[Dull Tool]

I was wondering if you guys would mind sharing some tips on thread milling stainless steel. I've done next to nothing as far as thread milling so starting off on stainless in a job shop environment is a lot less forgiving that aluminum...if you know what I mean?

Anyway the questions are :

Should I mill the thread starting from the bottom to top or vise versa?

Should I use a spring pass for finishing the thread?

I'm thinking I should start with a multi point threading insert ( Vardex Type ) to save some cycle time by swinging just a few passes vs. single pointing the entire threaded hole depth.

What kind of tool wear can I expect to see? We work on large one off type pieces with plenty of large diameter threaded holes ( 2.00 + ). I'd like to structure the programming with some stops for tool wear and gaging threaded holes and so forth.

Any other advice and stupid newb humor is welcome. Thanks in advance. :cheers:

Louie.

[RCaffin]

I was wondering if you guys would mind sharing some tips on thread milling stainless steel.

Nasty stuff. Start slow, maybe use coolant if you are set up for it.

For thread milling holes of that size in SS you are probably stuck with carbide. Consider coated tools.

Should I mill the thread starting from the bottom to top or vise versa?

Always go for climb milling for this. So exterior threads you go down and for interior threads you go up. Going upwards a turn or two excess is never a problem, but watch out when going downwards!
I suggest avoiding going in the opposite direction ('conventional milling') as the thread always seems to end up VERY messy.

Should I use a spring pass for finishing the thread?

Depends on the type of SS and the cutter material. You will have to experiment with this one. With a slowish feed and the right revs, a single pass should be enough, and may result in less tool wear.

I'm thinking I should start with a multi point threading insert ( Vardex Type ) to save some cycle time by swinging just a few passes vs. single pointing the entire threaded hole depth.

Much less wear on the tool, but I have only used 'single'point' tools. My knowledge is limited as I mainly work with small holes in Al.

What kind of tool wear can I expect to see?

One of those cases where buying a really good coated tool is worth the money - as long as it survives the learning experience!

Cheers

[Shane1234]

make sure you add your cutter comp commands in so you dont have to go back to your cam program to program in wear...... I use a single point, and I usually do about 2 .02" passes, 2 .005 passes, and a spring.

[extanker59]

I used to do threadmilling in ss on threads 1" to 2" in diameter. Internal. I used Vardex tools with inserts. Lasted almost forever. They had a catalog that gave pretty good speeds and feeds but I admit that I usually went slower on my feed than they recommended. Climb mill with coolant like has been recommended.

[mcphill]

Where does one find a reasonable list for Vardex style tools, with prices, and where to buy them? They have 10 catalogs on their site and no apparent "newbie" info...

[extanker59]

MSC carries them but I had a tough time searching for them. Here is the on-line big book page link, inserts on next page: Browse the MSC Big Book

Holders on previous page-edit- and I think Kennametal bought them since the holders seem identical

[mcphill]

Great link, thanks! They've been bugging me to make an order, too, so now I guess I have a reason... The holders are quite a bit spendier than I was hoping, though....

[brokencarbide]

Just my 2 cents but i'd go to Advent's website and download their selection software, there you can speck out the material and depth, they'll shoot back some selection of tools, you pick which one you'd like (length, helical or not, etc.), then they'll shoot you the program. Carmex also has a very nice set up on their website for this as well, I haven't programmed a thread mill for a couple years, just used Advent's & Carmex's programs, works slick every time. I do prefer Advent a little more, they seem to be beefier in their design's.