what size hss bit do you typically use when threading a barrel 1/4, 3/8 etc.

I use carbide insert. You can use any HSS that fits your tool holder. It's just a matter of how you grind the tool.........Tom

quote:

Originally posted by Tapper2:
I use carbide insert. You can use any HSS that fits your tool holder. It's just a matter of how you grind the tool.........Tom

Right on...and if you have an Aloris-type QC tool holder,which I recommend to everyone just for its convenience, it will take any of them up to at least 3/4".

Personally I pretty much always used 3/8" or 1/2" tools depending on what was on sale when I was stocking up....and though I didn't usually use carbide, I did often use something harder than plain HSS.

My bits are 3/8" Mo-Max & I grind my own. Performed threading bits are too sloppy for my taste.

quote:

Originally posted by D Humbarger:
My bits are 3/8" Mo-Max & I grind my own. Pre-formed threading bits are too sloppy for my taste.

Well, I sure agree with that. Grinding to the exact shape and size I want is too easy to use some kind of off-the-shelf stuff at double or triple the price. Besides, I like the way my own tools break chips better than some of the commercial ones.

I thought everyone ground their own tools...that's about the second thing a person learns when taking machine shop as either a student or an apprentice...right after the safe kind of clothing to wear around machine tools.

When using high speed steel I liked the following

Rex 95 for general use - easy to grind.

Mo-Max - lasts longer but harder to grind

Most of my tools were 3/8" just because I found the 1/4" tools harder to hold when I ground them. But all my grinding was free hand. I am not sure many people do it that way any more.

3/8" or 1/2" whatever I have on hand. i have four tools ground two for 55 degree two for 60 degree

For those who grind there own do you use a sine plate?

Well, I have carbide inserts, ground cemented carbide, HSS tools, and now I use Warner Tools HSS threading inserts. They give a much better finish than any of the others.

quote:

Originally posted by J_Zola:
For those who grind there own do you use a sine plate?

Yes

Actually A sine chuck or I dress the wheel at an angle with a J&L radius/angle dresser

Thanks guys for the replys.

There are lots of commercially available "canned" cutting tools for sale out there which will work fine. For my own though, I still prefer to grind them myself, and for cutting threads in barrel steel I usually use 3/8" or 1/2" cobalt steel tools.

quote:

Originally posted by J_Zola:
For those who grind there own do you use a sine plate?

No, I free hand grind them using a precision protractor to check progress and the V on the thread fish. I have threading bits ground in everything from 1/4" up to 1/2" blanks. I pick the tool for the size of the threading job and clearances around the part and tail stock. I have threading tools that are ground significantly off the center line and off axis of the blank to create greater clearance around my live center.

It has been debated here before about the use of a hand ground tool, the use of a 60* tool on a 55* threaded receiver. The precision involved in the set up.

I'll simply say this. When you have a lot of variables involed in a process stack the tolerances in your favor. Meaning if you use carbide inserts or a precision ground tool you have one more level of controll over the threads. The reason I grind mine with a sine chuck is so that the V is square to the side of the tool. This makes setup much faster the using a fish gage and insures your threads are square to the barrel axis.

But your thread is only as good as the finished size and surface finish. You can not take too little on you depth of cuts. You also should take a few spring passes now and then. And have your compound setup to one degree less then half the included angle. ie for 60* threads set your compound at 29* and for 55 set it at 27.5. This gives you side clearance when cutting the thread and reduces tearing of the steel.