VaughnT

What do we know about Taps and Dies?

Recommended Posts

I've lately gotten on a threading kick.  Of course, I've never needed much in the way of threading gear since I could likely find a bolt and nut, or use a rivet instead.  As such, my collection of taps, dies and wrenches is lacking.

Watching a vid from Adam Booth, he noted that round dies are for creating new threads while the octagonal dies are only supposed to be used for chasing existing threads to clean up damaged areas.  I had never heard of this before and it got me wondering about what else I might not know.

On the vintage set that I just picked up, all the dies are stampled "1/32" in addition to the expected numbers.  Why?  What is this denoting?

s-l1600.thumb.jpg.4ab276fccf4595cbb8ffa087268fd9b3.jpg

 

One set that I passed on was interesting because I recall Peter Ross using something similar in a video.  These tapered taps are supposedly for blacksmiths because it allowed you to thread a nut even though the whole might not have been punched perfectly to size.  You thread down from one side, then flip the blank over and thread in from the other side. I don't totally understand what's happening, but it did get me wondering.  

s-l1600-1.thumb.jpg.2cf9d5515e2ab97a19f891c35f872926.jpg

Were tapered taps commonly used back in the day?  How rare were drills that punching the hole was the best option... yet they could make such nice tapered taps?

Or were the tapered taps used for something else entirely?

Whether I'd ever use something like this or not, I love the designs of the old kit.  The inlet wood, soaked through with ages of oil, grease and grime... the sweeping lines on the tap handles, often with color case hardening still swirling around them.... it's hard trying to NOT collect the blasted things!

So where do you stand on taps and dies?  What sizes do you find most practical?  Got a favorite thread pitch?

For most of what I do, 1/4-20 and 3/8-16 will cover me just fine.  I don't see a lot of need for the larger sizes, but there have been a few instance where I wished I had a 1/2" or 5/8" die.  

Share this post


Link to post
Share on other sites

I don’t know a darn thing about your question but just wanted to say it is a very nicely written post and will have me looking at old taps and dies in a different way. 

Share this post


Link to post
Share on other sites

Vaughn T, I have no idea what the 1/32 means! There are hex shaped dies that are for chasing threads and there are hex dies for cutting new threads. The long tapered taps are used to make multiple size threads. You just screwed them in until your thread was large enough. When I was younger and worked for the old farmers I was taught to keep nuts and bolts paired up because they wouldn’t match up sometimes! One rule of thumb for tapping holes is to take the diameter of the tap and subtract one pitch of the thread to get the drill size for the hole. 1/4-20 tap= .25(1/4”) - .05(1 pitch of 20 threads per inch)=.2” hole size(17/64 (.203)is close enough)

 

hope this helps! Bill D

Share this post


Link to post
Share on other sites
18 minutes ago, horse said:

I don’t know a darn thing about your question but just wanted to say it is a very nicely written post and will have me looking at old taps and dies in a different way. 

Thank you for the very kind words, horse.

Compare this beautiful machining and color case hardening to what is produced today......

s-l1600.thumb.jpg.440480236e5c5f37d8943af86d188167.jpg

And, honestly, you can get vintage gear for as cheap or cheaper than you can buy new stuff.  When I was looking, I found plenty of brand new sets in garish plastic cases, undoubtedly made in some factory overseas.  They often had a larger selection of taps and dies in the kits, but they also had a complete lack of soul.  They looked cheap and chintzy, especially in those ugly injection-molded cases.

I wish you well on your journey down this particular rabbit hole. :D

 

16 minutes ago, lazyassforge said:

Vaughn T, I have no idea what the 1/32 means! There are hex shaped dies that are for chasing threads and there are hex dies for cutting new threads. The long tapered taps are used to make multiple size threads. You just screwed them in until your thread was large enough. When I was younger and worked for the old farmers I was taught to keep nuts and bolts paired up because they wouldn’t match up sometimes!

How do you tell which dies are for chasing and which are for cutting new?  If it's not the outer perimeter style, what then gives it away?

How do you use the tapered taps to "make multiple size threads"??  I'm missing something there.  

If you drill the hole to the size proper for the thread you need, what's the benefit of a tapered tap?  Even in a punched hole, there's only so much you can do because the threaded hole will always end up with an hourglass cross-section.  As such, I'd think it's a pretty weak joint since the bolt is only hanging on a very thin thread right at the waist of the hourglass.  

 

Share this post


Link to post
Share on other sites

On the hex dies made for chasing threads, there is a small fairly steep (45degrees or so) taper leading into the threads. On ones made to cut new threads the taper is 3 or so threads long leading into the die so it is easier to get it started cutting. The “advantage”of the tapered tap is that the same tap can cut several sizes of thread, just by starting with different size holes or simply screwing the tap further in.

 

hope this helps, Bill D.

Share this post


Link to post
Share on other sites

I’ll try to help with what little I know. The large split round dies are adjustable in size (diameter). Taken out of their holders, there is a small screw adjustment. That screw is for setting the amount of opening at the split. Cranked in for a larger gap (split)(diameter). Put back into the die holder, the outside thumb screw mating with the small depression in the o.d. makes the die turn with the handle to thread the rod. The small adjustment screw prevents the outside thumb screw from collapsing the desired size of the die setting. You can by initial threading and subsequent readjustment sneak in and produce a nice pretty set of threads on a rod. I’ll suppose that round rod might be sized by top and bottom swage and might just be off size a smidge. Perhaps you are then in need of a close, but a little off size nut. You could forge a nut and punch a hole. If you used the 1/2 - 12 ( half inch with 12 threads per inch) then you would select the tapered tap with the number 12 on it. You would thread and test until your newly threaded rod would screw in halfway into your new nut. At that point, you could flip the nut over and thread from the other side until the same depth of tapping was reached. Now you have a nut (that fits) your barely off size threaded rod. 

All your dies are SAE standard except for the 1/2 - 12. Standardized is 1/2 - 13.

I have no answer on the 1/32 marking. I await enlightenment. I might forward a guess. Perhaps the dies will accommodate a round rod up to 1/32” oversized.

Share this post


Link to post
Share on other sites

I can't answer your questions either.  However i couldn't be without my taps and dies.  When i go to the local hardware/box store, all they have are hex. But when i go to say Fastenall, or the like, they are always round. My assumption was that round were better quality and more often used by machinists. Note i said assumed.

 I do know that on the smaller sizes like 1/4" and smaller, the taps are far more likely to snap than those bought at Fastenal. And there is nothing more frustrating than trying to remove a broken tap!

Heres two other types of taps i use. Gun taps. They send the burr?/swarf out the bottom of hole, not back at you. For little things this is great.

The other is bottoming taps. The "usual" kind you buy are starting taps and the working end is tapered.  They do not cut threads all the way to the bottom of a blind hole. Bottoming taps are flat cut and will ct threads to the bottom.  When making a blind tenon always finish the hole with a bottoming tap.

For your info, a blind tenon is where you screw a piece of threaded round into the end of say the end of a 1" square bar. Its used when you need a tenon, but cant fit it into the hole. drill and use a tapered tap and finish with a bottom tap.  Thread your round stock. Put your piece into place and screw in the stud. Peen the tenon.

If you dont use a bottom tap, your stud will not go all the way to the bottom and will not peen tight.

Sorry, didnt mean to steal your thread.  

Share this post


Link to post
Share on other sites

Not the way we did blind tenons in wood working!

In smithing I've seen them done with 1 piece by  putting the tenon in HOT in a reverse tapered hole and upsetting the bottom of the tenon inside the mortise to let the shrinkage while cooling lock everything tight.

Share this post


Link to post
Share on other sites

Left to right: 2 flute gun tap, 3 flute gun tap, 3 flute plug tap, 4 flute pipe tap, 4 flute taper spiral tap, and 5 flute pipe tap. I did not have a thread forming tap (forms threads without cutting) nearby to show you. I know there are more kinds of taps, but this is kind of a tangent to the original questions.

CCBA70E5-B150-4FC5-8A62-68BE47DF2777.jpeg

2CB0F18A-C81F-4502-8802-062DEBEFE232.jpeg

Share this post


Link to post
Share on other sites

Vaughn,

Peter Ross was a guest on Roy Underhills PBS show for an episode where they dealt with those tapered taps and swage threaders.  The two piece "dies" are actually swages because the tool doesn't cut, it swage-forms the threads.  This was particularly significant with wrought iron.

The tapered taps were used on a wrought iron nut that had the hole punched.  They ran the tap in until it basically jammed itself, then went in from the other side.  If I recall correctly, the tapered "tap" isn't cutting so much as it's swaging the threads in.  The wedging action pushes the form into the ID of the hole.  Peter Ross made a point of saying that these tools avoided severing the fibers on the wrought iron as that would weaken the joint.

 So long as the thread pitch on the swage set and the tapered tap match, they would generate mating fasteners so long as round stock was a close fit in the hole.  I surmise that the tapered tap creates an hourglass shaped thread pattern in the nut.  The very middle of which is a good match to the swaged threads on the bolt.

I suspect (but can not prove) that a tapered tap was faster than cutting full depth threads through the stock.  They also seem a bit tougher to break than a straight tap.  It seems like the slag inclusions of wrought iron would be a real bear on cutting tools.  As for the why they might prefer these in a time when drills were in common use,  I suspect that a wrought iron hole was stronger when punched/drifted than if it had been drilled.  

I have a guess about the 1/32" mark.  What if that is the gap measurement at the dies adjustment?  Shim stock or feeler gauges could provide a way to know if the dies are set properly for a standardized thread.  

Share this post


Link to post
Share on other sites

Just tossing a bit more out there.  I have a set that goes up to 3/4 where the dies are screwed into the handles...basically the old set is more handle than die.  It was missing the tap wrench and a couple of taps when I got it but the die handles are so nice (and the dies are still good)--couldn't pass it up.  Those handles take up so much space that it's a 2-layer box.  Not sure what the value is in having them mounted in handles rather than one handle for several dies.  Seems like it really increased the original cost for someone.  

s2v02o.jpg

Just to confuse things, In going through my box I found dies with 3,4,5,and 6 lobes.  The "one" lobe shown is actually a thread gauge..go, no-go just as an example.  I suspect there are no true 2 lobe dies as they'd cut unevenly but now I have to hunt for the anomalous 2-lober just to see....

27wrmdf.jpg

And an old [amateur] blacksmith-made tap wrench.  Back in the long-long ago, many taps didn't have a square top, they had a tab on top.  This is punched for 2 sizes of tab.  Once in a while you'll still see a tabbed tap today.  

50o2fs.jpg

I suspect that 1/32 stamped on yours is the adjustability range.  All older dies were meant to be sharpened so needed that adjustability to compensate for wear and sharpening.  

Finally, if buying new dies and taps, it REALLY pays to buy quality.  The home center/hardware store versions are pretty crappy.  Once you use a good quality tap or die, you'll never go back to over-the-counter consumer-brand stuff.  Well worth the little extra money (and that's an understatement).  Oh..and once you try gun-taps for through-holes, you'll never go back either.

Forgot to mention...my 3 old wooden-boxed sets are not labeled as taps and dies, they're all labeled as "screw-plate" sets.  The one I didn't show has replaceable teeth sections in the dies for both adjustability and ease of sharpening.  I'm not sure when the terminology actually changed to taps and dies rather than the much older "screw-plate".

Share this post


Link to post
Share on other sites
On 10/29/2018 at 12:44 PM, ThomasPowers said:

Not the way we did blind tenons in wood working!

Interesting thread,  he, he,,

Thomas, I've no clue how blind tenons are done in woodworking. I can imagine a slit and wedge setup where you slit the bottom of the tenon and I sort a wedge. drive it Into the hole and the wedge spreads the tenon. that may work with iron as well. 

Also what's a reverse taper hole? Sounds like its wider at the bottom than the top. How do you do that quick and dirty? 

I e a friend, long distance friend, who uses a hot tenon upset into a straight sided hole for a blind tenon and swears they stay tight. I've never seen it in person and am skeptical. hot iron shrinks so it seems that no matter the upset, when it cools it must shrink. I can conceive it bending a bit and jamming but in a hand rail it seems that over time it would loosen up. I don't really have any idea how they were done back in the day, but I do know using a tapered tap and a bottoming tap is reasonably fast and works well.

On 10/29/2018 at 4:03 PM, rockstar.esq said:

As for the why they might prefer these in a time when drills were in common use,  I suspect that a wrought iron hole was stronger when punched/drifted than if it had been drilled.  

Lol, if you have ever spent much time on an armstrong powered post drill, you will quickly learn why blacksmiths prefer a punched hole to a drilled one.  ;)

A slit and drifted hole makes a stronger hole  because you do not lose any material around the eye. A punched hole removes about the same amount of material as a drilled one and is far quicker to make if you are using a hand  powered drill of any type. Add a powered line shaft of any sort and the equation changes.

Share this post


Link to post
Share on other sites
5 hours ago, anvil said:

Thomas, I've no clue how blind tenons are done in woodworking. I can imagine a slit and wedge setup where you slit the bottom of the tenon and I sort a wedge. drive it Into the hole and the wedge spreads the tenon.

Anvil, you're pretty much on track regarding wedged blind wooden tenons. Here are some additional details:

First, let me say that a "blind" wooden tenon is not necessarily always wedged, but without wedges the tenon would still need to be secured somehow, such as with wooden pegs, screws, glue, etc.

In terms of wedged blind wooden tenons that don't depend on glue or fasteners, the most common secure type is often referred to as a "blind fox-wedged joint" or a "stopped fox-wedged joint," and to work well it requires high accuracy in joinery. Here's how it works (and your take on it is very close...just needs some details):

A blind mortise is cut into the wood with a taper, so that the mortise gets wider as it goes deeper into the wood. The tenon is straight, but two narrow kerfs are cut into the tenon to receive wedges, typically fairly close to the edges of the tenon. The wedges are inserted a short distance into the kerfs, and then the tenon and wedges are inserted together into the mortise. When the wedges hit the bottom of the mortise and the tenon is pushed in farther, the wedges are pushed deeper into the kerfs, which spreads the edges of the tenon so that the tenon tightly fills the mortise.

I published an article some years ago in Old House Journal dealing with restoration work, and this was one of the joint types that I discussed.

I've restored a number of old wooden items with these joints, and they can be VERY difficult to take apart, sometimes requiring surgery.

The Japanese have a special name for this joint. Check this link: http://www.aisf.or.jp/~jaanus/deta/j/jigokuhozo.htm

That said, these joints do have the advantages of hiding the end of the tenon for a "clean" look while protecting the end-grain of the tenon from moisture incursion, which is good for exterior doors, since moisture penetrates wood most easily via the end-grain. However, when used in doors, this kind of joint typically cannot be tightened if the joint loosens due to wood shrinkage, since the construction of the door usually prevents a tenon from being pushed farther into its mortise.

In other situations, however, the joint can sometimes be tightened. For example, in the case of straight (or relatively straight) round dowels such as those that are often used as cross-braces between chair legs, the dowels can sometimes be forced in farther to tighten the joint if the wood has shrunk (assuming that the tenon has not bottomed-out in the mortise), although this means that the chair legs will end up closer together, which might loosen or damage other joints, depending on how far the legs are moved.

I prefer not to use wedged blind tenons in my own built-from-scratch woodworking projects. I much prefer through-tenon joints where I can access the wedges for future tightening/adjustments.

That's probably more than you wanted to know about these joints, but there you go.

Al (Steamboat)

Share this post


Link to post
Share on other sites
35 minutes ago, Steamboat said:

Al (Steamboat)

Actually not. That's fascinating.  Thanks for taking the time. I should have thought of glue right off.

I can see the shrinkage problem. If using wedges I would think wedging  both ends might be an option. The bottom to keep the tenon in the mortise, and the upper to account for shrinkage.

Now I'm jazzed fo try this in iron.

 

Share this post


Link to post
Share on other sites

Another thing that was often done with chairs (especially the old split-and-shaved variety) would be to drill the holes for the stretchers with a spoon bit (which is round at the bottom and therefore less likely to cut through the leg when it reaches full depth) and use that to scoop out a mortise that's wider at the bottom than at the top. The tenon would then be turned round with a matching dovetail-like shape. The stretchers would be dried in an oven or next to a wood fire to shrink them slightly and then pounded into the holes in the legs. The stretchers would expand slightly at the same time at the same time as the green wood of the legs would shrink slightly, creating a very strong mechanical joint even without the use of glue.

1 minute ago, anvil said:

Now I'm jazzed fo try this in iron.

In one of his videos about recreating the Sutton Hoo axe, Rowan Taylor demonstrates this method as a way to put a swivel on the end of the handle.

Share this post


Link to post
Share on other sites
28 minutes ago, JHCC said:

In one of his videos about recreating the Sutton Hoo axe,

Have you got a link handy to this vid?

I meant to ask in the above post as well but I cannot concieve how a non thru mortise is made wider at the bottom either in wood or iron.

I had this conversation with Francise Whitaker about blind tenons and his solution was the one I layed out above. It came up because I was curious about a reverse tapered hole. He a actually did not answer me about that, instead did a verbal with a bottoming tap. That was such a clean and simple solution that I've never run into a situation where a bottoming tap didn't work.

He also turned me onto gun taps. And the gent above is right on. Once you have used a gun tap in a thru hole, you will never go back.

An excellent use of this decorative rivets. Grab the slugs from an ironworker. They have a nice dimpled and centered divit on the bottom. Drill this out, use a gun tap and thread the hole. I always counter sink the visable side slightly, or chisel/file the surface of the hole slightly out of round to ensure the shaft won't unscrew, then thread in a stud and either peen it flush or head it and you have an instant decorative rivet or screw. Oh, dont forget to detail the surface as you want.  ;)

Share this post


Link to post
Share on other sites
1 minute ago, anvil said:

Have you got a link handy to this vid?

Here's the link to the four-video playlist: https://www.youtube.com/playlist?list=PLSIdU5LVae4YhaKSp_u9gRlvzGnJDXwdS. Can't remember which video is the one in question, but the whole series is fun to watch (as is his lengthy series on recreating the Sutton Hoo cooking chain: https://www.youtube.com/playlist?list=PLSIdU5LVae4aJdxVEiUaCFZ7BQoTcdmf7).

 

Share this post


Link to post
Share on other sites

He has a wonderful dry sense of humor, my favorite example of which is actually some very useful advice: "When heating metal for upsetting, I always think of midget supermodels: short and hot."

Share this post


Link to post
Share on other sites

Great information.  I've learned a lot.  I've always wanted a set so if anyone has one they are wanting to sell send me a PM.  

Share this post


Link to post
Share on other sites
4 hours ago, JHCC said:

Another thing that was often done with chairs (especially the old split-and-shaved variety) would be to drill the holes for the stretchers with a spoon bit (which is round at the bottom and therefore less likely to cut through the leg when it reaches full depth) and use that to scoop out a mortise that's wider at the bottom than at the top. The tenon would then be turned round with a matching dovetail-like shape. The stretchers would be dried in an oven or next to a wood fire to shrink them slightly and then pounded into the holes in the legs. The stretchers would expand slightly at the same time at the same time as the green wood of the legs would shrink slightly, creating a very strong mechanical joint even without the use of glue.

Yes, "stretchers" would be the traditional term for the cross brace in a wooden chair...couldn't think of that last night for some reason (CRS syndrome, maybe?). 

The spoon-drill-and-round-tenon wood joining method you mentioned (I can't think of a name for it) is not one that I've dealt with, but quite interesting. I can see that it would require some precise fitting, as moisture-related shrinkage and expansion produces relatively small dimensional changes in such a small-diameter joint. The smaller the joint, the smaller the dimensional changes, and the more precision is required. The actual dimensional change will vary with the nature of the wood, of course, but I think the general idea still applies. Also, the moisture-related dimensional changes relative to the grain will be generally be greatest tangentially, moderate radially, and minimal along the grain (longitudinally), which I think would need to be allowed for in such a joint.

Since you said the tenon would be "turned round," I assume that it would be spherical, in which case one potential pitfall that pops into my mind is that when the mortise wood (in this case a chair leg) shrinks and the spherical tenon expands, it could exert force not only along the grain of the chair leg, but across the grain as well, so if not done correctly it has the potential to split the chair leg. A good deal of experimenting and/or a long tradition of closely-followed practices would probably minimize that possibility, but it's still a consideration in my mind. I have never attempted that particular type of joint, but my guess is that to do it successfully without risking split chair legs, one might make the tenon slightly aspherical to allow a bit of extra space to accommodate the fact that the chair leg will shrink more across the grain (tangential/radial shrinkage) than along the grain. I'm also thinking that by experimenting and measuring the actual dimensional changes in the dried-out tenon as it regains moisture, there could be a favored orientation of the tenon relative to the chair leg, so that if, for example, the diameter of the tenon shows greater expansion in one direction, it could be oriented so that the direction of greater expansion is aligned along the grain of the chair leg instead of across the grain. Maybe some combination of those approaches would work best...just a guess.

An obvious advantage of using wedged tenon joints is that you can direct virtually all of the wedging pressure along the grain instead of across the grain, which can produce very tight joints and pretty much eliminate the chance of splitting.

Well, maybe not all of this wood-related stuff crosses directly over to metalworking, but I'm always discovering different ways in which seemingly distinct skill and experience sets overlap and contribute to each other in a symbiotic manner.

Getting back to the tap-and-die topic. I have a set of antique sliding-block-type dies like the ones that duckcreekforge posted, and I have found them useful on a few occasions, since there is more adjustment capability than in a split-type round die, although mine are not exactly what you would call high-precision dies, so I don't use them for any critical application.

Al (Steamboat)

Share this post


Link to post
Share on other sites

How to make a hole bigger in the blind bottom than on top:  chisel, wallering it out with a drillbit, die grinder or the simplest method: give the piece to an apprentice and ask he make a straight sided blind hole in it. (Hey it's a Friday!---and I've been an apprentice.)

Share this post


Link to post
Share on other sites
21 minutes ago, Steamboat said:

I have never attempted that particular type of joint, but my guess is that to do it successfully without risking split chair legs, one might make the tenon slightly aspherical to allow a bit of extra space to accommodate the fact that the chair leg will shrink more across the grain (tangential/radial shrinkage) than along the grain. I'm also thinking that by experimenting and measuring the actual dimensional changes in the dried-out tenon as it regains moisture, there could be a favored orientation of the tenon relative to the chair leg, so that if, for example, the diameter of the tenon shows greater expansion in one direction, it could be oriented so that the direction of greater expansion is aligned along the grain of the chair leg instead of across the grain. Maybe some combination of those approaches would work best...just a guess.

Short answer: a spoon bit doesn't cut the same on the long-grain sides of the hole as it does on the end-grain sides, so a hole drilled with one tends to come out oval anyway. The bulbous tenons on the stretcher would get flattened a bit on their tangential sides to better fit the oval holes and to accommodate the movement as described.

Share this post


Link to post
Share on other sites
2 hours ago, JHCC said:

Short answer: a spoon bit doesn't cut the same on the long-grain sides of the hole as it does on the end-grain sides, so a hole drilled with one tends to come out oval anyway. The bulbous tenons on the stretcher would get flattened a bit on their tangential sides to better fit the oval holes and to accommodate the movement as described.

I'm sure that whoever was building the chairs came up with a technique for the "bulbous tenon" type joint that worked, and as you said, it could easily have been a self-regulating effect of their drilling equipment and technique (and the type of wood) that achieved what I had suggested with regard to dimensional compensation for expansion and shrinkage effects in the joint.

Antique chairs (and many reproduction chairs) are likely to have been built using some combination of slow-speed and hand-held tools. An asymmetrical result from drilling or turning wood  can be much more pronounced when using a low-speed hand-held drill as opposed to drilling wood clamped securely to a drill press table or mill table, or when turning wood on a low-speed wood lathe with hand-held turning tools vs. (at the other extreme) a high-speed CNC wood lathe. When using hand-held tools and low cutting speeds, the cutting edge paths can be significantly influenced by wood grain characteristics. I experience it all the time when working with woods like southern yellow pine, with its surprisingly hard slow-growth layers. I get pretty uniform results when drilling SYP with a hand-held drill if I use a freshly-sharpened bit and the optimum cutting edge speed for that particular bit, but if I want even better results, I will take the extra step of clamping the SYP in a drill press or using a portable jig/press to secure the wood relative to the drill, in which case I almost always get nice straight, round holes. Of course, the type of drill bit can also make a difference.

Al (Steamboat)

Share this post


Link to post
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now