Tracy tools all day long, Carbon steel more than enough for for a Stuart model.

If your mill has a quill, use it to ensure accurate positioning and tapping exactly perpendicular to the drilled hole.

Simple, and no better, way to avoid joining any list of people breaking chinese taps is to avoid cheap chinese taps!

Have used both Tracy Tools and tap and Die Company.

Both have been satisfactory.

I seem to be able to break carbon steels taps more easily, so opt for the more expensive High Speed Steel,ones

I shan't wear them out, and am less likely to break them.

Always lubricate, Rocol RTS, Trefolex, Bacon fat or even plain lubricating oil – better than nothing.

The purpose for reversing every half turn or so is to break ant swarf so that it clears more easily. (Failure to take my own advice caused me to break a M10 Tap; so there! ) If in any doubt, withdraw the Tap or Die and clean it from time to time..

using a slightly oversize tapping drill reduces engagement, but not disastrously so, for most purposes.

An undersize tapping IS likely to result in a broken tap, and most probably a scrap workpiece. Broken taps rarely come out easily.. Unless you have access to a spark erosion machine

In the lathe, I use a sliding Tailstock Die Holder, and made a a sliding Tailstock Tap Holder.

This means that the Tap or Dies is suybject to the minimum load as the thread is cut, rather than trying to drag a Tailstock along the bed.

Pulling the chuck round by hand, or using a Mandrel Handle prevents the Tap being subjected to excessive torque, and allows you to feel the toque applied to the Tap.

In the Mill, I use a spring loaded guide ("Tap in Line" ) to steady the end of the Tap while driving the Tap with a small Tap Wrench.

For other times,I made up a Tapping Aid. This is modified Pistol Drill stand (There bis probably a picture in my albums). Thea tap is held in an ordinary small Drill Chuck, and driven by a short handle on the sliding spindle.

By these means, Taps are not subjected to bending (which is very likely to break them ) and are kept "square on" to the work.

HTH

Howard

1/4 x 32 etc are ME thread form, you will be able to get these from the suppliers mentioned above and most of the model engineering suppliers too.

I don't use BA much now but the last few taps I bought came from EKP I would also look at the Volkel ones that Rotagrip sell, I've a few of their metric taps and does. You also have an option of spiral flute from them which means you just need one of each tap rather than two or three. You don't need to keep backing these one off just keep on tapping and they drive the swarf out the top of the hole.

I like the idea of making a Stuart 9, a little larger than most engines.

Taps usual break when they are bent. Therefore some form of guide is a must both when tapping and removing the tap. As for carbon steel or HSS it does not really matter with cast iron or brass. However the piston and valve rods on your model will be stainless steel as HSS dies would be sensible.

I buy my taps and dies from a local industrial supplier because of convienence, place the order over the internet, have a cup of coffee, drive four miles and collect the order. May be more expensive than a lot of suppliers but they have always had on the shelf what I needed (BCY, small BE, small ME etc). A no brainer.

JA

It's my hobby horse I know, but 'good quality' is meaningless without a specification. I guess what you mean is 'which brand is super strong, super cheap, and affordable?' The answer is none of them!

To my mind cutting tools fall into three broad brackets:

• Too cheap. Likely to be poorly ground, with dimensional errors, and maybe faulty heat treatment. The class includes fakes, counterfeits, manufacturing rejects etc.
• Mid-range. I find these suitable for amateur use, that is working them moderately rather than hard and not expecting them to last forever. The occasional faulty one sneaks in,
• Industrial. These are highly reliable in the sense they're carefully made to specification but they're not necessarily super strong. They can still be broken by an unskilled operator. However, they save bother in the long run when used a lot, lasting longer than cheaper types. But! They're expensive, and you have to do cut a lot of metal to get the investment back.

Many newcomers to the hobby naturally want 'quality' tools, perhaps thinking spending a little extra will solve all their problems. It's not that simple, notably because Industrial tooling is expensive. As most of us are on a budget, there's usually a rapid retreat when the size of the bill becomes apparent!

In practice, unless something special is planned, I buy mid-range tools. It's where I get them from that matters. In my view the tactic most likely to cause disappointment is buying 'bargains' online from unknown suppliers, especially from abroad where UK consumer protection is unenforceable. Buying from UK based hobby-suppliers is much safer, and I've done OK for taps and dies from Tracy Tools, ArcEuro, and another I can't remember. They don't sell the best tooling in the world, but I've found it fit for most hobby purposes. I also have a Lidl set, where the 4mm tap was rubbish, but all the others – so far – are OK.

Carbon-steel and HSS taps and dies both work well. Carbon-steel doesn't stay sharp for as long as HSS and is inclined to be brittle.

What snaps HSS and Carbon steel is poor technique:

• Hole too small for the tap, or rod too big for the die. (In hobby work it pays to oversize holes and undersize rods slightly.)
• Failing to start and maintain the cut at an exact right-angle. Threading manually without a guide is high-risk. I avoid doing it, instead using my mill or lathe to maintain the angle accurately at all times.
• Failing to lubricate appropriately
• Keeping the cut going for too long (frequently reverse quarter turn to break the swarf so it doesn't wedge the cutting edges)
• Allowing swarf to build up, especially in the hole when tapping.
• Keep a separate set for Brass, because the metal demands sharp edges.

As a beginner I broke small taps depressingly often! Much less likely now, entirely I think because I avoid the mistakes listed above. It's not because I buy 'quality' tools!

Dave

If you are going to do a lot of tapping of blind holes, it may be worth trying to find Spiral Flute Taps, which will will remove swarf from the hole, more easily than straight flute taps.

But, they may not be available in the sizes and threads that you want to use.

If this is the case, break swarf, and withdraw tap to clean, frequently, and keep lubricated.

In every case, avoid bending the tap; they DON't!,

Howard

I am with Jason and Howard, Spiral Flute taps every time. I have tapped M2 in brass "without looking" just use a guide to ensure a square start.

Just to throw anotherspanner into the works, if you are metrically minded then you can always change to metric threads. Stuart's tend to use a lot of 5BA and 7BA which work out quite nicely to M3 and M2.5, combine that with small hex metric nut sand you will have a larger choice of taps & dies as well as a nice looking engine.

The Ones from ARC are reasonable and not expensive, I use them for general works and keep my YG-1 taps for where it matters

The ME threads can be substitured with Metric fine unless you are going to buy in UK made steam fittings which all tend to have ME threads but metric are available from Europe.

Personally I won't buy carbon steel taps or dies, I think they're crap.

And you don't have to spend a fortune to get top quality HSS anyway, there's literally thousands of NOS ones available on ebay at good prices!

The good brands being Dormer, SKF, Osborn, Hall, Warrior, Guhring, and Presto (old).

If you absolutely must have brand new then Osborn Europa tool from GBR engineering are good value, or Sherwood brand.

Surely if the carbon steel tap or die is correctly and accurately ground then there is no reason for it to be of low quality even if it wears a little quicker. It’s the quality that counts more than the material.
regards Martin