Taps and die recommendation

Hello all.

can anyone please recommend good quality taps and dies as I am starting a Stuart No 9 and this will be my first time machining and working with cast iron.

I have read about people breaking cheap Chinese taps in cast iron, I don’t want to add to this list.

many thanks John

Hello from another John!

Good to see another new model Engineer haning a go.

Your subject has been done to death in the past but I will try to help, using my experience and knowledge. A fellow model Engineer, ex - school metalwork teacher told me that he always uses the next larger tapping drill than recommended. Cast Iron, tap dry, no lubricant. Half a turn or so forward with tap wrench then reverse to cut the swarf formed. You can feel it happening especially on larger diameters. Use some means of guaranteeing squareness of tap to the work. Failure to do so greatly increases the risk of breakage. Being new to this, obtain a piece of cast iron to practice drilling and tapping so to gain proficiency and avoid breakage in the job. I have used Tracy Tools who seem OK and they deliver fast. I have also used The Tap And Die Co of West London. They take a little longer but their taps appear to be first class. They claim to supply big names in engineering. Satisfied customer with no other connection. Good luck and don't rush things. If further help needed, will try to oblige.

John

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

Hi John,

I assume you will need BA taps, which will restrict your choice of suppliers. I've used Tap & Die Co (in the distant past) and I've no complaints about my threading tools, although I've not needed to purchase anything new recently. They seem to have a 'deal' on BA taps at the moment. You probably won't need all sizes, so you could just purchase the ones required - HSS are best if affordable.

I would also take Tubal Cains advice and drill at 70-75% (ish) engagement - you will not notice any difference in thread strength and it greatly lowers the risk of breakage. A set of drills in 0.1mm steps is very useful for drilling tapping sizes and not expensive. Also (especially for the smaller sizes) tap guidance helps a great deal. Whilst perhaps not essential in cast iron, Trefolex is your green friend in steel.

Regards,

IanT

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!

Sorry I should have said cheap imports!

are HSS better than cobalt?

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

Thanks everyone, It looks like I will stump up a little more money and get the HSS taps and dies from a UK supplier. I was looking for a complete selection but will get them individually as required.

on a slightly different note when a drawing say’s 1/4x32or 1/8x32 what thread are these? As I was planning on getting BA taps do I need different ones for these?
sorry for the silly questions

John

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 agree with Howard's recommendations but only for straight through holes. I query drawings with blind holes, thinking are they really necessary? What's the reason? If I cannot justify the heightened risk involved with a blind hole, then I avoid it like the plague and go for a through hole. I prefer plain clearance holes and use a nut and bolt, if there is no obvious reason for tapping. Quicker and safer. Even taking Jason's advice of a spiral flute tap to push swarf back up the hole, I always use a thin cutting oil, rather than my usual Trefolex. Any remaining swarf in the bottom of the hole is easier to dig out with a piece of coat hanger wire, holding job upside down.My usual way. Not used semi- solid sludges like Trefolex in blind holes as I think that they may hold on to swarf at the bottom. Brass and Cast Iron are the 2 metals usually recommended for lubricant free tapping.

John

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

As an aside, a nice project for the long term might be the well known Universal Pillar Tool - Makes life a dream especially working with small taps! (See Hemingway kits web site).

I wouldn't be without mine.

Regards Mike

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

I make small knurled aluminium disks to put on the shanks of small taps to use a finger and thumb to turn them. It gives good feel for what is happening and there is very little weight to assist in snapping them. You can see one in this video. I just Loctite them on and have not made a depth stop as shown in the video but they make tapping small holes feel a lot better.

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 usually buy carbon steel taps for those threads that I rarely use and HSS for those common threads that are regularly used.

Unlike most members, I find that HSS taps are the ones that break. I have yet to destroy a carbon steel tap (that is tempting fate!)

I normally get my taps from Tracy Tools or the Tap and Die Company. I have a special need for some largish odd ball taps and I get these from China. I can't afford the prices of UK suppliers for these items.

If you buy reasonable quality carbon steel taps (I use "quality" despite Dave's objection) from Tracy Tools, then I find them to be sharper than the HSS ones that they also supply. OK they do lose their edge quicker than HSS, but then it depends on the frequency of use as to which gives the better service.

I always use either a pedestal drill, or a unit made from a cheap Lidl electric power drill stand (like Howard) and better still, do your tapping in the lathe. Unless it is impossible, I NEVER tap a hole freehand.

As a rider, I did buy some taps and dies from Argos about 40 years ago. They were very cheap and would qualify for the description of rubbish using price as the determining factor. I still have them and most of them are still sharp. So cheap and nasty can actually be cheap and good!

Andrew.

Edited By Andrew Tinsley on 15/12/2022 11:35:04

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.

I buy standard metric taps from industrial suppliers, mostly Dormer brand. Other thread form taps are bought from Drill Service. The exception being for ME theads which are from Tap & Die, and are carbon steel, cut thread not ground. I no longer buy from Tracy Tools. Most of my larger taps, up to 1-1/2", have been bought secondhand, or NOS, on Ebay. Taps for one off use are normally bought on Ebay, the most recent being M3 x 0.6mm.

When buying hand taps I normally only get taper and bottom. I prefer spiral flute taps as I do a lot of machine tapping on the vertical mill and repetition lathe. However, spiral flute taps work fine by hand.

Split dies come from the same sources, although I don't use dies that much. Most external threads are screwcut or done with Coventry dieheads.

I normally drill for ~70% thread engagement prior to tapping. A bit more for fine pitch threads, less for coarse pitch and/or tough materials like stainless steel. I rarely use cutting lubricant, simply not needed, and is a pain to clear up. When I do use lubricant (coarse pitch/large diameter/tough material) I use Rocol RTD.

For tapping by hand I don't use a guide, just line the tap up by eye. This is easier with hand taps than for spiral flute taps as the long taper on a hand tap aligns the tap to start with.

Tapping blind holes doesn't bother me, the vast majority of tapped holes on my traction engine cylinders castings are blind. Spiral flute taps really come into their own as they will thread to within a pitch or two of the bottom.

Andrew

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.

I failed to finish my earlier posting due to Microsoft deciding to download a Windows upgrade!

Do not accept the perceved wisdom that industrial tooling is expensive. For example standard sizes of conventional milling cutters from Drill Services cost about the same as those sold by model engineering suppliers. Drill Services offer a next day delivery (in normal times) and are quite happy to take your money.

I find tapping into a blind hole (I think you will have to do a few of these on the Stuart 9) is not a problem. Just don't be gung-ho about it. Stop early if you are worried, clean out the swarf from the hole and tap, continued until you meet definite resistance Most small taps have external coned ends for holding during grinding. I frequently grind the one at the tapping end of a bottom tap back to increase the depth of the threaded hole. This should be done with great care, I have broken taps doing this

I have found that liquid Rocol RTD tapping oil stains steel if left (So I use paste instead).

A simple guide. Now days I usually use a smaller, home made, tapping wrench for anything smaller than 6BA.

JA