Thread turning with a grooving tool

[gregormarwick]

If you had a program that would do it, that would be great. The way I showed, the only thing that takes time is finding the start points. My old bobcad program spits the code out in seconds.

For an idea, I just modelled a 100mm x 30mm pitch custom buttress thread and programmed it using a 4mm grooving tool with a 0.2mm corner radius, .1mm stepover.

The result was 280 passes - that's a lot of time to do manually, not to mention the mistake potential.

 

[cuttergrinder]

How well does it work for rope drums. That's what I use the sub program for. I come in at a 45 Degree angle so the tool doesn't dive right in because our rope drums have no undercut at the beginning or end of the thread

 

[gregormarwick]

How well does it work for rope drums. That's what I use the sub program for. I come in at a 45 Degree angle so the tool doesn't dive right in because our rope drums have no undercut at the beginning or end of the thread

Pretty good the few times I've done it, however I did cheat as the featurecam function has no control over continuous threading, so I made a custom post that behaved like it was using G32 but called an incremental sub instead of G32, then defined the lead in/out in the sub.

Pretty close to the way you've done it, except featurecam figured out the start points for me.

 

[cuttergrinder]

When you set your grooving tool offset in your lathe, do you set the center of your tool or the edge of the tool?

 

[gregormarwick]

When you set your grooving tool offset in your lathe, do you set the center of your tool or the edge of the tool?

Depends on how the tool is defined in FC tool library, you can do either. I do edge except in some very specific circumstances.

 

[YoDoug]

Relating to the original post, be careful trying to use a groove-turn insert to cut Acme or large profile threads. The back angle of groove-turn inserts is usually not great enough for the IPR needed for threads. Most ACME inserts either have the extra angle needed built in or the holder has the insert at an extra angle.

 

[gregormarwick]

Relating to the original post, be careful trying to use a groove-turn insert to cut Acme or large profile threads. The back angle of groove-turn inserts is usually not great enough for the IPR needed for threads. Most ACME inserts either have the extra angle needed built in or the holder has the insert at an extra angle.

Yes, it's pretty normal to have to hold the tool at an angle when doing this.

Nice and easy in a millturn where you can just index the tool spindle...

In basic turret lathes I have milled the tool shank at an angle so that the cutting edge matches the lead angle.