Threading tool and holders

[Brento]

Ok so i wanna make a few threading tools. One for metric threads atleast for a 25m X1.5
A internal threading tool
An external threading tool for small threads and for larger threads

I also would like to make a boring/threading bar holder for 3/16 hss stock

(All of the tools will be made from hss)

Does anyone have any drawings for the boring bar or ideas on how to make the tools? I think i have a idea on how to do them but i dont wanna just go grinding and not know what im looking for.

 

[mikey]

ISO metric threads have a 60 degree included angle, just like Imperial threads. Therefore, the threading tools are the same. To grind an external threading tool for this, grind a 30 degree angle on each side of the tool tip and be very precise about it. Also grind a tiny flat at the very tip to prevent breakage.

An internal threading tool is considerably harder to shape/make. There are a number of ways to do this and I've done many of them but to be very honest, you will be better off buying these tools. This especially applies to very small internal threading tools because a steel tool can only hold its accuracy for a short distance. For example, a steel internal threading bar that can cut an M6 thread will be about 3/16" OD at the head. Once the cutting edge is ground, the resultant OD at the neck below the cutting edge will be about 1/8" if you're lucky and the max depth of thread you can cut accurately is about 1/2". A carbide tool can go double that distance, about an inch. Given the limitations of these bars in small holes, I suggest you buy solid carbide internal threading tools instead of grinding them.

As for a boring bar holder, what are you using to hold the bar? If using a QCTP then just make reducing sleeves that fit in your boring bar holder. More info would help here.

 

[Brento]

Well im just starting out right now so i dont have the lathe yet its on its way. I’m kind of just trying to get tools ready and projects lined up to give myself a plan. When the lathe first gets here it will be a basic tool post and i plan to switch it out for a quick change at some point.

As for the boring bar i was talking about the boring bar itself not the holder. Sorry for any confusion

 

[ddickey]

If you're going to grind a threading tool the first thing you should probably have is a fishtail, or make one.

 

[Brento]

I do have a fish tail. I was just getting screwed up with looking online how if you buy a threading tool they have tpi designations so i just wanted to make a tool for the most common threads

 

[Dan_S]

I do have a fish tail. I was just getting screwed up with looking online how if you buy a threading tool they have tpi designations so i just wanted to make a tool for the most common threads

The different TPI designations, have to do with clearance. Coarser threads have a greater helix angle, and thus require more clearance to prevent rubbing.

Most people will use taps till they get to decent size threaded holes, say 1/2" or so. Then it's usually pre-ground bars like micro 100 makes. beyond that you get into old school boring bars that hold HSS blanks, and then modern insert tooling.


What type of internal threading do you see yourself doing?

 

[Brento]

Well as you said i prob wint be doing and internal threading below a 1/2” since i have taps up to that size.

 

[Dan_S]

Well as you said i prob wint be doing and internal threading below a 1/2” since i have taps up to that size.

I think you missed my point, how often do you see yourself actually needing to generate an internal thread larger than your largest tap? I've had a lathe for over a decade, and I've had to do internal threading over my largest tap size maybe 3 times.

Large internal threads isn't that common a task unless your doing a certain kind of work.

 

[mikey]

Well im just starting out right now so i dont have the lathe yet its on its way. I’m kind of just trying to get tools ready and projects lined up to give myself a plan. When the lathe first gets here it will be a basic tool post and i plan to switch it out for a quick change at some point.

As for the boring bar i was talking about the boring bar itself not the holder. Sorry for any confusion

Okay, no lathe yet and you're getting ready. Trust me; I totally understand the anticipation and getting ready part. To be honest, I'm excited and happy for you but I urge you to slow down a bit and take your time. Threading is a basic skill on the lathe and it isn't difficult to do but it does take some familiarity with the lathe. Learning to turn an accurate OD and drilling or boring an accurate ID will need to come first.

Can you tell us which lathe you're getting? Do you have a project in mind that requires threading or is this about being able to thread in general? I ask because there is a lot to thread cutting aside from the tooling.

Dan is right; you can tap a thread. However, there are times when you need a precise fit and a tap my not give you that so you have to cut it. I've done this many times and there are tiny threading bars that will fit in a tiny bore to enable you to cut accurate threads so it's useful to know how to do it. But you are not there yet.

At this point, my suggestion is to get the lathe and the basic tooling you need to get going. Then we can tell you how to make sleeves or a holder for a boring/threading bar or even tell you how to grind one from HSS.

 

[Brento]

The lathe i am getting is the grizzly 7x14. Do i see myself threading more then a 1/2” thread? As of now no. I have threaded before but it was external only and it was on a much bigger machine. I have the hss stock already and just wanted to cut them to have them done. As i said earlier i just wanna get job ideas inline and see what stock i need or how i can plan to do it is all.