CAD print output. ‘white’ text on a black dial face. (silhouette?)

[Ian PParticipant @ianp]

I have created 2D CAD drawing of some scales to fit onto meter movements and want end up with text and index marks in white on a black background.

I have a monochrome laser printer but I cannot find any setting that allows it to invert or reverse the way it prints. Colour laser printers seem to offer inverting the colours, but using inverting or reversing as search terms has led me down many rabbit holes.

I have created the dial designs with 2D autocad and a solid ‘fill’ with a black hatch pattern works for all the calibration ticks and arcs, with the text it just shows the character bounding box rectangle. Autocad has all sorts of layer features but does not seem to have ‘bring to front’ control.

Has anyone tried using white toner, I believe it exists

Ian P

[Michael GilliganParticipant @michaelgilligan61133]

It’s a long time since I used Autocad, but I don’t recall any problem adjusting the order of the layer-stack.

A quick search found this, which looks relevant:

https://help.autodesk.com/view/BLDSYS/2022/ENU/?guid=GUID-52E7EC1F-4663-4D8D-994E-004279747678

MichaelG.

[JasonBModerator @jasonb]

Can’t help with Autocad but easy enough with Alibre

PDF

[Ian PParticipant @ianp]

The Autocad command is too new for the version I have but I know what I want to do is possible but I’ve forgotten how!

Picture is of some dials I did in 2007 which I did in Autocad (although I may have exported them to CorelDraw for printing).

I think I will also investigate using a printshop as they may be able to print white on to some surface which is ‘dead’ black, another thought is a vinyl cut out of black, so a sort of mask, but long term stability in a vehicle interior might be a problem.

For interest, the small gauge on the right is ex helicopter and has a non reflective glass and the dial face seems to be some ‘light absorbing’ paint.

I will do more experimenting with Autocad, I know one method that will work but its longwinded, as each character (of the TTF font) has to be converted to polylines so the unbroken outline is a barrier to the (surrounding) hatch filling.

Ian P

 

[Ian P]

On 13 May 2024 at 16:17 Ian P Said:

…does not seem to have ‘bring to front’ control.

DRAWORDER or _DRAWORDER has been in AutoCAD since forever.

[Michael GilliganParticipant @michaelgilligan61133]

I date back almost forever … the newest version of Autocad that I have ever used was Release 9

… and that was only on a City&Guilds course, after I had changed employment.

MichaelG.

 

[SillyOldDufferModerator @sillyoldduffer]

Does AutoCAD have an option for exporting the screen as an image (jpg, png or bmp)?   If so ‘export’ may have an invert option along with setting the image dimension etc.

If AutoCAD can’t export a bitmap, then use Windows Snip to capture the dial from screen and save it as dial.png.

dial.png can be edited by any image manipulating program, such as Paint, and these usually support colour inversion.

As an example, I created a dial in QCAD to show the steps.  The original dial in QCAD looks like this, note the yellow construction circle is converted to black:

 

I exported the QCAD drawing as a png, which when opened with Explorer on my system appears thus:

 

Then I used ImageMagick from the command line to negate the image into a new file, dialinv.png

convert dial.png -negate dialinv.png

This is the result in dialinv.png:

The advantage of ImageMagick apart from being free and open-source, is that it can operate on lists of files, which is handy when gazillions of images all need the same treatment – mass production.   Such as producing thumbnails of all the pictures in a folder, thousands of them.  Downside is having to learn the commands, rather than just pointing and clicking on a GUI.      But as can be seen from the example, inverting (aka negating) a single file isn’t difficult.

Dave

 

 

 

 

[Ian PParticipant @ianp]

Thanks to Michael, Jason, Dave and DC31k my problem is solved!

DrawOrder was the key really and I can now see a path to getting the images on paper. Oddly when I exported from Autocad (wmf) the height and width proportions were screwed up giving ovals for circles.

Printing direct from Autocad is fine but my printers output is grey not black.

A little more work to do tomorrow.

Ian P

 

[Ian PParticipant @ianp]

This is one of the dials I want to get onto a suitable media. I created the this as a jpg by screen capture from the  Autocad screen (I may need to capture again with the dwg zoomed out to get the highest resolution).

Now to find a way to get this printed onto a thin substrate that will already have a matt surface or will accept a matt varnish/lacquer.

Ian P

[Michael GilliganParticipant @michaelgilligan61133]

I haven’t had time to do more than skim through it, but this looks like a very informative page:

https://granthams.co.uk/blogs/insights/the-whys-hows-of-white-ink-printing

MichaelG.

[Ian PParticipant @ianp]

Transferring the design to paper is a lot more complicated than I thought!

In Autocad the final artwork is now finished and because it is a vector based program the resolution is (effectively) infinite. I can print (onto white paper) from Autocad to either a Brother mono laser or to an HP multifunction inkjet. Both printers have sufficient resolution to give sharp edges to the scale characters and marks, however the black from the laser is not really dense enough so I have spent time trying to print onto matt photo paper with the HP inkjet but the printed output shows banding and is also not dense black.

In photo editing programmes when printing to the HP there are options to tell the printer what type of paper is in use so it can adjust its ink quantity (or whatever) to get the best results for, say photographs. In Autocad however many of the printer features are greyed out and whatever I do I cannot get access to paper type settings. The one thing that Autocad printing is good at, is producing images at an exact size, something that I suspect might get lost if I convert the drawing to another file format.

I phoned a high street photoprinters today and my plan was to convert to jpeg which is the only format they said they could accept. Autocad will export as wmf but when I open it in a photo editing prog (to then save as jpg) getting the scaling gets cocked up so getting the dial diameter correct has so far defeated me.

So, still work in progress.

Ian P

 

 

[DC31kParticipant @dc31k]

Have you searched ‘speedometer dial printing’?

You cannot be the first person in this country with an old vehicle who requires this service.

Speedy Cables come up as the first result when I do so. Also Classic Speedometers and Lockwood International.

You have done the hard work, the artwork. Relative to this, the cost of printing should be quite low.

To me, someone who prints on rigid media (e.g. machinery tags) might better align with your needs than someone who prints on paper.

[Ian PParticipant @ianp]

I know of (and have bought from) Speedy Cables but I’m not sure the cost of printing would be quite low. If the dials were flat then possibly they could be done using a silk screen but these gauges are like biscuit tin lids and have their edges turned up about 2mm so were either transfer printed or dished after printing.

After many experiments with the inkjet printer I gave up, then I wasted time trying to convert my CAD drawing to a high resolution monochrome JPG whilst retaining dimensional accuracy, this was proving hard to do, when late last night, it dawned on me to put a new toner cartridge in the laser printer….. problem solved!

Over 10 years ago I was given a few sheets of some special paper by a company that designed and re-faced the instruments for a low volume production car and it prints dense black in my Brother laser so I am now in the process of sticking it to the dials and very carefully cutting all the apertures with a scalpel.

Ian P

 

[Ian P]

On Ian P Said:

… then I wasted time trying to convert my CAD drawing to a high resolution monochrome JPG whilst retaining dimensional accuracy, this was proving hard to do, when late last night, it dawned on me to put a new toner cartridge in the laser printer….. problem solved!
…

Doh, new technology has created many new opportunities for gremlins.   Not only can they hide tools, now they can block inkjets, fade toner cartridges and make 3D printer filament go brittle.

Unfortunately jpg and other bitmap formats have no notion of scale.   They represent proportions, colours, and contrast but the image has no idea how big the original was.   A camera cannot tell if it’s attached to an x1200 microscope or a reducing lens.      So sizing a bitmap image to fit can be a tricky trial and error process.   And what the operator wants can be deranged by the print software.   It attempts to be idiot proof, assuming for example, that the user wants margins and layouts that fit on the paper sizes the printer understands.   It’s possible to get into a fight between the operator, what the application thinks is sensible, and what the printer will accept.

Dave

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