[ZOMGVTEK]

I received a K40 5 days ago, purchased for a whopping $740 shipped. I did zero research prior, and have never used, witnesses someone use, or been around a laser cutter prior. You could say I didn't know a thing about them. Go ahead and yell if you notice i'm doing something wrong.

I have quite a bit of experience with the machine now, as well as the well designed Moshidraw software, but have a few questions.

Heres the machine I received... It's been a bit modified to increase the cuttable area, as well as work out better for my application. I don't have any interior shots of how it came new, but I assume most are familiar with it.























1) I'm making files in Illustrator CS5, saving as uncompressed 10 .ai's, importing into CorelDraw 11, exporting as HPGL, and sending to the cutter via Moshidraw. Most small circles are cut twice, larger circles and squares are not? Why? Is there any better way to do this? 95% of the time I will be cutting. Is NewlySeal/NeawlyDraw entirely useless as well? It was supposed to be included, I think, but I didn't get it.

2) There was a broken piece of glass in the laser tube, is that an issue?

3) Would a 100mm (4 Inch) lens work out better for cutting, even if the materials are not that thick? Most things will be .1-.25". Just get the cheapest 18mm 100mm CO2 lens on eBay and drop it in?

4) Is there any good way to adjust the height of the work to easily focus the beam? I've just been dropping things down and cutting, and it works for the most part.

5) All edges are not cut very vertical. This is actually better on thicker materials, but fairly bad on thinner ones, is this from the laser being out of focus? Would a 4" focal length lens help this, by making focus less critical? The bottom of the cut is narrower than the top, and the 'edge' formed always points away from the piece. The sides are always 'pyramid' shaped on 1/16 - 1/8" acrylic. Its barely noticeable on the 1/4" acrylic.

6) I've basically been using 10mA for everything, since above that isn't really helping. As low as I can get it to reliably fire is about 4mA, 5mA works best. That burns quite deep into acrylic engraving at 45mm/s with that power. No way to improve this? Nothing wrong with running 10mA all day?

7) Anything I should know about these units? It's basically just a cheap unit to screw around with. If it works out well, it will be replaced with something more serious.

[Gadroc]

1) I'm making files in Illustrator CS5, saving as uncompressed 10 .ai's, importing into CorelDraw 11, exporting as HPGL, and sending to the cutter via Moshidraw. Most small circles are cut twice, larger circles and squares are not? Why? Is there any better way to do this? 95% of the time I will be cutting. Is NewlySeal/NeawlyDraw entirely useless as well? It was supposed to be included, I think, but I didn't get it.

Moshidraw is not good. It can work but it's finicky. Moshidraw does have CorelDraw integration, there is a config CorelDraw button in the settings screen which will install a CorelDraw plugin. You can then use it to export directly from CorelDraw to MoshiDraw. That should help with the odd circle cutting issue. I did have problems exporting as bitmap but vectors always worked for me.

2) There was a broken piece of glass in the laser tube, is that an issue?

Not sure how bad this could negatively affect it, but it can't be in the "good" category.

3) Would a 100mm (4 Inch) lens work out better for cutting, even if the materials are not that thick? Most things will be .1-.25". Just get the cheapest 18mm 100mm CO2 lens on eBay and drop it in?

Probably not for this machine the cutting area is not deep enough to deal with that focal length.

4) Is there any good way to adjust the height of the work to easily focus the beam? I've just been dropping things down and cutting, and it works for the most part.

No, the cutting bed on this machine is not adjustable. You will have to remove the existing cutting bed and create your own. I replaced it with some standoffs and angle iron and then used some aluminum egg crate. I then cut several 1/8" and 1/16" shims to raise the egg crate enough to raise it to focus on a piece of paper. I then remove enough shims to equal the material I'm engraving/cutting.

5) All edges are not cut very vertical. This is actually better on thicker materials, but fairly bad on thinner ones, is this from the laser being out of focus? Would a 4" focal length lens help this, by making focus less critical? The bottom of the cut is narrower than the top, and the 'edge' formed always points away from the piece. The sides are always 'pyramid' shaped on 1/16 - 1/8" acrylic. Its barely noticeable on the 1/4" acrylic.

This is the way a laser works. The beam is smallest at it's focal point (58mm or so with the default lens) and tappers down to that above and tappers out below. To get the best cut raise the bed so the focal point is halfway through the material your cutting.

6) I've basically been using 10mA for everything, since above that isn't really helping. As low as I can get it to reliably fire is about 4mA, 5mA works best. That burns quite deep into acrylic engraving at 45mm/s with that power. No way to improve this? Nothing wrong with running 10mA all day?

45mm/s is a very fast cut on acrylic for this machine. You'll get much smoother cuts if you slow it down. I cut acrylic form 6 - 10mm a second with about 30%-80% power depending on thickness. I could probably raise the power and go somewhat faster but the edges is not as nice.

Items 5 and 6 are definitely affected by 4. You are not focused at the beams best power concentration which will affect cutting power and change the angle which is noticed on the material. The fixed cutting bed is one of the biggest physical limitations of this machine, and once you fix that MoshiDraw/Controller is next. I upgraded my controller to a DSP based one and have been VERY happy (it has it's own quirks but is light years beyond MoshiDraw).

[ZOMGVTEK]

I noticed the Coreldraw integration box, but I never really looked for what it did in Coreldraw. I didn't use Corel in several years, and prefer AI, so I just ignored it more or less. I'll see if this does indeed work, and if it fixes some of the quirks im having.

I contacted the seller about the broken tube, and as expected, they basically said "Does it work?", and left it at that. I'm not going to try and pull a fairly expensive part out of the seller unless this is going to be a serious issue. It appears to be OK, the tube has a few hours on it and its working fine.


By 'not deep enough to deal with the focal length', you mean the issue would be the beam would not diverge sufficiently to just let it bash into the bottom of the machine, by the time it reaches there? The bed is definitely deep enough to lower it 2", no problem. Would even a 3" lens help, or be worthwhile?

I suppose with something like this 'egg crate' material, I could just cut some acrylic squares of various thickness to jam between the stock aluminum plate, and the cutting surface. It would be nice if there was a better way, but for the most part, this will be used to cut stuff 1/16-1/64th.

JESMOND HUBBARD CREW 77N75 ALUMINUM EGG CRATE RETURN | eBay


The stock lens is probably a 58mm one? Any good way to check, or verify this? Space the material around and compare test cuts?


45mm/s is what I was testing out raster engraving at, on 1/4" acrylic. 4mA, 45mm/s (as fast as it almost reliably goes), and the etch was about 1/32". Nice and even, but DEEP for the lowest power engraving this thing will do on Acrylic.

I've been cutting .080 Acrylic at 8mm/s, 10mA, .125" Acrylic at 7mm/s, 10mA, .250" Acrylic at 4mm/s, 10mA. Is there anything wrong with going a little too slow, to make sure its cut through ALL the way? Inputting decimal speeds makes Moshi react funny, so my reliable increments are basically in huge 1mm/s bumps. Is it best to cut in 1 pass, when possible?

I'm just trying to get this thing working about as good as it can, and use it as is. If it proves to be useful enough, it will be upgraded to something much larger and more capable. This machine is a little on the small size as is, but it will work OK for now.

[Gadroc]

By 'not deep enough to deal with the focal length', you mean the issue would be the beam would not diverge sufficiently to just let it bash into the bottom of the machine, by the time it reaches there? The bed is definitely deep enough to lower it 2", no problem. Would even a 3" lens help, or be worthwhile?

As I stated above when cutting you would set the focus depth half way through the material. With that point 4" below the focus lens (which is in the bottom 1/4" of the head assembly) you would end up with very little room for objects. Keep in mind your egg crate or honeycomb table and supports will take at least 2" as well.

JESMOND HUBBARD CREW 77N75 ALUMINUM EGG CRATE RETURN | eBay

That's the stuff I use, but look up their website and order direct from them. The shipping on the ebay is WAY overpriced. I think I got it direct from them at about half what buying it from ebay would cost.

The stock lens is probably a 58mm one? Any good way to check, or verify this? Space the material around and compare test cuts?

That's the very un-scientific method I used to tune my bed. Moved it around until I had the smallest kerf on the lowest settings cutting paper. Also be sure that your cutting bed is parallel with the X gantry!

45mm/s is what I was testing out raster engraving at, on 1/4" acrylic. 4mA, 45mm/s (as fast as it almost reliably goes), and the etch was about 1/32". Nice and even, but DEEP for the lowest power engraving this thing will do on Acrylic.

I've been cutting .080 Acrylic at 8mm/s, 10mA, .125" Acrylic at 7mm/s, 10mA, .250" Acrylic at 4mm/s, 10mA. Is there anything wrong with going a little too slow, to make sure its cut through ALL the way? Inputting decimal speeds makes Moshi react funny, so my reliable increments are basically in huge 1mm/s bumps. Is it best to cut in 1 pass, when possible?

Ahhh. 45mm/s is very very slow for engraving but fast for cutting. You should be engraving with this machine between 100mm/s and 200mm/s (keep in mind that MoshiDraw I think sets engraving speed in cm/s not mm/s pay attention to the screen).

It is best to cut in 1 pass. Your speeds look fine and keep in mind that power/speed are related. Faster = more power needed. Slower = less power needed. It also varies greatly by material acrylic you want more power so you melt some of the edge to get a nice "flame polish" type finish. The slower you go the more time it will heat up surrounding material and risk melting/charring so for other materials like wood you'll want different combinations.

[Exsecratio]

Hiya Zom,

Have a read of THIS followed by THIS to give an explanation of lens focus etc...

Cut quality can be improved by using better quality Lens's, Mirrors and a much more powerful air supply.

On a machine like yours though such items would soon add up to near the price of the machine so may not be worth bothering with

best wishes

Dave

[ZOMGVTEK]

Will do.

What makes the lens better quality, and how do you know its better? Would a GaAs lens be better than the ZnSe? The stock lens in this machine looks kinda questionable. Its a little scratched, and appears to have some sort of an uneven coating on it. All of the mirrors look great, perfectly flat and gold deposited, well aligned from the factory. This is quite surprising, give how poor condition the machine was when it arrived. I've dealt with some cheap stuff from China before, and this was by far the poorest assembled product I came across. It was dirty, had black fingerprints on it, has rust spots, coolant all over, chipping paint, dents, theres several types of screws used to secure the same component, some were stripped, the tube was broken, there was a chinese card of sorts spacing the laser tube up, etc... However, it works, was quite cheap, and it does the job. It sure takes a fairly knowledgeable operator for the thing to even work, let alone work well.

I'm familiar with DSLR cameras, so DOF is a familiar term. I always assumed these machines collimated the beam, rather than focused it. I suppose it makes sense for etching, making the power and speed less critical if the beam were to quickly disperse. I'm assuming the processing on these machines is quite poor, and the laser may be in one place longer than it should, if the movements are complex?

It wouldn't be a big deal to double the cost of this machine to make it work very well, but I'd rather just keep a cheap junk laser as cheap as can be. Is there anything thats inexpensive that can improve the cut quality? Currently, its actually not bad at all, but better is always better. I have an air assist nozzle on order from Makerslide. Still need to get an air pump for it, just a big aquarium one works?

Hiya Zom,

Have a read of THIS followed by THIS to give an explanation of lens focus etc...

Cut quality can be improved by using better quality Lens's, Mirrors and a much more powerful air supply.

On a machine like yours though such items would soon add up to near the price of the machine so may not be worth bothering with

best wishes

Dave

[osphoto]

Here's my laser k40 machine after a few updates.

I bought the mAmp meter off ebay along with digital temp gauge and water wheel.

I added the additional switches to turn on/off the water pump and exhaust fan.

I'll have to add another switch to add an external air supply while cutting.

Not a bad first laser machine.

My milliamp meter stopped working, not sure why, I'll have to trace it down. Even reconnecting the analog meter fails.

I can't get the Corel Draw to work with the Moshidraw. I have to export from Corel to Moshidraw.

All in all, I can see getting a bigger machine with better software interface.

[Exsecratio]

Moot point Zom in many ways , GaAs are superior but it all depends on who they come from. Chinese lens's of either type are pretty much even when it comes to performance but once you start using RMI or II-IV from your side of the pond things do improve by quite a bit when using Gallium.
The gold coated mirrors fitted as standard have a great index of reflectivity but almost no resistance to damage Molyebdunum are a lot more resistant to both scratching and burn-in halo's but have a 1% lower IOR (not that it notices much)

The biggest difference I've found is in air assist, that can make a good difference to both speed, surface staining / damage and amount of power required but it does take a good air assist to do it. I'm currently using a modified aircone on my baby laser (A Rabbit/HPC/XongIng 1290) that runs 6psi of air through a 1.5mm exit hole from a dental grade compressor and get very good results.
It seems to be true that Chinese lasers can be improved in many areas but then again what we get for our money compared to Epilog / Universal etc really does make them good value.

All I'd really suggest is maybe going for plenty of air on yours, that assist really can make a huge difference (probably more so than any lens / mirror / tube combination)

best wishes

Dave

[Exsecratio]

Here's my laser k40 machine after a few updates.

I bought the mAmp meter off ebay along with digital temp gauge and water wheel.

I added the additional switches to turn on/off the water pump and exhaust fan.

I'll have to add another switch to add an external air supply while cutting.

Not a bad first laser machine.

My milliamp meter stopped working, not sure why, I'll have to trace it down. Even reconnecting the analog meter fails.

I can't get the Corel Draw to work with the Moshidraw. I have to export from Corel to Moshidraw.

All in all, I can see getting a bigger machine with better software interface.

That's some tidy work my friend

best wishes

Dave

[ZOMGVTEK]

I got used to the raster settings... Not bad quality at all.
This was done at 997 DPI horizontally, 249 DPI vertically, 35cm/s, 10mA, no air. This was as fast as this machine will reliably go, while still being a solid etch.

The input to Moshi was a 1000DPI 1Bit BMP made from a vector graphic. The original file was not perfect.

[brind0g]

Sorry to hijack the thread, but I have one of these lasers and cannot for the life of me get it to install the laser as a printer, I am doing this on Windows XP and via USB. The laser is a week old, from Ebay...Thanks

[Exsecratio]

Sorry to hijack the thread, but I have one of these lasers and cannot for the life of me get it to install the laser as a printer, I am doing this on Windows XP and via USB. The laser is a week old, from Ebay...Thanks

It won't, the machines don't use print drivers.

Epilogs do, chinese machines dont.

best wishes

Dave