Some advice requested for a newcomer
Gents / ladies, I have just purchased one of the K40 clone machines, and have spent yesterday setting it up. Today I am trying to get it to produce some test pieces to familiarise myself with what the machine does and how etc, but from the off I am having some issues that I need some advice on.
Using Inkscape and K40 Whisperer I designed a simple design that used raster and vector engraving, plus vector cutting. Noting fancy, just a gauge face and outline. K40 Whisperer connected to the machine fine, the design looked fine on the display screen. I had checked the alignment of the laser and mirrors and am satisfied that while not perfectly centred, it's within a millimetre or so.
So first I tried raster engraving. I used a piece of MDF as the test piece, however my first attempt resulted in nothing - I had set the laser power too low. Another try, with the potentiometer set at 50% power started well, but as the laser mover towards the front the engraving got fainter and fainter, until the engraving was barely visible. The gauge dimensions are 60mm x 60mm, not large by any stretch of the imagination. I tried Vector engraving, and that seemed to be better. Finally I went for the out line cut, and set the laser to maximum. The laser barely engraves the surface, for the 4mm MDF I was using I estimate it would take a minimum of 40 passes before breaking through.
The focus is obviously OK because the engraving and 'cutting' that was done was nice and fine
I tried again, bringing the part a bit closer to just see if focus was an issue. This time, with the laser on full power ( the only way to make a mark) the engraving only did the 'back' half of the gauge, by the time it got to the front it was doing nothing at all. On full power. Just to see if there was any difference I set it to cut the outline, again at full power, and while it did make the outline all the way round, the outline engraved was noticeably more aggressively produced at the back than the front. As for cutting, I would have more luck cutting with a feather duster I suspect! However the 'power meter' shows full scale deflection while 'cutting' so in theory at least it is on full power
So, there seems to be a problem somewhere. The fact that the laser peters out nearer the front seems to be consistent both with cutting and with engraving. If it supposed to be powerful enough to cut through MDF, then either the laser is not working properly or the power is insufficient or maybe both.
Before I go back to the vendor to see about money back or replacement parts I want to check with you guys to see if this is an issue that is known with a known fix.
Any help / insight you give would be very gratefully received!
Thanks
Les
Re: Some adviec requested for a newcomer
Guys, I'm trying (without success) to post a picture of the last trial with cutting and engraving at full power - hopefully it shows up
Les
Re: Some advice requested for a newcomer
Another try at attaching
*****Edit***** doesn't matter how many times I try, the attachment thing says XX% attaching, then seems to fail. It also says 'posted via mobile device' when it it is a rather prosaic desktop PC. Oh well
Just for info, after two or three minutes the Laser seems to lose power
Cheers
Les
Re: Some advice requested for a newcomer
It was definitely an alignment issue - but not quite how I thought. I had done the alignment of the mirrors per the lasergod's site instructions, and as mentioned got the laser to fire within a millimetre or so of the centre of the mirrors. However that counts for nothing if the bracket it is mounted on is loose....
Because I was over cautious I didn't want to look at the work while the laser was firing, but when I did so (more by accident than by design) I saw the third mirror head nodding as it moved. I've tightened it up and it's a vast improvement. However, I still have to find the correct height, I image that will just be trial and error.
One thing I am surprised at is that with my test piece, even after fifteen cuts at max power I was nowhere near cutting through 6mm MDF. I imagined it would take less than that. I also for attempting to find the correct height put a piece of 4mm acrylic on the bed at a shallow angle so that I could see where the best cutting depth was. The maximum cut depth at full power was 1mm, less than I expected
Cheers
Les
Re: Some advice requested for a newcomer
To find the correct focal distance use the slant method place a piece of mdf with one end higher then the other and cut a straight line where the line is the thinest and looks the best that will be your focal length measure it to the bottom of your nose cone and make a sizing gauge that big.
Re: Some advice requested for a newcomer
Quote:
Originally Posted by
fixtureman1
To find the correct focal distance use the slant method place a piece of mdf with one end higher then the other and cut a straight line where the line is the thinest and looks the best that will be your focal length measure it to the bottom of your nose cone and make a sizing gauge that big.
Thanks, I did that, and found the height. Not that there was much difference in the width, it was pretty wide all the way along with a pinch in the middle at the focal point, but still wider than I expected. The power was at max, and the maximum depth it cut was 1mm - I was expecting considerably deeper than that for this machine. Is this in line with what I should expect for this type of machine (notionally 40w, but probably less)
Cheers
*****EDIT*****
Well, the quality product reveals itself again - the water pump that can with the unit has given out, less than two days after getting it. I also am having to adjust so much, like putting spacers on the CNC board so that the USB port lines up with the case hole, I removed the really rubbish clamp and plate that was incredibly poorly assembled, so I am so far from impressed! You definitely get what you pay for
Les
Re: Some advice requested for a newcomer
Since I can't work with the laser (public holiday here so can't buy a replacement water pump) I decided to take a good look at the machine and see what else could be up. The K40Laser.se site provides quite a bit of info which I'm following but one part I don't understand fully is the lens alignment part. I had done the alignment how I believed it is supposed to be, but I am not so sure now, so if anyone can point to photos and info on that I would be grateful.
As I said, I was checking over the machine, and one thing I thought couldn't hurt is to clean the mirrors and lenses, and that's when I found the lens was fitted with the flat side up. The information that I saw on the web seems to indicate that the flat side should go downwards, so that is a line of enquiry too. If I read it right, if the lens is the wrong way up, it would diverge the beam rather than converging it?
Ultimately though, I am concerned that the failure of the water pump may have irreparably damaged the laser tube. It still fires when you press the test button, but I am not sure exactly how long it ran with the pump not running as the noise of the extraction fan masked the lack of noise from the water pump. Maybe the damage is done. I obviously switched it off the moment I noticed, but the water was tepid, not cool. Hopefully I'm wrong and I haven't inadvertently cooked it. It was operating at low power at the time
I am on to the seller to get a replacement pump, from what I read they tend to be fairly good in rectifying issues so I hope that this one will do so. I am loathe to criticise harshly, after all we choose to pay less, and the machine obviously has potential. I just need to get it to a point where it's actually usable.
A question I did ask but have not received a response to is what thickness of MDF / acrylic would this type of machine be expected to cut through? As of yesterday, the deepest cut I was able to make was about a millimetre, and the width of the cut was approximately that too. Should I be expecting a deeper thinner cut?
Thanks as always for the help / comments
Les
Re: Some advice requested for a newcomer
Hi again guys
I finally found somewhere to buy a replacement pump, after the vendor credited me 30 euros back for the one that failed. The week that it took to find somewhere that sold a suitable pump was used to go through everything that I could and to study potential improvements. The first most obvious thing that I needed was air assist, so I cobbled together a nozzle using fine brass tubing and an air supply from my airbrush compressor. If nothing else, the air assist seemed to be necessary to prevent the cut making a carbon barrier in the acrylic sheet that I am using to make my parts. I have 2mm opal acrylic which is spray painted black on the face that will be cut, to make engraved and cut panels that are back lit. The first pass with the laser would essentially just char the paint and top layer of the acrylic, which then prevented any further cutting.
With the air assist, I now can cut the surface and it stays clean as the air blasts the charred material away, much much better. However I still need 4 or 5 passes with the laser before the acrylic is cut through.
For MDF, it simply will not cut through no matter how thick the MDF is. 3mm thick MDF was the thinnest I have, and after 10 passes with the laser it still is way short of breaking through. I also tried cutting transparent acrylic 2mm thick, and similar to the MDF it seems to get part way through and then is unable to go any further. In case anyone wants to know, the cooling water is kept at about 10 degrees using blocks of ice.
So to sum up, it is falling way short of my expectations. Yes, I have finally been able to produce some parts that are good using the 2mm acrylic, but my expectation was that the 2mm acrylic should be cut in one pass. As for other materials, it's just a plain fail, unless all I want is surface engraving.
Where do I go from here? Am I going to have to buy better mirror and lens head sets like the CloudRay ones, and another laser tube in order to do what I expected to be able to do? Again, I would appreciate any feedback from anyone who has experience with any particular hardware, especially if they have noticed a significant improvement by using them
Cheers
Les
