Taps

Hi Guys

I want to buy an M8, M10 and M12 tap they are all 1.25 pitch, and are for hand tapping not for machine tapping.

My question is whats the best to go for HSS, HSS-E, HSS-G or HSS-R

I'll be tapping mainly mild steel not stainless.

Thanks to anyone who can give me a quick crash course.

Clive

Clive. I find it best to buy good brand names. For hand tapping nearly anything will work but as they say "you pays your money and takes your choice." In short , the better quality always works for me.

regards

IMO the higher cobalt content of the E, G and R only really comes into play for drills or lathe cutting tools, where they have a better heat resistance.

For hand use you should be fine with decent basic HSS from someone like Tracy Tools.

Use plenty of lube, and back the taps off to clear them frequently.

As your M12 is quite a hefty size you might like to consider a set of 3 serial taps, where they actually vary in size from no 1 thru no 3. Like these **LINK** These make it much easier to tap the larger threads. Plenty of cutting lubricant makes a big difference too.

A normal set of three taps only vary in the length of the taper on the taps

For mild steel the exact type of HSS will make no difference. Rather than buy nine taps I'd by spiral flute taps, so you only need buy three. Just because they're machine taps doesn't mean they don't work fine as hand taps. With decent quality taps there should be no problem threading all sizes in one pass; M12x1.25 in particular is extra fine. I've had no trouble with M12 coarse pitch spiral flute taps in steel.

I only buy from professional suppliers, not those aiming at the ME market. For online purchase of taps and dies I use Drill Service in Horley.

Andrew

+ 1 for Andrews comment . The other thing with spiral taps is you can use the drill press or mill to get them started squarely , just mount the tap in the drill chuck and run the machine up to speed ( i use something around 200 rpm ) then swich off the power as you feed down on the quill . The inertia inside the machine is usually good for a turn or two and you simply undo the drill chuck and remove your part with the tap still in the hole ready for hand tapping .

If i have a few to tap on the same surface i wind the tap out while it is still in the chuck and move to the next hole , once they're all done i move the part to the bench and hand tap , the tap is guided by the first few threads done under power .

The downside is they are usually more expensive but when you weigh it up with the fact you only need one tap per size and not two or thee the cost is negated .

I don't rhink i even have a starter tap in my collection as i use intermediate to start off with when using straight flute taps and a bottoming tap if required .

I use spiral taps from 3mm up and they make tapping a pleasure ! You can also use a battery drill with them and a tapping guide to set you off straight although you need to take care as it is easy to get off kilter and snap the tap .

They can all work. The usual method is to use the mill or lathe to line up the tap accurately to the hole, not necessarily starting the thread by the machine power. Alternatively using a bush to line up the tap is recommended. Crooked threads easily cause broken taps which are a 'B' to remove. Do not buy cheap unless well experienced - they can easily be broken in the hole!

Possibly surprisingly but the 'economy' Metric HSS sets are usually serial type.

Look for one ring on the shank of the first tap, two on the second and none on the finishing tap.

Neil

The "Innterstate brand from MSC are good value when they appear on the monthly offer sheet. Whatever you buy stick with HSS

Thanks for all your replies chaps, I’m just deciding whether to buy a M12 x 1.25 taper.

Let me put you in the picture, I’ve taken some bolts out from underneath the car and I’ve already got an M12 Volkel HSS-G second tap, but haven’t I managed to cross thread the existing hole doing it upside down lying on my back so I’m just hoping the bolt will hold when I refit it.

I’m thinking maybe I should have run a taper tap in it to begin with.