Beware of HCS tap!!!

taiwanluthiers · Jul 26, 2017

I swear, if I ever have to buy taps again it will be HSS. Not that there's anything wrong with HCS if you buy expensive ones that has been properly heat treated and ground (like Greenfield), but avoid brands like Hanson, Irwin, etc. because they're all hardware store HCS crap.

I broke enough HCS taps in my receivers that I have had enough... I bought a few Walton Tap Extractors hoping I will never ever have to use them (and put how good they are to the test).

Basically it seems like it's real hard to break a HSS tap, I do not think I have ever managed to break one except this one time when I forced one into a piece of aluminum into a hole that's too small, under power (this will break any tap), basically my fault...

But I broke so many cheap HCS taps doing it carefully by hand, using plenty of lubrication.

I got a HSS 6-48 tap, a few bucks more than the HCS Hanson but it taps pre-hardened receivers so well I was afraid I'd overload it. I'm told HSS is harder to break too... I tried to break a HSS drill bit before and it was hard to do to say the least (they are not as brittle as you think).

GeneT · Jul 26, 2017

taiwanluthiers said:
I swear, if I ever have to buy taps again it will be HSS. Not that there's anything wrong with HCS if you buy expensive ones that has been properly heat treated and ground (like Greenfield), but avoid brands like Hanson, Irwin, etc. because they're all hardware store HCS crap.

This is absolutely true, add "Vermont American" to the list - those are all barely worth their place in the trash can.

taiwanluthiers said:
I bought a few Walton Tap Extractors...[\QUOTE]
Now you have another problem... ;-) I have never seen, or met anyone that has seen, one of those Walton-type tap extractors work. What they're good for is filling in the extra space around the broke tap. Carbide burrs, carbide drills, or edm are the only successful methods to remove broken taps that I know of.

GsT

DMF_TomB · Jul 26, 2017

taiwanluthiers said:
I swear, if I ever have to buy taps again it will be HSS. Not that there's anything wrong with HCS if you buy expensive ones that has been properly heat treated and ground (like Greenfield), but avoid brands like Hanson, Irwin, etc. because they're all hardware store HCS crap.

I broke enough HCS taps in my receivers that I have had enough... I bought a few Walton Tap Extractors hoping I will never ever have to use them (and put how good they are to the test).

Basically it seems like it's real hard to break a HSS tap, I do not think I have ever managed to break one except this one time when I forced one into a piece of aluminum into a hole that's too small, under power (this will break any tap), basically my fault...

But I broke so many cheap HCS taps doing it carefully by hand, using plenty of lubrication.

I got a HSS 6-48 tap, a few bucks more than the HCS Hanson but it taps pre-hardened receivers so well I was afraid I'd overload it. I'm told HSS is harder to break too... I tried to break a HSS drill bit before and it was hard to do to say the least (they are not as brittle as you think).

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i have had hss taps break easy too. when heat treated they can make them harder but more brittle or softer, tougher but dull faster
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in general hss taps are better cause they tap more holes per tap than carbon steel taps
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carbide taps being harder break even easier but with certain alloys you cannot tap with hss but have to use carbide taps
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when power tapping usually a spiral point or gun tap, or a spiral flute tap works 10x better than a hand tap. spiral point and spiral flute taps push chips ahead or pull up out of hole. a hand tap chips clog flutes and if you keep turning clockwise usually it will jam and break tap. thats why hand tapping you reverse every so often to let chips fall out of flutes or you pull tap out of hole and clean chips off flutes then continue tapping deeper into the hole

tobnpr · Jul 26, 2017

I tap a lot of milsurp receivers and prefer HSS....
Went through a bunch of trials before settling on Kodiak, 4-flute for this job. I'll never power tap with these small #6-#8 holes, old school with a B&S alignment tool in the spindle, and the tap wrench in my hand for "feel".

Times I've been lucky and gotten maybe ten holes from a single tap, others I've burned through two or three on a single hole. I learned after breaking one off it just isn't worth pushing for "one more" hole. Even a quality tap is cheaper than the time spent breaking one out (or drilling with carbide burrs) so as soon as the resistance gets to a certain feel it's time for a new tap....

DanielG · Jul 26, 2017

GeneT said:
Now you have another problem... ;-) I have never seen, or met anyone that has seen, one of those Walton-type tap extractors work. What they're good for is filling in the extra space around the broke tap. Carbide burrs, carbide drills, or edm are the only successful methods to remove broken taps that I know of.

Now you have. I've broken my fair share of HSS taps, and the tap extractors sometimes work. They obviously don't work on spiral flute taps, but I've had okay luck on extracting broken spiral point taps.

I refuse to buy hand taps, they suck. The only exception is the set of cheap harbor freight carbon steel taps & dies I keep around for chasing threads in odd sizes.

taiwanluthiers · Jul 26, 2017

Is there a way to buy taps in bulk, if they only last a certain number of holes?

How do manufacturers who tap these receivers like all the time do it, do they throw out taps after a certain number of holes? I am sure they power tap.

DanielG · Jul 26, 2017

taiwanluthiers said:
Is there a way to buy taps in bulk, if they only last a certain number of holes?

How do manufacturers who tap these receivers like all the time do it, do they throw out taps after a certain number of holes? I am sure they power tap.

If you're doing these by hand, you're probably not going to wear out many taps. YG-1 taps are very good and inexpensive. I've also had good luck with FMT. They're more expensive, but I needed it fast and Fastenal had it in stock.

The most important thing is to use a good tap of the right type and lots of lube, I like Rapid-tap. If you're doing through holes, use a spiral point tap. If you're doing blind holes, use a spiral flute tap.

DMF_TomB · Jul 26, 2017

taiwanluthiers said:
Is there a way to buy taps in bulk, if they only last a certain number of holes?

How do manufacturers who tap these receivers like all the time do it, do they throw out taps after a certain number of holes? I am sure they power tap.

.
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a cnc machinist usually the cnc keeps track of time the tap was used and after 60 minutes it is expired and wont come back out to spindle automatically. sometimes tap squeals and is changed more frequently
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some alloys like aluminum bronze only work with sharp taps and if tap is dull at all the tap will break easy. often critical jobs new taps are used just to avoid a broken tap and scrapping part. also often a part is hand bottom tapped by hand as machine tapping by machine near the bottom of a hole is risky and often not worth machine tapping
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usually hardware store taps are hand plug or middle taps. they are not meant for machine or power tapping. you would break a hand tap trying to machine tap any hole more than 1 diameter deep usually. with a spiral point or gun tap often you can tap 3 diameters deep by machine or power tapping cause chips are pushed ahead of tap

DMF_TomB · Jul 26, 2017

taiwanluthiers said:
Is there a way to buy taps in bulk, if they only last a certain number of holes?

How do manufacturers who tap these receivers like all the time do it, do they throw out taps after a certain number of holes? I am sure they power tap.

.
you can buy a box of taps often 12 taps to a box

GunBum · Jul 26, 2017

Finding good 6-48 and 8-40 taps in bulk is often a chore. I don't know why so many "gunsmiths" are cheap bastards. If I'm going to tap someone's expensive receiver, I use a new tap for each job, and pass the cost along to the customer. If they aren't willing to pay me what I want to put a threaded hole in their receiver... well, they can keep their job and find a cheap bastard to screw up their receiver.

Not being a cheap bastard saves me from having to chip out broken taps...

taiwanluthiers · Jul 26, 2017

Well, if I'm tapping my own homemade receiver and isn't getting paid 15 bucks a hole, then yea I am going to do what I can to save money. If someone pays me that much to tap a receiver then I will buy a tap for the job.

Why do guns use such an oddball thread anyways? Why not use 6-32 and 8-40? Or tap it in m4 or m5? I tapped my receiver in M5 and the target doesn't know the difference... and I can easly find the screws at any hardware store and not have to beg a gunsmith to sell me some.

James H Clark · Jul 26, 2017

I have been told that the reason gunsmiths use carbon steel taps is so they (the carbon steel taps) can be annealed with a torch tip and then easily drilled out when it breaks. Not so easy with HSS taps.

JH

taiwanluthiers · Jul 27, 2017

Well you could just use a carbide spade bit anyways, and it cuts through HSS or carbon steel like it's nothing.

GGaskill · Jul 27, 2017

Why not use 6-32 and 8-40? Or tap it in m4 or m5?

6-32 is about the weakest thread that is made, and it is sufficiently coarse that you wouldn't get enough threads through common thicknesses found in receivers. 6-40 would be better; 8-40 would be "more better." 6-48 gives you more threads in any given thickness, but it is not hardware store available. But mounts usually come with the screws so that doesn't matter.

The metric threads have only become commonly available in the US in the 21st century. You can buy 6-48 screws from Brownells.

gwilson · Jul 27, 2017

James has it correct: HCS taps are more easily gotten out than HSS. I have dozens of NOS HCS taps in many sizes. Probably from the 40's and 50's.

Of course I PREFER to use HSS. But,when they break,I can easily drill them out with small TIN coated solid carbide end mills. I used to do that for the gunsmith Shop in the museum,where I was the toolmaker. I could drill them out without even touching the threaded hole! For larger taps,straight flute solid carbide drills work very well. I run them at high speed,and they seem to de temper the taps and scoop out the shavings as they drill.

I had come across a guy at gun shows who sold little assorted diameter CHINESE MADE miniature end mills. 10 pieces for $10.00. They are carbide,and well TIN coated(Which most of their larger mills are not well coated). I don't know WHAT system those little end mills are made to,as far as diameters are concerned. They seem to range between about 1/16" to 1/8" dia.. I wish I had bought more,but I think the guy died. They are 4 flute,and will mill out HSS taps like butter.Their assorted diameters are very handy for milling out small taps without milling the threads off!

I have seen some on Ebay,but not in the 10 piece sets. Anyway,Chinese or not,these little end mills are GREAT!

taiwanluthiers · Jul 27, 2017

..Two Flute Endmills - Individual Quantities - Lightly Used - Super Value! - Drill Bits Unlimited.com

I don't know what happened to the Kyrocera end mill sets... they used to have them on ebay. This site has some small carbide end mills, only 2 flute ones and not 4 flutes (which is really helpful for hard materials like broken taps)

DMF_TomB · Jul 27, 2017

i have used a lot of carbon steel taps from the hardware store and very rarely ever break any.
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of course i am not power tapping using a hand plug tap which are not made for machine tapping. spiral point tap is made for machine tapping usually up to 3 diameters deep. i have never seen spiral point taps at a hardware store. they only sell hand taps usually

gwilson · Jul 29, 2017

Of course,recall that for literally hundreds of years,everyone made many beautiful pieces of work when ONLY HCS milling cutters and taps were available. Just yesterday I tapped a 1/4-20 hole with a HCS tap. About 3/4" deep. It worked pefectly,but,as in all things,you have to have a little skill to do it.

I spent 40 years in a museum,where we often made our own taps and the screw plates,too. As toolmaker,I made 18th. C. tools for all the craftsmen in the Historic Area,and some for other museums as well.

CarlBoyd · Jul 29, 2017

GeneT said:
I have never seen, or met anyone that has seen, one of those Walton-type tap extractors work.

Back in the 70's, so my memory is fuzzy on how often I had success withthe waltons, but it was more than once or twice.
Significant heat (bright cherry red) was required.

CarlBoyd

taiwanluthiers · Jul 29, 2017

Back in the day we made guns by hand without precision machine tools either.

Older doesn't necessarily mean better.

Beware of HCS tap!!!

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