Printing Grey(Gray)!

[monk]

Hello

 

We have two plotters where i do some work HP 1050's and they are colour plotters.

 

What my aim is, is to take our xrefs which are building outlines and plot them on 253 as grey.

 

This is so they are thinner and lighter than our services on top.

 

The plotter however cant cope with plotting grey! The lines that come out are a mixture of the 3 colours but are somewhat obviously but lots of dots rather than a grey line. So if you imagine there will be a red,blue,red,blue, yellow etc etc

 

Any one else had issues plottting in grey?

[ReMark]

These are normally colour plots to begin with and not black and white?

[monk]

These are cad drawings with our usual CTB file which I have set this particular color to plot as 253 using object colour at 0.05 etc. I have also tried using truecolour. The drawings plot fine other than the plotters cant actually seem to "make" grey. The drawing will PDF ok and look right. so im thinking its the plotter. Just seeing if anyone has come across this.

[ReMark]

It doesn't sound like an AutoCAD problem. Sounds more like a problem with the plotter itself or the driver.

 

Have you been able to plot the colour gray in the past?

[monk]

Not to this plotter. For another company i used designjet printers and they worked ok. Ive tried all sorts of settings both within the CTB and on the plotter. i.e dither, screening, truecolours, to no avail!

[ReMark]

And you are using the latest available driver right?

[rkent]

I used a 1050C for years, plotting in color and never had a problem with grays. I did use color 8 or 9, I don't think I ever tried 253.

[irneb]

Try setting that colour in your CTB to an RGB value instead of the 253 ACI colour. Also a lineweight of 0.05 is going to give you huge problems with any DPI below 700:

 

• Lineweight of 0.05mm => 0.05 / 25.4 = 0.001968503"
  
• DPI700 => 1 pxiel width = 1 / 700 = 0.001428571"
  

And then generally grey (and any other "non-standard" colour - i.e. not black, cyan, magenta or yellow) will be made up by placing a mixture of these dots next to each other. So actually you'd want an absolute minimum of 3 dots linewidth to get a "descent" looking "grey" line at a "normal" 300DPI: 1/300 * 3 = 0.01" = 0.254mm

 

For that reason I try never to use coloured / grey lines thinner than 0.25. Unless you can up the DPI on your plotter to 3x700 = 2100DPI as a minimum, you'll have these "dashed" / colour-bar like lines when using 0.05mm. And don't be surprised that a printer stating 4800DPI will still cause problems - the print head definitely doesn't print at that DPI, it goes over the same spot numerous times to place so many dots on that area (usually overlapping them). Not to mention your prints are going to me infinitely slower.