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Discussion in 'Laser Cutters' started by Kevon Ritter, Sep 6, 2020.
Large Format CO2 Laser Cutter
Kevon Ritter published a new build:
Read more about this build...
The downside to the compact nature is the lack of space for the controller's display. From the beginning, I knew this would be an issue. My two options were a swing arm and to mount it on the front an at angle. The swing arm idea just seems like an unnecessary exaggeration. Here's a rough idea of the angled front mount.
I see nothing wrong with this setup for the display. Many compact machines use it.
In case anyone is wondering, the 24V PSU will not sit on top of the CO2 PSU. It's just there for representation. This is 2020 after all.
The objective was to decrease wire runs as much as possible. All of the motion control is on the right. Everything with a mains connection is on the left. The cooling solution will be located near center.
Airflow should be guided through the system. Pic explains better. I will probably try to enclose the entire electronics compartment to avoid even a slight amount of fumes being ejecting into the room. Speaking of fumes, I plan on using a brushed 70mm ducted fan. This would then be ducted through 3" tubing to either the side or rear of the machine.
I also saw the lid notches or whatever you want to call them on the tube (MW Laser). Beyond aesthetics, it also provides space to mount struts without having them drop below the frame. I also have no clue what I should be looking for for struts.
Negative pressure ventilation on the duct, with plenty of open gaps to suck in air (for high CFM and to avoid loading the blower) but not enough to lose the vaccuum - aka Static Negative) is the best way to go. In which case a little airflow from every nook and cranny and compartment can help avoid the stuffy leftover smells (;
It is counter intuitive, but works if done right. Easier than sealing everything airtight.
As long as the system keeps drawing air out and thus keeping the cutting area in a negative pressure compared to outside, with a HEPA on the outside, you (and the neighbours) wont smell a thing
Also, from my bookmarks On extraction fans : lasercutting
I see what you're saying. Brilliant! I would still some sort of chamber to keep clean air going to the radiator.
I see 360mm radiator is that the 360x120mm computer cooling rads? I will say in my experience its worth getting a CW5000 chiller. You can use it for a VFD spindle too (; - laser tubes crack from heat, so worth protecting it with a chiller. And its cheap enough (considering its about two tubes to break even, or, one summer weekend with insuficient cooling hehe) CW2000 is just a radiator and blower, but the CW5000 is actually refrigerated
Also properly chilled tubes give higher power (;
A chiller is the preferred option but a bit out of the budget. That along with a larger tube would be part of a later upgrade path if needed. For what I intend to cut (foam), I'm sure I'll be under a 25% duty cycle with a 60W.
One of my other hobbies is PC building. My personal computer will getting a 420mm radiator, but with everything else I'm working on, water-cooling my PC isn't a priority. I will go ahead and get the 420mm for this build and just move it over to my PC at a later date.
If I feel like I'll actually have it running for an extended period of time, I'll just expand the loop with a temporary ice bucket.
Drill a couple holes in the side of a $99 mini fridge under the table with one large bucket of water in it? It's just plastic and styrofoam. Could silicone and Great Stuff around the holes.
Bonus: might be able to keep a beer bottle on each side of the bucket.
I was thinking of doing this with a spare mini-fridge freezer combo this Spring. Then Covid-19 came along and my wife went into full-on hoarding mode so she could limit her trips to the grocery store (two teenage boys can consume a lot of milk). And yes, there would have been beer stored in it to prevent large fluctuations in temperature. Oh, and for drinking.
LOL, great idea! I'll keep it in mind for the future!
"I can't get this thing to cut properly. You know what... HOLD MY BEER!!!"
I've been busting my brain on what I want to use for wiring. I'm leaning towards using:
24/3 - Controller > CO2 PSU
24/3 - Controller > Stepper Driver (x4)
24/2 - Controller > Limit Switch (x3)
24/2 - Controller > Air Assist Relay
24/2 - Controller > Water Flow Switch
20/4 - Stepper Driver > Motor
14/2 - +24V PSU > Bus Bar
18/2 - Bus Bar > Controller
18/2 - Bus Bar > Stepper Driver (x4)
22/2 - Controller +5V > Stepper Enable (daisy chain)
20 - Ground (Drain Wire)
Here is the controller documentation if anyone cares. A total wiring schematic is on page 8.
http://cloudray.oss-us-west-1.aliyu...a/RDC6445G/User's Manual of RDC6445G V1.0.pdf
I'm taking screenshots as I go. I'm liking the black frame more and more as I go. I did also go back to the original hood setup.
The green line represents a light strip. It would be white though, and would be one with the machine. Of course it is purely for looks.
I do want a visible window for the electronics bay.
The air pump and power supplies aren't set in stone yet.
Space is starting to get a bit tight, but I do still want to try to fit the extractor fan internally. My original plan was to just dump it outside as I don't have neighbors to worry about. I honestly don't know anything about HEPA filter sizes and formats. What you see in the picture is a 140mm fan which technically can't fit, but anything sub 130mm won't have an issue.
I was juggling with the idea of a vent above where the radiator would be, but then I realized that the vents could possibly become an intake for the extractor.
Everything is pretty much finalized. At this point, I'm just tinkering. Many parts are already on order.
About the negative pressure thing again blower on inlet side of the vent line, pressurises the vent line - so you have to really seal up any joints after the fan. But again, with the blower sucking from the far end, negative pressure keeps the fumes in the vent tube
I hear you loud and clear. If the fan is internal, it would be the very last component in line. It would also have to be an axial fan. If I had to work completely indoors, then a separate unit housing a larger blower with a HEPA and carbon filter would work. Due to the nature of how it's all going together, it would be an easy part swap. It's just a giant Lego set. There is a very slight collision with one of the tube brackets, but that's a minor fix. The pics show a 120mm x 38mm fan.
The bed was something I couldn't quite figure out. Honeycomb was seemingly super expensive and not that great due to the tight cell structure. The second two methods I found were the slats and pins. Slats were really tall, needed a serious enough support structure, and started getting pricey at this size. Pins seemed to just be a hassle. Then I randomly saw egg crate, found it in aluminum with a 1" grid, then somehow ended up on reddit. There, I saw the idea of using music/guitar wire stretched across the bed. I also saw this 1" honeycomb. The issue with my bed is the size. It's not a size that has an easy overlap for a 24" x 48" drop in bed. I would have to make a support of some sort, which wouldn't be difficult, but then I'll have a bit of unsupported space (green area). I'm juggling the two last ideas.
All of the panels will be secured with nylon bolts/screws. It may not be as strong, but I will have a rust concern. I also don't want bright silver stainless hardware on the outside.
A side note:
30 series profiles are quite a bit pricier than 20 series. I'm glad this is my only 30 series based machine. The T nuts alone from the source is almost half the price of the extrusion itself.
Lookup FreeBurn 1 on here under my old openhardwarecoza account. Used stainless mesh over a alu frame for the bed. Worked great
Did you have any issue with "splash back" or whatever they call it? I was shooting for a minimum of a 1" grid.
Played around with the front panel for a bit...
I reduced the size of the front panel a little more.
There's a good idea of how much material is needed for paneling. The large sheet is 4x8. The smaller blue sheet is is a 4x6.
The hinges are all figured out. This will be mounted directly to the frame.
I did also decide to change the assembly method due to the cost of hardware for a million corner pieces. It may seem like a minor cost, but $200 worth of t-nuts for $400 worth of extrusion is ridiculous. Directly bolting the extrusion together is stronger as well. The negative would be the requirement of square edges, having to tap the ends, and drill through the extrusion. None of that is an issue.
Pretty much all of the small hardware is on order.
is it possible to build the frame with 2020, 2040 extrusions ?
Definitely. You'd be using 2020 and 2060. At this size, the longest extrusion is 1370mm (54"). I didn't want to have to add extra bracing. I have a size threshold where I bump up to the larger 4040 or 4080 (20 series), which was overkill for this. Another reason for 3030 is the fact that this may be moving around more than the average cnc machine. History definitely finds this to be true for me.
I really don't have anything to show for progress as this is in the "waiting for parts" phase. As of now, all of the mechanical parts and more basic electronics are on order. The only parts left are the big stuff; CO2 equipment, controller, air pump, and cooling loop.
I did make a few refinements here and there.
A few more refinements.
All limit switch mounts can be mirrored for two end switches. There is also a mount for the door safety.
I made two Y motor mounts, but never really took the second version anywhere due to the fact that I have 76mm long steppers. The second version requires the shorter 56mm long Nema 23. The next size up (76mm) sticks out past the frame. The real reason for the second version of the mount is to hold a longer tube. This option should allow for a 1250mm laser tube, which isn't bad considering that the frame is only 1430mm wide.
I would like to hear from folks on the safety concern (if any) of using two steppers for the Y axis, one for each side. I've seen somewhere that using two steppers runs the risk of laser beam mis-alignment and possible stray beam hitting something it shouldn't if one of the steppers/drivers were to fail.
I would strongly advise singe stepper, with driveshafts. Much much safer
The only exception would be with quality servo drives, but even that doesn't come close to using a single driveshaft. I also can't fathom the mental thought process going through the head of someone that would use two servos instead of a shaft.
I have most of the smaller parts in hand. One thought was to use a diode laser as just a temporary test mule. I was trying to at least get the frame components before leaving the mainland US, but this lockdown crap dug into my spare change. The new goal is before the year is out.
The Trocen AWC7824 looks pretty good. It is completely touchscreen and is also Lightburn compatible. Thepanel is slightly smaller than the Ruida RDC6445G, but the main board is a little larger. One big detail is that it's black. It is a little more the the RDC6445G though.
A few sleepness nights ago, something was bugging me to make sure I had the correct pitch lead nut. I ordered 2mm lead screws as speed isn't a concern, but there will be a little weight on it. Also because I wanted fine adjustment and easy leverage for the stepper. While checking, I noticed that I ordered 8mm lead nuts. I went ahead and ordered more blocks and the belt needed for the external Y axis stepper mount (picture 61 and 62).
I'm also officially set on the AWC7824.
I have looked as the AWC7824 as well. I have pretty much looked at them all. They are not that much more than some of the other "K40 drop in replacement" I have seen that can do 4 axis so I was leaning towards the Ruida or Trocen varieties, but then it also doubles the price of Lightburn. So, I am still stumped on what to get. I am not in much of a hurry though. I still have to modify my CNC router first because I needed parts (wheels and such) for my laser mods. But I needed to be able to cut aluminum parts for my lathe build so I couldn't move forward on the router mods yet. All my mods are too intertwined because I wanted to reuse parts.
The original Ruida panel design was larger than what I could print. Because of that, it would have been made in parts. The Trocen is small enough to fit completely on my printer, which means I wouldn't need assembly screws. The only downside is the giant "CN" cable connector on the bottom, but that shouldn't be a big deal.
Trocen: 200mm x 115mm
Ruida: 260mm x 125mm