Hello all, I need to screwcut a l/h thread but am a bit confused about correct tooling. Im set up for normal r/h threading with inserts in a presumably r/h tool with a 1degree positive shim under the insert. The question therefor is, can I cut a l/h thread with what Ive got by changing to a negative shim, or do I have to obtain specific tooling to suit ?.. JBL dont sell anything for l/h threading it seems, unless Im looking in the wrong place.!. Many thanks.

Kwil, thanks for the reply. Ive just waded through the Sandvik Coromant threading PDF, and it says in there that you can use a R/H insert to cut a L/H thread as long as the shim is changed to a negative one. Conversly, you can cut a R/H thread with L/H insert, provided you use a positive shim !.

Certainly saves buying both types of insert, just 2 different shims.According to the blurb, using the "wrong" insert may cause insert movement at the beginning of the thread, so care is needed. Thats what it says anyway. Cheers.

Hello Kwil, yes I emailed him and he sells -1 negative shims, but at nearly £15, I will shop around first ! Cheers.

Hello Nigel, yes you are right, thats what I used to do, but after trying insert tooling, it seems to me anyway, so much easier this way , especially as Im not particularly brilliant at sharpening HSS tool bits !. A lot more expensive of course, but hey ho !. Incidently, you can get set up with an insert threading toolholder and insert from JB Cutting tools for just over £20. Cheers.