Printing Strategies

Getting size and resolution right:

Getting bit-mapped Images printed at the correct scale and resolution has been a pain for me since my bit-mapped image editor (L-View Pro) is not good in this area. I found that I had the easiest time by embedding the bit-mapped graphical files into MS Word documents and then printing the documents. (All word processors these days are quite good at incorporating graphics so non-Word users are likely to find this a good approach in their word processors as well.)

Here is the math:

t Word's printing drivers assume that an embedded picture (scaled at 100%) is intended to be printed at 96 dots-per-inch.

t I wanted 4 times better resolution than this, so I set up my bit-mapped graphics files so that they were 4 times 96 dots-per-inch, that is 384 dots-per-inch (152 dots-per-cm).

t After each graphic file was embedded into Word as a picture, I scaled the picture to 25%.

The only way to keep this all straight was to include an "Inch by cm" rectangle like the following in each file that I printed:

t This was originally created in Visio as a one inch by one cm rectangle. (In Visio, the actual measurements are displayed on the status-line.)

t The drawings were exported from Visio (saved as) GIF-files. There is a parameter in this operation where you can set the pixels per inch. I used 384 pixels per inch. Therefore the export drivers built a bit map for this rectangle that was 384 pixels by 152 pixels. (For Visio, the boundary of the rectangle is only half-included – ie, one of the black edges is part of the 384 pixels but not the other.)

t In each graphic file, I checked this by using the rectangle-selection tool to select the rectangle's pixels and read out on the status line that the selected area was indeed 384 pixels by 152 pixels.

t After embedding the file into Word (and rescaling its size to 25%), I turned rulers on and scrolled the document so that the rectangle was right next to the ruler so I could verify that the rectangle was exactly one inch long.

t After printing, I got out a real ruler and double-checked one more time.

Two-sided Printing:

Often, both sides of a one-sheet thickness model-part show in a model. Wouldn't it be nice if the back side of the part was colored?

It turns out that this is quite easy to do with today's printers (even cheapo HP-inkjets like mine) by doing two-sided printing.

Okay, to print a two-sided sheet, you need:

t Two graphics files - one for the front-side and one for the back-side. (See below for what I used for the rebuilding of the Krakus.)

t The back-side graphics file must be horizontally flipped from the front-side.

t The printer will never exactly register the two printing passes, so the back-side image must be colored "outside of the lines" to compensate for the slight registration errors.

§ In my HP printer, the top-of-the-page registration is excellent.

§ But the side-to-side registration can be off by up to 1 mm. If it is really off, just print it again because it appears to be random!

t You have to center the front-side picture and the back-side picture on the page so that they register. Word helps with this chore a lot:

§ When you insert the graphics-files into the word document there are two ways that the pictures can be embedded into the page: The picture can float over the page or it can be embedded (like a great big character) right in a line of text.

§ Choose to embed each picture like a great big character within a line of text. (On newer versions of Word: Format Picture: Layout: Advanced… In Line With Text)

§ Place each picture as the top line on the page with no other chars. Specify centered-text for that line. (Format Paragraph: Alignment = Centered)

t When printing, you have to know how to insert the once-printed sheet for the second pass. For almost all printers the rule is: HEAD IN, FACE UP.

For rebuilding the Krakus, I had two two-sided sheets: one printed on card-stock (1/3mm) and one printed on thin (1/10mm) paper. Here are the graphics files so that you can see the techniques.

(The images are shown in reduced scale;
Click on the images to see actual sheets at 4-times resolution.)