Trouble with Acme threading on puma300

B

BobMachines

Plastic

Joined

Jun 7, 2021

• Jun 8, 2021

• #1

Hello . First time using this forum. I am having chatter problems with acme threading on a puma 300. I am using g76 threading code, and material is 360 brass sometimes also 17-4, 410. I am having problems with chatter in threads. I am using s"plit bushings, and carmex tools. Anything above 3" long threads give me trouble. Has anyone had success with anti vibration bars for threading these deep acme threads. Generally it is from 6tpi to 3tpi, and sometimes I have to do dual lead. I know I need the right helical angle, and is even more important with dual leads. Im thinking of switching to Iscar, but want to hear what others use. Thanks

 

B

BT Fabrication

Titanium

Joined

Nov 3, 2019

Location

Ontario Canada

• Jun 8, 2021

• #2

heavy cutting, you might need a steady rest follower depending how much that part is flexing.

 

H

HuFlungDung

Diamond

Joined

Jan 19, 2005

Location

Canada

• Jun 8, 2021

• #3

Might have to create your own threading program written out in full. In general, Acme threads need 3 cutting strategies if chatter becomes an issue: a front flank pass, then a rear flank pass, then a center pass. Too much tool contact with more than one surface creates the chatter tendency.

Or, use a tailstock support.

 

B

BobMachines

Plastic

Joined

Jun 7, 2021

• Jun 8, 2021

• #4

Doesn't the g76 create a compound in feed for threads? You have to enter the angle of insert in the program for this reason i thought. Does the step by step threading need a g32 code? Do I alternate between flanks each pass.

 

B

BobMachines

Plastic

Joined

Jun 7, 2021

• Jun 8, 2021

• #5

Im making a drive nut. Left hand internal acme threads and the piece is only about 3" long

 

F

Fancuku

Cast Iron

Joined

Dec 7, 2018

• Jun 8, 2021

• #6

What is your spindle speed?

 

C

CarbideBob

Diamond

Joined

Jan 14, 2007

Location

Flushing/Flint, Michigan

• Jun 8, 2021

• #7

This is internal and longer than 3 inches? You do not spec the ID but a 6 to 3 is a goodly sized hole and can take a big bar.
Bob

 

DouglasJRizzo

Titanium

Joined

Jun 7, 2011

Location

Ramsey, NJ.

• Jun 9, 2021

• #8

BobMachines said:

Hello . First time using this forum. I am having chatter problems with acme threading on a puma 300. I am using g76 threading code, and material is 360 brass sometimes also 17-4, 410. I am having problems with chatter in threads. I am using s"plit bushings, and carmex tools. Anything above 3" long threads give me trouble. Has anyone had success with anti vibration bars for threading these deep acme threads. Generally it is from 6tpi to 3tpi, and sometimes I have to do dual lead. I know I need the right helical angle, and is even more important with dual leads. Im thinking of switching to Iscar, but want to hear what others use. Thanks

Click to expand...

The tool is only part of the equation. Your DOC is critical as is your RPM.

 

B

BobMachines

Plastic

Joined

Jun 7, 2021

• Jun 9, 2021

• #9

My minor diameter is 1.51. I am running about 800 sf my rpm is around 1700.

 

F

Fancuku

Cast Iron

Joined

Dec 7, 2018

• Jun 9, 2021

• #10

I am hoping you typed an extra zero by mistake for that spindle speed. If you didn't, then that's actually insane.

 

Y

yardbird

Titanium

Joined

Jul 3, 2013

Location

Indiana

• Jun 9, 2021

• #11

BobMachines said:

My minor diameter is 1.51. I am running about 800 sf my rpm is around 1700.

Click to expand...

Well Bob I'd give slowing it down a go?

For ACME that's fairly quick.

Brent

 

R

Rstewart

Stainless

Joined

Jun 14, 2006

Location

Huntsville Alabama

• Jun 9, 2021

• #12

BobMachines said:

My minor diameter is 1.51. I am running about 800 sf my rpm is around 1700.

Click to expand...

Jesus! That tool must be Flying thru the nut lol. SLOW IT DOWN