1. Home
  2. ⏣ Metalworking Craft
  3. Thread Tapping Newbie Question!

Thread Tapping Newbie Question!

Hi

I have decided to try making my own Dremel precision router base where the Dremel's threaded collar screws into a piece of thick perspex (or wood, depending on what I choose to use).

A bit of googling came up with suggestions that 3/4" 12TPI taps would closest suit the job. So I bought some, in particular these ones:

formatting link

In the description it says "A FULL SET OF TAPS INC 1ST, SECOND AND PLUG (3 TAPS)"

Coudl someone tell me what it means by "1ST, SECOND AND PLUG"? Are they for different purposes, only all three look the same to me!

The other thing is - does anyone know what the ideal drill bit size, in mm, would be for these? I have had a look here:

formatting link

But can't find a 3/4" 12TPI one, but then I am a complete novice to this so make have missed it.

Thanks Bigus

Reply to
Bigus
Loading thread data ...

This group is dead. Try: news:rec.crafts.metalworking

Reply to
Michael A. Terrell

under Series with Uniform (Constant Pitches - 12-UN has a value for 3/4 12-UN.

See if you have a Machinery's Handbook in the library. Or your shop.

First, second and plug - first tap into a hole. It is easiest to cut with. Doesn't cut deep and sets the thread.

The second deepens the thread and finishes the job.

The first two are for sheet / bar / etc. Hole through.

The plug is for a blind hole. Drill a hole part through a block and it is just a well. The plug cuts a thread into the hole but the process is constantly in/out threading - getting out bad metal shards. Then back in. The plug has cutting very close to the end.

The first two have a tapered lead-in and a pointy end to help center.

Hope that sorts out the taps and such.

Mart> Hi

Reply to
Martin Eastburn

Hi Martin

Many thanks for that explanation. This is a "hole-through" application, about 1/2 to 1", so the 1st tap is probably sufficient. The drill bit size is apparently 16.5mm.

Thanks Bigus

Reply to
Bigus

I was pleasantly surprised to visit this group and see actual metalworking posts instead of having wade through a 30-50 total garbage threads per on topic thread over there.

Reply to
Bob La Londe

That's OK, if you're willing to wait months between posts.

Reply to
Michael A. Terrell

I have to confess that I am not metalworking - more like perspex/wood working! I managed to find some great help on a model engineering newsgroup though.

Reply to
Bigus

I never heard of "1ST, SECOND AND PLUG" In the US a set of three taps is Taper, plug, and bottom

The differance is how many threads at the tip are ground to form the cutting edges of the tap.

Taper taps have 5-6 threads lead. ( count the thread from the end of the tap until you get to the first full thread that's not ground off for the starting taper)

Plug taps have 3-4 threads lead.

Bottom taps have 1-2 threads lead.

New are semi-bottom taps with 2-3 threads, used mostly in CNC or tapping machines.

FYI -Never use a taper tap in stainless steel, as stainless is cut it leaves a work hardened surface behind, the next cut on a taper tap is so small it does not get under the hard surface but has to cut through it. tap will dull fast and break.

I'm late on this answer but maybe someone else will find it useful.

Randy

Reply to
randy333

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.