lite - or does it come with drivers?

Thanks for the info BTW.

The HF air compressor isn't loud enough to hurt your ears but it is noticeable in the room. With no resistance on it (like filling a pressure vessel to a certain level) it just runs continuously which causes it to get fairly warm, but I've been using it for 6 or 7 months without any problems.

I purchased their K40 upgrade kit which came with drivers: https://www.lightobject.com/X7-DSP-upgrade-kit-for-DK40-small-CO2-laser-machine-P942.aspx If you buy the controller from another source it will almost certainly not come with drivers because they'll be application-specific.

You'll find all kinds of things to do with lasers once you get started. I'm about to take some 1/8" plywood over to my friend's laser to get turned into 2 rockets worth of fins and centering rings. You have absolute design freedom with little extra work. For example, one of the rockets will have dragon wing fins modeled on bat wings. Curves all over the place? No problem. A tight fit every time is also really nice.

It also cuts acrylic really nicely, which opens up more scale modeling possibilities. Another thing to look at is using the laser on a lower power setting to engrave rather than cut. It makes real nice markings to show where your altimeters go, where holes should get drilled, etc.

My friend just upgraded to a more powerful laser, and I need to take a piece of G10 over to see if he can slice that up as well. If so, I can theoretically do everything up to an L3 rocket without kits.

smapdiage9 said:

I purchased their K40 upgrade kit which came with drivers: https://www.lightobject.com/X7-DSP-upgrade-kit-for-DK40-small-CO2-laser-machine-P942.aspx If you buy the controller from another source it will almost certainly not come with drivers because they'll be application-specific.

Click to expand...

The upgrade costs more than the base system.

Ari.

Yes, the base system is being sold at ridiculously accessible prices which is great but makes the upgrade seem hideous by comparison. Alternatives to the stock controller/software are arduino based systems and commercial controllers. I tried arduino for a while and didn't like it, now I have this controller which I can easily transplant to the 36x24 gantry I built for bigger jobs.

OK. I can't deal with this anymore. I ordered a K40 last night. (Just the base machine for now, want to see what it does out of the box first, then buy the upgrades when I understand what I got into).

Ari.

The stock controller is quite capable, I just got greedy.

Treat it as a parts kit not a fully finished machine. Take it apart, ensure the movements are straight and parallel and all the stuff is set well. Do a lot of internet reading about the machine, especially safe operation.

Whatever is bent or broken take a photo and send a polite request for a replacement part from the seller, they will send you parts from China for free. My laser tube had a broken water inlet tip and with one email they sent me a new one on the 30 day boat. The one I had worked just fine after I used a little sealant to attach the water tube, but broken is broken and they've got an infinite supply of parts across the left pond.

Wow. I come back from a launch, and what do I find sitting in front of my door. Such shipping!

Ari.

So I got the thing all set up and calibrated (the mirrors weren't even close). The aquarium pump looks like a disaster waiting to happen... what do people use for cooling?

Also, my box included a roll of tape and a tube of mystery compound. Any ideas what these might be for?

Ari.

If I remember correctly it's silicone sealant and sealing tape for the water tube hookups at the pump and at the tube. I didn't use either of them.

My stock pump is going strong after six months of regular use, I just use it in a five gallon bucket of room temp water without issue.

Good to know.

On closer look, it appears that the X axis is not perpendicular to the Y. The skew is small but noticeable. Black is a scan of a rectangle as the machine vectors it; red is an actual rectangle superimposed on it. I'm sending this picture to the vendor also.

Ari.

Figured it out. There are independent belts that drive the left and the right side of the gantry. Removing a cover reveals a rod that connects the Y stepper motor to the left sprocket. Undoing the coupler allows for adjustment of lag/skew. My squares are square now.

Ari.

I was looking at picking one up and its on my christmas wishlist...
What software are you using to cut with?

So far I've only used the stamp-engraving nonsense that came with it, WinsealXP or somesuch. I'm unclear yet where I want to go with software.

Ari.