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Adam Gregory 1	30/09/2011 21:22:09
20 forum posts 11 photos	Hi May be a daft question but when using taps do you have to use the second or botton to get to final thread size or should the taper get to final thread size, or have i just got a miss stamped ME 5/16 x 32 taper, or is there a different kind of 5/16 x 32 thread size that is used on a safety value which is labeled 5/16" x 32 tpi
DMB	30/09/2011 21:57:18
1585 forum posts 1 photos	Hi Adam, No I dont think it a daft question; we all have to learn everything in life at sometime. I just think I am one of the lucky older ones who were trained in basic metalwork (and woodwork) at school. Taps are produced in Taper, Second and Plug types, each size. The taper should be used first, the taper giving an easy lead-in to the hole to be threaded.The Second is what it says, used second, to cut a full depth thread throughout a straight - through hole. Only use a Plug to cut a full - depth thread right down to the bottom of a blind hole. Depending upon what the threaded hole is for, I try to avoid tapping blind holes like the plague, since you run into trouble with swarf collecting in the bottom of the hole ahead of the tap. Usual advice as a cure for this is to bung up hole with grease first so tap forces it out along with swarf. I have not tried this. Sometime you have to tap a blind hole like say for studs in a cylinder block. Hope above helps. Regards, John.
Gone Away	30/09/2011 22:59:39
829 forum posts 1 photos	The taper tap is full thread diameter above the taper at the top end of the tap. Thus if you have a through hole and the material thickness is not too deep you can just run the taper tap in to its full length. With blind holes, I often drill them deeper that they really need to be so that I can get sufficient full thread using the taper tap. Some people skimp on just owning second taps instead of the full set reasoning that there is enough of a taper to start the tap and enough thread length for anything they need. Personally I think that's a major pita and always use as many of the set as will make the job easiest.
Michael Cox 1	30/09/2011 23:09:32
555 forum posts 27 photos	Hi John, Most taps are full thread depth irrespective of whether it is taper, second or plug tap. However, there are some taps, progressive taps, which are different. The taper, second and plug tapseach cut a progressively deeper thread. They are said to require less torque. Mike
JasonB	01/10/2011 07:41:52
25215 forum posts 3105 photos 1 articles	Its also possible that your tap is cutting full size but whoever made the safety valve cut the thread a bit oversize, do you hace a matching die so you can cut the male thread a little deeper. If you bought it in the UK then its likely to be 5/16x32ME, the only other similar pitch is the virtually obsolete 5/16 UNEF. J
Andrew Johnston	01/10/2011 10:44:30
7061 forum posts 719 photos	Posted by Adam Gregory 1 on 30/09/2011 21:22:09: Hi May be a daft question but when using taps do you have to use the second or botton to get to final thread size or should the taper get to final thread size An interesting question; and one on which it has proved difficult to get a definitive answer. The only reference I can find to the taper tap being undersize is in the WPS book 'Drills, Taps and Dies' by Tubal Cain. None of my other books, or the manufacturers' websites, mention it. From a practical point of view I have never had a problem using just the taper tap to produce a 'to size' thread, thru-hole or blind. If thread depth is limited in a blind hole, for soft materials like aluminium, low carbon steel or cast iron, I follow the taper tap with the bottoming tap. I rarely, if ever, use 2nd taps. If a blind hole is too shallow to start with a taper tap then I use a spiral flute machine tap by hand. This will cut a thread to within one or two pitches of the bottom of the hole in one go. I do quite a lot of machine tapping, so I have spiral flute taps to hand anyway. The 'progressive' taps mentioned by Mike are also known as serial taps. As stated they cut a deeper thread with each tap. So it is essential to use all the taps in sequence. I've never had the need to use serial taps, but I understand they are intended for tough materials, like some stainless steels. The only place I am aware of that sells serial taps in common sizes is ArcEuroTrade. Regards, Andrew Edited By Andrew Johnston on 01/10/2011 10:46:17
Gordon W	01/10/2011 12:11:36
2011 forum posts	All the above is true, but be aware that some sets of taps are not brilliant, and may need the full plug tap to cut to size. I know 'cause I have some.
Stub Mandrel	01/10/2011 19:52:30
4318 forum posts 291 photos 1 articles	I use Tubal Cain's 60-70% thread depth, and I find that means some taper taps are not much use. Second and plug if I get the choice. In my gorgeous HSS metric set the taper is smaller than the second, is smaller than the plug. This means you can tap a nice tight thread if you want something to stay put, or to expand the end of a mandrel, for example. Neil
Andrew Johnston	01/10/2011 22:58:20
7061 forum posts 719 photos	Likewise, I tend to use Tubal Cain's drill sizes for about 65% thread depth. However, for stainless steel I might choose to be nearer 50%. Neil: I'm curious, who made your metric HSS set? On the whole I've only got odds 'n' sods bought off Ebay, except for metric and BSP where I've bought new as I need them. Regards, Andrew
Adam Gregory 1	02/10/2011 12:52:41
20 forum posts 11 photos	Hi all. Had some time this morning so threaded a piece of hex with a ME 5/16 x 32 die bought from different supplier. The nut on the outlet of the steam valve i'm making the bush for screws onto bottom of same valve, the safety valve and the newly threaded hex. The valves screw into the die, but the valves and hex will not screw into bush made earlier with tap in question. So i'm guessing it's got to be a rouge miss/badly made tap. I checked where i bought it from and it's described as a taper and not of the serial type mentioned earlier in this thread. Thanks for all the help.
Adam Gregory 1	02/10/2011 13:00:08
20 forum posts 11 photos	Sorry forgot to ask earlier, but tried to add a picture to the above post but it wanted me to add it to my album first, tried to drag and drop a picture in but when hitting the post button it said i had to many characters. Is there a max size of picture.
JasonB	02/10/2011 13:12:26
25215 forum posts 3105 photos 1 articles	One other thought, check your tapping drill size. See if the drill you used will pass through the die and the nut, there is a bit of variance in tapping drill sizes given for ME threads depending on where you look. What size drill did you use? J Edited By JasonB on 02/10/2011 13:13:04
Richard Parsons	02/10/2011 13:16:05
645 forum posts 33 photos	John I was always taught that there were 4 taps in a ‘full’ set. As you write there are the ‘Taper, Second and Plug’, but there is also a ‘Bottomer’. All the three taps you describe all have a taper on them to a greater or lesser extent. Then ‘Bottomer’ has no taper at all. It is used to finish a blind hole and is quite rare. Syd I will agree with you but the supply of a second in place of a taper is 99 times out of 100 down to the supplier. They do not know any better (nore do they care) Andrew I am interested in getting sets of progressive/serial taps in the smaller BA sizes. After a few weeks using 12, 14, 16 BA, 8 BA seems like ‘heavy engineering’ Some of the taps I have are badly oversized which gives me problems (so I avoid those sizes).
Clive Hartland	02/10/2011 14:26:10
2929 forum posts 41 photos	For many years I was able to use Brutsch Reugger in Switzerland as a tool supplier and they stock taps for specific materiels. An example are Stainless steel taps, these cut cleanly and easily whereas ordinary taps seem to bind in the cut thread. Most of their taps are 'Serial' taps and come in sets of three. In the larger fine series, ie. 16mm/,5 then only one tap is supplied as it has a short taper on the end to start. I have even bought 5 start thread taps from them that are used in eyepiece mounts. These are adjustable to account for variations on the male threaded part. Unfortunately now they require a minimum SF500 minimum order so i do not use them anymore. Clive
Adam Gregory 1	02/10/2011 16:20:03
20 forum posts 11 photos	Jason I'm using a 7mm drill as shown on tapping drill size page on the GLR web site. Adam
Adam Gregory 1	02/10/2011 16:47:26
20 forum posts 11 photos	Finally managed to put picture on, bit long winded!
JasonB	02/10/2011 17:03:26
25215 forum posts 3105 photos 1 articles	Yes I have got tables that give 7mm, my tap has 7.1 on it and ME handbook gives 7.2. Try drilling the bush out to 7.2 then run the tap in again or if you don't have a metric set in 0.1mm steps 9/32 will do. Richard as for bottoming taps all my ME series taps have the end ground off so there is no lead or taper, lets me get right to the bottom when making steam fittings. Likewise the back face of several of my dies are ground down for the same reason J Edited By JasonB on 02/10/2011 17:04:02
Clive Hartland	02/10/2011 17:27:19
2929 forum posts 41 photos	All my ME tapscut oversize threads, I feel that they have been badly made or are seconds! Not much I can do about it except to remember it is so and make things accordingly, pity anyone who has to make good in years to come. It pays to buy the best in the first place as you only end up paying more out to get replacements later. Clive
Stub Mandrel	02/10/2011 19:59:42
4318 forum posts 291 photos 1 articles	Hi Andrew, My HSS taps were £12 at a market(!) for M3 to M10. No name on them, just G6 on the dies (which aren't split). Unlike Clive I find them an excellent set to use, and the plug taps and dies give a result which is a spot on match for good, new screws and nuts. My ME ones are odd and sods from various exhibitions, while my BA sets are a full odds and evens down to 10 from Tracey Tools and an 'antique' evens set 0-8 that belonged to my Grandfather. All carbon steel. I have a few HSS extras, 12BA, 10BA, M2, M2.5,. again randomly garnered from the shows. I'm an urepentant bargain hunter. I got 7 1/32" jobbers drills (left from a pack of 10) for 50p this morning. Ideal for circuit boards. Too tired for the workshop today - two loads to the tip, lay a patch of pavement grade slabs then empty, dismantle, move, re-erect and refil the enormous wendy house (2 floors) that's turned into a storage shed. I had to cut a slit along the apex of the roof to separate it into two bits, I nearly fell off when doing a temporary repair with Duck tape! Now sitting at very nice, but incredibly heavy walnut dining table that was in the shed, but my wife spotted it and decided it would replace the computer desk. Unfortunately the dining chairs are NOT as comfortable as the old computer chair so apologies as I'm in Victor Meldrew mode at the moment... Neil
Andrew Johnston	03/10/2011 18:51:55
7061 forum posts 719 photos	Hi Neil, Interesting; likewise most of my taps and dies are random buys, mainly on Ebay, with these exceptions. I have a complete set of ME taps and dies, a birthday present from long ago, although I rarely use them. Most of my metric coarse and BSP taps and dies have been bought new. Otherwise BSW, BSF, UNC and UNF are mix 'n' match! I'm probably in a minority of one in that I almost never use BA, so I have a very limited range of BA taps and dies. Blimey, 1/32" drills; that's a bit big for PCBs isn't it! I hope you have recovered your sang-froid and are now safely ensconced in the workshop. Regards, Andrew

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