Speaking of blind holes, my 7th and last tip is to mind the depth on blind holes. Crashing the tap into the bottom of the hole will almost certainly break it.

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Harvey grew up with his parents and elder siblings in Cleveland. He attended Kent State University but left without graduating. He returned to Cleveland and picked up what work he could, most often finding employment in sales. He was selling insurance when in 1985 he won an amateur night contest at a local comedy club and decided to focus on becoming successful in stand-up comedy. Harvey used observational humour drawn from situations in his own life and spent the next few years largely on the road playing in any club willing to book him. By the early 1990s he had become a headliner in well-known comedy clubs in big cities; he also appeared on TV on the 1990 Johnnie Walker National Comedy Search and in 1993 on cable TV network HBO’s Def Comedy Jam.

The reason is the machine is limited by acceleration of spindle and axes on how closely it can synchronize the tap to the threads it’s making. There’s always some axial force pushing or pulling.  A floating holder will relieve stress from lack of perfect synchronization.

Breaking Tapszach

Many are not aware, but you can calculate how much clearance to leave at the bottom and it’s probably more than you’d think.

The red-orange dots are tapping torque. Look how fast it climbs when thread percentage gets above 60%.  The blue dots are thread strength—it flattens out just when the torque starts climbing. The recommended drill size is almost always a 75% thread. Great strength, but well into that too much torque zone.

Zachary Tong

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Most machine coolants, especially water soluble, are not as good for tapping. If you’re having problems, try using special tapping lubricant. Put it in a spill proof cut that sits on the machine table and program the g-code to dip the tap automatically in the cup.

Be sure to check the requirements on the job—your customer may require a particular thread percentage. But if they don’t, or if it’s within the ranges in this chart, dial back the thread percentage and your taps will thank you.

It’s important to realize there is no one drill size for a tap. Different drill sizes result in different thread percentages.

Good video. I’m having problems tapping 4-40 blind holes in 6061-T6. Snapping the taps off so much I’ve switched to tapping by hand. Roll forms bulge the material out because it’s only .188 thick. Your tip about a Dip Cup is great, we would stop the machine and hand lube the taps. Never thought of a Dip Cup.

Bob is responsible for the development and implementation of the popular G-Wizard CNC Software.  Bob is also the founder of CNCCookbook, the largest CNC-related blog on the Internet.

Note that spiral fluted taps are not as strong as the more common spiral point taps, which is why they’re not used all the time. Just use them on blind holes.

Here’s what’s key—a 100% thread is only 5% stronger than a 75% thread, but it requires 3 times the torque. So, for just a tiny bit stronger thread you wind up with a much greater chance of breaking your tap.  The chart on this slide shows the relationship:

Harvey’s radio show, which included advice to callers about relationships and other life situations, inspired him to begin writing self-help books, beginning with Act like a Lady, Think like a Man: What Men Really Think About Love, Relationships, Intimacy, and Commitment (2009), which became a best seller. His other books included Straight Talk, No Chaser (2010) and Act like a Success, Think like a Success: Discovering Your Gift and the Way to Life’s Riches (2014).

Steve Harvey (born January 17, 1957, Welch, West Virginia, U.S.) is an American comedian, actor, author, and television and radio personality who first gained fame for his observational humour and later became known for his self-help advice, especially about relationships.

First, form taps can’t be used on hard materials. You can only form tap up to 36 HRC hardness materials. That’s a lot more materials than you’d think, but there’s definitely materials that can’t be form tapped. Second, some industries don’t allow form taps because the process can create voids that trap contaminants on the threads. Form Tapping can also create stress risers on the threads.

I walk you through the math below and you can see that for the example ¼-20 roll form tap we needed not quite a ¼ inch of clearance from where the tap stopped to the hole bottom.

To start, use a holder that locks the square shank on a tap so it can’t twist in the holder. Tapping uses a lot of torque, so having a positive lock on that shank is helpful.

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Harvey in 1993 became the host of the syndicated TV show It’s Showtime at the Apollo, a gig he maintained until 2000. In addition, he developed a TV comedy, Me and the Boys, in which he played the widowed father of three sons. Though the show won high ratings, it lasted only a single season (1994–95). A second TV series—The Steve Harvey Show (1996–2002)—attracted a large and stable audience; the sitcom, set in an inner-city high school, featured Harvey as a former funk musician turned music teacher and comedian Cedric the Entertainer as a gym teacher. Harvey later began hosting the game show Family Feud (2010– ) and its spin-off Celebrity Family Feud (2015– ). His uplifting talk show Steve Harvey debuted in 2012 and ran until 2017, when a new show, Steve, was launched. That program ended in 2019. From 2016 to 2019 he also hosted Little Big Shots, a comedy-variety series that showcased extraordinary child performers. His later series included Steve on Watch (2020– ) and the courtroom show Judge Steve Harvey (2022– ).

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Breaking tapscnc

I just finished the 11th episode of CNC Chef for Cutting Tool Engineering. This video gives you 7 ways to avoid breaking taps:

In 2015 Harvey made news as host of the Miss Universe beauty pageant when he mistakenly crowned the wrong contestant as the winner of the competition (but quickly corrected the error). From 2010 he helped head the Steve & Marjorie Harvey Foundation, a philanthropic venture that provided mentoring to fatherless young people.

Every machinist hates breaking taps. It’s a real pain to extract a broken tap without damaging the part. Plus, tapping always seems to be one of the last operations done on a part, which just ensures the highest cost if you need to scrap the part.  But, there are 7 things I’m going to show you in this video that will great reduce the number of broken taps you have to deal with.

Crashing a CNC machine in a way that does costly damage is worse, certainly. But breaking a tap off in an expensive part that’s nearly finished has got to come in a close 2nd place.

In 1996 Harvey began hosting a morning radio show on Chicago’s WGCI; he led other radio programs beginning in 2000 and started The Steve Harvey Morning Show in 2005. He continued his stand-up career as well and released a comedy album, Steve Harvey Live—Down South Somewhere (1997). During the late 1990s he participated in the Kings of Comedy tour with Cedric the Entertainer, D.L. Hughley, and Bernie Mac; a performance from the tour was made into the Spike Lee film The Original Kings of Comedy (2000). Other movie credits included The Fighting Temptations (2003), You Got Served (2004), and Johnson Family Vacation (2004).