Thread whirling

I hate tapping!
Unfortunately, since I am using step motors, LinuxCNC will not be able to help me either. Or so I thought, until I came across this: www.directindustry.com/prod/dixi-polytoo...ct-32469-848505.html

Can anyone provide some insight to what it takes to whirl threads like this?

Thanks,
/Chris

I have used this method once on my cnc mill along time ago for large diameter threads.

I cant remember the exact details but I think I just set software to do a helical cut at the correct thread pitch as the depth of cut.

Why does step motors stop you from tapping?

Chris M

I've always heard it referred to as thread milling. I use steppers and it works great. If you're not familiar with the concept it doesn't use a tap but rather the tooth profile and mills the thread instead of tapping. It uses a spiral move and advances at the pitch.

The easiest way I've found is to use a CAM software like Fusion360 which has a built in thread milling feature. Just program the sizes and pitch and it generates the code. Depending on if you're cutting outside or inside diameter threads determines if the whole being cut is the minor or major diameter of the thread.

I think that the link is to a thread _milling_ tool.
Thread whirling is slightly different, it is used for external threads.
A tool rotates eccentrically to the workpiece with cutting teeth on the inside.

Aha, so it is generated in the CAM software! Makes sense now that you say it. I guess that pushes me toward an investment in a more sophisticated CAM tool than Heeks or FreeCAD that I am currently using.

cmorley wrote: Why does step motors stop you from tapping?
Chris M

It has been said numerous times around here that tapping is for encoder based machines only.

Thanks for your responses!
/Chris

Fusion360...free for the little guy and not too much investment if you're a larger outfit. Give it a shot. Top notch CAD/CAM software by Autodesk.

cahlfors wrote: It has been said numerous times around here that tapping is for encoder based machines only.

You need a spindle encoder, but all the axes can be stepper.

My lathe threads like a champ, and that's all steppers.

The encoder need not be anything more complex than some hall sensors looking at a gear in the headstock.

Oh, I see!
But who needs such complexity now that there are thread milling/whirling tools that will chamfer, drill and finish tap to the bottom of a whole in one operation? Oh, and will not break, rendering the part destroyed. Or if it breaks, can just be lifted out and the operation run again with a new tool.
I am probably being a foolish romantic here, but the concept looks really nice! I will have to explore it!

Thanks,
/Chris

cahlfors wrote: But who needs such complexity now that there are thread milling/whirling tools that will chamfer, drill and finish tap to the bottom of a whole in one operation?

You don't actually need any special tools if you have a boring head. A couple of days ago I cut an internal 1.5 inch x 1.5mm pitch thread using a lathe internal threading tool in a boring head in my mill, then cut the matching external thread on the lathe.

You do need a spindle encoder on both machines to do that.

However, you can thread-mill on a CNC mill without a spindle encoder.