RIGID TAPPING, LATHE
Could someone explain rigid tapping in a lathe.
Is this so I can tap from the carriage?
I am gathering that it is a device; Are they universal? What are some good brands to look at?
If anyone has tips and tricks for this procedure I would like to hear them.
Rigid tapping usually refers to holding the tap in a rigid holder (no axial play) and having the infeed contolled in a CNC machine.
I'm not aware of attachments to do this other than with a CNC controller. Even then, all CNC controls are not capable of rigid tapping. Most newer CNC controllers have rigid tapping as an extra dollar option. It takes a very precise coordination of feed and spindle speed to avoid breaking taps.
One advantage of rigid tapping over other methods is the ability to control tap depth within a fraction of a turn of the tap.
The nearest thing to non-CNC rigid tapping I can think of would be the method Hardinge used on their chuckers with a lead screw and follower. Come to think of it, that method could be adapted to a coventional lathe.
Thanks for the reply.
So, in a CNC case it is software and hardware?
Say if the controller supports the function then is the tap just held in a regular toolholder?
In true rigid tapping the CNC controller keeps track of spindle angular position in addition to carriage lead. The spindle can stop and back up and the cariage will back up in unison and not break the tap. You can't do this in a regular manual lathe due to gear train backlash; the spindle will turn but the carriage won't start backing up until the gear backlash is taken up.
Easy way to do this is just leave the tailstock loose on the ways (assuming it slides free). Move the tap close to the hole (with spindle running), and turn crank until tab grabs. Let the tailstock slide in until desired thread depth is reached (preferably through hole, blind holes can be kinda scary). Stop/reverse the spindle, tap comes out.
Rigid tapping in CNC always scared me for some reason, I've done it, but my finger never left the lil red button lol.