3" NPT threadmill tool recommendation ?

P

phatbob

Plastic

Joined

Jan 5, 2019

• Jan 27, 2021

• #1

Hi need to do some 3" NPT holes (inside) in alu, looking at tooling options everything I have is 11TPI min.. so this looks like 8TPI.. can anyone recommend a decent tapered toolholder / tool (ideally indexed single as I can change it up for other jobs).. not a common job so I'd prefer to go that route vs. a dedicated tool..

was looking at carmex but that is all i found at a quick glance..

 

M

Milland

Diamond

Joined

Jul 6, 2006

Location

Hillsboro, New Hampshire

• Jan 27, 2021

• #2

I just use a suitably sized single-row threadmill. It's cheaper, lets me do a range of pitches and while it takes a little longer, if it's just a few holes it's usually not an issue.

 

M

mmurray70

Stainless

Joined

Jan 11, 2003

• Jan 27, 2021

• #3

Iscar and Tungaloy make great single tooth threadmills that work for range of threads. I have both sizes and use them fairly often. Both are nearly identical but Tungaloy inserts are a little cheaper.

You can use these for NPT but you need to machine taper on first, and its much easier to mess things up. Probably be a lot safer to get proper tool for NPT if its critical application.

 

N

nateacox

Aluminum

Joined

Mar 29, 2012

Location

Traverse City, MI

• Jan 27, 2021

• #4

I like advent and carmex insertable if the quantity is high. Otherwise single point from SCT USA for low volume

 

B

Booze Daily

Titanium

Joined

Sep 18, 2015

Location

Ohio

• Jan 27, 2021

• #5

If you’re going to go with a single point tool, just throw a lathe ID threading bar in there. No need to buy anything.

 

Hardplates

Stainless

Joined

May 8, 2019

Location

What once was a free country

• Jan 27, 2021

• #6

I think when most people are saying single point they actually mean single tooth which if it were 4 flute would have 4 cutting edges. At least that's how my tool library refers to the nomenclature.

But I do have a 3/4" threading bar in a CAT40 holder

 

B

Booze Daily

Titanium

Joined

Sep 18, 2015

Location

Ohio

• Jan 27, 2021

• #7

Well sure. Just feed it slower.
I haven’t found an online code generator for single point npt though, so programming might take a bit.

 

Hardplates

Stainless

Joined

May 8, 2019

Location

What once was a free country

• Jan 27, 2021

• #8

Booze Daily said:

Well sure. Just feed it slower.
I haven’t found an online code generator for single point npt though, so programming might take a bit.

Click to expand...

Now you really got me cornfussed That's what the CAMs for no?

 

B

Booze Daily

Titanium

Joined

Sep 18, 2015

Location

Ohio

• Jan 27, 2021

• #9

I can’t remember doing anything bigger than 3/4 and I use thread mills for those.
Thread Mill Code Generator – Scientific Cutting Tools, Inc.

I’ve actually never sat down to program a single point npt.

 

Hardplates

Stainless

Joined

May 8, 2019

Location

What once was a free country

• Jan 27, 2021

• #10

Booze Daily said:

I can’t remember doing anything bigger than 3/4 and I use thread mills for those.
Thread Mill Code Generator – Scientific Cutting Tools, Inc.

I’ve actually never sat down to program a single point npt.

Click to expand...

I just program it as a tapered threadmill but single tooth and it automatically cuts the taper. I've played with CAM that doesn't officially support pipe threads but was able to cut them by drawing a tapered helix and following the sketch with a trace type tool path.

 

G

gregormarwick

Diamond

Joined

Feb 7, 2007

Location

Aberdeen, UK

• Jan 28, 2021

• #11

Hardplates said:

I just program it as a tapered threadmill but single tooth and it automatically cuts the taper.

Click to expand...

You mean in cam right?

I have seen so many people over the years claim that you can just get a tapered threadmill and program a basic (cylindrical) helical path with it, and the threadmill itself will generate the taper. That this doesn't produce a true conical thread often doesn't compute in their heads...

On topic - my preferred threadmills for larger threads are Sandvik's Coromill 328 (actually made by / licensed from Simtek, but not sure if they are available in the US)

CoroMill 328

 

Mtndew

Diamond

Joined

Jun 7, 2012

Location

Michigan

• Jan 28, 2021

• #12

Vardex.
If it's a thread, they have a tool for it most likely.
And they have a handy program where you enter in the thread dimensions and it will tell you what tool to use, AND spit out a program for you.
https://www.vargus.com/thread-milling

 

Hardplates

Stainless

Joined

May 8, 2019

Location

What once was a free country

• Jan 28, 2021

• #13

gregormarwick said:

You mean in cam right?

I have seen so many people over the years claim that you can just get a tapered threadmill and program a basic (cylindrical) helical path with it, and the threadmill itself will generate the taper. That this doesn't produce a true conical thread often doesn't compute in their heads...

On topic - my preferred threadmills for larger threads are Sandvik's Coromill 328 (actually made by / licensed from Simtek, but not sure if they are available in the US)

CoroMill 328

Click to expand...

In SolidCam if you program the taper into the tool library but only have a single tooth cutter it automatically does a tapered helix.

And yes I understand even with a full form threadmill you still need to have a taper to the helix since the diameter changes with Z

Anyway if it's only a few holes I would just use a single tooth cutter.