NAREX MTE - first page
...Expert in Boring


Search site NAREX MTE through Google.

| Home | Czech |












Czech Republic





Office work





RTH - Reversible thread-cutting head NAREX
205bh - Fine boring head
205bh - Fine boring head

Favourable actions here ...



Product description RTH - Reversible thread-cutting head


RTH - legend

RTH - legend

2 - locking screw

3 - clutch sleeve

11 - chuck

13 - collet type RUBBER FLEX BJ

14 - collet nut

16 - stop bar holder

22 - tap

Usage advantages

  • taps protection against damage

  • possibility of thread-cutting into the blind holes

  • 2x revolutions acceleration by reversal

  • possibility of repeated starting into the already intagliated thread

  • Range of thread-cutting
    RTH 22BJ M2÷M7
    RTH 32BJ M5÷M12
    RTH 42BJ M8÷M20


RTH - Reversible tapping head is used on drilling machines or on milling machines.

Head principle ( via pictures in catalogue):
Tap (22) is clamped in slide-out chuck (11) by collet (13) and nut (14), it is insured by gripping of driving square by opposite screws or jaws against through turning.

Chuck (tap) has regarding the body of head 3 positions:
1. fully driven-in the head – work position for cutting of right-hand thread
2. fully driven-out the head – work position for backing-out the tap
3. position in the middle of head – NEUTRAL – spindle is still turning but tap is stopped
CHANGING OF POSITIONS – implements machine operator by movement of drilling machine spindle.

Skidding clutch protects tap against damage and is adjusted on necessary torsion moment, which cut out fluently thread and by reverse rotation get tap out from the hole. Skidding clutch is adjusted by clutch sleeve (3) and it´s arrest is proceeded by locking screw (2).

Basic presumption of correct head operation – stopping of stop bar holder (16) – it is planetary gearing, when ring must be out of motion.

Function of axial compensation ensures compensation of necessary axial movement for cutting calibre thread on conventional machines.

Taper shanks are exchangeable.




RTH - Reversible tapping head NAREX


RTH - Reversible tapping head NAREX


RTH - Reversible tapping head NAREX

  RTH models   RTH a Zhr   RTH - sectional view
  RTH - Reversible tapping head NAREX        
  RTH 22        





General Dealers Czech Republic


  • M & V, spol. s r.o. (Vsetín)

4. května 288, CZ-755 01 Vsetín

tel:  420-571 484 817

fax: 420-571 413 126

  • TTI, s.r.o. (Brno)

Údolní 40, CZ-602 00 Brno

tel: 420-543 216 868

fax: 420-543 249 300

  • Stim Tools, a.s. (Brno)

Bratislavská 49, CZ-602 00 Brno

tel: 420-545 212 092

fax: 420-545 211 163

  • HOFMEISTER s.r.o. (Plzeň)

Mezi ploty 12, CZ-326 00 Plzeň

tel: 420-377 242 058

fax: 420-377 243 161

  • BOS HK a.s. (Teplice)

Přítkovská 152, CZ-417 12 Teplice-Proboštov

tel:  420-417 560 721

fax: 420-417 560 385

  • HANÁK NÁŘADÍ, s.r.o.

Osvobození 129, CZ-763 16 Fryšták

tel: 420-577 110 711

fax: 420-577 110 733


  • NTV - Naradie, s.r.o.

Farská 86/2

SK-019 01 Ilava

phone: 421-424 466 316

fax: 421-424 464 279

  • M&V, Slovakia spol. s r.o.

Vsetínská cesta 1487-9

SK-020 01 Púchov

phone: 421-424 634 548

fax: 421-424 634 549


Sumracná 27

SK- 821 02 Bratislava

phone: 421-243 338 080

fax: 421-243 335 501


Horská 1311/2

SK-958 06 Partizanské

phone: 421-387 491 373

fax: 421-387 491 373


Frequently asked questions (FAQ)

  • What use is scale on the sleeve by which is torsion moment adjusted?

Scale does not say anything about torsion moment. It identifies place of sleeve on the body of the head.

  • Is it possible to use heads RTH and Zhb to forming screwing taps clamping?

It is possible, but ATTENTION! Especially by heads RTH can not be diameter of forming screwing tap bigger than is half of head work range. For example: we do not clamp forming screwing tap to head RTH 22 but to RTH 32. It is because of the big beats during reverse revolutions what makes for premature attrition or head destruction.

  • What revolutions are suitable for thread cutting heads?

Revolutions are chosen according to recommended cutting speed which is given by producer or supplier of screwing taps. Each thread cutting head has only narrow maximum revolutions.

  • Is it possible to cut threads in impassable slots to the bottom with these heads?

YES it is possible, both types RTH and Zhb have skidding clutch, so if it is correct adjusted, the screwing tap can not be break off. But WE DO NOT RECOMMEND this way of using, it is too fierce and not safe everytime. Especially by bigger diameters of screwing taps.

  • Is for screw tap clamping to the head better collet RUBBER FLEX or plastic collet?

Collet RUBBER FLEX simultaneously centralizes and clamp screw tap. Plastic collet only centralizes screw tap and with worse accuracy. Anyway collet RUBBER FLEX is more favourable though it is more expensive.

  • Original reversible heads were named ZHR. What is main difference between ZHR and RTH?

Head ZHR were applicable on left hand and right hand threads but they had some defects: length, volume, lower service speed. Heads RTH are shorter, there can be exchanged shank, lower weight, more sensitive gofer and higher service speed.

  • What is the best way of adjusting the skidding clutch of tapping head?

Procedure is described in instructions for use. The best way is experimentally. Stepwise is torsion moment increasing to the time when screwing tap is fluently cutting thread and can be easily screw out from the thread.

  • Slip on the skidding clutch is fluent or fitful?

In all cases except head Zhr 21 is slip fitful.

  • Is produced type RTH-L for left hand thread?

It is not on the stock but you can demand it and delivery term is about 4 - 6 weeks.

  • Is produced type RTH-A for quick tool exchange?

Not now, but if customers will be interest in it we start with its production.

  • Does firm NAREX MTE repair heads GSA 2,GSA 3, GB 2 a GB 3?

Because there are heads from import (NDR), these heads are not repaired by firm NAREX MTE. Only for heads GB2 and GB3 are delivered plastic collet chucks.

Product repairing


NAREX MTE standardly provides repairs of produced and delivered products. There are guarantee repairs or normal non guarantee repairs. During repair is product dismounted, there are found defective parts and up to it is determined range and price of repair. After customer´s repair price confirmation are defected parts exchanged, product is again mounted and tested.

Repair speeding

For repair speeding and lower price is suitable to enclose to repair order letter with information about problems (during which conditions defects occurs or indicate required range of repair).

Repair ordering

For repair ordering you should send product for repair, order of repair and specifications of defects on our address:


sales department

Moskevska 659/63

CZ-101 00 Prague 10
Czech Republic

Information about repair

About repair you will be informed by e-mail or by phone, with any questions you can contact export department on phone: +420 246 002 249, e-mail:, fax: + 420 246 002 335


NAREX MTE s.r.o.

Moskevska 659/63

CZ-101 00 Prague 10
Czech Republic




+420-246 002 321

+420-246 002 249

+420-246 002 335

+420-246 002 343



  Technical support is at the disposal of you on phone +420 246 002 249 or you can contact us by e-mail: or by fax: +420 246 002 335.


Basic technical information you can find also on reference service.


NAREX MTE s.r.o.

Moskevska 659/63

CZ-101 00 Prague 10
Czech Republic




+420-246 002 321

+420-246 002 249

+420-246 002 335

+420-246 002 343


  Catalogue of Tapping heads  -  Download (PDF)
  • Catalogue of Tapping heads (PDF)




  RTH - Catalogue (PDF) NAREX
  • Reversible thread-cutting heads RTH (PDF)





  Zhb - Catalogue (PDF) NAREX
  • Safety thread cutting heads Zhb (PDF)




Display of products lines (quick reference)
  • Display of products lines (quick reference)

| Contact us | mexin - Spain | Sitemap | © 2016 NAREX MTE® s.r.o. All rights reserved .