Taps and dies

This topic has 9 replies, 7 voices, and was last updated 27 May 2013 at 17:13 by colin hawes.

Viewing 10 posts - 1 through 10 (of 10 total)

Author

Posts
25 May 2013 at 23:17 #6724
rebekah anderson
Participant
@rebekahanderson95322
Advert

25 May 2013 at 23:17 #120637
rebekah anderson
Participant
@rebekahanderson95322
Hiya guys,

Another question for yah.

I have been trying to cut a left ahnd thread. Its M3 size.

I turn a bar down to 3mm then cut the thread using a M3 LH. Once i have a good cut i then try and screw it into the female LH thread hole. However it just zips in, no screw required. Obviously not the desired effect. I measured the outer diameter and find that it's 2.5 mm. Again undesirable.

I have cut a normal RH thread doing exactly the same with the correct result.

So I am thinking i have been sold a duff LH die that isn't M3 size.

Would I be correct in my fury or am I being mince and missed something out?

Cheers

Becky
26 May 2013 at 01:48 #120642
Chris Heapy
Participant
@chrisheapy71135
Possibly. Is the die a split-die (i.e., adjustable)? If so, it may be you have tightened it within its holder to the extreme minimum size. There are 3 screws in the holder (normally), and when you tighten the center one it wedges the die open making it cut a larger diameter thread, the two screws either side just lock it to the desired cutting size and prevent it springing open further.
26 May 2013 at 08:37 #120649
David Jupp
Participant
@davidjupp51506
The size will usually be marked on one face of the die. Should allow a quick check.
26 May 2013 at 08:43 #120650
rebekah anderson
Participant
@rebekahanderson95322
I may be a bit blond but not that much lmao.

Yes it does say M3 LH lol
26 May 2013 at 08:51 #120651
Springbok
Participant
@springbok
Rebekah,

Use firstly the centre screw only, use cutting oil, check what is stamped/engraved on the die, gently clean up the cut with a VERY fine abrasive once again useing cutting oil, Now loosen centre screw and lightly tighten other 2 then centre, go for 2nd cut then once again clean up.
I am presuming that you have a nut to check tollerances.
good luck (I usualy need it)
Bob
26 May 2013 at 11:58 #120662
MICHAEL WILLIAMS
Participant
@michaelwilliams41215
A common mistake is to turn the die the wrong way when doing LH threads . Under end load it will still cut but more like a hollow milling cutter than a die – basically reduces bar to core diameter .

MikeW
26 May 2013 at 12:56 #120673
Ian S C
Participant
@iansc
You could check the size by putting the shank of a tapping size drill through the die, if it's a split die, it will proberbly need opening. Ian S C

Edited By Ian S C on 26/05/2013 12:58:17
27 May 2013 at 15:30 #120763
rebekah anderson
Participant
@rebekahanderson95322
Ian,

you are correct. Although opening isn't easy. Lol
27 May 2013 at 17:13 #120775
colin hawes
Participant
@colinhawes85982
You may need to turn the dia. to about 2 thou undersize to get a clean thread. There are some poor quality dies about that will never be capable of cutting on a full diameter. Colin
Author

Posts