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2.4. The rests with the ball hinge

A rack-”goat” has evident shortcoming - a lace maker has to rotate often a heavy bolster around all axes of gyration. Using tool like “a goat” demands outstanding physical endurance when plating takes place all over a workday. But it is completely inadmissible to burden hands busied with the skilful work.

The overload of a lace maker is eliminated when a bolster has a ball hinge with three degrees of gyration freedom. Ideally a center of bolster gravity must coincide with a gyration center. As soon as it is not practicable one must deviate from the ideal cinematic layout. Practically a bolster 1 is set on a platform 2 that is joined with the ball 4 by means a rod 3 (Fig.2.24).

Fig.2.24. Ball hinge of a bolster

In this scheme a bolster is controlled well but moving a center of gravity out of a gyration center hampers fixation of the platform. Long levers L₁ and L₂ arise which demand to create great strength to fix the platform at any given space position. The task becomes a little easier when ball diameter enlarges.

Pillow rest having a ball hinge was invented in Viatka province [8] about 40 years ago (Fig.2.25).

Fig.2.25. The rest with a ball hinge. Viatka province

Many contrivances use a ball hinge, for instance, the rests for a plane-table and an easel (Fig.2.26), the rests for cover plating (Fig.2.27). These devices do not demand often to change position of the table. Rotations are fulfilled inside narrow angle range - about several grades.

Fig.2.26. Plane-table

Fig.2.27. Rest for cover plating

Much more diapason is needed in plating of link laces. A bolster is rotated very often, each rotation taking place in range from 10 to 40 grades. On these reasons Russian lace makers can not use devices shown on Fig.2.26 and Fig.2.27.

The construction from Viatka proves to be the best rest for them, but it is created for workshops and stays practically unknown to mass lace makers working at home.

The Viatka rest is ideal as to bolster fixation but its controllability stays unsatisfactory. It is seen on the Fig.2.25 that fixation of the bolster tray is released by pressing brake-pedal. However the rest has nothing to return the pedal at start position. Hence the lace maker has to pull back the pedal lever by her hand to fix the bolster again. Naturally she tries to avoid excessive movements. That is why she finds some intermediate position of lever when it is still possible to turn the bolster by hands but the bolster does not move already when the thread is being stretched. It is clear why all lace makers say that they do not use the brake-pedal, considering it is an excessive detail.

It is curious that the rest exists with the mentioned shortcoming more than 30 years! But this annoying defect of the rest can be easily corrected with pair of springs as it has been done by authors of the book (Fig.2.28).

Fig.2.28. Advanced rest

Improvements of the rest are achieved with the next transformations:

1. The control lever of the ball hinge is enlarged 3.5 times to decrease breaking strength.

2. The staff brake-pedal and its lever are moved away.

3. Some details are added:

- a spring that returns the control lever at start position;

- a driving sheave with pedal to pull the lever.

New details are mounted on the slab that is set under the cross-piece of the original rest. Adjustment of the rest is being made by means of tension of springs.

Now lace maker does not touch the control lever by hand. She presses the pedal and releases the bolster brake. Both springs stretches out and save energy. Lace maker turns the bolster at the new position and releases the pedal. The springs compress and due to released energy return movable details at their normal position. The bolster is being broke again.

Control possibilities depend on the characteristic of the ball hinge braking mechanism (Fig.2.29).

Fig.2.29. Control characteristic of the ball hinge

An ideal characteristic is to be linear with two distinctly expressed points of total braking and total releasing. In fact braking and releasing take place gradually. That is why the rotation angle of the control lever increases approximately from 30 to 70 grades. It means that the sheave (as well as the pedal) rotation angle increases two times.

Due to modernization the rest weight is decreased at 23% (20.8 against 27 kg). The rest would be easier, if it projected using modern materials and techniques.

The construction from Vyatka proves to be the best rest for them, but it is created for workshops and stays practically unknown to mass lace makers working at home.

A rest with the ball hinge can be made easily in domestic conditions if one happens to get ready ball joint with braking mechanism inside. Authors of the book have got possibility to buy a hinge named “Kombihalter mit Kugelgelenk” (Fig.2.30) that is produced by the Kaindl Industrie (Germany, www.kaindl.de).

Fig.2.30. Kombihalter mit Kugelgelenk

The firm prompts the mechanism for decision problems that are far from lace making but in the context of the task under discussion the hinge proves to be the main unit of the universal rest. The ready joint can be mounted into the rest after minimal completion. It is necessary only to enlarge the braking handle.

“Universal” means that the rest will fit to set different pillows, including cylindrical and flat ones (bolsters, cookies, mushrooms etc.). The rest I shown on Fig.2.31 and Fig.2.32.

Fig.2.31. The universal rest. View 1

Fig.2.32. The universal rest. View 2

The universal rest acts in the same way as the modified viatka rest. The lace maker presses pedal and release the ball hinge of braking. At this moment the spring becomes longer. The lace maker turns the bolster at some new position and then release the pedal. The spring compresses pulling the break lever at start position. The bolster is being stopped at given position.

The rest stands upon pair of “skis” that are destined to change the hight of a pillow lifting. The skis ase attached to the slab by means of hinges and can take two positions - vertical (upright) or horizontal (flatways). Position changing creates difference in lifting about 12-13 cm (5 inches). The slab sizes are enough to deliver steadiness of the rest when the pillow with the largest sizes is set.

Changable equipment is made as a tray for a bolster (Fig.2.33).

Fig.2.33. Changeable trays for the bolsters

Handles are attached on the sides of the tray to control position of pillow. Two examples of bolsters setting are shown on the photos (Fig.2.34, Fig.2.35).

Fig.2.34. The small bolster setting. The skis are upright

Fig.2.35. The big bolster setting. The skis are flatways

A contrivance for setting of a flat pillow is made as a box with three radial holders on it (Fig.2.36. Fig.2.37). Restrictors are attached at the ends of holders.

Fig.2.36. The tray for a small disk pillow

Fig.2.37. The tray for a big disk pillow