Tap Drill Sizes

Some explanation:

What kind of tap do I need? As explained in the screw guide, coarse threads are much more common, stronger, less likely to jam during installation (cross thread), and faster to install. So, if you’re deciding between coarse and fine threads for a custom hole, use a coarse thread unless you’re going into sheet metal. If you’re trying to make a hole for an unidentified screw, chances are it’s a coarse thread. Metric coarse threads are in between English coarse and fine threads. Metric fine threads are finer than English fine threads and are rarely used.

50% vs 75% tap drill sizes: 100% engagement of a male and female thread means that both threads are fully formed and fully engaged. 50% means that only half of the thread height is engaged, and is what you’d have if you ground off the top half of a fully formed thread. According to the machinery’s handbook, tests have shown that more than 60% thread engagement provides no significant increase in strength. For thread engagements more than 1.5 diameters deep, 50% is usually sufficient. Most taps drill are sized to drill a slightly larger hole than what a 100% thread could be cut into, typically 75% or 50%. More commonly, holes that will create a 75% thread when tapped are used as a margin of safety, and this is what we sell. The downside with drilling a hole that a 100% thread could be tapped into is that it is much more difficult to tap (deeper cuts into the metal), and therefore much more likely to break a tap. We recommend 75% tapping drills unless deep holes in steel are being made.

Clearance holes: A clearance hole is large enough for the screw to slide through without being turned. Many tapping charts will have two types of clearance drills: tight and loose. We list the tight clearance drills and recommend choosing whatever bit is handy and larger than the major diameter for larger clearances–just make sure the screw head or washer is larger. Note that if several holes are being made, the tight clearances don’t leave much room for misaligned holes.

Coarse Threads – English


tap size
(major dia. – threads / inch)
screw
major dia.
tap drill size
for 75% .dia
tap drill size
for 50% .dia
clearance drill
#0-80 0.060 3/64 (.0469) 55 (.0520) 50 (.0700)
#1-64 0.073 53 (.0595) 1/16 (.0625) 46 (.0810)
#2-56 0.086 50 (.0700) 49 (.0730) 41 (.0960)
#3-48 0.099 47 (.0785) 44 (.0860) 35 (.1100)
#4-40 0.112 43 (.0890) 41 (.0960) 30 (.1285)
#5-40 0.125 38 (.1015) 7/64 (.1094) 29 (.1360)
#6-32 0.138 36 (.1065) 32 (.1160) 25 (.1495)
#8-32 0.164 29 (.1360) 27 (.1440) 16 (.1770)
#10-24 0.190 25 (.1495) 20 (.1610) 7 (.2010)
#12-24 0.216 16 (.1770) 12 (.1890) 1 (.2280)
1/4-20 .2500 7 (.2010) 7/32 (.2188) H (.2660)
5/16-18 .3125 F (.2570) J (.2770) Q (.3320)
3/8-16 .3750 5/16 (.3125) Q (.3320) X (.3970)
7/16-14 .4375 U (.3680) 25/64 (.3906) 15/32 (.4687)
1/2-13 .5000 27/64 (.4219) 29/64 (.4531) 17/32 (.5312)
9/16-12 .5625 31/64 (.4844) 33/64 (.5156) 19/32 (.5938)
5/8-11 .6250 17/32 (.5312) 9/16 (.5625) 21/32 (.6562)
3/4-10 .7500 21/32 (.6562) 11/16 (.6875) 25/32 (.7812)
7/8-9 .8750 49/64 (.7656) 51/64 (.7969) 29/32 (.9062)
1″-8 1.000 7/8 (.8750) 59/64 (.9219) 1-1/32 (1.0313)
1 1/8-7 1.1250 63/64 (.9844) 1-1/32 (1.0313) 1-5/32 (1.1562)



Fine Threads – Metric

tap size major dia.
mm (inch)
tap drill (mm) tap drill
(inch)
clearance (mm) clearance inch (dec.)
M1.6×0.35 1.6 (.0630) 1.25 #55 1.8 #49
M2x0.4 2.0 (.0787) 1.60 #52 2.4 #41
M2.5×0.45 2.5 (.0984) 2.05 #46 2.9 #32
M3x.05 3.0 (.1181) 2.50 #39 3.4 #29
M3.5×0.6 3.5 (.1378) 2.90 #32 3.9 #23
M4x0.7 4.0 (.1575) 3.30 #30 4.5 #16
M5x0.8 5.0 (.1969) 4.20 #19 5.5 7/32
M6x1 6.0 (.2362) 5.0 #8 6.6 G
M8x1 8.0 (.3150) 7.0 J 9.0 T
M10x1.25 10.0 (.3937) 8.8 11/32 12.0 31/64
M12x1.25 12.0 (.4724) 10.8 27/64 14.0 35/64
M14x1.5 14.0 (.5512) 12.5 1/2 16.0 5/8
M16x1.5 16.0 (.6299) 14.5 37/64 18.0 45/64
M18x1.5 18.0 (.7087) 16.5 21/32 20.0 51/64
M20x1.5 20.0 (.7874) 18.5 47/64 22.0 7/8
M22x1.5 22.0 (.8661) 20.5 13/16 25.0 1
M24x2 24.0 (.9449) 22.0 7/8 27.0 1-5/64
M27x2 27.0 (1.0630) 25.0 1 30.0 1-3/16


Fine Threads – English

tap size
(major dia. – threads / inch)
screw
major dia.
tap drill size
for 75% .dia
tap drill size
for 50% .dia
clearance drill
#1-72 0.073 53 (.0595) 52 (.0635) 46 (.0810)
#2-64 0.086 50 (.0700) 48 (.0760) 41 (.0960)
#3-56 0.099 45 (.0820) 43 (.0890) 35 (.1100)
#4-48 0.112 42 (.0935) 40 (.0980) 30 (.1285)
#5-44 0.125 37 (.1040) 35 (.1100) 29 (.1360)
#6-40 0.138 33 (.1130) 31 (.1200) 25 (.1495)
#8-36 0.164 29 (.1360) 26 (.1470) 16 (.1770)
#10-32 0.190 21 (.1590) 18 (.1695) 7 (.2010)
#12-28 0.216 14 (.1820) 10 (.1935) 1 (.2280)
1/4-28 .2500 3 (.2130) 1 (.2280) H (.2660)
5/16-24 .3125 I (.2720) 9/32 (.2812) Q (.3320)
3/8-24 .3750 Q (.3320) S (.3480) X (.3970)
7/16-20 .4375 25/64 (.3906) 13/32 (.4062) 15/32 (.4687)
1/2-20 .5000 29/64 (.4531) 15/32 (.4688) 17/32 (.5312)
9/16-18 .5625 33/64 (.5156) 17/32 (.5312) 19/32 (.5938)
5/8-18 .6250 37/64 (.5781) 19/32 (.5938) 21/32 (.6562)
3/4-16 .7500 11/16 (.6875) 45/64 (.7031) 25/32 (.7812)
7/8-14 .8750 13/16 (.8125) 53/64 (.8281) 29/32 (.9062)
1″-12 1.000 15/16 (.9375) 61/64 (.9531) 1-1/32 (1.0313)
1 1/8-12 1.1250 1-3/64 (1.0469) 1-5/64 (1.0781) 1-5/32 (1.1562)



Coarse Threads – Metric


tap size major dia.
mm (inch)
tap drill (mm) tap drill
(inch)
clearance (mm) clearance inch (dec.)
M8x1.25 8.0 (.3150) 6.8 H 9.0 T
M10x1.5 10.0 (.3937) 8.5 R 12.0 31/64
M12x1.75 12.0 (.4724) 10.2 13/32 14.0 35/64
M14x2 14.0 (.5512) 12.0 15/32 16.0 5/8
M16x2 16.0 (.6299) 14.0 35/64 18.0 45/64
M18x2.5 18.0 (.7087) 15.5 39/64 20.0 51/64
M20x2.5 20.0 (.7874) 17.5 11/16 22.0 7/8
M22x2.5 22.0 (.8661) 19.5 49/64 25.0 1
M24x3 24.0 (.9449) 21.0 53/64 27.0 1-5/64
M27x3 27.0 (1.0630) 24.0 1 15/16 1-3/16

Metal Working

Metal Working

Some basics of working with metal along with demonstrations of useful tools. Corrections and feedback appreciated…

Comments:

Dec 10 2007admin said:

Feedback and corrections are appreciated.

Jan 02 2008anonymous said:

A very infomative video for people getting started. I am a machinist myself and can agree with everything you said for hand drilling and tapping.

Jan 02 2008scott (admin) said:

Thanks. We talked with several machinists to make this, and there was some debate on how often reversing a tap was necessary. Any thoughts? Surely it depends on everything (metal, tap sharpness, cutting fluid, etc), but what do you do in general?

Jan 08 2008anonymous said:

Good videos! I just watched the soldering video before this one, and I have to say I’m very impressed with the accuracy of the information and the quality with which it’s presented.

Jan 11 2008anonymous said:
Hi Great videos mate, a good idea for filing aluminium is to first rub chalk into the teeth of the file, it embeds into the teeth and makes cleaning the file a whole lot easier,( and maybe stops you getting abused if you are using someone elses tools) This is probably the best site I’ve found for soldering advice , well sourced and professionally presented.Thankyou and regards
Gary
Jan 27 2008anonymous said:

Great video! Very useful. Thanks.

May 22 2008anonymous said:

I’m very impressed by your Metal Working video. Looking forward for your next online video’s on this subject!
Question: Do you ship to the Netherlands?

Keep up the good work!

Regards, Bjørn
bkeizer@gmail.com

flag
May 22 2008scott (admin) said:

yep, just follow the instructions on the check page. we can’t ship flux or batteries, though.

Sep 18 2008Daletone (unregistered) said:

You did a great job with this video. I am a machinist and have found everything you described to be very accurate and useful for the basics of drilling a hole.

The video has a lot of information for the beginner, but the beauty of online videos is that you can slow them down and watch them over and over. Keep up the excellent work!

Sep 18 2008scott (admin) said:

Wow, thanks!

Oct 05 2008Paul (unregistered) said:

To echo Daletone’s comments, I have been a machinist for 22 years and I am impressed with your metalworking video. Excellent job. I came here for your soldering information, so I imagine it is of the same quality.

Regarding reversing the tap: This is on the conservative side, especially for Al. But in the home shop environment it definitely pays to be conservative.

Thanks for a great site!

Jul 13 2009kayman (unregistered) said:

good stuff. highly recommended!

Tutorials for KiCad – A Free Open Source Schematic and PCB Layout Editor

NOTE: This tutorial was written in 1847, and kicad has changed a lot since then!

Intro:

kicad tutorial

This set of tutorials will cover some essentials to designing circuits and pcb layouts using kicad (link goes to author’s site + download), an open-source tool for circuit (board) design that’s free and has no restrictions on number of layers or size (like Eagle). We’ll focus more on the unintuitive things as well as tips & tricks rather than re-write the manual.

Contents:

KiCad Overview and Schematic Tutorial

NOTE: This tutorial was written in 1847, and kicad has changed a lot since then!

The main KiCad project window:

The part of KiCad that may not be familiar to users of other CAD software is cvpcb. This assigns pcb footprints to components in the schematic. Unlike Eagle, where component libraries contain both schematic and footprint information, in KiCad the schematic version (symbols) of a component and its physical layout (“module”) are stored in completely different libraries, and must be mapped together with cvpcb. It’d be confusing, but you could map a resistor in the schematic to a capacitor’s footprint.

main kicad screen

The project file (.pro) contains preferences. For instance: component libraries that should be loaded with a project, trace width setting and drawing colors.

The main project window shows documentation files (like pdfs) as well as board and schematic files.

Making a Blinking LED with a 555 Timer:

Drawing the Schematic:

Open eeschema (the schematic editor) and click the tool that adds new parts.

add component in kicad eeschema

Click somewhere in the schematic to open the component selector.

kicad component selector

Now click “By Lib Browser” to see a list of all the libraries, their components and diagram previews. You can also type “*555*” (no quotes) and click “OK”, or type some keywords, like “audio” and click “Search KeyWords”. Not all components will have keywords, however.

kicad library browser

KiCad actually comes with a large set of pdf spec sheets that you can quickly access by clicking the documentation button.

 Click “Export to Schematic” to place the component.

Repeat the procedure to add a resistor, which is located in the “device” library and called “R”. You can also just type “R” in the “component selector” box.

kicad shift select copy

Make 2 copies of the resistor by holding down Shift and dragging a selection box over the resistor.

kicad rotate by pressing R

Now add a LED (also located in the device library), but before clicking to place it, hit “R” to rotate 90 degrees.

555 timer parts

Add a capacitor (C), polarized capacitor (CP) and Pot.

Finally, add power and ground connections by clicking the Add Power (“place the power”) button. add power connections You can also add power or ground connections using the Library Browser and normal Add Parts button–the Add Power button is a shortcut to the Power library.

add power in kicad add power in kicad add power in kicad

Add 9V and GND connectors.

Drawing Wires:

555 timer circuit in kicad

First, arrange the parts by hovering the mouse over them, and typing “M” or “R” to move or rotate.

Then select the Wire Drawing Tool. 

kicad connecting components

Note: you must start and end wires on the pins of components, it’s not enough that a wire visually connects with a component. For instance, if a wire is drawn between R1 and R3, R2 will not be connected.

erasing wires in kicad

Tip: To erase part of a wire, draw back over it.

connecting nets with labels

You can also connect nets and components by applying labels to wires. Just right click on a wire. Labels can be helpful for identifying traces when designing the pcb later on.

Where are the power and ground pins for the 555 chip?

show pins kicad

Clock “Show Pins” to see the hidden power pins.

hidden power pins kicad

Now you can see pin 1 and 8. Because they are marked as being power pins in the component library, KiCad automatically connects these pins to wires that have power pins labeled VCC and GND. Note: If your select a different power pin, say 9V+, the implied connection won’t work. You would have to unhide the hidden power pins and manually connect them.

Annotating Components (numbering… R? –> R1, R2, C1, U1, etc.):

annotating schematics in kicad

You need to number the components before moving on to the pcb layout. Click the Annotate Tool,  set the params, and kicad automatically numbers all the components.

annotating schematics in kicadannotating schematics in kicad

Adding values to components (10k, .01uF, etc.):

Just double click on the component to change its value.

 

 

<-Back                                                                                       Next->

Going from Schematic to PCB Layout in KiCad (using Cvpcb)

NOTE: This tutorial was written in 1847, and kicad has changed a lot since then!

This section will explain the process of going from the schematic to pcb layout in KiCad. The process is a little bit more involved than in Eagle, and requires 4 steps:

  • First, make sure all components are annotated (numbered).
  • Generate a netlist that contains all the components and their connections.
  • Use cvpcb to assign pcb footprints to all the components (not necessary if new components have not been added.)
  • Load the netlist in pcbnew.

Netlist Generation:

generating a netlist in kicad

Assuming your schematic is already annotated (numbered), click the “Netlist Generation” button.

generating a netlist in kicad

Just click the “Netlist” button unless you want to generate one for a different layout program or circuit simulator.


Assigning PCB Footprints to Components using Cvpcb:

run cvpcb in kicad

Now run Cvpcb.

cvpcb in kicadfiltered component list in cvpcb

Click the filter button to only show capacitor footprints.

assigning a module or footprint to a component

Double click on the footprint (module) to assign it to the schematic component.

Inspecting Footprints:

 previewing modules in kicad's cvpcb

We’d like to use a cylindrical upright electrolytic cap for C2, but clicking the preview button reveals that none of the choices in the filtered list look right.

After clicking “display footprints list documentation”, we can look through all of the built-in footprints and pick a better choice. Turn off the filtered list and choose C1V8.

Continue mapping the components, and then click Save to store the mappings in the netlist.

But wait, if it’s saving with the same name (.net) that was used when eeschema made a netlist, won’t it overwrite the original file?

When either eeschema or cvpcb saves a netlist, it doesn’t overwrite a pre-existing netlist, but rather adds or changes info inside one.

before and after cvpcb saves a netlist

The above picture shows the netlist (.net) file before and after cvpcb maps the modules. There are “noname” placeholders that get filled in by footprints after cvpcb runs.


Loading components in Pcbnew:

run pcbnew to begin making the pcb layout

Now that modules have been assigned to the components, run Pcbnew to begin designing the circuit board.

read netlist in pcbnew

First, click the “read netlist” button.

click the read net list button to load components

Click the read netlist button to load components.

You’ll do this same procedure when you make changes to the schematic:

  • annotate
  • write netlist (from eeschema)
  • run cvpcb (if new components were added)
  • read netlist (from pcbnew)

It’s a little tedious, that’s how the system works (to the best of my knowledge–add a comment if wrong!)

 

Some of the options when reading in a netlist can be dangerous. I’d recommend backing up your .brd layout file before reading from any netlists, as there’s no undo in pcbnew yet.

Say, for instance, you’ve added screw holes that aren’t in your schematic or netlist. If you check “Remove Extra Footprints” it will delete those screw holes when you read in the new list.

 

components loaded into pcbnew from netlist all on top of each other

 

 

<-Back                                                                                       Next->

Designing PCBs in Kicad and PcbNew:

NOTE: This tutorial was written in 1847, and kicad has changed a lot since then!

Contents:

Arrange Components:

Grid First!

adjust the grid size in kicad adjust the grid size in kicad

You’ll probably want to adjust the grid size before moving anything. The pull down contains the user grid size as well as several sizes listed in mils (thousandths of an inch).

Group Move:

move a group of components by selecting

When you first read a net-list, all the components will come in on top of each other.

Start off by moving the whole pile of components by drawing a selection rectangle around them and then click in the middle of the sheet.

Auto Un-Piling

turn on auto-move moderight click and select move all to unpile the components

Pcbnew will automatically unpile the components. First, enable the automatic mover by clicking the “Mode Module” button in the top toolbar. Then right click and select “Move All Modules”. Pcbnew also has an “auto placer,” which is different in that it tries to minimize the length of the connections between the modules (the ratsnest). You can fix components to prevent them from being moved by either command.

General Moving and Rotating–use keyboard shortcuts:

move components by pressing m or r

Continue moving components around by hovering the mouse pointer over them, and then pressing “m” or “r” to move or rotate.

Rats Nest (show rubber bands where all connections should be):

show the rats nest

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Designing PCBs in Kicad and PcbNew: Drawing the Board Outline

NOTE: This tutorial was written in 1847, and kicad has changed a lot since then!

Drawing the Board Outline:

edges.gif

drawing a board outline with the polyline tool

First select the edges layer, and then draw an outline using the line tool. Double click to finish the poly-line.

Tip: Drawing set lengths and measuring:

measure by hitting space bar to zero the relative position readout.

Hit space bar at the start of a line to zero out the relative coordinates at the bottom of the screen. The coordinates will then measure from that point.

 

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About

CuriousInventor launched in late 2006 (pre-arduino era!) as a place to enable hobbyists, students, and musicians to create their own technology. We sold open-source kits and tools, and offered numerous guides & videos on things like soldering, metal working, screws, electronics, and more. 

The store is now mostly empty, but we’ve kept the product pages and guides up since they have useful information. Many of our guides and videos still rank on the first page of google searches and have been seen millions of times. Content on this site and the CuriousInventor YouTube channel produced by Scott Driscoll.

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