What tools should we use for engraving lines? How to do it? Where we need to be careful in/cautious about?
As far as I know, the most basic method required for linE engraving is merely one utility knife. Although it would create embossments along the edge (See Figure 1), but they can be removed later using the knife. As shown in Figure 2 is the line engraved by the author with a utility knife; and Figure 3 shows the result after removing above mentioned raised edge. In Figure 4 you can see the effect of Gundam Marker quick lining and polished with 1000# silicon carbide paper; now you know what it should look like after the process of line engraving.
Yet there is still one downside with this method: The line engraved can be too shallow that it can be flattened after painting (Especially by hand brush). To prevent that from happening, usually I would deepen the line with utility knife or P-shaped engraver (See Figure 5). And Figure 6 is how it looks after painting by Mr. Surfacer 1000 (So it is convenient for checking and observing). As you can tell, even with thick base painting applied the engraved line is still quite clear.
Frankly the method I have just introduced is one of many ways to engrave line, in the real modeling cases, (See next figure) various methods and scribing tools should be used for different surface situations (e.g. flat surface, convex surface, and concave surface). From left to right: p-shaped engraver, utility knife, awl, v-head scriber (From Hasegawa Tritool), saw scriber (From Hasegawa Tritool) and Screwdriver (See below).
One problem of line engraving is that you can still make mistakes with the best method and finest tools, (Figure 8 shows a wrong scribing situation after polishing and painting) so it is necessary to master the repair technique. Here are five helpful steps to share with you learned to my own experience. (collectedly smiling):
Apply Tamiya Putty to concave surface of the wrong scribing. (See Figure 9, used Tamiya Poly Putty because could not find any Tamiya Putty); wait until the putty is completely dry out and done shrinking;
Use fine silicon carbide paper polish the putty-applied area (Figure 10); then redo the scribing (Figure 11 is the painted result after redo). Because dried putty is more crispy in nature compared with regular plastic, thus be careful not to press too hard when scribing or you might scoop up small pieces of it.
Before we go to more details of ling engraving, we need to clear out the reasons of why we need to engrave lines on model especially robot, usually there are two:
The lines came with model need to be deepened (e.g., some lines scribed by the manufacturer are too shallow for perfect display), so we have to do it again; or there is no line at all, and we want to add lines for more details on the surface for aesthetic purpose. Either one, in my opinion, requires straight and clean lines if we are to make them ourselves.
To keep the surface clean, I would always make tiny dots marking the distance from the line to the side measured by metal ruler (Figure 12), repeat this several times every certain distance, for example you can make one every 10 cm, then connect them into line, now use metal ruler or DYMO tape(Figure 13) to guide while I scribe with special screwdriver (Figure 14). The advantage of this technique is: Measured distance is precise and convenient to connect, so you would have straight and clean line; metal ruler is tough and unlike those plastic ones might have damaged edge; DYMO tape can be pressed firmly to the model surface without scratching it; the special screwdrivers I use are all minus screwdrivers made in Taiwan, which come in a pack. I made them quite sharp by grinding, that turned them into handy scribing tools, the sweet thing about them is the different sizes are available for various surfaces compared with awl and utility knife both have only one size.
Other situations include line engraving on convex or concave surface (e.g., the waist armor of Zeong), or line with complex shape (e.g., trapezium), so how it is done? In that case I recommend use thin (Like 0.5 mm) transparent plastic plank, cut it into the desired curved shape (Figure 15), and stick it to the corresponding surface by double sided tape and start engraving. You can turn one complex shape scribing into an easy task. Of course, with the help of ruler and more plastic planks, you can have more complex designs become possible; which take practice to make proficient. Because the plastic plank can be cut into almost any shape you want, plus it is transparent, so this is extremely customizable method and very easy to navigate your scribing tool during engraving.
