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

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.

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.

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?

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.

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 ?

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

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

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

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

Are there a few sizes which keep cropping up ?

I'm not a traction engine dude yet but have found a 20quid metric HSS tap and die set extremely handy for general duties

You can buy metre lengths of threaded bar from B+Q up to 12mm for a few quid each

In many cases you don't even need any nuts, the threaded parts simply screw flush into one another via the bar

1. No lathe yet and not for quite some time !

2. Sorry for the confusion but I am trying to cut the thread on the outside of the tube ie. I am using a HSS 3/16-40 die. The tube is 4.76 mm which I have been told previously is the correct size tubing.

Take a piece of brass bar, drill a hole the size of your tube (plus holes for other sizes while you're at it) and saw along the centres of the holes like this:

Then put that in the vise to grip the tube without distorting it.

Russell.

The tube is not distorting ; the problem is that the vice is just not gripping it enough. The aluminium soft jaws I am using have notches for gripping tubing but it does not seem to be helping much.

Brian

A good fit between your tubing and the vice block is important. When doing work on gun barrels a few years back, I used powdered rosin between the barrel blocks and the barrel with good results. The rosin provides quite a bit of additional grip. I have continued to use the same technique for some of my metal work.

Bill

Brian. try sliding the soft jaws sodeways a bit so the small Vee that you are using is directly in line with the screw of the vice

When the pipe spins do the jaws leave marks all along the pipe or just at the very bottom, this would indicate the jaw is lifting and not applying the same level of grip along the whole length of the pipe

Might be worth trying a variation on the trick used in turning / milling to get a better grip, wrap a turn or two of paper round the tube and then put that in the vice jaw vs. The paper will make the tube slightly bigger so that the vice has more to grip and will also "bed" into the tube surface and that of the jaws.

Also worth looking to see how tight you've got the die set. Assuming that it's a split die try easing off on the two angled holding screws and tightening the one in the split - don't go to heavy handed you don't want to break the die. If you can get a thread cut with the die opened slightly then it's an easy matter to nip it up and run the die down again to cut a bit deeper if you need to for the female threaded part to fit ok.

Other things that come to mind - is the tube in a hard or annealed state, much easier to thread if it's annealed - how much of a turn are you putting on the die before you back off to break the swarf string. The latter I find has quite an effect but then I'm, usually threading steel with something in the M8-12 range

The paper trick above might be enough otherwise try rubber from cycle inner tube, old gloves etc, Instead of a V groove in the jaws which only grip along 4 lines try two pieces of wood held together and drilled down the interface, size allowing for the rubber grip, to get all round contact.

However have a think about the cutting action. You have 3 or 4 lobes on the die with say 6 teeth each in contact as you move down all tryig to take a cut ?? deep. That's a lot of force. Hence it is a lot easier if you can get a split die and make several passes. With taps you are stuffed on adjustment which is why taper taps were invented.

Hi Brian,

Are you using any lubrication on your die? This can make a big difference.

Peter.

Tubal Cain advocated Russell's device, but made from ebony from an old bowling ball*.

Neil

For bowls rather than bowling, I imagine.

Sorry Brian - I've just tapped some tube (as an extension handle) and my 'brain' was still in tapping mode (e.g. internal threads)

However, dies also cut easier if the thread engagement is lower. If you had a lathe you could have tried 'easing' the tube diameter slightly - or if you are using a split die then you could try opening it up (over size) to get the thread started and use several passes as suggested by Bayzle.

Better and/or stronger work holding may well be the solution to your problem here but whenever I find myself having to use (excessive) force, it's normally time for me to stop and think again. Are you sure your tube diameter is the same as the nominal size of the die or is it just over?

It doesn't take too much 'over' to start causing problems. Just a thought.

IanT