# Question about taps



## kquiggle (Feb 11, 2015)

This is a question about the cost of taps.

Recently I made myself a drill and tap index. While I was at it, I included spaces for taps I don't normally use, with the idea that I would have space for them if I needed them later.

Recently, with the idea of filling in some of the gaps for taps that I do use, I also looked up prices for #5-44 and #12-32 taps and found that not only are they somewhat hard to find, they are also about four time more costly than similar size taps.

So her is my question, why are #5-44 and #12-32 taps so costly? Is it just because they are rarely used, or is there some other reason?

And why we are at it, what are these tap sizes commonly used for? I am under the impression that gunsmiths use these, but that is mostly a guess.

P.S.

Here is a link to my index build, so you know what I am talking about:

https://sites.google.com/site/lagadoacademy/machining---lathes-mills-etc/build---drill-and-tap-index


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## kvom (Feb 11, 2015)

5-44 is a UNF thread, but UNF for 12-32 is UNEF.

Looking at the McMaster website I don't see huge differences between the size pairs.


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## bazmak (Feb 11, 2015)

Any common sizes are mass produced in larger quantities and sell more
hence cheaper price.Supply and demand


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## rklopp (Feb 11, 2015)

In my many years of machining, I have never ever come across a 5-44 thread specified anywhere. I wouldn't buy one until I really needed it. A 5-40 is already proportionally fairly fine, and 5-44 is little different. I could not tell you the last time I've seen #5 screw threads of any pitch in commercial design practice. I admit it is a handy size for model work.


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## Wizard69 (Feb 11, 2015)

kquiggle said:


> This is a question about the cost of taps.
> 
> Recently I made myself a drill and tap index. While I was at it, I included spaces for taps I don't normally use, with the idea that I would have space for them if I needed them later.
> 
> Recently, with the idea of filling in some of the gaps for taps that I do use, I also looked up prices for #5-44 and #12-32 taps and found that not only are they somewhat hard to find, they are also about four time more costly than similar size taps.


Odd sized taps are best purchased when needed.  


> So her is my question, why are #5-44 and #12-32 taps so costly? Is it just because they are rarely used, or is there some other reason?


Supply and demand.    Generally you don't see anything other than 4-40 and 6-32 in US built machinery.  That is if they are using English fasteners at all, the trend these days is to specify metric fasteners in custom built machinery.  


> And why we are at it, what are these tap sizes commonly used for? I am under the impression that gunsmiths use these, but that is mostly a guess.


Gunsmithing is a possibility.   I've worked on a lot of instrumentation over the years and have never seen this thread size used.  Most of the optics industry has been metric for pretty much ever.  


> P.S.
> 
> Here is a link to my index build, so you know what I am talking about:
> 
> https://sites.google.com/site/lagadoacademy/machining---lathes-mills-etc/build---drill-and-tap-index


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## kquiggle (Feb 12, 2015)

I put together the table below by grabbing some prices from Enco and McMaster-Carr, by way of illustration. It also shows why I generally don't buy from McMaster-Carr unless I can't find what I'm looking for anywhere else. I don't mean this as a slam on M-C, but I do find there prices high for a mere hobbyist like myself.

I do agree with the comment that it's better not to buy a tool until you need it (so I won't be buying 5-44 or 12-32 taps anytime soon), with the qualification that there are some exceptions like drill sets and other common stuff that will nearly always be used.



```
SIZE    TYPE           Enco      McMaster
5-44    Bottoming      $5.55    
5-44    Taper          $5.57     $6.13
5-40    Plug           $3.08     $6.61
5-40    Bottoming      $2.94    
12-32   Plug          $17.71    $24.46
12-32   Bottoming     $17.71    
12-28   Plug           $2.89     $5.76
12-28   Bottoming      $2.76
```


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## Wizard69 (Feb 13, 2015)

kquiggle said:


> I do agree with the comment that it's better not to buy a tool until you need it (so I won't be buying 5-44 or 12-32 taps anytime soon), with the qualification that there are some exceptions like drill sets and other common stuff that will nearly always be used.




Just to clarify what I have said before, it is the odd size taps that you want to resist from stocking before you actually need them.  It really pays to have a set of common taps on hand so that they are there when you need them.    It just greatly reduces the frustration level.  What is the common tap sizes of course depends upon ones interest.   I just don't see a need to buy an odd sized tap before you need it, filling up an arbitrary sized collection of taps just doesn't cut it as a good reason to buy such taps.   

I sort of liken this to drill bits, buying a set of jobber bits most certainly reduces frustration when it comes to working on a project of any sort.  However I wouldn't suggest buying a set of Aircraft length drills if you need just one for that odd pulley drilling problem.  Buy the odd length drill bit when needed. 

The trick then becomes what is a reasonable clock ion of taps to have on hand.   Here I'm afraid to offer a range because there are so many competing interests, sizes and types of engines.  In any event let's say 8-32 to 3/8" to start.  This co every a lot of stuff including light fixturing.   If you have access to a Bridgeport or other larger machines you probably should extend that to cover larger fixtures and clamping arrangements.


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## kvom (Feb 13, 2015)

My mechanics set of taps and dies go from 10-32 to 3/4.  The smaller sizes I've used so far are 2-56, 4-40, 5-40, 6-32, and 8-32.

Anything smaller than 2-56 is beyond my fingers and eyesight capability.


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## Brian Rupnow (Feb 13, 2015)

I use #5-40 fasteners on almost all of my models. It is one of those sizes that "Just seems right" for much of the stuff I design and build. I don't find the taps to be any more expensive than comparable sized taps. I do have trouble with the fact that nobody stocks #5-40 fasteners. I buy a box of 50 or 100 at a time and they last me for years.---Brian


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## kvom (Feb 13, 2015)

5-40 is good for models as you make pins and studs from 1/8" or 3mm rod.

On my current build I'm using a lot of 10-32 as it works well with 3/16 stock.

For scale fasteners I buy from American Model Engineering in these sizes.


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## kquiggle (Feb 13, 2015)

Wizard69: I think you have it right, although sometimes I come down with "toolitis" and find myself wanting to buy some tool or other just because it looks interesting. My antidote is to maintain a "wish list" of things I need or would like to buy - when I make a purchase I consult the list to make sure I am prioritizing the "needs" over the rest of the list.

With respect to fasteners, here are some links to suppliers of interest to hobby machinists:

https://sites.google.com/site/lagadoacademy/useful-links#fasten


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## Ozwes007 (Feb 13, 2015)

Another good thing to remember is the quality your buying. Generally taps are made in Carbon steel, chrome vanadium steel, high speed steel(M2), 5% Cobolt high speed steel (M35), 8% cobolt high speed steel(M42) and carbide. The quality and price usually go's in the same order and the material you can tap as well. Eg. M35/42 HSS is good for RC 35-RC70 steel tapping ([email protected]) .
Just as an aside, drills are also along these lines.


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## bazmak (Feb 13, 2015)

Will agree everything said above.I have bought cheaper sets of high carbon steel for taps and dies that are not overly used.IE model engineers,fine threads for gas and pressure fitting etc.Used occasionally and for softer materials they are more than adequate.For more regular use and harder materials,IE common metric,BA and BSW etc
i buy HSS taps and dies, more expensive but much better quality


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## DJP (Feb 13, 2015)

My Dad said that carbon steel taps are only meant for thread chasing to clean them up. They may cut one fresh thread but after that they are dull and frustrating to use. He was right, as usual.


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## deverett (Feb 14, 2015)

DJP said:


> My Dad said that carbon steel taps are only meant for thread chasing to clean them up. They may cut one fresh thread but after that they are dull and frustrating to use. He was right, as usual.



I wouldn't necessarily agree with your Dad.  I have used carbon steel taps successfully (down to 10 BA).  Used with a suitable tapping compound such as Trefolex in the 'normal' range of model engineering materials they do not pose any problems.  We are not in a production environment and if the tapping is taken slow and easy with the correct size hole a decent thread will result. 

I'm not decrying the use of HSS, but just saying there is nothing wrong with well made, brand name carbon steel taps (such as Warrior, among others, in the UK).  Whatever works, everyone to their own devices.

Dave
The Emerald Isle


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## Wizard69 (Feb 14, 2015)

kquiggle said:


> Wizard69: I think you have it right, although sometimes I come down with "toolitis"


Honestly I think I have the worst possible case of toolitis there is.   Last week I was down hard with what was likely the flu, literally a couple of days in bed.   Once I got better to the point of standing a bit, guess what I was doing  -  sharpening my wood chisels and then some old HSS lathe tools.   I was still too sick to feel comfortable operating power tools so most of the work was done with hone stones.  The only thing that gets in my way tool wise is work - this is a terrible sickness all on its own but generally it only hurts the wallet.   


> and find myself wanting to buy some tool or other just because it looks interesting. My antidote is to maintain a "wish list" of things I need or would like to buy - when I make a purchase I consult the list to make sure I am prioritizing the "needs" over the rest of the list.


What hurts more is choosing between tools, a new roof, a new bath, rubber for the truck and other goodies.   Let me tell you running slicks in the winter sucks.  


> With respect to fasteners, here are some links to suppliers of interest to hobby machinists:
> 
> https://sites.google.com/site/lagadoacademy/useful-links#fasten




Thanks for the link.


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## Wizard69 (Feb 14, 2015)

DJP said:


> My Dad said that carbon steel taps are only meant for thread chasing to clean them up. They may cut one fresh thread but after that they are dull and frustrating to use. He was right, as usual.




Ive heard an opinion expressed a long time ago that carbon steel taps are good for things you can't risk a jammed tap in.   This was from a gunsmith.    The idea was that if a carbon Tap does break it is so brittle that you can crush it with a punch and remove it that way.  I'm not sure I buy that argument, on the other hand I don't work on one of a kind firearms.


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## kquiggle (Feb 14, 2015)

I started with a set of carbon steel taps from good old HF, and as deverett notes, they can work well if used with care and good tapping fluid. When one of my carbon steel taps breaks (and I have only ever broken two), I replace the broken tap with an HSS tap.


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## Blogwitch (Feb 14, 2015)

In fact, I very rarely use anything other than carbon taps and dies, but on the other hand there are carbon t&d's and CARBON T&D's. The ones I use are about twice or more expensive than HSS or any other thing that is in general use in our hobby.
Over the years I have found that they will cut anything that they are asked to, and cut much better threads. They are really designed for cutting stainless steel and I can cut hundreds of threads before having to resharpen with a diamond lap.

This is where I get my tap sets from, I must have at least 6 or 7 full sets of different threads. Quality really pays when it come to T&D's, they seem to last forever.

http://www.tapdie.com/

John


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## bazmak (Feb 14, 2015)

I still go back to my previos post.Cheaper carbon steel taps are good for occasional use and softer materials.HSS are far superior and more expensive
but its what more experienced engineers use for most work


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## Blogwitch (Feb 14, 2015)

You are quite right Baz, cheaper carbon t&d's are only good enough for grinding down to make centre punches. I have tried cheaper ones many years ago, and they really were abysmal. Oversized and undersized threds and continually snapping down a hole.
Of the metric HSS taps I do use are from Arc Euro and are serial taps, and for the price, they are great.

http://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Taps/Serial-Taps---Metric-BSW-BSF


John


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