2-56 tap - can only buy one

I need to cut 2-56 threads in phosphor bronze for my Rudy Kouhoupt mill engine. Years ago I bought a Woodlands Scenic Hob-bits tap from the hobby store where I worked. Looking at it does not instil confidence that it will cut clean threads or not snap in the job.

If I purchase only one decent tap for this job, what style should it be? I expect I'll use a drill press to guide the tap while I cut by hand. Most of the tapped holes in this job will be blind, so I'm assuming I'll need to use a bottoming tap. Am I pushing my luck starting threads this size with a bottoming tap?

Any recommendations for brands available on Amazon would be a plus as I will be in the States for a couple of weeks soon.

Hi I would recommend Tracy Tools as they deliver very quickly and have never had a bad purchase. I also think it is false economy to try and use one tap and risk having to remove a broken tap especially small taps.

David

Why not get a tap you are more likely to use in future and also be able to get fixings more easily. M2 would be a very close substitute.

A spiral flute tap would do the blind holes but would need carful guiding if doing by hand so I would tend to suggest picking up a set of 3 taps though a lot will depend on how deep you can drill the blond holes, if say 5x dia then you can just use a taper tap which would gibe at least 2D engagement before it hits the bottom but will require the swarf clearing out a couple of times on the way in.

Having just tapped nearly 200 small holes in a crankcase and luckily without any breakage, I would suggest that you buy the highest quality set of taper,2nd and plug HSS taps that you can find regardless of cost. I have another 36 holes to thread 2-56 and again will use a new high quality set. Why risk scrapping an item that is an investment of several hours careful work for a broken tap. Trevor.

I'd use a spiral flute tap. Only one tap needed and it should get you within a couple of pitches of the bottom of the hole. It's easy enough to use them by hand, even though they're usually thought of as machine taps. The "official" metric equivalent is M2.2, but a more practical (very close) substitute is 8BA.

I wouldn't even dream of buying a tap on Amazon. Buy a quality brand from a commercial tool stockist.

Andrew

Spiral flute is a good idea but that's gotta be really fragile at these sizes. I don't know as I'm any more likely to use M2 than 2-56. Seems like most of the steam engine plans I see are imperial anyway. Also, I've already purchased the hardware in 2-56!

I was looking at brands like Guhring, Redline, or Tool America. Looked at Tracy Tools UK; I'll have to email about spiral flute availability as they don't list it as stock. And they ask £10 for shipping to NZ.

Guhring would be on my list of suitable suppliers; I have no knowledge of Redline or Tool America.

Andrew

Andrew,

Many top quality taps are available on Amazon: Dormer, Guhring, YG1, Widia, Union Butterfield, Sandvik, OSG, Titan, Kodiak, Morse, and more. You just have to be particular about which brand to purchase.

So has anyone successfully used a spiral flute two in 2-56 size? I've found a couple of quality ones but am hesitant to drop half a day's pay on a tool that may not be suitable.

Not 2-56 but I've tapped about 800 8BA holes, blind and thru, in brass under power; at 800rpm if I recall correctly. The tap was spiral flute, by Dormer.

Andrew

Why can you only buy one?

Tracy Tools do carbon steel for £9 a set of three or HSS for £27.

My experience with PB is you will probably be OK with carbon steel if you keep it down to 60% thread engagement.

Neil

Because if it's spiral flute you only need one tap per thread size.

Personally I've had bad experiences with taps from TT, so don't use them any more.

Andrew

How about tapping all your holes with the taper tap, and when finished grind off excess length to reduce tap to a bottoming form. If in future you need to tap more holes you could then justify the purchase a new taper tap. Alternatively you could also counter bore the hole slightly to allow a bottoming tap to be aligned.How much thread engagement do you need? If you have plenty of depth you could use shorter screws or shorten your screws as per an earlier thread on screw shortening screws

Neil

Edited By Nimble on 16/05/2018 22:31:50