Material. 140 mm of 12-mm diameter bar and a hand length of the same material.
Additional tools. A 30-mm diameter drift.
METHOD
This method is useful for making heavier eye-bolts and similar items with large-diameter eyes. For practice, again use a 12-mm diameter bar, but you may try heavier sizes if you want to. Figure 6 illustrates the production steps but leaves all dimensions optional. Assume an eye with an internal diameter of 30 mm. Calculate the amount of metal needed to form the eye and cut off that amount.
Calculation
| Inside diameter of ring | = | 30 mm |
| Mean diameter of ring | = | 30 ± 12 mm = 42 mm |
| Metal required | = | 42 x 3.14 ± metal thickness x 2 42 x 3.14 + 24 |
| = | 131.88 ±24 =155.88 | |
| = | approximately 156 mm |
Cut off metal required, heat and upset both ends, bend and adjust (Fig. 7). Scarf in the manner used for a chain link, using the edge of the anvil or a small fuller. Close up and fix the position of the scarfs (Fig. 8). Take a full-welding heat and weld (Figs 9 and 10), leaving surplus
material slightly pointing outward from the eye (Fig. 10).
The welded joint is then scarfed over an edge of the anvil to give a V-shaped indentation (Fig. 6B). The hand length is then upset and scarfed (Figs 6B and C). Take a full-welding heat on both scarfs, position (Fig. 13) and weld with light, rapid hammer blows.
Reheat and make final adjustments to the workpiece. Cut the shank to length and check the end diameter for
threading. Use a hole gauge to ensure that the diameter is accurate. Heat to a dull red heat all over, clean with a wire brush and allow to cool in the air.
Take care to leave the junction of the shank and the eye well-radiused (Fig. 6D). Do not use a swage unless it is well-radiused to give the correct section. The eye may be rounded up by using a 30-mm drift or gently working the piece around the beak.
