Rough threads after threading with die

[BrewNinja]

Hello all. Purchased a lathe a little while back to fabricate some parts for my pinball machines that are no longer made. Ive always been a tinkerer and a DIY kind of person. Anyways, I'm trying to thread a portion of some steel with a die and no matter what I try, it wont come out "clean." The threads are always rough. I tried the same thing on aluminum and it worked fine. I also bought a brand new die just to make sure, and still the same. I've also tried under and oversizing the metal diameter. I also tried different grades of steel. The first stuff I got locally I have no idea what it was, so I ordered some cold rolled 1018 and 1117 to try out, same thing there. I also tried a few different things for cutting oil (WD40, actual cutting oil, etc). Does anyone have any idea what is going on? Hopefully one of these pics can kind of show whats going on. Any help or direction would be greatly appreciated. Thanks!

 

[mmcmdl]

What type of die ? There are cutting dies and there are forming dies .

 

[BrewNinja]

I assume it was a cutting die, but you know what they say about assuming things... The first one I had was just a cheap Chinese one I had laying around. Its an odd size (10-32) so its not something you normally use. The one I bought was an American Vermont 20763. Its an HCS die, but that's really the only info I see about it. Here is a pic if that helps.

 

[Braeden P]

that die is for re threading damaged threads because it is hex a round die is for cutting threads so that is the problem

 

[mmcmdl]

Generally high carbon dies are maintenance grade dies for re-forming damaged threads . They are not expensive . High speed dies are for thread cutting and are more expensive . Some materials are tough to get great finishes regardless which you use . Most likely you have a combination of the two .

 

[BrewNinja]

I know that generally chasing dies are hex (I have a set), but this one is definitely not that. From American Vermonts website, they basically make them hex so that they fit in the tools you probably already have. Anyways, sounds like it still may be the die that is the issue here, so Ill look at getting something else. Any recommendations for a place to get a high speed die from? I did a few searches and mostly see cheap chinese ones (in 10-32 anyways). The only other place that even came up was McMaster. Maybe Im searching wrong.

 

[markba633csi]

If your lathe will cut threads you should get better results than with a die, although steel does tend to "tear" somewhat depending on the type. Dies cut the thread all at once which some steels don't like. Single point threading on the lathe allows you to take small passes and get a smoother thread
-Mark

 

[BrewNinja]

My lathe will cut threads, I just have never used it. Guess its time to look into it. Thanks for the tips!

 

[Winegrower]

Just only incidentally on topic, but I have been really pleased with the quality of threads cut by my Geometric die head and various chasers. This is so much easier than either single point threading on the lathe or running a die over the work. And it happens in literally a snap.

Watching eBay, I've collected a good range of common thread sizes including NPT. Even though I forget every time how to change chasers, it's easy every time once I remember.

 

[mmcmdl]

Die heads are the bomb !