tapping on lathe

[naughtyboy]

want to make some stoppers as a first project on lathe, need to tap some holes in centre.
am i right thinking i need a set of taps with spiral flutes?
also how would i thread bar using die?

cheers

 

[madkayaker]

By hand is the best way. Centre drill and drill your hole put lathe in N set a rolling steady up in head stock so it apply pressure to tap (held in tap wrench with a leg agains a flat bit on carriage) then use chuck key in one hand and winder on tail stock wind the tap in while keeping pressure on with tail stock.

Using a die is same but use a flat steady to keep square till its going.



Will try to take a photo at work that will show better than my English! (Unless someone else gets there first)

 

[outofthefire]

That's how I do it, except I just use a chuck in the tailstock instead of a flat steady.

 

[madkayaker]

They saw a picture is worth a thousand words you then rotate chuck and feed in head stock at same time

 

[Pete.]

I do the same but I use the end of the tailstock ram to keep it square, and just push on the tailstock with it unlocked.

 

[brightspark]

i do as above post , but if u are doing a fair few get a set of tailstock die holders

 

[naughtyboy]

cheers for that.

 

[graffian]

I put the tap in a drill chuck and leave the tailstock unlocked and just push[or wind] the tail stock till the tap engages and when it's to depth I hit reverse and reverse it out. I stick the spindle drive in back gear for tapping. You can use hand taps but your better off with machine taps, spiral point or spiral flute. I prefer fluteless taps. It takes a lot to break a tap, they will slip in a chuck that's pretty tight.

I made a die holder years ago, it's a cylindrical die holder that slides on a bit of tube that's pressed on the stub of an old morse taper drill, drive for the die holder bit is by a stud screwed into the bit pressed on the tapered bit and it goes in a hole in the die holder. The stud works as a depth stop, I made a load of studs one afternoon, after the first one I made the die holder to do them. It worked great, but over the years the depth stop hasn't always been reliable, sometimes the cutting force is to much for the two bit's of the holder to slide against each other and the stop to disengage. Again I run the lathe at back gear speeds, though I very rarely use it as I am pretty used to single point threading. The die holder is ugly as I didn't plan it, I looked in the draw of rubbish and picked out some bits then nailed them together and had it working in a matter of minutes.

 

[hareng]

Depends if its got to be accurate or not.

Usually using taps in tail stock and pushing in to a bored central hole will be pretty accurate. Of course need slowest speed possible relying on torque and cutting oil.
Same with in the mill, drill hole, drop speed and tap in one, power out, job done.

Threading using dies can be very iffy with any accuracy, ok for nuts.
A die has first cutting edge on one leading edge, so when feeding in on initial cut thats where the problems arise from.
A quick job not critical i would thread cut half way if not more then send the die down. Less tendency for die to pull or veer off and remain reasonably concentric.

 

[MrFluffy]

I made a tailstock die holder and tailstock tap holder. They must be free to float in the X axis once its started so the tailstock is just there to guide it, ditto your tap wrench.

I tap or thread with them with the lathe off, and wind the chuck round by hand so I can back off a quarter turn every turn as per recommendations. Theres a hole on them that a bar fits into that catches on the toolpost to stop rotation.
Probably rdg or cronos sells a die or tap holder in morse taper fitting to suit your lathe, theyre not expensive.

I have a tapping head for the mill after a spate of shattered taps after bumping the knee the wrong way by accident...

 

[brightspark]

i got a set of tailstock die holders from rdg cant remember price about 30 quid i think, well made. only one problem 2 of the holders didnt fit the dies so needed boring out a bout 12 thou no great hardship but u would think they would be right