A dummies guide to tapping on the lathe

[skiprat]

Most of this stuff is pretty basic and I'm not even going to get into any technical jargon ( even if I knew it :redface but I figured this might help one or two people. I hope so, or I've just wasted a few hours when I could've made a pen or even had a beer. :biggrin:
Please also note that this is just the way I do things, I'm no expert and there are sure to be other and maybe better ways.:wink:

In this exciting episode, I'd like to share a couple of things about taps and how to use them in a lathe. I'll try and do something similar for dies, this weekend too.

OK, lets look at a couple of taps. These are not anything special with regards to spiral flutes or even for special purposes. Just general purpose taps.
In the first pic (DifTaps.jpg) there is one very obvious difference between them. They have different names depending on where you live, but basically they are named after the amount of taper on the front.
You can see that the one on the left has very little taper. In fact this tap requires only about one or two turns to fully form the threads.
This is often the type of tap you will get in a Pound Shop ( Dollar Store )
But they do have a purpose. They are often called Bottom Taps, because they are used to thread to the bottom of a blind hole. The are also called 3rd cut taps, because if you need to thread to the bottom of a hole, it would be the third tap you use.
You shouldn't even attempt to start a thread with this kind of tap. You can be pretty sure that you will either strip the threads as you try or just break the workpiece.

Next tap has more taper, probably around 4 -5 turns before a thread is fully formed. These are pretty good taps and most of mine are like this.
They are often called Plug Taps or 2nd Cut Taps. These are not ideal for brittle stuff like PR, but can be used.

Next is my favourite. The long taper on these means that it is taking smaller bites out of the workpiece and needs several turns to form each thread. Because the thread is cut so gradually, they are ideal for our pen making purposes. Infinitely less stress on the work as the threads are cut.

In the next pic ( Edges.jpg) the taps are shown from the business end.
Another reason that I like this particular brand of tap is that it has four cutting edges which makes it even less aggresive.
If you understand about rake angles then note which taps offer a nice positive cutting angle. This is similar to the difference between using a skew instead of a scraper.

Next pic is a great little tool. It's called a Tapping Guide. (TapGuide.jpg)They are very cheap. It really is only a spring loaded pin. It keeps forward pressure on the tap while it enters the work but also keeps the tap aligned with the centre of the hole being tapped.

Next pic is the same tool but dismantled. (TapGuideDis.jpg)The pin can be reversed for different taps.

Next is the pin on its own with various taps. IMHO all good taps have a little hole in the end. Now you know why. The pin has a small hole in the end to guide taps that have a point on the end, but I have never seen points on anything but the smallest taps. The tap in the middle is chamfered on the end and I have searched high and low to find a Tap Guide that can take it. Pretty useless if your lathe bed is short.

Next is just a selection of my tap wrenches. With the exception of the T-Bar one in the front, can you spot what they all have in common??:wink:
You got it!!! They all have a little hole in the end. Mmmmm, I wonder why?:biggrin:

There a many ways to hold a tap in a lathe. (Important to remember is that the lathe is only used to keep everything aligned steadily. Of course the lathe MUST be switched off and preferably unplugged!!)
This is often determined by the length of your lathe bed. Do you remember when everyone kept saying to get the longest one you could afford?:wink:
My prefered method is with the T-Bar wrench. Don't worry if the T-bar is longer than the swing of your lathe. Just hold the wrench and rotate the work. :wink:
If you are stuck for space or don't have the wrench or tap guide, then you may be able to fully extend your tailstock so far that the little key dissengages and allows the shaft to rotate freely. This works well but has a couple of drawbacks. You have to re-align the keyway to get the spindle back in. And when you are re-winding the tap, it is easy to rip the first few threads out. But easy if you are careful.

I'll add some tricks about threading PR later if I get a chance. And add a bit about selecting the correct hole for the tap.

 

[drayman]

steven, thats great to know as i am thinking of getting some gear to try my hand at kitless pens. thanks for the info.

 

[Lenny]

Nice of you to write this just for me! :biggrin:

Thanks!

 

[Jim15]

Thank you very much Skip., helps me a lot.

 

[ribanett]

Skip,

Thanks for the info. I have always wondered what the dimple in the end of the tap was for

 

[stolicky]

This is great.

Thank you.

 

[ribanett]

Skip, thanks for the info, make a few things a lot clearer. Always wondered what the dimple in the end of the tap was for.

Found this tapping guide at Little Machine Shops
http://www.littlemachineshop.com/products/product_view.php?ProductID=2901&category=

 

[skiprat]

Larry, those are neat little tools and great if you have the bed length. But they are over 6 inches long and IINM, they can only handle a small tap (upto M5?) I don't know what size #0 to #12 is. Do you know if they are made with a morse taper instead of having to be held in a chuck?

 

[wood-of-1kind]

Great article, Stephen.... one question for "I've just wasted a few hours when I could've made a pen or even had a beer".


How large of a glass if your beer lasts a couple hours?:biggrin:

 

[PenMan1]

Thanks Skip! Great demo! Now, if I could only find a pound shop that sells taps with holes!

 

[randyrls]

Next is just a selection of my tap wrenches. With the exception of the T-Bar one in the front, can you spot what they all have in common??:wink:
You got it!!! They all have a little hole in the end. Mmmmm, I wonder why?:biggrin:

Good info Skip;

The hole in the end: If you can see thru the center of the tap end to end, it is for coolant/lube to keep the tap flushed out when power tapping on a milling station.

If it is just a dimple it was used to turn the tap between centers.

OOPS; Added later; You can often find a set of three taps of the same thread. a tapered tap to use first or if doing a through hole, a (mind blown - not sure of the term) tap to use next on a blind hole, and a bottom or finishing tap to finish off a blind hole.

 

[randyrls]

Great article, Stephen.... one question for "I've just wasted a few hours when I could've made a pen or even had a beer".


How large of a glass if your beer lasts a couple hours?:biggrin:

Well he *IS* in Wales, so the glasses (we'd call them barrels) last a long time! :biggrin::biggrin::biggrin:

 

[RAdams]

Add my name to the truely appreciative of your skills and abilities, and most of all, your willingness to share! I learned a tremendous amount from reading this and will be on the edge of my seat almost literally, waiting for the next issue!

THANK YOU SKIPRAT! You are the coolest Rat i have ever known!

 

[Paul in OKC]

Good info Skip;

The hole in the end: If you can see thru the center of the tap end to end, it is for coolant/lube to keep the tap flushed out when power tapping on a milling station.

If it is just a dimple it was used to turn the tap between centers.

OOPS; Added later; You can often find a set of three taps of the same thread. a tapered tap to use first or if doing a through hole, a (mind blown - not sure of the term) tap to use next on a blind hole, and a bottom or finishing tap to finish off a blind hole.

Would it be a plug tap you are refering to? =8^). Skippy, good info with pics. The four flute taps are generally called hand taps, not for power tapping. But for woods and acrylics not a problem. Another good tap for blind hole tapping is a spiral flute tap, it will pull the chips up and out of the hole while tapping.

 

[RAdams]

Akk of my taps are the "Plug"? type... The middle one in Skips picture.

 

[NewLondon88]

ooooo .. this is gonna help! I was just looking through the albums recently trying
to see if I could find someone who might like to take on some threading work..
Your timing is perfect

 

[altaciii]

Steven, thanks for the mini tutorial. It cleared up a lot of questions I had about what I needed to purchase for my next stage in my penmaking.

 

[mbroberg]

I too appreciate your taking the time to right this. I've been experimenting cutting threads into different materials. Can't wait to see what you share about polyresin. Thank you!!

 

[ribanett]

Tapping Guide with a MT2 base

Larry, those are neat little tools and great if you have the bed length. But they are over 6 inches long and IINM, they can only handle a small tap (upto M5?) I don't know what size #0 to #12 is. Do you know if they are made with a morse taper instead of having to be held in a chuck?

Skip,

Found this TG with a MT2 base

http://www.littlemachineshop.com/products/product_view.php?ProductID=3104&category=

 

[skiprat]

Well I'm really pleased this has perhaps help a few guys. Remember that no one is born with knowledge and I'm simply passing it on. :wink::biggrin: I just try to simplify it and put it in plain English.
I'll add another reply here in a second or two, but you are gonna hate me for it!!!!! It is VERY long and it may seem ages before I get to the actual point. Apologies in advance:redface: Tomorrow, I'll add pics, but I'm brain dead at the moment and need another big beer:biggrin:

 

[skiprat]

Here it is....I wrote this in Word and just copied/pasted.

Why does a ½ bolt fit in a ½ inch nut? Well, I hate to be the one to tell you this but the simple fact is; It Doesn't!!!
Simple physics demands that for any object to pass through a hole, it needs to be smaller. The amount that it needs to be smaller varies by the requirements of the job.
This as we know can range from the very loose fit of a washer over a bolt to lightly pressed in parts to specially heated and shrunk fit machine parts.
But the fact remains….two objects cannot be in the same place at the same time.
Unless of course you are a Star Trek boffin, in which case anything is possible!!!:biggrin:

Lets get back to our ½ inch nut and bolt. Lets assume that we agree that either the bolt needs to be slightly smaller than the nut or vice versa or even both.

Have a look at the first pic ,( tomorrow ) this threaded rod has Vee grooves. The nut also has Vee grooves. Lets call the zigzag surfaces of both of them, the Diameters. There are of course two diameters for each ( major and minor) but lets just count the surface of the zigzags as the diameters for now.
The difference in the diameters of the nut and bolt will determine the class of fit.
Most often we prefer this difference to be as small as possible but still be practical.

Lets get back to the zigzags. If the vee grooves were absolutely sharp at their peaks and roots ( bottom of the groove) it would cause us lots of problems.
The edges would be sharp and cut us, they would be fragile like any fine point and possibly break off and jam in the thread, there would be no place for the dirt etc etc.
It would also make the cutting tools ( taps, dies etc ) extremely expensive to make and render them useless after one or two uses.
Sharp points also serve no purpose as the sides of the vees are the surfaces that do the work.
So we can get rid of the points. This will make them easier to manufacture and less likely to fail. I reality, when we use taps and dies, these peaks and roots are somewhat rounded. There are very specific and exacting dimensional standards set for these rounded parts but this has nothing to do with us.
It might be interesting to note that the peaks are more rounded than the roots.
Can you think why?

OK, this is going on far too long. How does all this gibberish help us and how can we use it?
The sides of the vees have a length. We have knocked off the sharp peaks and made this length a little less. When the nut and bolt are fastened together, these sides of the vees bear against each other and they do their stuff. The amount of surface length of these bearing surfaces determines the maximum force the threads can take.
The length of these touching surfaces can be expressed as a percentage of the maximum possible, depending on how much we shortened them by removing the peaks.
I think the most 'practical' percentage possible is around 89% and 'good' results are around 65-70%. Top quality nuts and bolts fit in this range.
But we are not interested in high torque capabilities; we just want to screw pen parts together!!!

Ok, ok!! Sorry!!:redface:
Taps and dies are designed to remove these useless points by the points of the bottom of the groove in the cutter, but they need effort or force.
Let's say that instead of actually 'removing' or 'rounding over' of the peaks on the threaded rod, we simply reduced the original diameter of the unthreaded rod?
How would this help pen makers?
Easy!! It would mean that only the tips of the cutting edges of the die would be applying force to our fragile material. Less force = less breakage. This would leave a flat topped peak.
Let's do the same with the nut. Instead of removing the peaks with the cutter ( tap), we increase the size of the hole that would accept the tap. Now only the tips of the tap are removing material. Less force = less breakage.

Theoretically, we could reduce the diameter of the rod and increase the diameter of the hole in the nut until we had only 1% of the vee surfaces touching. This would make it incredibly easy to threaded just about anything but not too practical.

So what is the happy medium???

A 12mm x 1.75mm tapped hole requires a hole of 10.25mm ( 12 minus 1.75) to give us a 65-70% percent surface contact between the parts.
But if we increased the drill size from 10.25mm to say 10.5mm we'd still have plenty of material to take the threads but the force on the material from the cutting action would be greatly reduced.
Similarly, a 12mm x 1.75mm die cut thread requires a 12mm shaft, but if we reduce this to 11.75mm before we attacked it with the die, then threading it would be far easier.
The only difference is that our newly cut threads have flat tops instead of rounded ones.
Once we polish and buff them, they will be rounded again.

So, very long story short ( sorry) ……if your material is cracking when you tap it, then increase the size of the drill.
If your material is chipping or breaking while using a die, then reduce the diameter of the material..

I'm really sorry this was so long……but hoped it was clear:wink:

 

[NewLondon88]

I'm sure it will be more clear when I have taps and dies in my hands and I start
ruining material. But don't worry.. I plan on doing just that.
(with this tutorial right beside me)

 

[ribanett]

Skip,

Go and have a pint or two, you have earned it!

You explaned things very well, and it will help all of us.:wink:

 

[skiprat]

Thanks Larry:biggrin:
By the way... that MT tapping guide is fantastic!!!! I have never seen one here in the UK, but I'm gonna investigate.
If I can't find one then I'm going to ask one of my Yankee buddies to get one for me.:biggrin:

For those that didn't see it... Larry's link showed a tap guide that will probably give the most space for tapping, even on a short bed lathe. It's far better than the one in my pic:wink:

 

[Texatdurango]

If I might add a bit......

I keep a little notebook of numbers and this sheet might come in handy for some.

As shown above, metric threads are easier to work with than standard threads (at least for me). The following might help with figuring sizes for standard threads. I also find it handy to work with both fractions and metric so I convert frequently, the bottom half of the page comes in handy.

----------- snip ----------

Calculate Tap Drill Sizes

Metric threads
Subtract the thread pitch from the tap diameter.

Example: You want to tap an M8 X 1.5
Subtract the 1.5 from 8 and you get 6.5

Standard threads
remember .9742
Divide the magic number by the thread pitch. Next subtract your answer from the tap diameter this will give you the drill size.

Example: You want to tap a ¼-20 hole.
Divide magic number .9742 by the pitch 20 and you get .0487
Now subtract .0487 from the diameter of the tap .250
You get .2013 this is your drill size.


Convert metric and standard
remember 25.4
For metric to inch divide the metric dimension by 25.4 and you get the inch dimension

For inch to metric multiply the inch Dimension by 25.4 and you get the millimeter Dimension

Example:
To convert 8 MM. to an inch, divide 8 by 25.4 and you get your inch dimension of .3149

Example:
You want to convert 3/8" to MM.
First you need the decimal equivalent of 3/8 Which is .375
Now you multiply .375 by 25.4 and you get your MM dimension of 9.52

 

[bgibb42]

Great thread (ahem), but I've got a couple of questions. Apologies in advance if these seem dumb:

Once we polish and buff them, they will be rounded again.

1. How does one polish and buff threads and leave rounded tops instead of flat ones?

2. While a penmaker should always be concerned about how a thread works, how much should one worry about how the thread looks? With flat topped threads, the perception (at least in my mind) might be that maybe the maker didn't do a quality job of cutting, regardless of how well the threads actually work.

 

[RAdams]

Thank you for the continued knowledge and input from everyone that is posting! Including the awesome questions. This info will come in very handy tomorrow when i actually sit down in my shop and do some careful measuring. Skiprat, If you ever find yourself around these parts, ALL the beer is on ME! I look forward to the pictures to go with the text! COuld you maybe throw in a picture of how you use the dies? That part is giving me ABSOLUTE FITS.

It is amazing to me now, what really goes into some of these pieces shown. All this new knowledge gives me a whole new respect for the kitless scene.

 

[ldb2000]

But when it all comes together , all the troubles are worth it .

 

[skiprat]

Great thread (ahem), but I've got a couple of questions. Apologies in advance if these seem dumb:

1. How does one polish and buff threads and leave rounded tops instead of flat ones?

2. While a penmaker should always be concerned about how a thread works, how much should one worry about how the thread looks? With flat topped threads, the perception (at least in my mind) might be that maybe the maker didn't do a quality job of cutting, regardless of how well the threads actually work.

Brian, those are perfectly good questions and I'll try to answer them as best I can.

The whole reason for this pictorial is to try and find a way to make threads in our often very delicate materials, as easy as possible and with less failures. If we are threading tough stuff like steel or brass, then we don't need a solution, as the normal standard practice already works. ie; simply choose the drill from a chart for internal threads and simply turn the metal to the finished diameter for external threads.

'Flat topped threads' is a relitive term. I don't mean to have them so that they look really ugly. But rather as a compromise between fully formed sharp threads and 'softened' threads that will allow us to thread these materials with reletive ease.

I'll take pics of some PR threads today, but in the meantime let's look at the pics I've just taken...

The first one shows a perfectly formed thread on a piece of rod. The size is not important. What is important is the finished shape of the threads.
On the left side, the peaks are pretty sharp. Not absolutely sharp, but reasonably. These peaks are formed by the bottom of the Vee in the die.
As we used the entire cutting edge of the die, we can safely say that the thread was 100% formed. If we had painted the surface of the shaft before threading, then there would be no paint visible afterwards.
Now look at the right hand side. This end of the rod was turned to a smaller diameter and therefore only a part of the cutting edge of the die was used to cut the thread. This leaves a small surface (Flot top) that was untouched and would still have paint on it.
Let's assume that the section on the left was turned absolutely perfect and the die did not have to remove any extra material. Now, depending on the material and the condition of the die, a certain amount of force is needed for the die to do it's work. Let's give this a number but without getting into technical jargon like Newtons or torque.
Lets just call it '10'

The section of thread on the right only needed 'some' of this force as the die only did 'some' of the work. You can judge for yourself from the pic, but I'd give this a '7'. This means we subjected the material to 30% less stress or force. With fragile material, this is often more than enough for the difference between breaking and not breaking.

If we reduce the '7' to say a '3' then like you correctly pointed out, it would look crappy. It's a compromise.

Next pic includes some nuts, one of which I cut in half to show the threads a bit clearer. Believe it or not, these are both very close fitting machined nuts. There is virtually no movement on their corresponding bolts. But look at the tip of the Vees, they are flat. I promise I did not alter them at all.
Like the die in the example above, this means that the tap used to make them also didn't use it's entire cutting edge to make the thread.
As internal threads are hardly visible, this is where we can get the most advantage. We could easily reduce that '10' to a '5' and thus half the amount of effort required. Less force on the workpiece = less breakage.

So, if we start at '10' and things break, then move to '9' and so on till things don't break but the resulting 'look' is still acceptable.

If we can't get rid of the breakage until we have unacceptable results,(find the compromise) then we'd need to find an alternative or stick to kits:biggrin:

 

[johncrane]

Very good Stev and well done many thanks for your time and effort! you deserve a slab or two:biggrin: or 3:biggrin:

 

[PaulDoug]

Thank you Skiprat. If you were here I'd buy you the beer! This is very interesting reading and educational. I hope you will add it to the library. There is soooo much here I didn't know and now I do.

 

[stolicky]

I agree. this continues to be a good thread and very informative. A little technical this early in the morning, but I think I'm following it. At least I can always go back and re-read it again, and again...

 

[fernhills]

Well at least i know i bought the right 60 piece tap & die set, because when i hold a tap up to the monitor screen, the profile is what Skip prefers and it has the 4 corners on the business end. After about 3 months of having it i finally pulled a tap out of that pretty case other then a 3/8 x 20. The fog is clearing. Carl

 

[RAdams]

I am excited to put this information to work in my shop! Thanks for clearing up what my mind was SLOOOOOOOOWLY trying to figure out. I will approach threading a little differently now!

 

[skiprat]

Whew!!! this is taking forever!!!
But I think I'm done:biggrin: I'll finish up on tapping then a little on dies, then a bit on die cut external threads. I'll do the threads on / in PR.

OK, the first thing we obviously need to tap a hole is to drill the hole.
If you haven't already got centre drilled holes that you used to make the blank round, then this is the first step. (Pic; Centredrill.jpg)
I don't step up in drill sizes to get to a final size, but just use the one I want directly after the centre drill. (pic;drill.jpg)
A little tip here; even if you have centre drilled or previously drilled a smaller hole, then advance the bit extremely slowly. You may see that just one of the cutting edges is removing material. Just let this one edge do it's stuff until the sides of the drill are actually in the hole. At this point the 'lands' take over and help keep the drill running true. The lands are the ridges that spiral around the outside of the drill bit.
Once the final holes are drilled and the ends squared then inspect them (pic; holeedges.jpg) Notice the tiny chips around the edge of the hole on the one on the right? Brittle stuff like PR and glass love these little chips.
Ever had a little chip in your car windscreen that suddenly became a unrepairable crack?:redface: You can just hit a pothole and the damned thing cracks right across the screen and you wish you had the chip fixed??
Simply remove these chipped edges with a bit of sandpaper.
Next pic (taper.jpg) shows the tap in the hole and ready to cut threads.
Note that it is halfway up the taper before we have started. This hole could be a tiny bit too big. But we don't want to crack the PR. We'll see.

After taking tiny back and forth turns slowly advance the tap until the thread is cut. Use lots of lube. You can use anything you like, but I prefer soapy water in a squeezy bottle. I just have to clean up everything when I'm finish to prevent rust.
If you use one of the spring loaded tapping guides method then don't let the next pic happen to you. You can see that I got carried away with the threading but forgot to advance the tailstock. Likewise, don't forget to retract the TS when removing the tap. There isn't a lot of travel in the spring. (pic; ooops.jpg)

Next pic shows the tap deep enough for my needs. ( pic;deepenough.jpg)
If you use a taper tap, then you need to check how deep you need to go to ensure you have enough full threads in the hole.

Last pic is the finished tapped hole. Perhaps I was a little too cautious in my drill selection. This hole is probably a '5' ( see previous explanation)
But as it's an unseen internal thread and also a snug close fit, it's fine.
(pic;internal1.jpg) As the material is pretty thick, then I may well have got away with using the 'proper' sized bit.

More coming soon:tongue:

 

[skiprat]

If threading with a tap is called 'Tapping', then why isn't threading with a die, called 'Dying'???:biggrin:

OK, dies. Just like taps, they come in a variety of types and shapes. I also think they have greater range in quality, unfortunately towards the bad side. They are more expensive than taps, mainly ( I believe ) because external threads are easy to do on a metal lathe with a single point cutter. This means there is less demand and so the price shoots up.
I think this could be the reason that there are more crappy ones available than good ones. Most dies from cheap sets couldn't cut threads in butter and should only be used to 'repair' a dinged thread, like a stud on an engine block. This is an example of where the hexagonal shaped ones are really useful.
As the first pic shows ( dies.jpg) , they come in different styles. The don't have as many types for special forms like taps do. They all seem to be basically the same.
The best ones are called 'Split Dies' , obviously because they have a split through one side. This split is so that we can get a tiny amount of adjustment on the depth of the cut. I don't think that most 'hobby people' will need to use this feature. The adjustment is done by three screws in the holder. Next we have the 'Dollar Store' variety( second from the right). I hate these with a passion. They don't have a split so they are easy to spot. In my opinion, they should only be used for thread cleaning like the hex ones. The one on the far right is weird but reasonably good quality.
It has a tiny screw that is used to adjust the cut but it works backwards to the norm. The split type are at their biggest size when relaxed and the screws in the holder squeeze it down if needed. But this one expands to final size by adjusting the screw. The problem is you need to remove it from the holder to adjust. And if you didn't 'stretch' it in the beginning then your thread could be too small, which of course you can't reverse.
Weird, but it cuts fine though.

Next gadget is a Tailstock Die Holder. ( pic; dieholder.jpg) They come in many different styles but I really like mine. It comes with holders for different diameter dies and has a morse taper to fit in the tailstock.
The holder part slides along and revolves freely around a sturdy shaft.
The individual holders have three screws. These match with the dies
The middle screw fits into the 'split' of the die and the other two screws are for adjusting the die. The three screws together, stop the die from rotating in the holder. These are very cheap for what they are.

Let's do some threading...

I turned down my blank so that it's diameter is exactly the same as the thread major diameter. The thread is M10 ( fine) so I turned it to 10mm.
I did not use my own advise that I mentioned previously:frown:

Next pic ( readytothread.jpg) shows the tool mounted and the blank turned down. The blank is sticking too far out of the chuck and the turned down section is vulnerable.
I won't need the material where the first few threads are going to be, so I sanded the end down a bit to make the threading start easier.
(pic; startedthreading.jpg)

You must have guessed what happened next? Yep, it broke

I turned down a new section ( pic; attempt2.jpg) and also turned it down to a gnats hair under 10mm. ( around 9.90mm) and then lightly sanded with 1200grit wet paper.
Next pic shows the job almost done. ( pic.almostthere.jpg)
And finally...the last pic ( success.jpg)

I should add that the blank is 'tubed' under the threads. It was drilled and tubed before threading. :wink:


Now....where did I put my beer???:biggrin:

 

[ribanett]

Decimal & Metric Tap Chart

Found this chart at Little Machine Shop. It lists Major & Minor Dia, tap drills for 75% and 50% treads.

The site view is only the decimal info, but the pdf download shows both decimal and metric specs.

http://www.littlemachineshop.com/Reference/tapdrill.php

 

[RAdams]

Dang it dang it dang it dang it...

I knew it would eventually catch up to me.

A while back, during a time when i actually had a few dollars in my pocket, I was at woodcraft. They had dial calipers on markdown from like $55 down to $40. I bought a pair. Shrortly after that i realized i could have gotten digital calipers for half the price. I have been punishing myself by not buying digitals. Now it looks like i will have to bite the bullet soon. All of this new info is all but useless with dial calipers i am afraid.. Or at least to me it is.

 

[PenPal]

Ratty

Hi Mate one thing I find is to do away with one of your stages tapping I fit the live centre up to the cutter end takes another wobble out and control the feed pressure with the tail stock wheel. I delight in yourtaking time out to help people on this site, it requires time and effort to simplify processes.

My kind regards as always Peter.

 

[bgibb42]

Ok, next question. If the internal or female threads are a "5", i.e. a 50% thread, and the external or male threads are a 75% thread, will they still mate together correctly? Will they feel right?