BA, ME, Metric Coarse or Imperial : which taps and dies to buy ?

[Rik ShawParticipant @rikshaw]

Brian – in answer to your question, my suppliers of taps, dies and all related engineering kit have for many years come from:

1. Car boot sales – although getting up at 06.00 on a Sunday morn to tool shop at up to five separate boots is getting harder and harder.

2. Auctions – another great source.

3. Dave the tool man at Dorchester market on a Wednesday – this week from him I bought a base ball cap full of milling cutters up to 15mm dia. Two of the end mills were even solid carbide viz. 1 x 15mm dia. and 1 x 10mm. The rest are a mix of end mills – some with pilots ground on the end and various slot drills. Also included in the lot is a very nice Moore and Wright metric micrometer stop. Five quid the lot! ……..and if that sounds good………

………….three weeks ago I bought a nice pair of matching steel bevel gears (I feel a governor coming on) from a house clearance bloke at a boot. He asked me what I was planning to use them for. When I mentioned model engineering his eyes lit up and he told me he might have something interesting at home.

Next morning I was on his doorstep and he showed me to a large tool chest. On opening the draws it was turn for MY eyes to light up. Scores of reamers, milling cutters and boxes of indexable inserts much of it new and still in cartons. It took two of us to lift it into the boot of my car. He was very happy with the £85 quid I gave him and I felt like I'd won the national lottery. I've not weighed it but chest and contents must weigh about fifty kilos

Bragging? – Well you did ask how I by passed retailers – right?

Rik

Edited By Rik Shaw on 12/04/2014 15:26:32

[Tim StevensParticipant @timstevens64731]

Can I add a couple of thoughts? Well, three …

1. In general, carbon steel taps & dies are made with cut threads, while HSS are usually ground threads. This makes carbon steel rather rough, and HSS smoother and more accurate, and can be a more important distinction for the home workshop.

2. It makes sense to keep the threads in a model consistent – from the same family. This will help you when you come to revisit the model (etc) for mods or repairs, and will be a huge benefit to anyone who becomes the owner later.

3. And it seems logical to match the thread family with the model in terms of origin and date. This means Whitworth + BSF + BSP for British or empire products up to WWII (or later) – UNC + UNF + UNEF + NPT for more modern British and all USA, and Metric for European stuff. BA is traditional in the UK for electric devices, with Cycle for two wheelers, and ME for, well, models.

Cheers, Tim

[NJHParticipant @njh]

Brian

To go right back to your original question my advice is to first decide on the engine you wish to build. Look carefully through the plans and instructions then buy the taps/dies that you will need for this project. The case of HSS against Carbon steel has been well aired above . My preference now is to buy HSS but if you are short of cash then I think it is more important that you progress your engine and Carbon Steel should be sufficient for one project – and more. As you progress to your next project ( which will, hopefully, use many of he same threads) then replace worn HCS with HSS. You will probably find that there are some sizes used very infrequently and HCS will always be suitable for these.

Good luck!

Norman

[thomas oliver 2Participant @thomasoliver2]

Stuart No. 10V – their smallest engine, uses mostly 7BA screws and only one 5BA grubscrew. It uses 5/16x 26 tpi ( either CEI or BSB could be used) for the gland. The bigger 7A engine uses 4BA, 5BA and 7BA + the 5/16×26 for the gland. Bigger engines go up to 2BA with some 1/4BSF even. Stuart engine do not appear to be fitted with any 6BA size threads.

The screws supplied by Stuarts have a thick head. Some of the egines illuatrated in their catalogues – have studs and not screws. Making 3/8in long 7BA studs is a real problem, so screws are to be recommended.

If you want to go the metric way here are some close equivalents and remember a someone has stated – BA is a Metric system where each successive size is 9/10ths of the previous size. starting with OBA which is exactly 6mm witha 1mm pitch. Only the angle of 47 1/2deg. is different.

2BA 5mm (Pictch is identical)

4BA 3.5mm

5BA 3 mm

7BA 2.5mm

8BA 2 mm

The half sizes are obtainable from Tracy Tools OK. I have had one or two dicey dies from them in the past – actually unhardened, but they are very good and change them without question

To enhance scale appearance – screws are obtainable with head size one size less.

The 0, 1 and 3BA sizes are little used from a full set of BA taps and dies.

As a fair guide, the tapping drills for BA sizes can usually be used as clearance drills for 2 sizes below, which can save buying a few drills.

Sources of good steel for some small BA, UNF and metric studs are bicycle spokes, umbrella ribs, welding rods and wire coat hangers.

To cut out breakage of the small BA or Metric taps, never use the tap wrench provided in a set as it is to provide torque for the larger sizes. Use chuck type tap wrenches with short tommy bars. This allows you to feel when the tap is tightening up. I rarely use a taper tap on steam engines as they vary in taper from one manufacturer to another. These steam engines have a lot of blind holes to tap and a long taper tap wll bottom out and will not give a good start to the plug tap. I can usually manage with a second, but even these can vary in the amount of taper There is a lot of discussion about tapping and staking set-ups but they are only one more complicated time consumer to make. I always check the tap squareness by eye in two directions at right angles and check frequently until I am satisfied as to the trueness before completing the thread. I can usually get my threads quite square thsi way.

If you go for the Stuart steam engines try and obtain one of the old Stuart Turner kits on say Ebay as the casting quality is far superior to what they are now

Do not obtain the castings and parts as you go along or you will end up paying about twice the price of the kit. which includes the fixings. This is because Stuarts now charge £5 for a tiny piece of brass for the valve nut and corespondingly for the other bits of stock material.

Do not go for a full set of number drills for tapping sizes. 15 of the set do not have any use for tapping, clearance, reaming or interference fits. Buys as you go.

to

.

[Bill PudneyParticipant @billpudney37759]

Posted by thomas oliver 2 on 15/04/2014 21:18:23:

Sources of good steel for some small BA, UNF and metric studs are bicycle spokes, umbrella ribs, welding rods and wire coat hangers.

Wire coat hangers!!!

I wouldn't even use wire coat hangers to tie up my sandwiches!! Soft bendy stuff. There must be a better way.

Otherwise agree with pretty much everything you say!!

cheers

Bill

[Ian S CParticipant @iansc]

I would suggest, and so would some others here, that you persevere, and use studs in the places where studs would normally be used, they are not too hard to make, I found when rebuilding a Stuart Turner S9 engine that I needed quite a number of 4BA studs for the cylinder heads, and steam chest, I think the other size may have been 7BA. I cut the thread on the lathe, only cleaning up with a die. I had some suitable sized hex bar to make the nuts, but the carbon steel tap cost over $NZ30, that hurt (HSS $NZ50 +), for the smaller stuff I used fluteless Threadflo taps, except in places where I used 1/8"Whitworth, and one place where a rescue was required 3/16" UNF, these latter two are my main stay when I'm building my usual hot air engines. Ian S C

[thomas oliver 2Participant @thomasoliver2]

Bill, I think that maybe you have not tried the strength of a very short length of coat hanger wire or used it to make short studs. It is obviously easy to bend a long length. I have used it quite often and find it adequate, for certain studs. The No 10V has either 7BA screws for the cylinder covers only 3/8th in. long or studs. It is difficult to grip this length firmly to cut the second end, hence my suggestion to use screws.

[Brian JohnParticipant @brianjohn93961]

My carbon steel taps and dies have arrived from Tracy Tools : set of three in each of 1/8-40, 3/16-40 and 1/4-40. These will be used for plumbing/pipe work so carbon steel should be okay for brass and copper.

I thought the taper, second and bottom tap would be stamped as such but they are not. I also thought the bottom tap should have a flat bottom, not a point ? Have I been sent three of each of the same thing by mistake ?

(I did buy a 1/8-40 bottom tap from a local supplier last month and it is clearly marked on the box as a bottom tap ; it has a flat end, not a pointed end.)

 

Edited By Brian John on 18/04/2014 05:00:35

[JasonBModerator @jasonb]

Most are not marked but if you lay the three taps side by side you should be able to see that one has a long taper, one a medium and one just a chamfer. Some taps have a single groove around the top of the taper, 2 grooves on teh second and none on teh plug. A lot of Tracy's tools don't come in individual boxes so you won't see it there but you saved money by not paying for packaging.

In the smaller sizes they tend to have a pointed end as there is not enough room to drill a ctr hole for grinding them during manufacture, the point fits into a female taper. You will find that a lot of people grind the ends flat to get that extra turn of thread into the hole.

 

Edited By JasonB on 18/04/2014 07:15:23

[Russell EberhardtParticipant @russelleberhardt48058]

1. In general, carbon steel taps & dies are made with cut threads, while HSS are usually ground threads. This makes carbon steel rather rough, and HSS smoother and more accurate, and can be a more important distinction for the home workshop.

Not in my experience. The only carbon steel taps in my workshop that are rough are those I've made myself!

Russell.

[NJHParticipant @njh]

Jason

Looking at your (startling !) WARNING image I wonder – have I been wrong all these years?

I thought the categorisation for taps was :- TAPER, SECOND, PLUG / BOTTOM …………….

Norman

[Bill PudneyParticipant @billpudney37759]

I thought it was Taper, Intermediate, Bottom; or 1st, 2nd, 3rd.

At the end of the day the first tap to be used has the flute end ground with a five or six thread taper, the next (intermediate, 2nd etc) tap has a shorter taper, the last tap has almost no taper.

The amount of taper is probably down to the manufacturer, the size, the intended use.

Some people have even been known to grind the working end so that a blind thread can be tapped deeper….heresy!!

cheers

Bill

[Brian JohnParticipant @brianjohn93961]

I do like the idea of the taps being marked with circles to denote first and second tap with no circles on the bottom tap. Can somebody give me a specific brand name of HSS taps that are stamped like this ?

I still have not ruled out the idea of buying sets. If you can get a set from which you know for certain that you will use at least four or five sizes, then that will often work out cheaper than buying them individually.

 

 

Edited By Brian John on 19/04/2014 10:36:10

[Steven VineParticipant @stevenvine79904]

| I thought the categorisation for taps was :- TAPER, SECOND, PLUG / BOTTOM …………….

Only last week I read that the Yanks call a Second a Plug.

Steve

[julian atkinsParticipant @julianatkins58923]

hi brian,

as a slight aside i think for steel and stainless the cutting compound you use is quite important. ive special stuff for stainless i was given called strawberry jam (!), and use rocol compound for steel. i still have a large tin of trefolex but it never gets used these days as inferior to rocol. (trefolex is cheap and nasty IMHO and has an awful smell)

i have only second and plug taps. ive a set of warrior brand carbon steel ME taps and dies that must be 50 years old and some sizes get used for stainless piston rods and valve spindles as well as non-ferrous stuff with no noticeable difference.

i do have quite a few BA taps and dies in HSS. i try and keep to the even sizes in the things i make.

the only BSW dies and taps i have for miniature loco work are for brake handle shafts usually 3/16" BSW, and for tapping studs for cast iron.

i was told many years ago not to tap anything in a cold workshop (or until it and the tools warm up).

cheers,

julian

[Brian JohnParticipant @brianjohn93961]

How about using light machine oil as the cutting compound ? I have been told that even butter will do in an emergency !

[Oompa LumpaParticipant @oompalumpa34302]

As an aside, Tallow is available from some polishing supplies stockists. I use it to lubricate some of the wheels while polishing Aluminium or Magnesium, it is recommended when polishing copper. It helps prevent the mops clogging quickly.

graham.

[thomas oliver 2Participant @thomasoliver2]

Over my long modellling life, I have acquired sets of threading gear for every type in common use. Some were boxed. Some not. I decided long ago to make my own boxes from hardwood.and made a rig using a router head mounted on a vertical drill stand clamped to the lathe bed, and provided with a multiple depth stops. I stuck a wooden fence onto the crosslide of the lathe, I scanned some original boxes and printed out the scans, then pasted then to the wood as a guide, and even clamped a vacuum extractor close to the router bit. This all worked fairly well. I set to with a face mask, and finished all the boxes off failry quickly. However,, to my dismay, when I finished, every ledge a cranny of my workshop was covered in fine wood dust, which took as long again to get rid of. So be warned about wood. Anyway I now how two neat piles of boxes and everything readily accessible.

A lot of my taps and dies were bought at the local boot sales, amd I found that some stallholders were not even aware of their value, so I could get them for coppers. Many years ago I was quoted £11 each for 10BA HSS taps by the Presto depot. This made a set £33. I have bought many sets of 3 small HSS BA taps for £1 a set. I have had many collossal bargains at boot sales. One of my first was a new 4in 4-jaw chuck with Boxford backplate to fit My AUD model for £40. Now, at my age, I am busy disposing of all my surplus spares on Ebay.

[Rik ShawParticipant @rikshaw]

Thomas – I know what you mean about wood. Yesterday I finished turning a 150mm diameter pulley from hardwood for a bit of kit I I want to get going. What an absolute mess it left the lathe in – and my 'dose as well! I will definitely think twice in the future re: wood turning on what was my sparkly clean Warco 250.

Rik

PS. I need to know when to start shifting my gear onto Ebay so I hope you don't mind – how old are you?

[thomas oliver 2Participant @thomasoliver2]

Rik, I am 89. Don't leave it as late as me.

Just as an addition to the lubricant problem, I once had a new Myford ML7 and used the recommended oil in the cups. I needed a regular drip to maintain lubrication. I then once used EP 90 oil instead and found that the lathe would keep going for weeks on end with just an occasional drip or two. I formed a very good impression of this high pressure back axle oil and have used it for threading and other things since. I also had a small open tin of pure turpentine for cleaning small brushes and over time it thickened up a lot. I found it magic for threading aluminium.

[Brian JohnParticipant @brianjohn93961]

Tracy tools offer three sizes of 2mm metric coarse tap : 2 X .25, 2 X .4 and 2 X .45. What do the numbers .25, .4 and .45 refer to ?

If a bar stock kit calls for a 2mm tap then how do you know which one to buy ?

[JasonBModerator @jasonb]

The numbers are the pitch of the thread one turn of the thread will move teh screw by that amount.

 Unless specifically stated on the drawing Metric Coarse is the most common and that is 0.4mm pitch

Edited By JasonB on 14/05/2014 14:25:01

[Brian JohnParticipant @brianjohn93961]

I am still having problems with the brass tubing (partially) turning in the vice when I try to cut a thread on it. Is the problem my vice or should I not be using the aluminium soft jaws ? I get there eventually but if I could stop the tubing from turning at all then the process would be much quicker.

Edited By Brian John on 30/10/2014 04:32:12

Edited By Brian John on 30/10/2014 04:32:45

[John BromleyParticipant @johnbromley78794]

Ideal would be to hold the tube in a collet and cut it on the lathe using a tap or die holder against the tailstock. Not under power, but by hand turning.

John

[IanTParticipant @iant]

Brian,

You don't say what size of tube you are trying to tap – but one thing I've motioned here recently, is that it does make quite a difference what tapping drill size you use. Industry use high thread engagements (100-95%) whereas 70-65% is good enough for our uses generally. You will really will feel the difference.

I purchased an inexpensive tap & drill set form Lidl's a year or so ago and used the drills provided without too much thought but found the larger ones really hard work. I checked the sizes against Tubal Cain recommendations and started to use larger tapping drills. Life became much easier. I guess I should have replaced the drills – but just printed a reminder for the box instead.

Regards,

IanT

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