Re: Chasing threads....>>>>....

On 31 Jan 2011 02:21:20 GMT, Deburr Guru <*> wrote:

"vinny" <friggenbozo@xxxxxxxxx> wrote in
news:ii4nfv$33s$1@xxxxxxxxxxxxxxxxx:

This post pertains to lathe thread chasing, but is relavent to all
thread
creation.

I recently had to chase my first threads on a cnc lathe. Ive done it a
million times on a manual, but not on a cnc.
I was hardcutting threads on 58rc stainless and it just ate up the
inserts.
I had to run the cut, change out the insert and run again. No biggie,
but it ddn't seem right.
After looking at the options in mastercam I noticed it had the ability
to
do what we do in the manual, move in on your thread on an angle, causing
it to cut on the side of the insert, not just cutting strait in. It even
has the ability to alternate each side of the insert reducing wear
further.

Pretty cool. But...the thread has a knife edge on it. Where it
starts. A
half a turn of sliver.
Yes I chamfered it, but theres still a sliver.
Ive removed this on threads I had to edm by literally 3d'ing the
quadrant
away. If you look on a lid of any plastic part you will see no sliver of
plastic.
So now I'm trying to figure out how to do this on the lathe.
If I could get a regular turn tool to feed like a thread I could maybe
turn
off that quadrant of sliver?

The reason for the post is I bet this is a super common thing to get
rid
of. I bet there's a trick to this.
The only thing in mastercam that holds promise is there's a value for
leadin chamfer? Maybe that's how they solved this? ?

A way to fix it would be for the thread insert to turn the diameter slow
and then start the thread feed all in one line of code?

Anybody got any ideas on this?



Hig-Bee or blunt start the threads.

Using thread cycle with grooving tool with the width as wide or wider
thread pitch.

Program as threads program with:
1- The end of hig-bee is about 1/2 turn from where thread begin.
2- Start of hig-bee is real trick, adjust starting point of program to have
front end of grooving tool matching thread root point.
3- The faster the rapid of tool to get out at the end of thread is the
better.

Just look at the end of threads gage, it should look similar.


dd.

My last CNC instructor told us all about hig-bee's, common for fire
equipment threads.

Thank You,
Randy

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