How to Make and Insert Cross Wires and Post Reticules

American Rifleman, vol 69, No. 24, Sept. 1, 1922 – pages 13, 25

By J. W. Fecker

ONE of the most vital parts of a telescopic sight are the cross wires or other mark used to center the image in the field. If they are not satisfactory, the entire value of the instrument is lost, for its accuracy depends to a great extent upon the clearness of these sighting marks, and their effect upon the shooter's eye.

There is no sighting mark which can be universally used. What is very well adapted for one particular shooter’s eye may be most unsuitable for the next person who tries to use it. In like manner, there is no sighting mark which is equally well adapted to indoor target shooting, outdoor range shooting or hunting in a dim, poorly lighted underbrush. For these reasons a shooter will often find the standard factory reticule unsatisfactory and is often tempted to try to change and make one to suit his own requirements, especially when the factory can not supply him with what he desires. He can readily do this if he has more than a little patience and is not tempted to give up too easily.

There are various materials which can be used for cross wires. Very fine wire can be had in copper, silver, platinum and tungsten. In wire thinner than one thousandth of an inch diameter, the copper, silver and platinum tends toward a crystalline structure and is likely to break, when used on a rifle with heavy recoil. Fine spun glass can also be used, but it is not as good as metallic wire. Tungsten wire can be obtained as fine as one-quarter of a thousandth of an inch in diameter, and it is remarkably strong. The one thousandth tungsten wire will support 3 to 4 ounces without breaking. Silk fibre and spider threads are very good for cross wires. Spider threads are as elastic as rubber bands, and when properly inserted will not shoot out on any rifle.

The spider threads are not those taken from the web of the spider, but from its cocoon. Late in August and early in September the large yellow field spider with a black cross on its back spins its cocoon in the fields. It is most frequently found on golden rod and around blackberry bushes. This cocoon is about three-quarters of an inch in diameter and is a round brownish ball with a rather hard crust on the out side. It should be cut open and thoroughly steamed to kill the eggs inside. Between the egg sack and the outer shell is a fine cushion of reddish down. This is the part to be used for cross wires.

The tungsten wire can be obtained from any maker of incandescent lamps. Fine silver and platinum wire can be obtained from Baker & Co., Newark, N. J. .

The reticule cell should be thoroughly cleaned before starting and should have the scores cut in for locating the wire. If no scores are cut in the cell, they can be cut in the following manner: Upon a large white sheet of paper, draw a circle 12 to 15 inches in diameter, and accurately lay off 4 points on circumference exactly 90 degrees apart. Put a pin through’ each point and stretch a fine thread over each pair of diametrically opposite pins, so as to give you two fine threads exactly at right angles to each other. Slip the reticule cell under these threads and accurately center it under the intersection of the threads using your eyepiece or other magnifier to set it as close as possible. With a fine needle make a dot where each thread crosses the edge of the cell, and take a very sharp knife and lay it diametrically across each pair of these points and press down, so as to leave a very fine sharp line across the cell. Use your magnifier freely to see that the knife edge is exactly over each dot before you bear down to cut the score. The scores should not be deeper than 0.003 to 0.005 inch.

In a factory where reticules are made, the reticule is centered upon a stud, mounted on an index head, and the scores are cut with a very fine dividing cutter and accurately indexed so as to be exactly at right angles.

If spider line or silk fibre is to be used, first prepare two bent wires, a long black hair pin is just the right weight, by putting a small ball of beeswax on each end and spreading them so that the distance between ends is about one-quarter inch greater than the diameter of the reticule cell. With a long needle, pick out a loose end of thread and take a hold of it, letting the cocoon hang down. Wrap this end about 6 times around one waxed end of a wire, then turn over the wire so that the thread comes over the other end of the wire, and wind the thread around the other end about six times, and pull off the cocoon. You will have a fine thread of spider silk, firmly fastened to the two ends of the hairpin. It should now be hung some distance over a small vessel of boiling water, so as to steam the thread and make it absorb all the moisture it will hold. If the thread is not steamed, it may slack up later on a damp warm day. After the thread has been steamed 10 to 15 minutes, take the hair pin by the back end, and slowly and carefully lay it over the reticule cell so that the fine thread will fall as nearly as possible in one pair of scores.

Allow the back end of the hairpin to rest on the table, but the two open waxed ends should not touch the table. They must hang free, supported by the thread laying across the reticule cell. If they touch, place coins under the cell until the ends of the hairpin hangs free. The weight of the hair pin puts just sufficient tension in the thread.

With a magnifying glass and a long pointed needle push the thread over until it drops into the scores. When it is in both scores, place a very minute quantity of thin shellac or collodion in the scores to stick the thread down. The less material you use to stick the thread in with, the quicker and more securely it holds the thread. A large drop of shellac will dry slowly, and contracting as it dries, it will pull the thread with it until it breaks. The least possible amount of shellac is the best. After ten minutes cut the ends of the thread, and place a new piece on the hairpin and put it in the other pair of scores.

Fastening the spider silk on the wire holder and laying it in the scores requires a little practice and patience, so do not be disappointed if you break the first dozen. Once you have it cemented on and dried you will have the finest and most uniform wire. This spider silk is about one ten thousandth of an inch in thickness, and when properly focused in the eyepiece it is as black and opaque as any heavy wire.

When using metallic wire, it should be soldered in the scores with a jeweller’s blowpipe, and placed in tension, by hanging a small weight on each end, the size of the weight depending upon the strength of the wire.

Care must be exercised to heat only the point where the wire touches the cell, very quickly, for if the entire cell becomes thoroughly heated before the solder sets, the wires will be slack upon cooling.

Tungsten can not be soldered or brazed, and only spot welded with great difficulty even with elaborate welding apparatus. The only secure way to fasten it in place is to clamp it under a washer, held down by a small watch screw. After the screws are all turned down securely and the wire firmly held, put a little shellac over the wire and screw-head as an added precaution. Mounted thus tungsten wire will stand any shock. The only advantage tungsten wire has over spider thread is that it can be obtained in a variety of sizes, while spider thread is pretty uniform in thickness.

The making of a good post, either flat topped or pointed, is an equally ticklish job. Post reticules are made of thin steel or hard brass wire. The thickness depends upon the focus of the eyepiece. For short focus eyepieces, which magnify highly 0.005 to 0.007 of an inch, is about right. For long focus eyepieces with low magnification, 0.010 to 0.015 of an inch gives best results.

The first operation is to thoroughly straighten the wire. Drive about a dozen or fifteen 1 ½ inch nails into a board about one-quarter inch apart and stagger them about one-sixteenth inch, as shown in the sketch.

Wind the wire in and out around the nails and slowly pull it through the row of nails. Repeat several times until the wire is straight and free from kinks. A little soap is a good lubricant for this operation. The alternate right and left bending will straighten the wire. After thus straightening it, examine it carefully with a magnifier and pick out a part which is particularly smooth and of uniform diameter, and cut it out of the piece. If you desire a square end post, clamp this wire firmly between two metal plates with square ends, so that the wire just barely sticks out beyond the plates, and using a very fine oil stone polish it down until the stone has polished the ends of the two plates thoroughly. Take the wire out and examine it with the magnifier. The end should be perfectly flat and square, with sharp, clean-cut corners. If not just right, place it between the plates again, and repolish the end. The finer the oil stone and the lighter the pressure, the sharper will be the square end on the post. With a little practice a very nice post can be easily made.

A pointed post is rather difficult to make without a speed lathe and a very small chuck. It can, however, be made by hand. To do this, take two small, narrow strips of metal and cut a shallow V groove in each, so that when placed together they will just clamp the wire securely in the groove. The wire is thus held like the lead in a pencil and holder and wire can be rubbed down to a sharp point, just as one would grind down a pencil on a stone. Considerable skill is required to produce a point which is sharp and uniformly round.

Having now made the post, the next step is to place it in the cell. The score for the post should be cut deep enough so that the post is half imbedded in the cell when it lays in the score. Then place the horizontal wire in its scores and fasten it. The post can now be laid in its score and the end allowed to rest upon the horizontal wire. The post should be slid back and forth until the end projects the desired amount above the horizontal wire. The post is now clamped in position with two small watch screws, or can be soldered with a blowpipe. The reticule should be carefully examined with a magnifier when completed and any dust or lint blown off the wires. A skillful operator can remove dust from a spider line with a sharp needle, but this is more often disastrous than not. With a little practice and patience, the average rifleman can soon achieve the necessary dexterity to make for himself any reticule he may wish, quickly and economically.