Tap Technical:
Below is everything you need to know technically when tapping! Below is Tap Drill Size Recommendations, Tapping Speeds and Feeds, Synchro Tapping Info as well as ANSI & DIN Tap Dimensions.
Tap Drill Size:
Below is a link to our tap drill sizes recommended for each tap but there is an easy way to figure it out on your own using the Formulas Below:
Cut Tap:
Tap Diameter - Tap Pitch = Tap Drill Size
Example 1: 1/4-20 Tap
.250" Tap Diameter - .050" Tap Pitch (1/20=.050") = .200" Tap Drill Diameter
Example 2: M6x1.0 Tap
6mm Tap Diameter - 1mm Tap Pitch = 5mm (.1969") Tap Drill Diameter
Form Tap:
Tap Diameter - (Tap Pitch Divided by 2) = Tap Drill Size
Example 1: 1/4-20 Tap
.250" Tap Diameter - .025" ((1/20=.050" Tap Pitch)/2=.025")) = .225" Tap Drill Diameter
Example 2: M6x1.0 Tap
6mm Tap Diameter - 0.5mm (1mm Tap Pitch / 2 = 0.5mm) = 5.5mm (.2165") Tap Drill Diameter
Click Here for Tap Drill Sizes for All Inch/Metric Cut & Form Taps Based on % of Thread
Click here for a Standard Tap Drill Size Chart (UN, Metric, Pipe & STI)
Tap Speeds/Feeds:
Below are starting speeds for a Cut Taps in SFM as well as a conversion table for UN Taps. To figure out RPM use the Formula:
RPM=(3.82*SFM)/Diameter
For Example on a 1/4"-20 Tap in 304 Stainless at 25 SFM:
(3.82 * 25 SFM) / .25 Tap Diameter = 382 RPM.
The Feed Rate is the Tap Pitch so for 1/4-20 it is .050" IPR (1 / 20 Tap Pitch = .050"). To figure out IPM use the Formula RPM*IPR=IPM
Example: 382 RPM * .050" IPR = 19.1 IPM
Here are Starting Speeds and Feeds for a Cut Tap. For a Form Tap you want to run it at 50% to 100% Faster SFM than a Cut Tap. For Example on a 1/4-20 Tap in 304 Stainless a Cut Tap is Listed at 25 SFM, you want to run a Form Tap at 37-50 SFM:
Tap Speed/Feed PDF (Includes Form Taps)
Synchro Tap Speeds Feeds
Are you tapping a lot of holes and looking to cut Cycle Time or Improve Tap Life a Synchro Tap is the way to go! A Synchro Tap has:
- A H7 Shank for better Runout compared to a H9 Shank of other taps
- More Back Relief to Lower Tool Pressure
- Better Chip Control (won't wrap around the tap)
- A Powerdered Metal Substrate for better wear resistance and toughness
- A Hard PVD Coating to improve tap life
This is available in Spiral Flute and Spiral Point Cut Taps as well as Form Taps with more Lobes to reduce Tool Pressure. You can run these in a standard holder and these will improve tap life. If you also use a Synchro Tap Holder that gives better runout and Axial Compensation then you can run it much faster:
Synchro Tap Catalog
Tap Dimensions
Below is a link to the standard tap dimensions all our ANSI and DIN Taps are manufactured to. Most Taps will be ANSI, which is on page 1. But if you need longer Reach then a DIN Tap is a little longer and will give you clearance in deeper holes, this is on page 2 of the pdf below. Anything longer than that will fall into 4" or 6" Extension Tap.
Tap Dimensions (ANSI & DIN)
