Fun with CNC

CNC tires print out job application 

It’s not our usual thing to post ads here on the Ponoko blog… but then again, seeing CNC machining pop up in an advertisement isn’t something that happens every day!

Click through to see a cute way that Mercedes have used digital manufacturing to draw attention to an otherwise less-than-spectacular utility vehicle. 

 

Another Tapping post from Makezine

Skill Set: More on Tapping Skills

In response to my post yesterday on tap and die, one of our fave MAKE contributors, Ross Hershberger, posted a set of tips we thought should have its own post. Then, reader johngineer chimed in with his own excellent tips. We love getting this sort of intel from our community. Thanks, guys! First, Ross:

Making threads is a very useful skill. Being able to fasten parts with their own threads can reduce the total parts count and the complexity of a project. When I worked in a tooling shop, I tapped hundreds of holes. Here are some tips:

1) For thick material, where ultimate hold is not necessary, you can use the next size larger drill. This will result in less thread depth but the tap will cut easier. The standard for 1/4″ – 20 is a #7 drill (0.201″). A larger #6 hole (0.204″) or 13/64″ will tap easier because the tap is taking off less material.

2) Definitely back off the tap 1/2 turn for every turn forward in thick material. The swarf must be broken loose or it will jam the tap in the hole. Everyone makes that mistake once and then never forgets the hassle of making the repair.

3) When tapping deep holes, periodically run the tap out, blow it off and blow the swarf out of the hole to prevent jamming.

4) There are different types of taps. The tap shown in the video is for through holes. Taps for blind holes have a squared-off rather than tapered end.

5) If you have to tap a bunch of holes in thin material, you can use the tap in a cordless drill on low speed. This is quick, but be careful because removing a broken tap from a hole is very slow.

6) Tap oil is essential to lubricate the working surfaces. Tap Magic is a good one. ATF (automatic transmission fluid) will work in a pinch, too.

 

And here is johngineer’s additional tips:

7) Know your material. Aluminum, brass, and steel all behave differently when cut, and each requires its own approach. Steel and brass tend to make chips better, which means a cleaner cut, but also that you need to clean out chips early and often. Aluminum, on the other hand, can be more “gummy,” and requires that you break chips yourse
lf. (Do this by backing out slightly every 1/4 turn, in addition to the backing out you’re already doing to clear chips).

8) A small tap means a small force. The amount of force you should exert on a tap varies in proportion to the size of the tap. This means that the force applied to tap a 1/4″ thread is at least half that required to tap a 1/2″ thread. Smaller taps break much more easily. For holes smaller than about 3/16″, you really need the kid gloves.

9) Know if your material can “hold” the threads. Plastics and soft metals like aluminum don’t hold fine (UNF) threads very well. Stick to coarse threads (UNC) If you’re going to be using them with steel or brass screws, which can easily strip fine threads in soft material.

10) A vertical hand tapping machine can be a godsend. Every metal shop I’ve ever been in has had at least one of these around. Grizzly sells one for about $80. I’ve also heard them referred to as “Lassy Tappers.”

11) (Just to repeat what Ross said) Use Tapping Fluid!. If you don’t have proper tapping fluid, you can get away with WD-40, or even mineral oil in a pinch. I use RapidTap myself.

More:
See our entire Mechanics skills series

Preat Taping post over at Makezine

Skill Set: The Basics of Tap and Die


Taps and dies are the two tools you use for cutting threads into material around a hole (tap) and for cutting threads into a rod (die) for mating with that hole. The basics of how to do it are quite simple. All you need to know are a few steps and you need a tap and die set. The above video gives you the most rudimentary rundown. Although the tap and die set linked here is from a 2007 Toolmonger review (that we included in one of our old This Week in Tools roundups), it at least gives you a good idea of what to expect in a decent Tap and Die Set.

Oh, and you also need to know what tap and/or die sizes you need for your specific fastening job. You can find tap and die calculators online. Here’s one.

Tip: As one of the commenters on YouTube reminds us, it’s a good practice to “clean the threads” as you tap (or die) by backing out three turns for every three turns you cut forward. This helps insure that you get a good clean cut.

More:
See all of our Mechanics Archives