Squeezing a K40 laser engraver, part 2.

Excerpt from “It’s been a long while II”, because I’m lazy:

Using moshisoft, whatever version, is just a pain in the ass for other than engraving (remember, you bought a ENGRAVING machine, it didn’t say anything about being a real cutter). Engraving tough, is quite nice and fast. You just upload a bmp, and BANG there you go.

Frankly, it’s engraving properties are quite good for me, but I won’t miss all of them:

1. It can’t engrave more than 200×200 (machine will go haywire). (why would you want to?)
2. Can’t reliably cut DXF’s, it will ALWAYS move the final vertex from each separate piece, to the “center”.
   When doing simple pieces, is just annoying, but keep in mind, it does not snap to grid or vertex, so placing them again won’t have any precision. Just don’t think about tons of pieces.
3. Software key (it has a hardware key) might reset amidst job, for no reason whatsoever.
4. Program may change language for no reason, and try to display one you don’t have an interpreter for. (luckily, I remembered where where the options I needed, but THAT was insane…)

Software VS. Ports VS. Price:

At this stage, you might be wondering “What options do I have”? Well, I think you might have too many. XD

• The expensive one:
  Mach3 + USB interface board (and you still need the drivers themselves)

• The somewhat cheaper one:
  Mach3 + parallel port interface + stepper drivers

• Even cheaper:
  Kcam + parallel port interface + stepper drivers

• Cheapest:
  Linux CNC software + homemade electronics.

Since I’m not much of a Linux guy, I was left with the two middle options, and you can guess wich one I picked up, can you?

Kcam, the little software that works (most of the time*).

It might not be the most advanced software and has some limitations wich I would change, but otherwise, it works for controlling a laser.

Not my screenshot.

It is interesting to comment some things, tough:

It doesn’t have a specific pin to control the laser so you must use a bit of a trick, with it. You enable “Z single step”, and (me at least) I used the direction pin of the Z axis as laser control. I had set it to activate the laser on 5V from pin 4 (I just like the settings to be in accordance with their function (5v-ON, 0V-OFF)

However, and this is quite IMPORTANT, the parallel port has it’s own mind when you switch on the computer, and you must observe how the pins are set, as you don’t want your laser to start firing for no reason, do you?.
Mine, had pin 4 ON all the time, until you powered it off through software, so I had to negate the activation of the laser. I changed the pin to one that doesn’t change state on power-up.

*I’m using an old version, so I haven’t had any experience with the latest updates, it might be better it might be worse.

Version 40047 (last one to work in Win2k) specifics:

• It can’t understand partial circles (includes chamfering), so it will draw a line between start and endpoints. (complete circles are OK)
  Solution: -Explode- all the drawing and then -join polyline-, it will convert curves to linear segments, and you’re good to go. I use DoublecadXT, wich doesn’t allow me to change how many segments I want when converting, so on big circles, it does show the individual segments. You have two half solutions there (apart of augmenting the segment count in your program of preference).
  -> For circles, draw polygons with a high facet count, treat them as circles.
  -> For curved lines, draw splines by fit points, and then explode, it will give nice and smooth curves.
• If you change engraving/cutting speed sometimes it doesn’t acknowledge the speed change, so you must compulsively compile (XD!) before starting a job.

Aaand this is all I have to say about Software…you know, I’m more of a hardware guy.

Next post (whenever that is) in the series:

Calibration

Because not all rulers are the same, and why your first piece should be one.

MAIN LASER POST <-

The linear Trickster (Image engraving for modified K40’s)

Unless you have spent a tad more in an Epilog laser, wich then makes me wonder why are you reading this (apart from having a laugh at my problems), many people say that you loose the engraving option once you change the hardware to a cheap one, however that is not entirely true. You still have a pair of tricks… (OR you can use Kcam’s built in BMP converter wich I just discovered. XD!)

Vector images:

For vector images, fill solid the areas to be engraved, then convert those polygons to horizontal lines with apropriate spacing (like the ones in CAD drawings). -Explode- , remove unwanted lines (probably the original vectors that made the outline) and there you go, a raster engraving of your drawing. As each laser is different, you must explore the spacing in order to achieve best results, for me it worked at around 0,1/0,2mm.

That was a cookie mold for Eurosteamcon 2013

Pros: It’s free. It works.

Cons: depending on your program, it might create artifacts, partial or repeated lines, or not fill the whole area at once, requiring of you to repeat the process in smaller areas.

B/W Images:

As far as I know, there is only propietary software to do that. Moshidraw did it, Epilog does that, and they work pretty well so far. (do you recognize the movie? XD!)

So, is there no hope? It is, if you have tons of patience and don’t mind somewhat convoluted ways.

You know, Altium does have a small little script to create logos. It does convert black and white BMP’s into  horizontal vector lines in whatever layer you choose. It also does it in an horizontal fashion, just the right vector for the lightest part of the laser to do the work (you WANT to engrave with the X axis so the Y, wich is heavier, doesn’t do much work). The drawbacks is that resolution is dependent on image size. So, it’s not the same converting a 100px image than a 1000px image.

Now we have a rasterized image just like we were going to do a PCB.

Closeup of previous image

Next thing is to convert this to DXF. Altium doesn’t do that directly, but can convert first to gerber, then to DXF. However, if you try very big images, it might give you a “Film too small” and won’t convert from the PCB to gerber, and anyhow, if you have to engrave more than say, solid fill of 150x150mm you’re just wasting your time. It can be done, but well…it will take AGES, seriously.

The following are 100, 500 and 1000px images to vector. At 4mils per pixel conversion, it gives us 10, 50 and 100mm image height at 0,1mm (0,1016) line separation. Denser than that and the laser will just waste your time and material.

Let’s get a closer look at each one:

100px (10mm)

Meh, useless.

500px (50mm)

A bit better.

1000px (100mm)

That’s more like it.

But, okay, now you have downconverted the images to lines, how will it look? Let’s print the DXF’s so we get a slight idea:

Frankly, not bad at all. Even the 500px one looks acceptably good, doesn’t it? Now onto the laser, let’s see what we get with the 500px one:

Yeah, that’s probably the most extreme example you will try with this technique. Anything that is less than 3 pixels wide, will be lost, so be careful. As an afterthought, the laser has about 0,25mm width, wich is more or less 3 pixels wide at 0,1mm/px…so, if we engrave the big 1000px one, it should look better, shouldn’t it?

Spraypainted black and rubbed with a rag to increase contrast in the wood.

Meh…probably I’m just picking up a graphic too complex. Just look at the hair… Let’s try a simpler drawing:

I like this picture a lot, erotic or not.

Not bad at all. I think the material I’m doing the tests isn’t the best choice…that, or my new laser tube doesn’t work well. I must investigate further. Anyhow, the method works more or less.

Same engraving on balsa wood. Looks nice, doesn’t it?

NOTE: the vectors are not optimized on the X axis, so the head will travel back and forth a bit, not like it will wander around like a mad dog, but you will nottice it. It will induce vibrations, so put a weight or secure somehow the smaller pieces you want to do.

Pros: It somewhat works, just don’t pick an image like the one I tried.

Cons: It’s very convoluted, I wish there was a program to do this right away and output DXF’s for us to engrave.

Squeezing a K40 laser engraver, part 1.

So, What do you get when you buy a K40 laser machine?

1. 200x200mm engraving area.
2. 300x200mm cutting area.
3. Rubbish usb controller PLUS usb key, wich will reset itself for no reason sometimes.
4. Even more shitty cutting software.

While engraving is fine, it is not dependable. You can’t etch and then cut in a reliable way (often, it will have about +-0,5mm drift, if not more) and cutting, due to software, is about the shittiest thing you can throw to anyone’s face. It is somewhat usable, but frankly, I’ve been driven nuts, then insane, by the software. It requires you to learn tons of tricks in aligning two works, it never saves your desired settings for different materials (altough it says it does) and the list goes on and on…

You just bought a cheap (mumble with me) EN-GRA-VER, got it?

So, what do you do (change) after you have extracted the most of the thing “as is”? (wich is not much, by the way)

• Air assist (Updated, if you already saw the post about it)
• Controller
• Software
• Engraving
• Piece holder
• End limits
• Fume extraction
• Calibration
• Control panel
• Waterflow sensor
• Temperature sensor
• Relay board

I’ll make a post on each topic, and link it here when it’s done.

Let’s begin, shall we?

1st. Controller:

Let’s be honest, the controller in the laser is not that bad really. It moves around the stages, quite fast while engraving, it’s silent and it handles the return to home all by itself. However, it all goes down the drain because of the software, but that will be covered in the next topic.

Right now, we will talk about the controller you will use once you realize that a decent software is needed. You’ll also probably go the parallel port route, because it is still very easy to find computers with parallel port at cheapass prices, and you can monitor and troubleshoot it if needed, unlike a USB port, where you needed a decent scope and knowledge of what you’re doing.

So, I had bought a TB6560 CNC board at first, but having to rework the flat cable of the X axis to connect it to the board, just didn’t appeal to me (pure procrastination, not that I can’t do it) so I continued with moshittisoft for a little longer…until one day I found this board that I could throw in directly and would solve all my problems…would it?

I don’t blame it on the board itself, it looks nice and does what it needs to do, however, the drivers (polulu) just don’t cut it. Their current chopping is just AWFUL! and made the motors noisy even at the lowest possible setting. Also, one of the drivers died on me with no apparent reason (remember, direct replacement, I could not do anything wrong).  I’m sorry chris, just change the drivers to something better.

So, I continued some more with the original shittycontroller and moshittysoftware, but it was just a question of time vs insanity until I could no longer endure the lack of precision, repeatability, functionality and more “ity’s” that you can think of. (seriously, if you haven’t tried it, you can’t imagine how bad it is)

While on holiday, I decided it was time to do what I had to do and spent a couple of days working on it. For a brief period I changed to the TB6560, and things were…acceptable. Not that it was the best solution, tough.

First, those CNC boards do not have especially good design (overworked 5V regulators, slow speed optocouplers and other things pretty much covered in any google search for “TB6560 board repair”.

My share of mods included the dreadful double inversion of signals through a schmith trigger (7414) to clean up the signal flanks, dealing with reversed microsepping DIP switch configurations and changing the sense resistors to enable “higher” setup current. What I mean is that, at “low currents” other than the max configured by the Rsense, what it does is a very bad chopping, that becomes audible as you configure lower and lower currents (25/50/75%). So, by decreasing the max current by Rsense, you can reduce chopping to a minimum. (can’t remember if more or less resistance, but doesn’t matter, if this post doesn’t convince you to change or NOT to buy that board, I can’t help you further, mainly because I’m a lazy bastard) (grin)

See what I had to do? (cries)

I had this setup around for about six months, until I decided to finally install the end limits, and after cleaning all the cable mess I had inside the machine, inadvertently trapped and shorted a pair of cables of one motor. When I powered the machine, the blue smoke of chip death welcomed me. So, back at square zero…what was I going to do?

For a while, I thought about buying the same board, because I already knew it, drawbacks and so forth. On the other hand, I considered the following: A suposed update on the TB6560 board, and a complete Module based controller.

The diference in price was not that much (90$ for the Modules vs 50$ for any of the other boards, including shipping) and after I found (and sort of remembered) that the chinese keep on cycling those two boards (when I bought the blue ones, I remember them being the “new” ones, and the red version was the older) decided for the Modules. Also, I looked up the longsmotor name, and it belongs to a chinese company that makes stepper motors and stepper drivers so…It should be at least as good or bad as the other board was.

So along came the drivers, and I swiftly installed them.

So neat. ^_^

ATTENTION: Those modules come in different current ranges! If you do, pick up the one with lowest max current (mine was 2A RMS, DM420A) otherwise, the minimum current might be too much for your motors! (just like the TB6560, but unlike that, this one works well at minimum currents).

Oh boy, that was like a dream. Probably you can buy even better, brand name drivers, and they will perform even better than these ones, but since this is a cheapass laser, this driver is so much good than all the other things combined that I could not be more pleased. Current chopping is good at any level, Smothness in microstepping is really good, and it has half current holding switch, so you can drive the motors harder, but let them cool when not in movement, whilist mantaining a suficient holding torque.

Microstepping is (big quote marks) really good, as current control is (no more dreadful less-than-20Khz-chopping). I am so much happy with it, you probably can’t understand, you had to be there. (clenches his lilac)

By the way, this is the motor pinout for the Y axis, in case you want to rework them. I can’t remember if the X axis had the same colors, but you should have a tester around to identify the coils, and advance from there.

• RED            -> A+
• BLUE         -> A-
• YELLOW  -> B+
• WHITE     -> B-

Next post (whenever that is) in the series:

Software

And why moshisoft programmers should disembowel themselves with a USB connector.

X-Y Stories.

So, I’m working on the laser engraver, and I have a half completed a big post about what you need, what to do and what can’t be done with a standard K40 laser engraver. (mostly a rant, and then the upgrades). Christoper tough, kindly asked about wire routing and air assist, so here’s a snippet about what I did (and found) about that.

Firstly, air assist:

I machined my own nozzle, threading it for the lens holder, so I didn’t have to fiddle with odd clamping systems (screws mainly). Be very careful with it, the thread in the chinese part is AWFUL. I had to machine a flat in the spline because the teeth haven’t been machined right:

That example is not to scale on teeth tip removal, but it accurately represents the shape of the chinese part.

Here’s the plan for it:

I didn’t want to make a new lens holder (mainly because I suspected that I would find the same ill machined thread in the third mirror support…and it still worked fine, so there was no real need of overmachining pieces)

Remember to machine the insides first or the piece will wobble and, apart from damage itself, become dangerous!

You need tons of air for this. At first I used one of those 1,5HP compressors, but they are too noisy, and besides, consume too much power (1500W). I Bought two airbrush compressors, that consume about 250W each. They give plenty of air, and can get to a decent pressure if needed (4Bar, altough they’ll get really hot if you work at such pressures for long. I might buy a third, but I have yet to decide if that is overkill or not. You have 25L/min per compressor, and 50 proves sufficient for normal lasercutting. 75 might represent a difference in cutting thick wood, but for normal work on 1 to 5mm thickness, 50 is enough.

As for Christopher real question, the cable carriers, I used the smallest knockoff from ebay I  could find. At 7x7mm internal space, it was incredibly cheap (8 usd per meter, with 2 end pieces) so I bought two meters, fueled by greed. XD!.

 
Be careful!, I have reversed my head position to be backwards! (in case it looked odd to you)

7x7mm have enough space to easily carry a standard aquarium air hose plus six 1,3mm (AWG 16) cables. (only 3 in this photo). Drill, thread and screw at will. (you can barely see a screw just underneath the hose. It’s threaded directly to the plate, no nut

I also guided the X stage cables (on the Y direction) but made a slight modification. Sinte the endpiece has free movement to almost 180ª, I was worried that the movement of the stage up and down might break the cables, so I glued the first element in a forced 90 degree angle, so to force the carried cables to a maximum deflection angle of 45º.

Sorry for the overexposure.

I used the original screw hole for the end limit to attach the carrier, so I didn’t had to risk damaging anything.

If you want to know more about those strange end limits, look at the previous K40 post.

 

Laser’s gone wild.

This, kids, is what happens when you are a lazy bastard who thinks that will always remember to turn on the cooling water supply on his laser, instead of properly building a flow detection system he had in mind since getting the laser.

I already ordered a new tube, and since the supply first got on open circuit and then discharged over the incoming water, I doubt it still works (and I don’t want to find out it doesn’t and then wait another month for a new supply to arrive). So I bought a power supply too. All in all, 238€ wich where all my savings for playing around with toys. It also gives me the opportunity to make some modifications I wanted to do, but was afraid because of the 70cm glass tube in the box. Now that it is gone, I can safely start making holes and whatnot.

Of course, I’ll also make that damn flow detection system, so this CAN’T happen again.

It’s been a looooong while – II

Since I warned on the presentation page that this was going to be updated whenever I felt to…

So, what have I been doing all this time?, working really hard to earn money for a 3D printer. Also, reworking my laser “engraver”.

LASER:

So I own, amdist other things, a cheap chinese laser engraver. It’s one of those “standard” K40 machines, with proprietari software and controller. And let me tell you this: It’s almost shit.

When you buy something this big or complex from china, always read the small print. In this case, What I really wanted was to get experience with a small, but real, laser, wich this is (unlike solid state 1W laser diodes, those are just dangerous toys). Anyhow, The machine, has some absurd limits that you will encounter if you did not take the info as literally as you should.
What does that mean?

It means that this machine is self limited, both in hardware and software, to work in 200x200mm. It might cut pieces beyond that, but it can also go crazy and ram the effector to one side (if you’re lucky, the one with the opto switches, if not…well, the sound is not enjoyable)

Using moshisoft, whatever version, is just a pain in the ass for other than engraving (remember, you bought a ENGRAVING machine, it didn’t say anything about being a real cutter). Engraving tough, is quite nice and fast. You just upload a bmp, and BANG there you go.

Frankly, it’s engraving properties are quite good for me, and I’ll miss them. Why?

1. Well, I can’t engrave, as said, more than 200×200 (machine will go haywire).
2. Can’t reliably cut DXF’s, it will ALWAYS move the final vertex from each separate piece, to the “center”.
   When doing simple pieces, is just annoying, but keep in mind, it does not snap to grid, so placing them again won’t have any precision whatsoever. Just don’t think about tons of pieces.
3. Software key (it has a hardware key) might reset amidst job, for no reason whatsoever.
4. Software may change language for no reason, and try to display one you don’t have an interpreter for. (luckily, I remembered where where the options I needed, but THAT was insane…)

Basically, all blame goes to the software. (machines can be improved one way or another). So, would I recommend this machine? Unlike most of the internets, I would…

IF

You are only going to engrave small areas, do some non precision cutting, or want to learn laser basics to build your own, and don’t mind spending money on a crash course. (It is understood that you MUST be a very capable (or responsible) person to get to that project, if not, just buy a somewhat expensiver machine, and simply enjoy what Laser power can do for you.

So, for us, who decide to get the hands on approach to laser, good luck.

NEXT POST: What did I change on my machine, and all upgrades, in ONE post. (instead of having to look for everything scattered over internet.

(preview: Air assist, TB6560 board, stepper motors, soldering iron)

3D PRINTER:

I earned enough money to buy a ROSTOCK MAX 3D printer, basically because I fell in love with delta robots, and also, because it is one of the biggest you can buy. I did my search over internet, and found both good reviews and found mixed opinions about the machine. Some praise it, some hate it. I too don’t like some of it’s parts, like the bowden extruder (I have plans for that). But first, I must learn how filament printers work, and once I extract the most of the printer as is, I won’t try to go further.

The kit hasn’t arrived yet (and I’m still working on the laser) so I don’t expect it to be working until October or so.