As part of my latest project (recreating Nuenen from episode of Band of Brothers), I had been considering whether to buy a laser cutter or not, for the purpose of being able to custom make the buildings with some precision. The kits which are available from the main MDF terrain manufacturers (4Ground, Sarissa and Warbases) are not similar enough to the houses in that episode of Band of Brothers to suit the project.
Anyway, I took the plunge and bought a laser cutter/engraver after several days of intensive research on forums, Youtube and manufacturers' web sites. What did I learn?.. that it is really confusing and complicated and that there are very few clear answers to the questions that I had! My main requirement for a laser cutter was that it could cut 2mm (or possible 3mm) MDF into the shapes I wanted, plus undertake a little bit of engraving to add some detail to the building fascias. Another requirement was that I did not want to spend a fortune on the device; obviously the more that you spend the more certainty there is about the cutting power. It seems as though you can spend several thousand on a "pro" device, which would make cutting 2mm MDF a breeze, but I don't have thousands of pounds spare, so I had to go to the budget end of the scale.
If you are prepared to pay upwards of £500, then you can move away from the "diode" type of laser to the big brother (CO2) devices. Given all the other bits that I needed to buy to complete my setup, I steered away from the low end CO2 lasers.
The Laser Cutter/Engraver
With some degree of uncertainty, I took the plunge and ordered a Neje Laser Master 2S Plus with the N40630 (30 watt) laser module. There is a web site called Banggood, which appears to be based in China, which had a lower price, but having ordered from Amazon plenty of times before, I thought that I would pay a bit more and have the peace of mind that if something went wrong, then I could easily return the item back to Amazon for a refund. I paid £280 for the last one that Amazon UK had in stock.
Neje's naming convention takes a little bit of figuring out. The "frame" of the device comes in three sizes, but there are several laser modules which can be selected. The bit that you attach the laser too, which moves, is called the Neje Laser Master 2S...all of them. The supplementary part of the name Max is the largest device, the Plus is the middle option and the Mini is the smallest. The "hobby" lasers, which seem to be the smallest available which are capable of cutting MDF, are the N40630 (30w input, 5.5w output) and the N40640 (40w input, 7.5w output). It is the output wattage which seems to be most important - this is the level of power that the laser diode emits and enables it to cut and/or engrave. Various wattages are claimed by all the manufacturers and this was one of the really difficult things to wade through in various forums, videos and claims made by manufacturers.
The Software
This decision was actually quite easy because there are two choices (or three if you count the native Neje software, though I had discounted that as an option prior to my purchase). Laser GRBL is free, but seems like it requires a bit more time learning how to use it. The option I went for, largely because they provide a really good support forum, is Lightburn. It is free for the first 30 days, then costs $46 to buy a licence. There are loads of features in Lightburn, though I have only skimmed the surface so far.
Lightburn is used to send instructions to the laser cutter to perform the cutting and engraving i.e. it controls what the laser does.
I use some other software packages to work on the designs (shapes and measurements etc). These are Powerpoint for creating rough sketches like the one below, and Visio, which I am already very familiar with, for creating the accurate "architectural" drawings. Visio allows you to export images in SVG format, which can then be imported into Lightburn. I have not found it easy in Lightburn to exert the same level of control over the shapes and dimensions that I can in Visio, which is why I will continue with Visio. If you are familiar with the Adobe suite, such as Illustrator, then files from that can also be imported into Lightburn.
Safety
There is plenty of safety advice about the use of laser cutters in the various forums, but it is probably worth repeating. The Neje package I bought came with some safety goggles, which cut out the glare of the laser, so I have been wearing those whilst my laser device is switched on.
The other health and safety consideration is around the effect of cutting. The laser generates a lot of heat, so being aware of the fire risk when cutting combustible material such as MDF is worth mentioning.
Cutting also generates a lot of smoke - essentially the laser burns its way through the MDF, so some decent ventilation is required. Therefore, another Amazon purchase was an extractor fan. I bought a Black Orchid 100mm silent fan, which cost £34; it is actually fairly quiet and does shift enough air so that my garage room does not stink of burning MDF.
I bought some 100mm aluminium ducting to attach to the back of extractor fan and vent the fumes through a hole in the wall. That cost another £7.60. To ensure that the ducting was securely attached to the fan, I bought some 100mm pipe clamps (again from Amazon) at £3.25 for two. Unfortunately, the outlet pipe from the extractor fan is really smooth so the ducting and clamps don't really have anything to grip onto. I might drill a couple of holes in the outlet pipe and then securely attach a ring of something around the pipe so that the fan outlet has something to prevent the ducting from sliding off.
Something else that I intend to do, once I have got the configuration dialled in, is to create an enclosure for the whole shebang. That way, I can catch all the fumes inside the enclosure and expel them via the exhaust system.
Software and Cutting
OK, so I have the laser cutter and the software to control it, but it is nowhere near as straightforward as that! You cannot just jump straight into cutting. ;-(
I decided that I would make a decent baseboard and screw the Neje onto it, mostly so that it was stable and not subject to the risk of being knocked or nudged whilst it was cutting (when the object is to achieve millimetre perfect accuracy). I screwed and glued two lengths of wood along the edge and then affixed the Neje to these rails. This had the effect of raising the Neje higher than it would normally be positioned, but the extra height allowed space for a cutting bed. Apparently, this makes cutting easier due to air being able to flow underneath whatever you are cutting. I bought one from Amazon which was large enough to sit underneath A4 sheets, though I had not accounted for the thick solid metal edges, so I now wish that I had spent a little more on a larger model than the £65 it cost for this one.
To aid with airflow, I have put some small wooden slats underneath the honeycomb cutting bed.
Focusing the Laser
One of the most, if not the most, important aspects of using a laser diode for cutting is to ensure that it is correctly focused. This sounds straightforward and the various Youtube videos showing how to perform a "ramp test" also make it look simple...my experience has been that this is actually quite difficult. Before undertaking a ramp test, you need to ensure that your laser is positioned at roughly the right height and is focused to somewhere near where it is going to end up being positioned (on the Z axis).
Once I had figured that out, I re-read a bunch of forum posts on the Lightburn forum and re-watched a bunch of Youtube videos about performing ramp tests and tried it out. The purpose of the ramp test is to find the sweet spot where the "waist" of the laser beam narrows to its thinnest point: that's the height where the laser should be positioned to maximise its cutting power. I think that I am almost there, but can probably do a little bit more fine-tuning.
Cutting Tests
I am pleased to report that I have managed to get my 30w Neje to cut through 2mm of MDF, though I think that I still need to perform some more tests and calibration before possibly getting better results.
Apparently, it is not a good idea to run your laser at 100% power all the time because it drastically shortens its lifespan, so I started off testing at 100%, then have dropped it down to 75% as I got a feel for the impact of making adjustments elsewhere. For example, focusing and height of the laser; whether to use air-assist or not; the speed at which the laser head moves.
I can cut through 2mm MDF using the following settings:
- 75% power
- 5mm / second
- 6 passes
- Air assist on/off doesn't seem to make any difference.
I have read that it should be possible to cut this thickness of MDF within 2 passes, hence why I've got a bit more experimentation to do. Even if it remains at 6 passes, then it's not a big deal. I'm not going into commercial production, so if it takes an hour to cut out a house, then there are plenty of other things that I can be getting on with whilst the Neje does its job.
"Air assist" is supposed to help with cutting, though it has not made a significant difference in the tests I have performed so far, so I am thinking that I perhaps don't have it set up correctly yet. I bought a nozzle from a chap on Ebay (£15) and connected it up to the air compressor that I already owned with a bit of plastic tubing donated from my Dad's fish tank. When the air is switched on, I can see it blowing the smoke and tiny particles of burning MDF (the whole purpose of having air assist) away from the cutting area, so it seems to be working, though the number of passes has been the same irrespective of whether it is on or off.
Conclusion
Would I recommend the Neje? It's probably too early to tell and I don't have experience of any of the competitor machine that I looked at in this price bracket, such as:
- Atomstack A5 Pro
- Ortur Laser Master Pro 2
- Neje Master 2S Plus with A40640
- Scuplfun S6 Pro
- Sculpfun S9
No comments:
Post a Comment