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Passionate about forging work, Guillaume Tempesta made a percussion tool, a cross between the "martinet" and the "bell". Called sheep, it lightens the work of hammering on anvil.

Mid-martinet and half-hammer percussion tool: the sheep

Difficulty: 4/4
Cost: less than 1,000 €
Time: about 80 h
Equipment: meter, square, locksmith tooling, drill, bench or drill press, grinders Ø 125 and 230 mm, sheet metal shears, arc welding machine, forge or oxy-acetylene torch, chain hoist, hydraulic bending machine, lathe metal, milling machine...

Not being able to make a "hammer" (big hammer powered by a paddle wheel) to work the steel bars, our reader was inspired by the "bell": a percussion device used to drive the piles using a cylindrical mass (sheep) falling vertically and reassembled by a cable winch.

A recovery mechanism

Here no winch, the cable is stretched by an eccentric driven by an electric motor. The eccentric consists of two rollers mounted in clevises welded at 180° to each other on a 13-inch rim. The rest of the mechanism is made from R5's rear drains, including the hub and the welded rocket at the center of the wheel that serves to drive the assembly. This mechanism can rotate about a quarter turn on the rim between the welded abutments near the edge. This has the effect of completely freeing the cable (before the other tensioner roller comes to take over) and allows the sheep to hit the anvil at full speed, 200 times per minute on average.

No chain, no belt...

It is an electric motor running at 700 rpm which is responsible for driving the wheel bearing eccentrics. The engine pulley rubs for it directly on his tire, which does not prevent the presence of a "clutch". Designed for safety reasons, this device also has the effect of preventing the engine from starting under load. Engine launched, its pulley comes into contact with the tire by pressing a large pedal. As soon as it is released, a spring returns the engine to its initial position and a limit switch cuts off its power supply.

Foolproof editing

The two large superimposed tubes that accommodate the sheep allow to position a small cylindrical anvil (interchangeable) and leave the 90 mm race of the sheep. Its 38 kg develops on impact a force of more than 30 joules. The tubes are assembled by welding seams of several centimeters and the sheep is guided by twenty ball bearings bolted on four plates arranged in a cross. All the nuts are braked and the screws, taking in threads, are put with a threadlocker.

1 MANUFACTURING OF THE TRAINING MECHANISM

1 MANUFACTURING OF THE TRAINING MECHANISM

Weld the rear hub rocket into the center of the rim (a string on both sides). Countersunk or ground, the stops correspond to the openings of the rim. Weld them at the back 180° from each other.

Metal work: making an electric sheep: making

Cut the center part (hub) of the brake drum. Overlay the drop (lamé and flipped) on the hub. Thread everything on the rocket, with the corresponding tapered bearings.

Metal work: making an electric sheep: electric

Tighten the nut in the center of the hub. Add crenellated washer, cotter pin and cover. Cut out the center of another rim, weld it to the drum chute. Bolt on the hub.

Metal work: making an electric sheep: electric

Make screeds (in flat iron 40 x 10 mm) pebbles. Weld the screeds 180° on the drum chute, welded under the flange. The supports of the clevises coincide with the abutments welded on the rim.

Metal work: making an electric sheep: work

Weld the other rocket onto a rectified spacer. Then weld together against the lower cylinder

Metal work: making an electric sheep: work

Finally, thread the bearings and the second hub (cut on the lathe).

2 REALIZATION OF MOTOR AND PEDAL BRACKETS

2 REALIZATION OF MOTOR AND PEDAL BRACKETS

Heat and bend the components of the motor bracket and pedal. Assemble them to the engine mounting plate and mount the whole (pinned pin) on the base of the lower cylinder.

Metal work: making an electric sheep: work

So that the pedal does not touch the ground while being actuated, a turned spacer limits its movement. It is blocked at the end of the threaded rod M16 which passes through the lower cylinder to retain the cable (actuating the sheep).

Metal work: making an electric sheep: work

Bolt the engine then the wheel and the eccentrics. Then add the reminder mechanism.

Metal work: making an electric sheep: making

Weld the ring at the top of the engine mounting plate and, just opposite, the M16 threaded rod and the spring.

Metal work: making an electric sheep: electric

Bolt the end switch bracket to the left side of the engine mounting plate. Just opposite, on the lower cylinder, solder the small flat iron stop of the switch.

3 ASSEMBLY OF THE GUIDING SYSTEM

3 ASSEMBLY OF THE GUIDING SYSTEM

Bolt bearings and spacers (turned) on their plates (drilled and tapped). Weld these plates on those of fixation, introduce them in the superior cylinder and screw them by the outside.

Metal work: making an electric sheep: metal

Drill the flanges of the upper cylinder (ground on the lathe) and present them. Mark the locations of the holes at the end of the flat bars of the fixing plates (to be drilled and tapped later).

Metal work: making an electric sheep: making

Turned around, the lower end of the sheep adopts a convex profile. Weld a ring at the other end and insert everything into the cylinder. Screw the lifting rings (bent to the hydraulic bending machine).

4 WELDING THE UPPER PULLEY AND ITS SUPPORT

4 WELDING THE UPPER PULLEY AND ITS SUPPORT

Starting from a steel chute, turn the upper pulley (Ø 240 mm) then make its peripheral groove. Drill the seven holes that lighten the workpiece and weld in the center the spacer that will receive the bearings.

Metal work: making an electric sheep: electric

Heat a square iron, bend it and solder it to the top of the upper cylinder. Reinforced by a 90° bent iron welded directly opposite, the square iron will support the coping of the upper pulley.

Metal work: making an electric sheep: making

Slide the bearings into the center of the pulley and bolt it into its clevis.

5 ASSEMBLY OF CYLINDERS

5 ASSEMBLY OF CYLINDERS

Point the connecting UAPs 180° on both sides of the lower cylinder. With a chain hoist, lower the upper cylinder between the UAPs. Adjust the gap between the two cylinders and point the one at the top. You will realize the cords thereafter *.
* It would be possible to perform the assembly horizontally on the ground and raise the assembly (300 kg) with the help of the hoist, but it is better to operate vertically.

Metal work: making an electric sheep: electric

Weld the handle on the cylinders, then fix on it the support of the three intermediate pulleys realized in flat iron.

Metal work: making an electric sheep: Sheep

Under the three pulleys a horizontal guide limits the lateral beat of the cable. Pass it through a clevis bolted 90° on the base and then into the welded ring at the end of the M16 threaded rod (through the base of the lower cylinder) and add cable ties.

Metal work: making an electric sheep: work

In order for the cable to remain in the groove of the main pulley, it needs a tensioner capable of limiting its side flap without hindering it: a small pulley whose pivoting ring is held by a spring.

Metal work: making an electric sheep: making

Fold or assemble the wheel guard (sheet of 8) and screw it under the handle joining the lower and upper cylinders. Then cut the front panel in 20/10 sheet and screw it onto the wheel guard.

Supplies (mm)
• Steel tube 1.5 m Ø 270 x 240
• Round steel XC 32 or 38, 1 m of Ø 90 (sheep)
• U-shaped iron of 120, ie 2.50 m
• Round iron: 2 m Ø 14 (pedal structure), 1 m Ø 18 (pedal shaft), 1 m Ø 22 (motor attachment), falls Ø 100 and 110 (anvils)
• Flat iron: 3 m of 25 x 7 (cable guides), 1 m of 40 x 20 (base), 1 m of 50 x 10; 5 m x 50 x 12 (mounting bearings); 2.5 m 50 x 25 (bearing mounting plates); 1.5 m 100 x 15 (intermediate pulleys), 100 x 10 drop (cable guide); 1.5 m of 180 x 8
• Square iron 30 x 30 (pulley sup., Structure of the pedal...): 4 m
• Black sheet of 20/10 (front panel): 2,000 x 1,000
• 3 m of 3 x 2.5 mm2 electrical cable and 2P + T plug, 3 m of IRL Ø 16 tube; 5 rollers Ø 88 x 34 x 12, pulley Ø 240 x 40 x 12, 3 m steel cable Ø 6 and cable clamp, lugs, 22 bearings Ø 40 x 17 x 12 (sheep guide); pulley Ø 30; 1 m threaded rod M16 / 200, screws; metal painting, thread brake...
• Recovery room: push-button, on-off and limit switches, 2 R5 half-rear wheels, R5 wheel and rim + 6 nuts, 1.1 kW engine - 700 rpm and grooved pulley Ø 75 x 140; 2 lifting rings Ø 73; springs Ø 30 x 190 and Ø 30 x 50, 4 washers Ø 250 x 35 x 30, 3 steel plates of 300 x 200 x 20 (fixing of the motor and anvils), sheet of 8 (covering)...


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