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Advice on Machine taps / grades / manufactuers


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Hi to those in the know   ie not me :lol:

 

I have bought a new toy - namely a Auto / Reverse Tapping head - and a big one - goes up to M20 !

Luckily the Mill I have is powerfull enough to take this, and I have found a M16 spiral machine tap,

and it works a treat (after having to make a arbour to get it to fit into acient International 30 ! )

 

Now, this is going to be used - A LOT, so I am more than happy to buy a properly decent quality Machine taps(s) for it, but there is the problem.

 

There are LOADS of manufactuers, all say they are "Quality" (even ones shipping from china :rofl: ) but are they ?

 

So, 1st Question, what are the best makers of quality taps ?

Please list makers !

Now the trickier part.

 

This tap is going to start on 2 x 12mm Plate s276 Hot rolled steel, that has been made ferkin hot as it will have been tigged a lot ....then under than is around another 6-7mm of Cast steel.

 

So, other than the maker, what GRADE of tap should / would be best ?

There are taps with rings on them - Red Blue White Green etc, and I have no idea as to if one would be better than another ?

 

Then the codes like :

Dormer M16 6H EO03 HSS Spiral Machine Tap

or

376-C M16x2 6H R40 SE 800 SPIRAL FLUTE HSSE HIGH PERF. MACHINE TAP 

HELP !

so, makers and grade types please !

 

Video ....Mmmmm saves me so much time and 101% perfect thread every time !

Luckiliy s/h missing bits - now sorted, was also only Morse 3 - which with an adapter and the Diff in Jig meant not enough room, thanks to some daft lathe work on a INT 30 > B44 its now INT 30 > M20x2 :D = sorted !

M16 Autotapping Pegging Diff.mp4

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No great experience here but Dormer have a pretty solid reputation for drills and cutting tools. I'd be sticking to things you can buy from UK suppliers who will answer the phone and stand behind things they say / send you a new one ASAP.

A couple from my bookmarks file:

http://www.cutwel.co.uk/

Taps and Dies, Reamers & Milling Cutters | Tracy Tools Ltd UK

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Spiral flute for blind holes, spiral point for through holes. They push the swarf in opposite directions.

 

Dormer and Guering is who I would go to for taps.... And don't be light on the cutting oil.

 

Couldn't tell you the grades I use.... I throw any old carp in.... If it cuts and doesn't break then that's plenty good enough.... It doesn't matter for me because on our big lathe she takes a few moments even at low RPM to get her arse into reverse so I can't run taps as they recommend. 

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I've not got an auto head but when tapping stainless I've broken a fair few taps. From unknown eBay specials to known brands like dormer. However, I'm yet to break a Presto tap (I emphasise yet!). Can't remember a specific grade off the top of my head but I believe they're HSS and listed as something like for steel upto 800N/mm2.

The 6H is the tolerance or fit. I believe that's standard. I think you can get oversize for if you plating or coating or something afterwards but I'm not that up on it ^_^

If the steel has been hot I would run a drill down it again incase it's distorted. Do you think there is a chance the heat work you do harden the surface of the steel around the hole? That would make it harder to tap. If so maybe leaving the hole undersize until you've welded then drilling or tapping before welding might work? If your tapping in a mill or drill wouldn't it be easier to tap at the same time as drilling anyway as then it'll all be set up in line?

 

There is a chart on this on page 4&5 that might help pick the type?

http://presto-tools.co.uk/uploads/general_files/355-3threading.pdf

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