What is the correct way to use a split die to cut a thread.

[Dave Harding 1Participant @daveharding1]

This subject may have been discussed before.

What is the correct way to set up and use a standard spilt die to cut a thread?

In what order do you tighten the three screws.

[Dave Harding 1Participant @daveharding1]

[Boiler BriParticipant @boilerbri]

Middle first and take a cut. If the nut will not go on loosen the middle one and tighten the outer ones equally until you get the correct setting.

B

[FMESParticipant @fmes]

Agree with Bri, and only add to ensure that the writing on the die faces the work.

Regards

[David George 1Participant @davidgeorge1]

The die should be a loose fit in the holder to a let it expand. The centre screw has a sharp angled point to make the die expand when tightened but the two outside screws are blunted and when tightened lock and close the die size. Put die in holder with die size info on outside as the cutting angle is this end but if you reverse after cutting thread you can cheat a little more thread up to a shoulder. You firstly loosen the outside pair and tighten the middle screw to open up the die. You can check the setting with a known screw if you like and I like to set it loose so I take two cuts and get a better finnish. Take the first cut by cutting forward and reversing a small amount to break of the swarf repeating till thread is cut to length, don't forget to use appropriate lubricant . Check the thread with a nut, adjust by loosening the centre screw and tightening the two outer screws slightly, 're cut the thread and check size. You can cut as many times as you like depending on material you are threading. I hope this helps.

David

[old martParticipant @oldmart]

I fully agree with the advice rendered, and would add that in my experience that doing the cutting in two or more stages gives a better finish, a better fit and possibly a longer life for the tap.

[Dave Harding 1Participant @daveharding1]

Posted by David George 1 on 03/06/2019 07:16:42:

The die should be a loose fit in the holder to a let it expand. The centre screw has a sharp angled point to make the die expand when tightened but the two outside screws are blunted and when tightened lock and close the die size. Put die in holder with die size info on outside as the cutting angle is this end but if you reverse after cutting thread you can cheat a little more thread up to a shoulder. You firstly loosen the outside pair and tighten the middle screw to open up the die. You can check the setting with a known screw if you like and I like to set it loose so I take two cuts and get a better finnish. Take the first cut by cutting forward and reversing a small amount to break of the swarf repeating till thread is cut to length, don't forget to use appropriate lubricant . Check the thread with a nut, adjust by loosening the centre screw and tightening the two outer screws slightly, 're cut the thread and check size. You can cut as many times as you like depending on material you are threading. I hope this helps.

David

Thanks I think I understand now. I tightened the two blunt screws first and got a very sloppy thread. I will have another go. Cheers.

[mechman48Participant @mechman48]

If you're die thread cutting on a lathe remember to use the tailstock barrel to keep the die holder square to the lathe axis; or better still, make your self a tailstock die holder, plenty of posts on this, also these can be bought very reasonably priced from the likes of Arc Euro or eBay… usual disclaimer applies.

George.

[Ian S CParticipant @iansc]

Just watch out for modern cheap dies, they tend to be nothing other than a round die nut, and as Roy garden, and I found the cutting edge was not formed, I cured mine with the Dremel, first split the die with a thin cutting grinding disc, then a cylindrical stone through the relief holes to touch up the cutting edge. The set of 5 dies and a holder cost $NZ 10, so nothing to loose. The sizes go from 12 mm, 10 mm, 8 mm, 7 mm, 6 mm. I don't think I have ever come across 7 mm threads?

Ian S C

[Speedy Builder5Participant @speedybuilder5]

If you are threading up to a shoulder without a thread recess, cut thread to size with writing towards the chuck. Then turn the die around so that the writing is towards the tailstock and pass the die right up to the thread shoulder. For large threads, I prefer to screwcut with the lathe and just use the die to give me the correct final size /crest / root forms.

[Author]

Posts