# HSS or carbide tap?



## s_vanhoveln (Nov 26, 2017)

I was threading a #4-40 into 1018 with a HSS tap today and I broke it off. Assuming I can weld a glob onto the broken tap and remove it (big IF) what should I replace the broken tap with? I've never used carbide taps before...are they easier to break since the material is more brittle? I'm getting a three tap set every time I break one ( and that decision is final!) so eventually I'll have better tools, but which material is preferred? Most of my work is AL, brass, and mild steel.


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## Ulma Doctor (Nov 26, 2017)

i would stick with HSS taps with the materials you are using them in.
maybe drill the tap hole larger (if possible) with a #30 drill
maybe use a different tap/cutting fluid that has sulfur, if you haven't already
bacon grease/mineral oil mix works wonders too in many materials

i'm much too heavy handed, i avoid trying to tap anything below #6-32 .


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## rgray (Nov 26, 2017)

Ulma Doctor said:


> i avoid trying to tap anything below #6-32 .



Did some 2-56's the other day......Now that's nerve racking!


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## mikey (Nov 26, 2017)

I agree - go one size larger than the recommended tap drill in steel and stick with HSS taps. There used to be a guy who made a sensitive tap wrench for these small taps but he has long since stopped making them. You might be able to make one from the instruction sheet: https://littlemachineshop.com/Instructions/SensitiveTappingKitInstructions.pdf


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## rgray (Nov 26, 2017)

Picked these up on ebay the other day.
Kinda like a sensative drill holder. The knurled wheel is attached to the tap. and the "guide rod" out the back is spring loaded and free to rotate on a bronze bushing.
The set screw for the tap is set deep so there is lots of support for the tap.
No name on the m. Pretty sure they were shop (homemade)built.


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## EmilioG (Nov 26, 2017)

I really like Guhring PowerTaps made with a TiCn coating. Guhring also makes Cobalt bright, which I use for small taps., m6 and smaller.


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## David S (Nov 27, 2017)

What was the application and what type of tap are you using.  I use HSS and all of my taps below #8 are spiral point or spiral flute.  I found the straight flute seemed to bind up too easily in aluminum.  For blind holes spiral flute just pulls the chips out the top.

David


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## Doubleeboy (Nov 27, 2017)

s_vanhoveln said:


> I was threading a #4-40 into 1018 with a HSS tap today and I broke it off. Assuming I can weld a glob onto the broken tap and remove it (big IF) what should I replace the broken tap with? I've never used carbide taps before...are they easier to break since the material is more brittle? I'm getting a three tap set every time I break one ( and that decision is final!) so eventually I'll have better tools, but which material is preferred? Most of my work is AL, brass, and mild steel.



3 tap sets are definitely nice to have but if they are all 4 flute taps the problem of breaking taps remains.  2 or 3 flute taps for me and I rarely use 75% engagement, like others have said, go to next larger tap drill.  Most all of my taping gets done with TapMagic fluid.  I use the current stuff for most work, real difficult jobs I pull out the old can with TCE in it.  TapMagic is very slippery stuff, makes tapping much easier IMO.


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## samthedog (Nov 27, 2017)

I tested Chinese offerings in M35 and M42 high cobalt steels. These were exceptional value and cut very nice threads. These were spiral machine taps. More info here:

http://hobby-machinist.com/threads/chinese-high-end-tap-die-and-drill-bit-review.63762/

The video of hand tapping with these taps is here:


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## EmilioG (Nov 27, 2017)

I read that by using wax, melting wax or pushing a bit of soft wax in the hole before tapping small holes helps to contain the chips.
For blind holes, a spiral flute tap, which pulls the chips up and out may work for you. Also, rigid machine tapping manually, and blowing out the chips as you tap, may also help.  I don't think you need a carbide tap. They are for harder steels. Hss, Hss-e or Vanadium should do just fine.
Granted, 4-40 is a small tap, so be sure that the drilled hole is clean and straight., chamfer the hole entrance, go slow, clear chips as you go.
You don't mention if you're hand tapping or machine tapping.  If using a machine, try it with no power by hand. Maybe a tap guide?

Cheap, import taps are usually not ground and will not stay sharp for long. I only use new, sharp, ground taps. McMaster has Widia taps in sets.
Pretty good tap, Guhring, Emuge..better.


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## s_vanhoveln (Nov 27, 2017)

Ulma Doctor said:


> maybe drill the tap hole larger (if possible) with a #30 drill


A #30 drill sure would make it easier to tap, though I think thread engagement might be lacking. 
A larger hole is always good advice when the application isn't critical. The Handbook called out #43, and I went up to 3/32" (my #42 drill is missing for some reason) and still broke the tap. I'm hoping the larger hole will make the stub easier to remove.


rgray said:


> Picked these up on ebay the other day


Those look pretty cool. I sense another project being added to my list.


Doubleeboy said:


> 3 tap sets are definitely nice to have but if they are all 4 flute taps the problem of breaking taps remains. 2 or 3 flute taps for me and I rarely use 75% engagement, like others have said, go to next larger tap drill. Most all of my taping gets done with TapMagic fluid. I use the current stuff for most work, real difficult jobs I pull out the old can with TCE in it. TapMagic is very slippery stuff, makes tapping much easier IMO.


The offender was a 4 flute tap, but the sets I'm looking at are all 3 flute.

Thanks for all the advice folks. If anyone wants to remove the broken tap for me I'll mail the part right away! I'm expecting to remake this one...


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## T Bredehoft (Nov 27, 2017)

For small taps I choose to use my mill.  If need be I shut off the spindle just before entering the hole and turn the chuck by hand. Much of my work is in aluminum, through holes. The majority of holes are tapped, in and out, by power. In holes that don't go through, I make a point of only starting the tap three or four revs, then take the piece out of the vice and finish it by hand. 

Tap Magic exclusively.


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## s_vanhoveln (Nov 27, 2017)

This was a blind hole in 1018. I used a standard 4 flute plug tap, started in the mill (turning the chuck by hand) and then put the part in a vice to finish tapping with the wrench. I didn't have a great "feel" with the part in the mill so I thought finishing by hand would help me be successful. Worked for the first hole...


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## David S (Nov 27, 2017)

s_vanhoveln said:


> This was a blind hole in 1018. I used a standard 4 flute plug tap, started in the mill (turning the chuck by hand) and then put the part in a vice to finish tapping with the wrench. I didn't have a great "feel" with the part in the mill so I thought finishing by hand would help me be successful. Worked for the first hole...



I would use a spiral flute for that application.

David


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## FLguy (Dec 3, 2017)

Thread form tap.


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## EmilioG (Dec 3, 2017)

Holding the part in your hand gives you better feel than when held in a vise. Something to consider for small taps.


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