bussola di riduzione

Step-down Bush from cylinder to morse taper

To be assembled on chucks of front drivers

Bushes for direct coupling to be assembled on spindle nose type:

  • ISO 702/I
  • ISO 702/II
  • ISO 702/III

Material: found hardened and tempered steel.

Built on demand.

The need to curb workmanship costs has led to study and design an alternative to ordinary self-centering chucks, in order for them to fully use the capabilities of machine tools. OMAP “autofretting” face drivers were launched on the national and international market in the 70’s. They were aimed for mass work on lathes, automatic lathes, duplicating lathes, lathes with hydraulic-thrust and revolving work support. They are also perfect for application to small serial work on center lathes. Highly reliable, simple and sturdy, they solve remarkable workmanship problems between centers, including parts with holes, pipes, unrefined and flanged parts, etc., and avoid their sliding under manufacturing load even when very severe:
they keep manufactured shoulders at a constant distance from support faces;
they revolve partshaving unfinished faces;
they process a wide range of diameters by the use of a few scalar-quantity drivers;
they enable the replacement of pins to quickly switch from one diameter to another with no need to disassemble driver parts;
sturdily manufactured out of adequately selected and processed steel, they do not alter centering accuracy under working load.


OMAP drivers work by virtue of mechanical action and are characterized by their “autofretting” quality (under patent). An appropriate pressure set at the work support - workpiece unit induces an “autofretting” axial movement that is proportional to the required load to be chipped, owing to the twisting moment effected by the tool and the configuration of driving pins. When machining, the unit composed of pin, ball andequaliser ring, interdependent yet free to swing, stops on any unevennes detected on the support face of the workpiece and therefore prevents slipping. The center is inserted from a rear plug. It is capable of an independent axial movement that grants a high margin of safety under malfunctioning or false working moves. Return springs and shock absorbers recall pins to their originall position after work.


Sizes 22/32, 30/45 etc. represent the minimum turnable diameter in mm, respectively by "internal" or "external" pins. TP-E stands for the version referring to the overall dimensions of drivers, i.e:
Type NP - Normal protected type; Type E - With extracting nut.
The available coupling (Morse taper) appears in Table 1 (Page 28), whereas mean use diameters are detailed in Table 2 (Page 30). Each driver includes set of pin (pin type according to the customer's request) and is delivered in a case made of cardboard and polystyrene. Pins can ben ordered for right driving (part. 09/10) or left driving (part. 07/08) respectively for clockwise or counterclockwise revolving machine (driver seen from the work support side).
Unless otherwise specified "Outward left" pins are assembled as standard (part. 08, appropriate for best work conditions and counterclockwise rotation). U-type pins (universal), both inward 08/10 and outward 07/09 U are the be used on machine with work cycles that revolve in both directions.
To be supplied on request: spare pins, centers and crozes for tube machining (part. 25/26) (Page 27).
For machines having no bar passage, type E with built-in extractor is recommended.
Each order should quote: pin size, type and quantity, Morse taper (if necessary, order tube centers (part. 25) as well as croze type and number (part. 26), by the aid of Table 3. Owing to ever-recurring technical improvements, OMAP reserves the riht to constantly update data and sizes.


Whe supplied, drivers are ready-to-use in average work conditions. Spring preloading on the movable center is proportional to the weight of the part and the load of the working tool; if the layout or number of Belville washer or either the thrust of the centre are modified, specific work conditions are easily be obtained, according to the features of the machine, the workpiece, the cutting speed, the depth of cut, the safety and duration of driving pins.
Prior to assembling the face driver, check the conditions of the conical seat on the machine and, if need be, remove any unevenness or fault. For good results, eccentricity between the face driving center and cone should be restrined to 0,01/0,02 mm.
Make sure that the load of the work support does not differ remarkably from ideal conditions (those shown on Table 2, page 30). Do not expose pins to impact. High-speed steel pins are processed purposely to resist the severest driving stresses. Disassemble pins by the use of a pair of pliers (or a wrench); turn them by 90°, thus nullifying the effect of return springs. Pin disassembly does not require removing any part of the face driver but working on the machine tool only. Pins can be sharpened normally, provided that etching angles are respected. To machine hard material (≥ 350 Brinell), we recommend sharpening pins and increasing etching angles from (60° + 15°) = 75° to (60° + 20°) = 80°. For soft material (≤ 100 Brinell) increasing etching angles to (60° + 30°) = 90° is recommended.
The unit composed of center, spigot and spring is disassembled by removing the rear plug. The whole front unit is released by loosening the face dowel. After working for a while, checking spring elasticity and, if necessary, replacing them with the pares supplied, is recommended.
Every now and then (especially if pins are replaced), lubricate with quality water-repellant grease.
No extraordinary maintenance is necessary.


  • Autofretting Face Driver 13/25 mounted on step-down bush from cylinder to morse taper with a grip on the chuck
  • Autofretting Face Driver 55/80 mounted on spindle nose while working on a lathe
  • Autofretting Face Driver while threading
  • Huge holed stuff + Face drivers with crozes for tubes
  • Autofretting Face Driver with crozes mounted on spindle nose

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O.M.A.P Officine Meccaniche Alta Precisione was founded in 1963 in Ponte nelle Alpi and specializes in construction and manufacturing of machine tools and equipment for special processing.


Viale Cadore, 69 Ponte nelle Alpi BL
Tel +39 0437 990 044
Email omap@gruppodepra.com

De Pra Group since 1929

Omap Srl - Viale Cadore, 69 - 32014 Ponte delle Alpi, Belluno, Italy - P.IVA 00062120258 | privacy

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