[Pierke]

Mike,

thank you for the picture, now i've got an idea how works the z-axis.

Pierke

[Pierke]

Hello Mike,

dave have right with converting the photo's with "Photograv"

Dithering and other, look at the tread:
http://www.cnczone.com/forums/showthread.php?t=86654

Pierke

[Mike F]

Thanks Dave & Pierke,

I read through the other thread and fully understand the process. However, when matching the DPI of the picture to that of the machine, I have a problem. Nowhere in my machine's specification does it mention DPI. It states the accuracy/resolution as 0.025mm (1/1000") so, does this mean I set my picture to 1000 DPI?

Mike

[Mike F]

First, a question about LaserCut 5.1:

This is the software supplied with the machine and seems to be pretty standard. When selecting the process for each layer, there is a drop down list that includes 'Engrave' and 'GradeEngrave'. As I understand, from the instructions, the GradeEngrave should be able to handle greyscale photos or even colour as the laser power is adjusted to the density of the grey/colour. If I can only import 1 bit photos, then there is no purpose for GradeEngrave as the image is reduced to black and white. The software can import 2 bit images. Does this mean that 2 bit images can support greyscale, whereas 1 bit is only black and white? If so, how does one produce a 2 bit greyscale image? OR, Is there another purpose for GradeEngrave?

Back to the DPI question. The two images below were produced at different dpi. The one on the left was produced at 254 dpi, the step gap of the Y axis, whereas the one on the right was produced at 1000 dpi, the resolution of my machine. It is evident that the image on the left is clearer than that on the right. The material is MDF and there is no discernible depth to the cut.

Dave, the fox and wolf on your gun-stock appears to be 3D, is it?

Mike

[dvdlock]

First, a question about LaserCut 5.1:

This is the software supplied with the machine and seems to be pretty standard. When selecting the process for each layer, there is a drop down list that includes 'Engrave' and 'GradeEngrave'. As I understand, from the instructions, the GradeEngrave should be able to handle greyscale photos or even colour as the laser power is adjusted to the density of the grey/colour. If I can only import 1 bit photos, then there is no purpose for GradeEngrave as the image is reduced to black and white. The software can import 2 bit images. Does this mean that 2 bit images can support greyscale, whereas 1 bit is only black and white? If so, how does one produce a 2 bit greyscale image? OR, Is there another purpose for GradeEngrave?

Back to the DPI question. The two images below were produced at different dpi. The one on the left was produced at 254 dpi, the step gap of the Y axis, whereas the one on the right was produced at 1000 dpi, the resolution of my machine. It is evident that the image on the left is clearer than that on the right. The material is MDF and there is no discernible depth to the cut.

Dave, the fox and wolf on your gun-stock appears to be 3D, is it?

Mike

Hi Mike.

I will probably end up rambling a bit here and no doubt you will already know much of what I will say, but here goes anyway.

Not a bad first attempt. I would recommend you get hold of some cheap birch faced ply to practice on, it burns very well and gives a good contrast for your photo's.
I haven't used the grade engraving feature very much. It wouldn't normally be used for photo engraving. I thik it would usually be used for theing like lettering. It would give the letters a bit of definition where the edges would have a somewhat sloping side rather than a square one. The image at the top of page 30 in your Lasercut 5.1 manual shows how you can infuence the shape. Imagine that image being a section through say, the letter I. Instead of the straight edged to the letter as with standard rastering, they have sloping edges.

On to the grey scale issue. Unfortunately our machines are not capable of using any more than a 2-bit bitmap (often called a 1-bit). Grey scale images are usually at least 8-bit but can be much higher depending on how many levels of grey there are in the image. However, when a black and white image is processed through Photograv, or dithered, it is basically looking at how many shades of grey there are and applies a different concentration of the number of dots in an area relative to the shade of grey the original image is. So black or dark grey would have many more black dots in it than a lighter grey area. A bit like an old newspaper photo really. So its a bit like a simulated grey scale.

Attached are 3 images, the first is a colour jpeg, the next is a greyscale and the last a 2-bit photograv (dithered) image.



You can see in this last image how the different shades of are represented by the density of the dots.

On to the DPI. Most of us are used to referring to the resolution of images in DPI, however our machines are metric and the resolution in Lasercut is the scan gap and is in metric. I have attached a file of a conversion chart which I have engraved on to a piece of laminate and stuck it on my control panel.
So if you have processed your image at say 300 dpi you would set your scan gap in the engrave dialogue to 0.085

The 1000 dpi is a bit ambitious. The problem here is the size of the dot the laser beam can focus to. I doubt very much it's a small as .001"
So here lies the dilemma. If your beam focuses down to say .005" the dot is 5 times bigger than the dpi of the image. So all you get is lots of overlaping dots which obviously spoils the image.
Ideally, the scan gap should be set no larger than the the spot size of the beam, but thats extremely difficult to measure. This is why your lower dpi result is better than the higher one.

You will no doubt have read on the forums about all lasers being different, even those of the same make and power, and that trial runs are needed to establish the best dpi, power and speed settings for your particular machine. Well, this is exactly that type of situation. I have generally found that my best results are achieved with 300dpi. I do sometimes use 600dpi but never more as the end result is actually a lower quality image.

Another tip that you may find useful is that it's OK to raster the image in multiples of the scan gap you set. For example, you could use an image with a resolution of say 600 dpi with your scan gap set to 200 or 300 dpi. However, it's not good practice to use the 600 dpi with your scan gap set to say 400 or 500 dpi. Divisibles are the key, if thats the right word!

Anyway, enough rambling. There's a lot to learn and you will pick it up very quickly. I've only been at it for just over a year and i'm learning something new, or picking up another great tip every time I log on to one of the laser forums.

Have fun

Dave.

PS. The fox and wolf are rastered with a bit extra power. The extra depth does provide a sort of 3d effect which I like as opposed to what is essentially a superficial finish you would get on say Granite.

[Mike F]

Hi Dave,

Thanks for the excellent reply. If it were not for this forum, we would all be re-inventing the wheel all the time. This was particularly true when I built my own CNC mill/router, without the people here, it would never have happened.

Unfortunately, my manual does not have an appropriate image on page 30. The manual was printed from the CD that came with the machine and much of it is in 'quaint' English but understandable.

I picked up the gist of dithering from Pierke's link and found the feature within Corel PhotoPaint. I have to say that Corel is excellent as it has seven different types of dither, four of which are pretty similar to the example you give here. I now understand what you mean by the scan gap and how it relates to the dpi. Basically, I can adjust my image to whatever resolution I like as long as the scan gap is adjusted to suit, either as a metric equivalent or as a metric divisor of the dpi. Yes, 1000 dpi was a bit ambitious and created a very large file but I was pleasantly surprised with how quick LaserCut calculated it.

Now a software question - I have had a look at the 'Options' menu under 'File' and noticed there are two, different settings for backlash that have been entered, one under 'Engrave' and one under 'GradeEngrave'. As far as I know, a machine either has a certain amount of backlash or it doesn't but it cannot have differing amounts dependant on a process. I tried changing these and I also wanted to use the small circle facility. However, when I came to save the changes a message box popped up saying it was password protected. There was a single character in the box and no matter what I tried nothing was accepted. I then tried to change the password and that gave a clue as it asked for numbers only. As far as I am aware, there are only ten single digits 0 - 9 None of these worked!!!!

My question is whether anyone else using LaserCut 5.1 has had the same experience and what is the cure? I have emailed JCUT but not heard anything yet. Neither have they replied to a much earlier request - It is beginning to look like they are a company willing to bend over backwards until they have your money then - nothing. I hope not.

Mike

PS Thanks for the scan gap chart. It will be very useful.

[dvdlock]

Hi Mike,

You are right, these forums really help. There's a bunch of people from whom I benefited from their experience and now I am able to pay back a little by sharing what little I know. It's great fun as well.


....and the Chinglish brings a smile or two. You have to admire them though, imagine us having to produce a manual for them with little understanding of their language :drowning:

The backlash feature I am not too familiar with but from what I understand it's more to do with how far the head travels from speed to standstill and back to speed in the opposite direction. Ramping up and slowing down. These are over and above the mechanical backlash as we would understand it. The laser need to know when to start and stop firing as it's for only part of the time it's travelling.
In the manual somewhere there is a test that shows a set of horizontal lines engraved with a very large scan gap. I think you basically draw a 50mm square with the shaped tool and set it to engrave with say a scan gap of 0.5 (ah, just found it on last page of the manual). The resulting parallel lines should start and stop at the same point. If every other one is staggered it means the momentum of the head ist causing too much travel. You can make an adjustment to compensate for it in the engrave options.

I think the grave engrave would be different because of some of the dimensional values in it's options box.

As I said, I'm not too familiar with that as I haven't yet hit a problem where I needed to delve into it.

Cheers

Dave

Just checked the manual for that grade engrave image and it chapter 5.1.4 if it's the same manual.
If not, PM me your email and i'll send over a copy.

[Mike F]

Hi Dave,

Our manuals are obviously different - I've PM'd you.

Mike

[Mike F]

Hi Dave,

Thanks for the manual - the difference appears to be that you have the MPC6515 control card whereas I have the MPC03-L card. I have no idea what the differences are but you do have a 'Download' option that I don't. Does this mean that you don't have a connecting cable between computer and machine and that you can download data via a USB stick? That is an option I would have preferred - can't change it now though

I did notice an error in you manual. On pages 31/32 under 'Test' the 'Step' checkbox does do something. If you check this box and put a value in the 'Length' box, when you press one of the direction keys, that axis will move the distance you input. This can be handy when fine tuning a start position. Your manual says 'No Use' for this checkbox. The 'Slow' button makes the axis move at the speed that is input under 'File', 'Option', 'Worktable', in the 'Slow Test' box.

Just had a thought, if your computer is not attached to your machine then these options cannot be used as you cannot control the machine from the software.

Mike

[dvdlock]

Hi Dave,

Thanks for the manual - the difference appears to be that you have the MPC6515 control card whereas I have the MPC03-L card. I have no idea what the differences are but you do have a 'Download' option that I don't. Does this mean that you don't have a connecting cable between computer and machine and that you can download data via a USB stick? That is an option I would have preferred - can't change it now though

I did notice an error in you manual. On pages 31/32 under 'Test' the 'Step' checkbox does do something. If you check this box and put a value in the 'Length' box, when you press one of the direction keys, that axis will move the distance you input. This can be handy when fine tuning a start position. Your manual says 'No Use' for this checkbox. The 'Slow' button makes the axis move at the speed that is input under 'File', 'Option', 'Worktable', in the 'Slow Test' box.

Just had a thought, if your computer is not attached to your machine then these options cannot be used as you cannot control the machine from the software.

Mike

Hi Mike,

Some good points. I never thought about your machine using a different control board.
Yes, mine is connected via a USB cable to a dedicated Laptop. I don't usually use the control panel on the machine, I use the controls within Lasercut itself.
I can load files into the machine using a USB dongle as well but I have never had the need to do that.
When I first got the machine I did change some of the 'jog' settings as it was a bit too quick for setting up. How I have it now, when I click on a direction button the axis moves slowly for 2 or 3 seconds and then speeds up.
I generally have the machine set to start at work piece centre as I find it easier to set up. I have used some of the other start options, top left, bottom right etc. on occasion though. I rarely use the datum as a start point.
Had Lasercut been able to take account of page size in the imported file, the datum would have been a nice feature to use.

This control board manufactures website is worth a look http://www.step-servo.com/english/le...page/first.asp just so you can keep an eye out for updates and stuff.

While I remember, If you ever have the need to use the '£' sign when using the text feature in Lasercut, don't bother. It's not recognised. It's something to do with the ascii code and being outside of the range of the ascii recognised by the software. You would need to import the sign as a vector.

You are obviously taking time to investigate 'all' the features in Lasercut which is great. The page 31/32 Test and Gap checkbox I hadn't even noticed it it 'on-screen'. I'll check that out later when I go in the garage to play.

Cheers

Dave.

[Pierke]

Hello Dave,

did you now if there is the possebility to change the MPC-03 with an MPC6515?
Where to buy the controller.
I've a few times send a mail to Leetro, buth no answer.

Pierke

[kewlkiwi]

Where to buy the controller.
I've a few times send a mail to Leetro, buth no answer.

I managed to get an email from them once - it came from a Mr Zhao Jie with the email address of [email protected].

However, once I'd told him I was not currently looking to upgrade - no further emails/replies came... :stickpoke

Bob

[Pierke]

Thanks Bob,

i'll try this mailadres to Mr. Zhao Ji.

Pierke

[Mike F]

Hi Pierke,

Please let us know how you get on as this is an upgrade I may well look at sometime in the future if it is possible to do.

Thanks,

Mike

[Pierke]

OK

the mail is sended to Leetro.

Pierke

[dvdlock]

Hi Mike,

Just wondering how you are getting on with your new machine.

Hope you are having fun.

Dave.

[Mike F]

Hi Dave,

Yes, I am having fun - not sure the beam is set up absolutely right just yet, but I have been doing quite a bit of cutting. At the moment, I am cutting 2mm Rohacell foam (acrylic foam) and it cuts beautifully at just 10% power and 50mm/sec.

I have had a little difficulty in setting the laser origin as the software is not particularly intuitive and I find this process a little confusing. Having said that, I am also finding out some useful little parts of the software that are not mentioned in the manual. For instance; were you aware that to rotate an object, if you cancel the dialogue box that first appears you can then click and drag a line from the centre of rotation? A further click will then rotate the object to re-align with the drawn line. You can also click anywhere on the screen and alter the centre of rotation.

When I first started to use the software and needed to rotate an object I was using the up and down arrow keys or putting a value in the dialogue box but once I found, by trial and error, the other method, I have found it much more dynamic and easy to use.

By mistake I have also found out the usefulness of the air assist. I had downloaded the Dinosoar file from elsewhere on this site and was cutting it from 1.6mm ply. There was a massive plume of flame and smoke and the parts came out covered in soot, very dirty and not cut through. On investigation, I found the compressor valve had closed itself, probably because the pressure was so low, and consequently there was no air assist.

I removed the lens and it was covered in residue from the burn so I cleaned it and tried again, this time making sure the air was getting through - a perfect cut. The air assist is definitely a necessity and for those without it, I would recommend fitting one.

I will report back with any more tips as I find them.

Mike

[dvdlock]

Good to hear you are having fun Mike.

I know the lasercut software is quite basic but I find it perfectly good for my needs. Lasercut 5.3 has been issued with some of the new machines but I found out that it was withdrawn because of some issues with it. Don't know what they were. I'd like to know was additional features it had.

I think I mentioned in another post somewhere that should you need to use the £ sign for any reason, you will need to import if from corel, or similar as the font is not recognised in lasercut.
I didn't know about the rotation feature you mentioned. I shall have to have a play with that.

Also, I found that when using lasercut text feature, t can be a pain to go back and change font size, especially if you have a lot of fonts installed. If you select the text and go to 'tools' and 'convert to curve' you will be able to scale them, and move each character around just by selecting them.

I agree, the air assist is a must. I have put on/off switches for it, and the extraction on the control panel so its easy to get to and easier not to forget. I may even look at making these start up automatically when you 'start' lasing but leaving the switch in place so it can be turned of if not wanted for any reason.

Did you go with the rotary table option? If you did I have a few tips to help with that, consisting of a modification to stop the glass/bottle from skipping on the rollers.

The Dino looks good, nice clean edges. I recently did a F15 fighter and a Beretta pistol.

Good luck

Dave.

[Mike F]

Hi Dave,

If you look at post 20, you will see the rotary attachment that I have. Unfortunately, it comprises a chuck and a large, live centre in the tailstock. I say unfortunately because I think the roller type is far more versatile for engraving things like glasses/bottles. However, I am sure I ought to be able to come up with something that will make it work.

Yes, I have already noticed the difficulty of editing text

My air pump, water cooling and extraction are all wired to the machine so whenever I start it, they all start too. But, it would be nice if the extractor and air pump only started when the machine was ready to cut - I presume this is what you are considering. Please let me know if you get it sussed.

Cheers,

Mike

[dvdlock]

Mike,

Never noticed the rotary in that picture before. I have the roller type and I can see pro's and cons with each. I think once you get going with it you'll probably come up with all sorts of ways to hold the work piece.

Sounds like your aux equipment is already wired the way i'd preffer. I'll let you know when I find a soulution for this. It'll end up one of those 'when I get round to it' jobs.

Regards

Dave.