[gamazard]

Hi guys, my name is Attila. Im working on a FANUC turnmachine. I have a problem and i hope u can help me.(and Apologies in advance for the bad english )
I got a job in which 55x6 trapezoidal threads have to cut a hole. I have to do 100mm length. My problem is that I gave him a 280 turn and I was very shaky surface. The knife is really suffering.
How and what should change the amine?

Thank you in advance for your help, i hope u guys!!!!


( i hope you understand my problem)

[handlewanker]

Hi it sounds like you have a vibration problem and the boring bar is vibrating with the size of the thread cut.

I take it that you are cutting a full profile thread with plunge cuts under CNC mode.

You'll need the largest diam boring bar that will fit in the hole.........a boring bar ratio of 1:4 is a guide line for preventing boring bar deflection.

So, if your bore is 55mm diam and the length is 100mm, for that length you would need a 25mm diam bar........that means you can use a bigger diam boring bar and not worry about deflection or vibration.....if your boring bar is smaller than that, then there is your problem.
Ian.

[gamazard]

I have a threading tool with 25 diam and 170 long and i can 60mm grabb and i have 110 mm outreach. I think i need a better spindle speed or not ?

[handlewanker]

Hi, I'm into CNC milling not turning, but I have had 50 years as a fitter and turner doing all kinds of manual machining etc.........you'd have to try different speeds........also depends on the material.

Just as a guess.....you could try adjusting the program to cut more with the left side of the tip as it goes deeper into the thread and leave the right side to the final cut to clean up.

Cutting a full thread profile puts a lot of strain on a boring bar and the lathe carriage too.
Ian.