another error message (Solved)

[donwatson]

Can anyone explain why I keep seeing this error message and what can I do to cure it.
"No supported entities were found, unblock and convert to segments". This message comes up when I try to open a dxf file in T2 after saving it from Inkscape. I must be missing something ??

Don W

[Zax]

It means there's no path data in the DXF, most likely you have some text or other objects that Inkscape does not export unless you first convert them to paths.

If you load the DXF into Inkscape or QCAD what do you get?

If you see the design but T2Laser gives an error either send me the DXF or attach it here and I will take a look.

[donwatson]

Zax,
I get nothing when I try to open them. I don't understand where I went wrong. I engraved a mat on Sunday and it was ok but a little small so I thought I would make another burn but a little bigger but have had nothing but a load of trouble since I tried that. I have attached the jpg I am trying to manipulate. I thought it was 80 x 80 mm but I can't be sure about that. I load it into Inkscape and select Trace Bitmap but nothing seems to happen.
I also attach a pic of the mat that was burnt on Sunday. I have spent a while at this today but seemed to be getting into deeper hole.
thanks again
Don W

[Zax]

Is the original design a vector in Inkscape or this image?

If it's an image why would you trace it to generate a vector and then convert to a raster image for engraving 

You could just load the image and run it.

[ggallant571]

That image is 227x228 pixels. Be somewhat close to 80mm at 72DPI resolution. Why non scale to 800x800 pixels at etch at 0.1. No shade of gray so it would be easy to get a dark burn (an the math is easy!!!).

[Zax]

T2Laser will do that automatically, just set the output size. I actually recommend 0.2 resoluton in most cases as 0.1 will result in overburning the same line and can create a more blurred engraving, but you could test 0.18 or 0.16 if you need fine details on some images.

[donwatson]

Thanks for the information.
@Zax, I will have a go at this later. Heavy rain will need to ease before going out to the shed. It will give me time to work out what I should be doing as I am a bit confused about various things, jpg's,png's, xcf's different programmes using different names etc.
@ggallant571, thanks George I value your comments as you know. I use Inkscape and Gimp for my images, mainly because they're free and I get confused about formats very easily. I have downloaded your image and will try it out later. One thing I do notice is that engraving on the laser machine and printing on a printer (HP Photosmart) gives 2 different results.
take care
Don W
PS I will be back

[Zax]

There are 2 different types of files when it comes to these machines, or any CNC in general.

Raster = images made of pixels, a raster image will be engraved by scanning back and forth to generate the result, these are jpg, png, bmp files.
Vector = drawings with coordinates and paths, for T2Laser these are dxf and plt.

You can trace a raster to generate a vector, the real term for this process is vectorization. If you fill a vector it becomes a raster, unless you use a pseudo fill (hatching) in which case it is still a vector but appears like a raster.

Are you more or less confused now  .

So if the design is for cutting you would want a vector, or if you want an outline like a line drawing a vector may be appropriate but for a picture, even black and white clip art like your design a raster is probably the correct format as you need it filled.

[ggallant571]

@Zax - I agree with your definitions but there are a large group of laser etchers who use the term "vectorise" slightly different. I have asked for clarification but do not get a clear consistent answer. I think (not a good verb for me) that they refer to starting with outlines and letting the tool generate the rasters which they call vectors. Seem to be aligned with the Lightburn community. I think the advantages to this scheme are that the shape can be readily scaled and the laser line density is set at burn time. Nothing that can't be done a multitude of other ways. I'm just annoyed that they reused (redefined) common terms.

A possible side effect is a reduction in time when etching small isolated shapes. Less less laser OFF travel time

I do 99.9% of raster images at 254 dpi because it:
  1. Is mentally easier to do the scaling.
  2. At a resolution that is denser than what the laser can burn.

With strictly ON/OFF images it doesn't matter because I just adjust the speed. For gray tones not so good.

[donwatson]

I have been busy today trying to get the results I want with T2 Laser. I have tried the advice set out in the last 2 posts and have had some great results so thank you both. Scaling was a problem/confusing so I just used the image that George posted and scaled it in 'Output'. I haven't quite solved all my worries But I am definitely getting better.
I ran trials using the image George posted using Black and White, Dithered and Greyscale modes. I used Diagonal, 1000mm/min, 10-245, 0.2 and the Output set at 80x80.4  The trials all ran around the same length of time (37 minutes) although I would like to see that reduced somehow. I wonder if a speed setting of 2000mm/min would half that time ??
More trials later if the rain stays off. Attached is the pic of todays burn on the other side of the ply coaster.

take care
Don W

[Zax]

Laser power should almost always be 0 to 255 (if using my default firmware and parameters).
Resolution at 0.2 looks good with your laser.
Feed rate 1000 looks like a good burn, increasing to 2000 would be faster (not quite 2X but close) however it will also be a much lighter burn.

As you are using a black and white image (ggallant571 version), those 3 settings (grey scale, dithered, black/white) will have little effect but of course black and white is the better option to ensure crisp edges. If you use your blue image then selecting black and white would be required.

I would say the result looks great.

[ggallant571]

I think the "Shed" needs a little decoration. Perhaps adding some shingles to the roof and/or some waves to the edges. Will play this evening  unless you do it first.

[donwatson]

Thanks for the comments.
I had a play today and did the dragon I like. I will paint him/her/it tomorrow.
@George, Feel free to decorate I will put it before the committee to see what they like.
Now that the weather has improved I look forward to doing some work tomorrow.
@Zax, thanks for the iinformation
take care
Don W

[Zax]

It looks like you are getting the hang of it nicely. Well done.

I'm not saying ggallant571 is wrong, but he's wrong. In my experience it's best to keep the logo simple. It allows you to make it from wood, acrylic, vinyl or even neon tubes if you wish and it will look great. Think of the big brands and their logos e.g. Apple, Nike, McDonalds.

[ggallant571]

I once thought I was wrong, but twas not the case.