Make a Good Dupont Pin-Crimp EVERY TIME!

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Introduction: Make a Good Dupont Pin-Crimp EVERY TIME!

About: Electrical Engineer by training; Electronics Nerd before it was fashionable.

Anyone working with an Arduino, Raspberry PI, Beagle Bone, or any other multi-circuit-board project has become familiar with .025 X .025 in, square post pins and their mating connectors. The male pins are usually mounted to the circuit board with board to board wiring accomplished through mating connectors and wiring. These connectors usually consist of female pins that are individually crimped onto the wires which are then then inserted into multi-position connector shells.

These connector pins, also commonly called “Dupont Pins,” and are manufactured by AMP, Tyco, Molex, Samtec and a myriad of others.

Crimping Dupont female pins onto a wire requires a special crimping tool, precise techniques, and lots of time and patience! When I first started home-crimping these pins, I found that only about 1 in 10 came out right, with the rest defective in one way or another.

Thankfully, a few soles before me posted documentation, a few Instructables, and some YouTube videos that helped me get a started. Even at that, it took lots of trial and error and many crushed, damaged and unusable pins before I was able to get my failure rate under control.

Over time I studied my problems and came up with this guide and document to share some common crimp problems and solutions. In particular, you will see a very simple “Pin-Guide Tool” that you can make that will precisely position and hold the female Dupont pin inside of your hand crimping tool throughout the whole process. By using this Pin-Guide and a few other basic ideas, you too I can get a good crimp every time!

Step 1: Tools and Parts Needed

Above you can see the items you will need. Although not shown, a good wire stripper is also required. Take care in selecting and using the stripper as you will see soon, consistent strip length, free of nicks, is crucial to good Dupont pin crimp results.

Step 2: What Goes Wrong?

I studied my many failed crimps in an effort to figure out what was going wrong. I came up with the DEFECT TABLE shown above. This table helped me determine the root cause(s) for each defect which in turn, led me towards solutions.

While I don’t claim this list to be a 100% comprehensive, it does represent a good summary of my most common reoccurring problems.

Step 3: Wire Strip Length

The figure above shows the anatomy of a Dupont pin.It is seen that the total length of wire going into the pin should not exceed .2 in (5.0 mm). This means that when the wire is correctly and precisely positioned in the pin, the optimum wire-strip length is only 0.10 in (2.5 mm). A shorter strip length will compromise the conductor crimp while a longer strip length will either cause the wire to penetrate into the pin too deeply or lead to a degraded insulation crimp. For these reasons, I conclude that strip length is critical to achieving a good Dupont pin crimp.

  • While I’m sure there are precision wire strip tools out there, I don’t have one. Therefore, I check each strip length and carefully trim away any excess wire whenever my stripped length is too long.
  • As a reminder, take great care not to nick any of the conductors during the strip process as this will compromise the quality of the finished connection.

Tip: I found that recycled stranded-wire Ethernet cable is a good source for the interconnect wire.

Step 4: Pin Positioning Inside the Crimp-Tool

Improper pin-positioning within the crimp-tool tool was also a major reason for many of my crimp defects.

Perhaps I am just ‘all thumbs’, but once I thought I found the best spot to place the pin inside the crimper, I rarely seemed able to get it there. Furthermore, even when my pin placement was perfect, I frequently found that the pin would be pushed out of position or even rotated as a by-product of inserting the wire into the pin.

To solve this problem, I came up with a “PIN-GUIDE” tool. The Pin-Guide tool is nothing more than a strip of male pins onto to which the female pin to be crimped is placed. While simple, this Pin-Guide provides many benefits.

  1. The Pin-Guide provides a ‘handle’ for the pin so that placement into the crimper jaws is easier.
  2. The Pin-Guide precisely sets the position and depth of the pin relative to the crimper jaws. This serves to locate the CONDUCTOR-CRIMP zone and INSULATION-CRIMP zone in exactly the right spots within the crimp dies.
  3. Since the Pin-Guide ‘stays in place’ during the crimp cycle. it prevents the female pin from twisting, sliding, or moving while inserting the wire or performing the actual crimp cycle.
  4. The Pin-Guide also provides a ‘wire-stop’ that keeps the wire from going too far into the center of the female pin and obstructing the Mating-Pin Zone. Note that this fault only revealed when you find that you can’t plug the finished connector assembly onto the male PCB pins!

The Pin-Guide is easily fabricated from a 4-pin strip of male pins. The key to success however, is precisely setting the pin depth.

Step 5: Making the Pin-Guide

It’s easy to use the Pin-Guide. Just cut the female Dupont pin from the carrier and place it onto the Pin-Guide.

Step 6: Loading the Pin-Guide

Step 7: Selecting a Crimp Port

The SN28-B crimp tool has three different crimp-ports. Each port has a slightly different die shape and will form the pin differently. As noted in the figure, I found that I get the best results using “port 1” with wire up to and including AWG 22 Ga; I do not get good crimps with 22 Ga wire in position 2. Your results may vary however, as each crimp tool is adjustable; your setup maybe different than mine.

While the tool markings implies larger gauge wire may be used, I suspect that anything much larger than 22 Ga may not fit into the 0.1 inch spaced shells used for most Dupont pin connector assemblies.

Step 8: Loading the Dupont Pin Using the Pin-Guide Tool

As shown, with the female Dupont pin on PIN-GUIDE post #2, place the pin into the crimper jaws and close the jaws until they “click” and the pin is held in place. Be sure the pin is properly oriented and take care NOT to over compress the pin at this time as that will make wire insertion more difficult.

Step 9: Loading the Wire & Completing the Crimp

Next, carefully insert the stripped wire into the pin. As shown, be sure the wire is fully inserted and is not ‘hung-up’ during placement. While holding the wire in place, compress the crimper-handles to complete the crimp. Release and remove the completed crimp and perform a QC inspection.

After each crimp, it is important to perform a VISUAL INSPECTION as well as a QC PULL TEST of the pin-wire combination. A few examples follows that show you what to look for. Since the pins are small, I recommend you use a magnifying lens for all visual QC checks.

Step 10: Inspecting Your Work: Example A

Step 11: Inspecting Your Work: Example B

Step 12: Inspecting Your Work: Example C

Step 13: Loading Connector Shells

When the crimped pins are completed, they are easily inserted into the connector shells as shown. Pay attention to the photo details as pin orientation is important. Note that the pins will only lock-into the shell when inserted with the proper orientation.

Step 14: Summary of Pin-Crimp Steps

Step 15: Troubleshooting

As another aid to diagnose and trouble shoot common crimping issues, I offer the expanded trouble shooting table above.


CLOSING COMMENTS

This Instructable aims at helping you get solid, consistent Dupont pin termination results. I have focused on female-pins but similar steps can be applied to help you achieve good results for male-pins as well. I invite you all to review and tweak these ideas as you see fit to get them to work well for you.

Take care and Happy-Crimping!

1 Person Made This Project!

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63 Comments

0
BeeE2
BeeE2

Tip 10 months ago

This works mostly by chance and because of the specific set of tools the author has. My SN-28B for example has the dies right side up - the ones in the tutorial are backwards from every crimper I've ever bought or used.

SN-28B is also not the right tool for the job. I'll say it again in caps. SN-28B IS NOT THE RIGHT TOOL FOR DUPONT M20-style TERMINALS.

The dies aren't sized to the right depth for Dupont pins. When you have the correct tool, you don't need awkward guide posts and if you seat the pin properly, you'll always get a perfect crimp. SN-28B will never make the perfect crimp - not even remotely close. Die is the wrong size and also not suitable for pins with triangular tabs that must be rolled offset from one another. The correct tool will create a ROUND barrel-shaped crimp on the wire insulation. Compare a professionally crimped terminal to the mangled ones that come out of SN-28B.

What you get when you crimp with SN-28B or even SN-01B used for JST, is a malformed insulation crimp that will make it difficult or sometimes impossible to insert the terminal into its housing. YMMV, but in general you might as well solder the wire to the connector and bend the crimp with small pliers - you'll have better results.

Yeah, this goes against the info presented here, but find another tool and you'll save a lot of heartache and headache.

See here for another source to back me up: http://www.mattmillman.com/info/crimpconnectors/du...

I can challenge any reader to make 3 decent crimps in a row with SN-28B or SN-01B that fit directly into the housing without effort. You'll spend 5 seconds making the crimps and 30-40 minutes trying to fit the terminals into housings.

0
ee_eng
ee_eng

Reply 2 months ago

Thanks very much for your comment. I agree with BeeE2 that the correct tool for the correct pin gets the best results. To that end, if you are buying pins from BERG, get a crimp tool from BERG. If you get your pins from AMP, get an authentic AMP crimper. If you get your pins from MOLEX, get an authentic MOLEX crimper. Note, however, that authentic crimpers from brand-name connector companies are high quality, precision tools and are so priced. It is not uncommon to see these high quality crimpers cost $200 to $500 each. A good investment for commercial applications, a little pricy for DIY builders.

If you are sourcing your pins made by ???? from eBay for example, you'll be hard pressed (no pun intended) to find the exactly correct tool. SO, crimpers like the 'generic" SN28B or any other 3rd party low-cost crimpers are generally less precise, not highly tuned to a particular pin, and therefore are a sub-perfect solution really only applicable to the DIY or home builder with more time than money.

The suggestions I made just shows the importance of correct wire prep and what a good crimp should look-like. I also tried to share some techniques that I use that might help other low cost tool owners get the best terminations with the low cost tools they have in-hand.

Happy Crimping!

0
TerribleTadpole
TerribleTadpole

Reply 6 months ago

While I agree that even with the instructions above getting a good crimp is still difficult and getting the pin into the housing is wretched difficult, your long post about the problems was completely unhelpful! You didn't give one single suggestion for a good crimping tool.

Reading the link you provided and hunting for some of the tools mentioned shows that the good options cost from many hundreds of dollars to thousands. Far out of the reach of the hobbyist.

So unless Matt Millman can provide more detail on getting a better result with a hammer, I think that this article is the best I've found for getting a result using an affordable toolset.

0
yojoe1103
yojoe1103

Question 2 months ago

I'm able to get as far as creating a solid connection into which I can snugly seat the male pin, but once I load the connector shell it, male pins aren't able to fully seat. Any ideas?

0
ee_eng
ee_eng

Reply 2 months ago

If I understand your problem correctly, you can achieve what appears to be a solid crimp and can successfully load the crimped FEMALE "pins" into the plastic shell but then, when you try to mate the connection to a MALE pins (typically mounted to a PCB board) the connector shell does not fully seat onto the MALE pins. If this is correct, it is usually due to one of the following two issues,
1) The FEMALE pin has been compressed, bent, or otherwise damaged during the crimp process. Compare an uncrimped pin with one of your crimped wires and be sure that the square opening of the end of the pin is intact and not damaged at all. Use care to be sure that the pin is properly inserted in the crimper and does not become camaged during crimping.
2) When I have had pins that just wouldn't fully insert onto a MALE pin, it was usually caused by the stripped portion of the wire I had just crimped was TOO LONG -OR- I loaded ted the wire TOO deeply into the pin prior to the crimp action therefore, the stripped wire protrudes into the prin TOO FAR and it blocks the the MALE pin from fully seating. Leaving the Pin-Guide inside the FEMALE pin during wire loading usually prevents excessive wire penetration problems..
3) Lastly, be sure that the MALE pin on your PCB is not TOO LONG. Is the pins are too long, the connector will not appear to be fully seated when indeed it really is. Slip an UNCRIMPED FEMALE pin onto your PCB connector and you can readily see how "deep" an uncrimped, undamaged FEMALE pin will sit onto your MALE connector pins.

Hope this helps! Gook Luck!

0
yojoe1103
yojoe1103

Reply 2 months ago

Your understanding is correct - though with the note that when I test the connection WITHOUT the shell, it seats perfectly as expected. It's almost as if the force of the male pin pushing in shoves the crimped pin back out of the shell. Not so much that it doesn't catch on the clip and hold, but enough that there isn't enough friction between the pin and its shell to allow me to fully insert a male pin.

0
ee_eng
ee_eng

Reply 2 months ago

If the pin is being pushed out of the shell, the pin is either not fully inserted into the shell (it hasn't locked into place) -OR- the FEMALE pin is UPSIDE DOWN in the shell. I frequently find that I have to take a very small screw driver or 'pick-like-tool' to push on the pin from the wire side to get the pin fully inserted and 'clicked into place". Also, note that there is only one orientation in which the pin will lock into place. When properly seated, you should be able to tug on the wire and the pin will not come free of the shell -- It is more than a friction fit. If the wire pulls out of the shell, the pin is not oriented properly or not fully inserted and locks in place.

It is also possible that the shell could be damaged. There should be a little flexible rectangle tab of plastic that actually engages with the pin as it locks it in place. If this is missing (ie: broken out) or 'bent-outward' the pin won't lock-in/stay-in the shell.

Hope this helps.

0
davidmrosner
davidmrosner

3 months ago

After spending lots of money on many crimpers, wire, etc. and with the help of this and other articles i've found a few things that might be helpful to share:

- each connector from each manufacturer is different enough where one thing that works for one doesn't work for another.

- if you really must get it to work you might just have to pay for the actual crimper from the connector manufacturer that goes with the connector's pins

- this article has a good crimper it recommends - but it doesn't always work for all pins. You can also try the Hozan P-707 which is more expensive but allows you to fine tune the conductor and the insulator crimps individually

- WIRE MATTERS (in some cases) - if you are getting your connectors from one of the reputable manufacturers (Molex, JST, etc.) and not some chinese knockoff then read the spec and see what the insulator diameter of the wire needs to be - then check your wire specs and make sure your wire isn't too fat (in my case 22g wire can vary greatly depending on where you get it)

- While your mileage may vary i believe most connectors that require crimped pins only work well with stranded wire.

- if you are going to do a lot of these get yourself a jewelers eye piece or some kind of magnifying device.

Good luck!

0
Taerzik
Taerzik

10 months ago

Thanks for giving us a thorough guide.

Only change was that it was necessary to start the insulation crimps manually with a pair of craft pliers since the wire was a bit small for them and wouldn't hold in place.

The big win was using the male pin strip to hold the female pin.

0
ee_eng
ee_eng

Reply 10 months ago

Glad you found the info helpful...Happy Crimping!

0
OliverB34
OliverB34

1 year ago

This tutorial is great for female pins but the male pins do not seat as well on the stop. A close up photo would be nice to show which side of the pin goes in wich way.

0
summitt.dweller
summitt.dweller

Reply 1 year ago

I'm thinking 3d printing an attachment for the pin-guide to make it easier to handle. Seems like it might be easy to create a similar male connector guide using a female connector (or block of four) with a 3d printed sheath to position it correctly. I'm wondering if anyone has already designed something of the sort?

0
summitt.dweller
summitt.dweller

1 year ago

After nearly 20 failures, male and female, I was ready to give up, then I found this lesson. You saved me (from throwing my crimper kit in the trash). Thank you. Following this guide, my new record is 1 failure vs. 12 successful connections.

0
jacklunn
jacklunn

2 years ago

Thank you for taking the time to put this together. This is the best tutorial on Dupont Crimping i've found. It's helped me immensely.

0
ee_eng
ee_eng

Reply 2 years ago

Thanks for your comment; glad this helped you! Take care.

0
trentbrown
trentbrown

2 years ago on Introduction

Thank you Sir, Though a tedious process, its worth the effort to follow it exactly. I've followed other instructables for making dupont connections, so far this is the only one that works with any degree of quality every time.

thanks again!

0
aabbcc1
aabbcc1

3 years ago

I had to create an account, just so I could log in and post a comment on this. Thank you for this intuitive guide on making dupont connectors, and sharing your idea with the pin guide. I was about to throw in the towel on trying to make good connectors. Your guide got me going in the right direction! This is one of the best documented instructable I've ever come across. Thanks for taking the time to put this together!

0
JamesG401
JamesG401

3 years ago

This is one of the best and most organized and detailed sets of instructions that I have ever seen on any topic. Thank you! I have struggled to make good connections using Dupont connectors - this answers every question I’ve had, and throws in a handy guide tool as well. Great job!

0
ee_eng
ee_eng

Reply 3 years ago

Great! Glad you found it helpful.