2 mm tapping

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Herbiev

Herbiev

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Hi all. Just after some advice on tapping 2mm threads. The Dubro tap came with a 1.56mm drill and I used Treflex tapping grease/compound but they keep breaking when tapping steel. Should I use a larger drill or different cutting fluid? Is there any such thing as a 2mm carbide tap? Any tips or advice greatly appreciated as at $10.00 a go it is getting expensive.
 
Mayhaps the tapping technique can be improved.

How do you guarantee that the tap is following the axis of the hole exactly? E.g., for a hole perpendicular to a flat surface, do you use a tapping block?

Take care

Tom in MA
 
It would depend on the application.

Many tap drill charts are for a 75% thread.
You really rarely need that in model scale.

If the fastener is holding high pressure, a 50% thread in steel is required.
If there is little pressure on the fastener you can get away with a 30% thread.

I always use a drill bit one size larger than recommended but that's just me.

Rick
 
For metric tapping size the easiest way to get the tapping size is to subtract the pitch from the diameter
M2 x.4 = 1.6 tapping drill, I use 1.65 - 1.7 for harder materials
Cheers
Paul
 
Paul is correct about the drill size for that particular tap. I am currently working on some very tiny steam engines and all the holes are 1.0x.25 mm threads. I am tapping mild steel (12L14) but have found that I had to go up .002 from the calculated drill size because the tap was turning very hard. I don't know what the Dubro taps are made of but I suspect they are carbon steel as opposed to high speed steel. All my taps are high speed steel. 2mm is .078 diameter so it shouldn't pose a big problem as I tap 0-80 (.06 dia.) all the time. Another suggestion is to use a small chuck to hold the tap as opposed to a tap wrench. With a tap wrench you have too much leverage with the handles. By using a small chuck you get a better feel for what the tap is doing.
Attached are a couple of pictures of the small steam engine I am building and the tapped holes I'm referring to.
gbritnell

AM.jpg


F.jpg
 
I've done a lot of M2 holes and use 1.5 or 1.6 for aluminium, 1.7 for steel and even 1.8 for horrible stuff.

Must use a tap guide. Normally they break because of side (bending) loads.

This is what I use - a free floating pin chuck - holds centre and finger power only.

Ken

tapchuck.jpg
 
Thanx to everyone. A lot of good info there so I feel far more confident now.
 
Hi Herby of hallett cove, i never use tapping grease ,it holds the swarfe.I always use WD40 its slightly abrasive.
For tapping small holes ie 3mm or smaller i always use a tapping chuck not a T handle, hand held and hold the workpiece in your hand
not in a vice.Its all a matter of touch you can feel any resistance,and clear out the swarf. every 14 turn you can check on perpendicular. Be patient slow is quicker than break
Barry (seacliff) Did you do any work in the 45o C the other day
 
Hi Barry. Thanks for the tips. The only work I did in the 45 degree heat was to open the refrigerator door and pull the ring off a tinnie or six.
 
I think that there are 2 issues here. Both were addressed by George Thomas but seem to be studiously ignored- and ignored. GHT wrote about this in Model Engineer way way in the past but his writings were published in book form by my friend Dr W A Bennett. Bill took on the task( and it was) at the request of George's friends and associates.
A few coins come his way in 'royalties' but I suspect they are of really little import.

Rant over? Well, what did he say? He described his professional experiences of broken taps in the - what it 3 engineering firms- that he owned. It certainly wasn't a 'one off situation' GHT made up a 'Universal Pillar Tool' and it became known as this because another guy - built model steam locos. The name was L.C. Mason. Heard of him?
Me? Well, I'm just an old, old amateur but I have made a pair of these UPT's over the years. The first when I could afford the castings and welded bits together. So the castings are still available- and so are the books.

No, the gripe isn't quite over because I wrote fairly recently- a month or so ago about making one from what was the con rods of a scrap Mini or BMC 1000 A series.

Back to my coffee- I'm too deaf to hear the crack of taps.

Norman
 
You could build or buy a hand tapping machine. I built one, it seems to work quite well, better as taps getting smaller.

1357979073102.jpg


1357979504884.jpg


Shawn
 
Last edited:
Most important while tapping small holes is hand holding the workpiece. I never use T-bars on the tap-holder. I always use cutting fluid.

After reading this topic I will try and use WD40. Just maybe it will cut even smoother.
Never to old to learn...;)
 
You could always try a Roltap or Fluteless Tap instead of a standard cutting tap. These tap are great on small diameter as they don't have flutes so are inherently stronger. You will have to drill a bigger hole, but you will get a stronger thread and are less likely to break the tap. Because there is no swarf produced, you can also get deeper into the hole. Not cheap though!!!! But should last a damn site longer!!
 
Hello guys!
I`m also tapping several 2mm holes on my project and I aways get scared to break the tap (here in Brasil they are very expensive). What I found to be very effective, is to usi the collet to hold a pin of abount 2 - 2.5mm and guide the pap wrench as you can see on the picturo bellow. Another good care is not turn more than 1/4 of a turn than tur back to break the ship/swarf otherwise it will jam the tap and cause the break.

DSCN1377.jpg


Hei Ken I liked your idea of the small chuck with free movement. I will do tha for me too I think it will work great.

Cheers,
Edi
 
Here's how I do it,with job piece held in tool makers vice and tap held by drill chuck,hand lever feed tap to hole and turn by hand with no reverse.Turning my hand gives good feeling.If too much force is required ,you have a problem.Drill hole too small.
I use Japanese machine taps for their high quaiity and sharpness.For blind hole I use spiral taps that brings chips out of tap hole and straight tap with chips down to hole for through holes.For 2mm x 0.4. A tap drill of 1.6mm is required. I use Tapamatic Tapping Oil.
Tapping with tap wrench is very risky with 2mm tap. Manual tap is not user friendly. Machine tap best. HSS tap best.
Foto shows a 2mm tap about to be downgraded to tap aluminium or brass.I paid S$8.50 fot 2mm tap.

IMG_1266.jpg
 
As a sort of followup, there is a problem which starts the possible breakage and that is a blunt or damaged tap. One lot of trouble is the fact that the tap is damaged by being used 'out of the vertical' and this breaks one side of an already thin tap. The next time the tap is used, it has to cut a thread with TWO flutes that are moderately sharp and one which isn't. The overload- and the possible misalignment- breaks the already damaged tap.I prattle on about tool and cutter grinders- but no one reads the blurb and the number who make a tool and cutter grinder. Taps and dies do not last for ever- but can be ground- but only with some simple device.

Time for more coffee

Norman
 
goldstar31 said:
As a sort of followup, there is a problem which starts the possible breakage and that is a blunt or damaged tap. One lot of trouble is the fact that the tap is damaged by being used 'out of the vertical' and this breaks one side of an already thin tap. The next time the tap is used, it has to cut a thread with TWO flutes that are moderately sharp and one which isn't. The overload- and the possible misalignment- breaks the already damaged tap.I prattle on about tool and cutter grinders- but no one reads the blurb and the number who make a tool and cutter grinder. Taps and dies do not last for ever- but can be ground- but only with some simple device.

Time for more coffee

Norman
Click to expand...


Hi Norman,
You are right. All Taps must be given a go over eyeball check before commencing tapping. Out of vertical is another cause.Blunt taps too.Too big a tap wrench is another cause.Have seen a steel casting with a 1/2 " BSF tap snapped inside a deep hole.They blamed the poor apprentice for the disaster. After a week's futile effort,they decided to make a new piece. Week later we were issued new taps--------"Triangle" Taps and no more recycled taps. The boss gave in.
 
Gus,

Unfortunately there is a lobby here which cannot relate that one cutting tool is much the same as another and behaves in much the same way. there is a lobby that is prattling on- seemingly forever about boring tools and here we have a lobby about boring tools which don't bore cleanly but bore with a thread. Other people make a sort of effort to clean up a boring tool- which left to its own state- will tap a sort of thread.

They are ALL mixed up. I'll go for more coffee-- and something for a headache-- which they are causing.

I CAN grind taps-- they can't.They have problems which I don't.

More coffee?

Norman
 
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