All that time... I was doing it wrong. (Tapping discussion)
This isn't necessarily applicable to the Tormach, but this is my go-to place on the forum so here it goes.
I experienced a true epiphany today. I've been making metal things for a number of years now. About 8 years off and on, as a hobby, internet taught. Last week, I broke a tap in a piece of aluminum and had a helluva time removing it. This was a #6-32 carbon steel hand tap as part of an Irwin/Hanson set.
After some extensive research, I replaced it and my #4-40 with some high quality HSS Morse and Cleveland brand spiral point taps. Oh. My. God. They are amazing. Is this some kind of a secret, or is it so blatantly obvious that no one bothers to mention it anymore? They cut through 6061-T6 like BUTTER. No resistance at all. I tapped over 250 holes using a clutched drill in less than an hour, dipping it in a cup of 25% concentrate coolant after every hole.
I feel like throwing all my stupid carbon steel hand taps away now.
Re: All that time... I was doing it wrong. (Tapping discussion)
Carbon steel taps are like the ones sold at Lowes or Home Depot. About all they're any good for is getting you out of a jam. Or getting you into a jam.
You should always use spiral point taps for through holes and spiral flute taps for blind holes.
There's another thread on here called tapping where I wrote an example of the procedure I use for tapping holes and I haven't broken a tap in 5 years. And with the hardware I make for remote control boats and trucks I tap a LOT of holes.
Re: All that time... I was doing it wrong. (Tapping discussion)
Steve is rights except I prefer form taps on the CNC for production. I throw my 2-56 form tap out ever 5-6 THOUSAND blind holes. No bird nest on the thing like you end up with when using spiral Flute. For 5 or 20 holes I'll do exactly what Steve said.
I prefer OSG modified bottom spiral taps as I can run them hard and put them away wet and they don't mind. Never had a single one brake without extreme stupidity on my part and have called the wrong TPI several times.
Wrong words courtesy of Tapatalk and Voice To Text. You bar well come.
Re: All that time... I was doing it wrong. (Tapping discussion)
In general I agree with Steve that spiral points for through holes and spiral flutes for blind holes is ideal. I always use spiral point taps for through holes because they perform better and the onlly real difference between them and a standard plug tap is the point design. Therefore they are no weaker than a plug tap. However, when talking about the spiral flute taps, I have found that the flutes are cut deeper that other taps and therefor the tap is a bit weaker and much easier to break. For this reason I don't generally use spiral flute taps for hand tapping of holes smaller than about #6 or maybe #4 depending on material. Other than that, they are far superior to plug taps. I also only use the hardware store variety taps in a pinch and always opt for a ground HSS tap rather than carbon steel.
I also agree with WOT. Form taps are awesome for machine tapping. However they are really only useful for machine tapping like in the CNC mill, or with a tapping arm of some sort. They are not very useful for hand tapping in my experience. The reason is because the form tap has to be aligned with the hole perfectly and they require more torque to make the thread. A cutting tap that is off a degree from the axis can still cut the thread. A form tap displaces the material and if not aligned right, farther in the hole one side is trying to displace more material that the thread profile has room for. So, by all means if you have a tapping arm, are doing the tapping in the mill, or otherwise have a way to insure the tap axis is aligned perfectly with the hole axis, the form taps are wonderful, but not so much otherwise.
Re: All that time... I was doing it wrong. (Tapping discussion)
Valuable input. Despite tapping exclusively blind holes, I went with spiral point taps since I have plenty of hole depth and they are supposed to be slightly stronger than spiral flute taps.
Now I need to look into CNC tapping with some kind of tapping head for my Tormach.
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Re: All that time... I was doing it wrong. (Tapping discussion)
When I was earning a living in the CNC field we used tapping arms like in the picture below for most of our tapping needs. It worked great in that the tapping wasn't included in the machining cycle and the operator could do the tapping with the arm while the next part was running. They aren't cheap but they work well up to about 1/2" taps. I have had it on my to do list for a while to build one that mounts a cordless drill for the drive motor. The rest of it is a pretty simple parallelogram affair with some springs to counterbalance. Haven't got around to making one yet though.
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Re: All that time... I was doing it wrong. (Tapping discussion)
Oh man sorry that you had to go down that route for so long! The only thing good about the Carbon Steel taps is that they dissolve quick when you snap them off...which you will do frequently. The only thing that I find them useful for is basic thread repair....for cutting or forming new threads the HSS taps with correct coatings are the ticket. Just remember that if you go with thread forming taps you need to use a different drill chart! I chased that dog about 9 years ago and broke 3 taps before I figured that out...oops! Oh yeah and if you ever try tapping titanium alloys definitely drill your holes a number size larger than is listed on the guide charts or else you will probably be getting prescriptions for blood pressure meds and rogaine...
Re: All that time... I was doing it wrong. (Tapping discussion)
Quote:
Originally Posted by
Steve Seebold
OSG makes good taps as does Balax or Sossner. But Brian is right about using form taps. Not only are form taps stronger than cutting tape, they actually make a stronger thread because they don't cut material away, they actually upset the grain structure of the material and FORM the thread instead of just cutting material away.
BUT, I'll bet Brian does more tapping on his Haas than he does on his Tormach.
Very true. 95% of my tapping (about 10K/year) are on the Haas rigid tapped. The rest are in a cordless drill if I am making fixtures or random junk. I do have a SWEET tap handle that I get excited every time I get to use I don't think I ever shared. It is ratcheting, open ended with a guide ball to use spring loaded guides on the mill or drill press as well. Best part is once it starts to back out you can 'hold' the tap shank and spin it like a helicopter blade and back it all the way out of a 1" deep hole in a second or three.
I picked it up from McMaster part number 8340A21 but it's made by Gear Wrench and available here on Amazon and it shows Home Depot too. Dang thing is NIIIIICE!
Re: All that time... I was doing it wrong. (Tapping discussion)
Add my vote on the form taps, I use them on everything from #2 to 1/4-20 now. I also use them for hand tapping with a guide block. At least in aluminum and acetal I haven't gotten into trouble this way. If you're pinching pennies, even the import grade cut taps from MSC etc are way better than the Irwin junk they sell at the big stores.
