Shop Note

Gratings

Clay Feldman

If you own a hobby table saw, here's a nice way to make gratings (this is from my Lexington Practicum manuscript):

Hatches

We have three hatches to make four gratings for-forward, main (two sections) and after-and we'll use the same format for all. That will be scale two-inch wide crossbars and two-inch square openings. For kit builders, the option of using laser cut grating material (Lumberyard), cast Britannia gratings (BlueJacket) or pre-cut interlocking gratings (Dromedary) should provide sufficient sources; just build the coamings and cut the gratings to fit. It's a little more complicated if you are scratch building. You can make the gratings out of longitudinally and crosscut solid blocks, as I usually do, or use one of the egg crate techniques that many other modelers use.

A block of pear 1 ½" wide, 4" long and 3/16" thick will do for all the gratings, with a little bit of luck (It's easy to break off some of the wooden "teeth" made in the sawing process). I used a Preac table saw for my grating work, with a 0.030" slitting blade, but the Byrne saw with the micrometer adjuster is just as good; even an old Dremel table saw with a wooden jig will do.

A half-done blank and the
saw setup
Do the crosscuts first, setting the blade to protrude the same height as your saw blade is wide, 0.030". Make the first crosscut fixing the fence-to-blade space with a short length of stock the same thickness as the blade. For the next and subsequent cuts, remove the spacer, back off the adjustment screw the thickness of two pieces of the spacer scrap, remove the spacers and move the fence to the screw and then make the cut. Keep repeating this process until you run out of table space, finishing up from the other end; they don't have to match in the center. (See Fig. 8 ⇒ for a half-done blank and the saw setup ). Complete the work on the blank by rotating it 90°, then doing the same sort of groove cutting, but with the blade now set to cut 3/64" deep.


A half-done blank and the saw setup

Cut some strip stock to blade thickness in width and thickness. Do a test strip first to make sure the stock fits nicely in the cross-cut grooves on the block and that the strip is flush with the surface of the block after insertion. When you're satisfied with the fit, cut enough strips to fit all the crosscut grooves. Cut the strip stock into about two inch long pieces and carefully glue them into the crosscuts using diluted yellow glue. Sand the surface of the block smooth.

Cut the four gratings blocks over-size on the table saw, then finish to the outside of stringers on all sides to give the appearance of a framed grating. Try to get the grating plus its coaming stock to fit right on a pair of deck seams on each side. The coaming will be about three scale inches thick, 3/64" and eight scale inches high, 1/8".

Completed double main hatch, gratings installed
You have already figured out, no doubt, that if you sand off the bottom of hatch blanks, you will have a see-through grating. On the other hand, at this relatively small scale and with no open frame structure to actually see through, there isn't much need. Probably better here to sand and file the deck curve into the bottom of each block and thickness the blocks on sandpaper to be the same net height (1/8") as the coamings. The coamings are half-lapped. The main hatch side coamings are the length of both hatch covers, plus 1/16", the thickness of the beam between them (removable on the real ship). The extra width of that part of the hatch frame is to accommodate the aft cradle for the ship's boat, to be installed much later. The installed main hatch is seen in Figure 9 ⇒ .


Completed double main hatch, gratings installed

While you're doing coamings, this is probably a good time to make the one that surrounds the scale one foot square (3/16") hole in the decking forward for the stove pipe.

Have fun!
{Clay Feldman}

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