# Best Style of Small Tap



## dwall174 (Apr 27, 2021)

I have about a dozen  #6-32 taps I need to make in some 5/8" round cold roll stock! 
The stock will be held in a "V" block in my drill press vise & I'll use the drill chuck/quill to align the tap handle, But the actual tapping will be done by hand.

Being that the smaller taps are prone to breaking  
I was wondering if one style of tap (Plug, Taper, Spiral, Etc.)  is better than another for small taps? 

Doug


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## Ulma Doctor (Apr 27, 2021)

i don't envy you one bit, i break 6-32 taps by merely being next to them 
i would suggest going up to the #33 tap drill bit, unless you are way luckier than i
3 flute or 4 flute- gun taps are sweet too, then to a bottoming tap if you are tapping blind holes


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## DavidR8 (Apr 27, 2021)

Ulma Doctor said:


> i don't envy you one bit, i break 6-32 taps by merely being next to them
> i would suggest going up to the #33 tap drill bit, unless you are way luckier than i
> 3 flute or 4 flute gun taps are sweet, then to a bottoming tap if you are tapping blind holes



I second upsizing the tap drill. I just did a whack of 6-32’s and the speced tap drill was definitely cringe inducing.


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## benmychree (Apr 27, 2021)

I prefer plug taps for most tapping.


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## mikey (Apr 27, 2021)

Ulma Doctor said:


> i don't envy you one bit, i break 6-32 taps by merely being next to them
> i would suggest going up to the #33 tap drill bit, unless you are way luckier than i
> 3 flute or 4 flute- gun taps are sweet too, then to a bottoming tap if you are tapping blind holes



I agree with the Doc, except I think he meant to use a #31 drill that is a bit larger than the recommended #32 for steel. I would also use a spiral point tap if going through and a spiral flute tap if blind.

Edit: forgot to add that if you have a tap guide block, it will reduce breakage. So will a piloted tap driver. I tap a lot of small holes, 6-32, 8-32, and rarely snap a tap. I upsize the drill as Doc said and use these contraptions to reduce side deflection caused by human error and it seems to work out well.


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## Larry$ (Apr 27, 2021)

I'm good at breaking small taps. To keep things exactly aligned keep the vice clamped to the DP. Drill, change to taper tap, lots of tapping fluid, I like to use a tap follower. Turn by hand and backup often. If it is very deep take the tap out to clean often. If this a blind hole. Swap to a plug tap and then a bottoming tap. Use high quality taps. Good luck!


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## darkzero (Apr 27, 2021)

I've had great luck with the Widia GTD (Greenfield) taps from Mcmaster. Aren't expensive & arrive the next day when I need em (or if it's an emergency I can drive down & pick em up any day of the week, even Sat or Sun).

I used a spiral flute Widia to tap a bunch of 6-32 blind holes. One single tap tapped over 1200 holes no problem but using a tapping head. But I won't talk about all the taps I broke setting up the tapping head.  




This was just one batch of many, two 6-32 blind holes per piece, 6061.




I've never used any myself & have been meaning to try them but I hear form taps work really well for small thread sizes. Balax


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## mmcmdl (Apr 28, 2021)

Greenfields and OSGs are great . The type of hole would determine the type of tap . Being a 6-32 , I wouldn't skimp on the taps .


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## mikey (Apr 28, 2021)

darkzero said:


> I've never used any myself & have been meaning to try them but I hear form taps work really well for small thread sizes. Balax



Form taps are awesome, especially for small holes. They don't make chips, form stronger and more precise threads and are much stronger than regular taps. They are usually only used in softer materials like aluminum and brass, not steels. Tap drills are larger for roll taps so be sure to use the right one.

I have a 10-32 roll tap that has been in use for over a decade and still going strong.


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## Ischgl99 (Apr 28, 2021)

This is a timely thread, I broke a 2mm tap the other day and was looking to see what to get to replace it.


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## Braeden P (Apr 28, 2021)

6 40 is harder to break than 6 32 and when making a good part im a lot more careful but good quality pays off


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## graham-xrf (Apr 28, 2021)

We have lots of great input about quality of taps, techniques, thread choice, etc. but I am still floundering a bit, not least because the mostly metric bolts I use might have different ratios of metal removal needs than for imperial.

Are we saying that using the specified (imperial) diameter first hole is too small? This by unlucky design choice?

Is it that the work (for the tap) in cutting the thread from core diameter to crest diameter is just too close to requiring breakage torque for a 6-32 combination?

Are the guys recommending drilling a larger tap hole than normally specified? It seems to be a popular strategy!

We have to be impressed at the @darkzero score. OK - there is the Tapmatic goodie, but here we are after what was doing the cutting. Is that a special technology tap?


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## mmcmdl (Apr 28, 2021)

The OP never stated if these threads were thru or blind , so tough to give a correct answer . Maybe he'll come back and follow up . As far as the minor diameter goes , if you're not doing NASA work and you don't need a full % thread , go oversize . No-one else will know ( if you don't tell them ) .


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## MrWhoopee (Apr 28, 2021)

I vote for thread-forming (roll, rocket) tap, much stronger than a cutting tap.  I've used them in mild steel and they work fine. 6-32 is probably the worst for breakage because of the coarseness of pitch vs diameter. Did anybody mention high-quality cutting fluid? It can make or "break" the operation. I've recently started using Tap Magic and the improvement over cutting oil is noticeable with small taps.

edit: if replacing that CRS with 12L14 or 1144 is an option, then DO IT!


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## dwall174 (Apr 28, 2021)

mmcmdl said:


> The OP never stated if these threads were thru or blind , so tough to give a correct answer . Maybe he'll come back and follow up .


The threads are basically thru taps since the drilled holes go thru to a 7/16" Acme thread! 

However I only need the threads to go 1/4" deep & I don't want the screw to interfere with the Acme thread. 

Doug


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## dwall174 (Apr 28, 2021)

MrWhoopee said:


> if replacing that CRS with 12L14 or 1144 is an option, then DO IT!


Yeah that's not an option, Since I'm using a already made part to start with!
As far as the CRS I'm just guessing on that? But being a standard production part I would assume it's not a high grade steel. 

Doug


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## dwall174 (Apr 28, 2021)

mmcmdl said:


> As far as the minor diameter goes , if you're not doing NASA work and you don't need a full % thread , go oversize . No-one else will know ( if you don't tell them )


I went by a Starrett pocket tap drill chart I've had for years & it showed drilling a 7/64" hole. 

Doug


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## dwall174 (Apr 28, 2021)

mikey said:


> Edit: forgot to add that if you have a tap guide block, it will reduce breakage. So will a piloted tap driver.


I do have & plan to use a piloted tap handle & the V blocks in the drill press vise as stated before.

Doug


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## Badabinski (Apr 28, 2021)

The only taps I've broken have been cheap ones, and removing a broken tap will never be anything other than a massive headache.

There's no getting around the fact that good taps are expensive, but I find that they're well worth the money if it means fewer scrapped parts. I'd rather spend $10-40 on a very high quality tap and not waste hours of my life re-making a part. I've had great luck with Union Butterfield, Clarkson-Osborn Blue Merlin, and Walter-Titex taps.

The other thing to keep in mind is the tap type. I almost exclusively use spiral-flute taps, but I seem to recall hearing that spiral-point (or gun) taps are stronger. They're also better suited for metals that don't form chips like cast iron.


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## Ischgl99 (Apr 28, 2021)

dwall174 said:


> I went by a Starrett pocket tap drill chart I've had for years & it showed drilling a 7/64" hole.
> 
> Doug



That chart uses 75% thread engagement on the course threads.  For steel, 50% is usually sufficient.  7/64th is in between those two, so might be fine, but unless the screws are going to need full strength on the threads, going to 50% would be the way I would go on steel.  This chart shows the recommended drill sizes for 75% and 50%.



			https://littlemachineshop.com/images/gallery/PDF/TapDrillSizes.pdf


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## Flyinfool (Apr 28, 2021)

For most of what I do a #6-32 is not a small tap, it is the big size tap where breakage is much less likely, most of my work is much smaller down to #0-80 into stainless. I only do hand tapping. with hand tapping you can feel the cutting action and once you have broken a few taps for the experience, you will feel when something is not right.

I use mostly plug spiral point (Gun point) taps for thru holes. and spiral taps for blind holes after having done as much as possible with a plug tap.
In hard metals I will go up 1 drill size. If you are more than 1.5 thread diameters of engagement the oversize hole will still be stronger than the screw.

It was not mentioned often enough, the tapping fluid used makes a huge difference. I also like Tap Magic.

Forget about "hand taps" from the hardware store. Those are only suitable for tapping soft butter or softer materials. Most any of the name brand taps will be good. Once you use spiral taps you will never want to even see another straight flute tap.

With spiral flute and spiral point taps you do not need to keep backing up to break the chip, The spiral point tap will drive a long stringy chip forward out out the end of a thru hole. they actually prefer to just be run in to the hole. The spiral flute taps are designed to pull a long stringy chip back up and out the entry side of the hole and they also do not like the chip broken. When you back up to break the chip with a spiral tap the chips will build up in the flutes and make it more likely to jam up and break the tap because you are not letting the tap design work the way it was intended and get the chips out of the way. It feels weird the first time you use one and just crank it thru, your brain has been breaking chips for so long it is hard to wrap your head around just plowing thru. Do some test pieces to learn how it feels.

Since you only need 1/4 inch of threads, then you do not have to run the tap all the way thru but having a thru hole drilled is still a big help with chip control.


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## MrWhoopee (Apr 28, 2021)

Since the holes are thru, if you go with a cutting tap, get spiral POINT taps.


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## dwall174 (Apr 28, 2021)

Flyinfool said:


> With spiral flute and spiral point taps you do not need to keep backing up to break the chip, The spiral point tap will drive a long stringy chip forward out out the end of a thru hole.


Thanks for the info. on the spiral taps! I've used them before, But I've used them like a regular tap with the back & forth chip breaking method.

 Doug


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## Mitch Alsup (Apr 28, 2021)

dwall174 said:


> I have about a dozen  #6-32 taps I need to make in some 5/8" round cold roll stock!



You are going to need to remove the tap at least 3 times on its way through to get rid of the chips from the fluted volume.


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## Flyinfool (Apr 28, 2021)

Mitch Alsup said:


> You are going to need to remove the tap at least 3 times on its way through to get rid of the chips from the fluted volume.


Not if using a spiral point tap, there is no chip buildup in the flutes.


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## dwall174 (Apr 28, 2021)

Mitch Alsup said:


> You are going to need to remove the tap at least 3 times on its way through to get rid of the chips from the fluted volume.





Flyinfool said:


> Not if using a spiral point tap, there is no chip buildup in the flutes.





Flyinfool said:


> With spiral flute and spiral point taps you do not need to keep backing up to break the chip, The spiral point tap will drive a long stringy chip forward out out the end of a thru hole. they actually prefer to just be run in to the hole.



Well I'll find out tomorrow how well the spiral point taps work!
I picked up a 3 flute spiral tap made by a company called SOWA 

I haven't heard of this manufacture before, But the salesman at a local tool supply store near me recommended it. He said they sell a lot of these taps to CNC shops & Gunsmiths.  

Incase someone here is familiar with SOWA, The full part# of the tap is: H3 GUN HSSE-V3 SPIRAL POINT 123300 

Doug


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## mmcmdl (Apr 28, 2021)

Chips will go downward thru the part .


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## mmcmdl (Apr 28, 2021)

I posted this awhile back , here it is again . Choose yer poison !


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## dwall174 (Apr 29, 2021)

mmcmdl said:


> I posted this awhile back , here it is again.


Thanks for posting it again, I hadn't seen that one before!

I've pretty much used the regular straight flute taps before & I never really thought about which way the chips were going.
The only time I was concerned with chips was when trying to tap a blind hole & I wanted close to full threads. In those cases like stated a few posts back.


Mitch Alsup said:


> You are going to need to remove the tap at least 3 times on its way through to get rid of the chips from the fluted volume.


Getting those chips or stringy strands out of the hole can be a PITA sometimes.

Doug


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## mmcmdl (Apr 29, 2021)

You're welcome . You won't have chips if you're blowing them out the bottom of the hole .


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## mattthemuppet2 (Apr 29, 2021)

If I'm tapping a smallish blind hole (esp. 6-32) in tough or hard material I usually start the thread with a spiral point tap as they're much stronger. Then blow out the chips and finish the hole with a bottoming spiral flute tap. Or drill the hole deeper and use only the spiral point tap. Spiral flute taps in the smaller sizes are fairly weak and you can sometimes feel them twisting, which is not a fun feeling!


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## Janderso (Apr 29, 2021)

mikey said:


> I would also use a spiral point tap


This and a sharp high quality tap has much less resistance imho.


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## dwall174 (Apr 29, 2021)

Thanks for everyone's response, The 3-Flute SOWA spiral point tap I picked up worked great!

Doug


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## ahazi (May 1, 2021)

mikey said:


> Form taps are awesome, especially for small holes. They don't make chips, form stronger and more precise threads and are much stronger than regular taps. They are usually only used in softer materials like aluminum and brass, not steels. Tap drills are larger for roll taps so be sure to use the right one.



I learned the hard way not to use form tap on mild steel - it broke pretty quickly. It was a Belax 1/4-20 that I bought several of on eBay so it did not heart that much. Now I am planning to use it on Nylon. I doubt it will work on 7075 aluminium, maybe softer materials.

Any inputs are welcome on proper and appropriate use of form taps is welcome.

Ariel


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## mikey (May 1, 2021)

I don't see why it won't work with 7075 if you use the right tap drill. If it binds, go one step larger.

Edit: you are using the tap Belax calls for, right? Tap drills for roll taps are larger than for standard taps.


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## ahazi (May 1, 2021)

mikey said:


> I don't see why it won't work with 7075 if you use the right tap drill. If it binds, go one step larger.
> 
> Edit: you are using the tap Belax calls for, right? Tap drills for roll taps are larger than for standard taps.


Thank you!!!

Novice mistake... This was dumb of me not to look at tables from Balax... I used #7 drill that I always use for 1/4-20 threads. According to the charts for 3B form tap, the right drill size is #5 or #4. 




Ariel


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## mikey (May 1, 2021)

Not dumb; you just didn't know and now you do. 

Try tapping with a guide block and hand drill - in and out is so much faster with a roll tap.


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