If the rod is not too long, transfer it to a milling machine and use a sprung-loaded tapping guide, taking care to adjust the spring force as the tap decends. That way you will get really good feel.

Especially for stainless and with regard to the application, consider drilling the hole a little larger than the theoretical tapping drill size.

As Peter does, I would recommend using a tapping-guide, and these can be used in the lathe (held in the tailstock chuck) in the same way as on a mill or bench drill.

I do find rotating a tap-wrench by hand on a lathe, physically slightly more awkward than on a milling- or drilling- machine, so raising the risk of breaking the tap. That is partly by more restricted access, but for me also due to being short, so the working position at my Myford lathe is not very comfortable unless I stand on a suitable platform. (Oddly, the much beefier Harrison is lower and more comfortable!)

When using the lathe tailstock as pusher for a tap or die, as Jason describes, I lock the tailstock’s position and gently wind the barrel forwards and backwards with its handwheel. For small diameters, by one finger on the handle. It’s more sensitive than trying to push the entire lump.

For tapping blocks and plates I’ve sometimes used the bench-drill as a tapper by slackening the belt and using the chuck as combined tap-holder / tap-wrench, manually. (Make sure the machine is switched off at the wall!). One hand rotates the chuck, the other gently eases the quill down and up – being careful to ease up when backing off the tap. The quill spring is quite powerful so I restrain the quill in this way, in both directions.

Vic

This is what I use when using small taps in the lathe (or the mill or drill press). I have two “T” handle tap wrenches that I have modified by drilling an 1/8″ inch hole down the centre so they can be held in alignment on an 1/8″ rod held in the chuck on the lathe, mill or drill. The picture is with a 1-72 UNC tap (1.85 mm) in the lathe. By supporting the tap wrench like this, all side thrust is eliminated and it allows a very fine feel of the rotation to sense any tightness telling you to stop and back the tap out to clear the flutes. I find backing out and clearing the flutes is beneficial even with spiral point or flute taps

John

My method is like John’s except the tap-holder is supported by a home-made spring loaded pusher in the tailstock.  The spring provides the pressure rather than me, which helps because I’m clumsy.

Dave

I for one would not countersink. For any tapped hole going in with a clearance drill to just sub surface is the way to do it. Tapping operations on a tapping sized hole will raise the surface slightly which is not what you want in most cases.
Alignment aid are a help but you need to drive the tap with a system that gives you a good feel for how it’s cutting. As taps get smaller then the way you turn them needs to adjusted to suit. For very small taps all you need is a knurled rod not much bigger than the tap. That way you can feel what’s going on. George Thomas’s pillar tool has an arbor for small taps down to 16BA which has a finger grip no more than 1/4” You only need enough torque to drive the tap whilst it’s cutting but not enough to break it.

Personally and this is tempting fate I cannot remember the last time I broke a tap. Feel is everything.

I agree with Martin, for small taps in the lathe I usually turn it by gripping the knurled chuck surface rather than the tommy bar, much more sensitive feel. For tapping free hand with small taps I use an Ecllipse #123 pin vice and support the tap body by holding it between my thumb and first finger, supporting that hand on the item being tapped while turning the pin vice with the other hand. This helps prevent any sideways force on the tap which usually means a broken tap.

John

That is why Bernard suggested CSk before tapping as it is less likely to be thrown off by the thread as you are countersinking a plain hole.

As I tend to use 90deg spotting drills they can be taken deep enough to do the job in one go and as it’s the same tool no problem with loss of concentricity.

Lots of good points. Lubricate accordingly. Only use good quality SHARP tooling. Minimise torque, sharp tools cut easier anyway, the knurled part of the tap wrench is sufficient between fingers. AND, clean out the hole regularly, every 3 or 4 threads worth of depth, back the tap fully out, clear out the hole and brush off the tap. Re-lubricate and carry on. The cleaning is the best de-risk strategy. I tap hundreds of 8Ba holes, not super small, but certainly small enough that one should tap with careful processes.

All the best…

I regularly drill & tap down to 1mm & I never use the lathe or the mill yes I start it in the lathe Pultra usually to get it straight but then do it by hand , I always use my spiral flute taps as they don’t bind although saying that I always turn a few theads then remove tap clean oil & go again

My main objection to countersinks is it’s difficult to control the diameter. If I am fitting countersunk screws I will always grind a drill to the correct angle and use that. It just looks neater.