Unreliable Crimps using generic Ratchet Criper

Every store, electrical supply etc seems to sell the exact same ~$40 ratchet (renamed) crimper (Chinese) for the standard red/blue/yellow terminals. Ours looks in 100% good condition, puts lots of pressure on it. We appear to use high quality crimps yet we have a non-trivial failure rate when we do a moderate test pull just after the crimp. Just can’t trust it for a competition.

It sure looks like a non ratching Channellock 909 does much more reliable crimp.

What is anyone else using ?

Gardner Bender GS-388 as pictured here. It requires a bit of hand strength and finesse to use effectively (I can make solid crimps by clamping with just my hand, but I like to push down on a table to ensure they’re solid).

We also have another type of crimper in our lab, but we tend to use those for screw cutting, if at all. The wire strippers are just passable, and the crimps are very unreliable.

We use a generic crimper with the same bad results. We now solder every crimp afterwards and it is extremely reliable.

If you have to solder your crimp to make it hold, then you’re not doing the crimp right. A proper crimp doesn’t need solder to hold.

our team uses Molex crimps and we have a non ratcheted hand powered tool which seems to never fail, and a ratcheted crimper which makes strong crimps but some times destroys them in the process or jams them inside the slot. For the most part our hand powered crimper has been our go to tool for Molex crimps and Anderson power pull crimps.

Are you using the correct wire size for the particular color crimp you’re using? Has the tool been damaged by attempting to crimp a wire size too large? You may be able to check this (depends on the tool design) by checking that the flat tool faces, adjacent to the actual crimp anvils, are coming completely together at the end of the tool travel.

If the tool is not damaged, the wire size is correct, and the crimp loaded correctly you should get 100% success rate, so it sounds like there is something wrong with your process.


Our team uses a pair of pliers I happened across in my basement.
They are very similar to these: http://www.hyperclaw.com/pic/products/combination-plier-726u-b.jpg

They cutter part is rather dull, which makes work rather well for crimping things.

After too many electrical issues we’ve gone to always using the proper crimping tool for each connector. It’s been a considerable expense, but when your tool lists the pull-out strength for the wire and has a UL listing you can have confidence that at least your wiring won’t let you down. The ratcheting design, by design, eliminates (most) operator error by not opening until the crimp is finished.

A well done crimp doesn’t need solder, and solder may hurt both its electrical performance and durability (it becomes brittle).

For the generic terminal crimps we use Thomas & Betts Stakon connectors with the company crimping tool. I’ve tossed everything else out. We also use tools from Anderson for the Powerpoles (battery connector and 15-45A) and have been using Tyco Series 1 connectors and their excellent tool. This year we’re also trying the Hansen Hobbies tool for pwm connectors, but may go pro for that too. Good tools are a pleasure to use, do a better job, and last a lifetime.

Here’s a great overview of crimping and how to do it well:

Several things can be going wrong. As far as your crimp tool goes, it doesn’t sound like the problem. Problem one: you might not have used the proper sized crimp connection. Be sure to match the connector properly to the gauge of wire. Problem two: you might have purchased poor crimp connectors. It may not seem the case to you, but through many years of experience with crimp tools, it is often a poor brand connector that can cause problems. Before discarding the idea of a ratcheting crimp tool, try using a different brand of connector and see if that solves your problem. Problem three: you might not be placing the connector in the proper section of the tool. Before you crimp, always make sure that the crimp you are making is inside of the proper colored crimp slot. If you dont do this, I can guarantee that your crimps will not hold up to any kind of physical load. I would always recommend using a ratcheting crimp tool. I have had mine for several years and it has seen the production of many robots and it still crimps perfectly. Try to keep using your ratcheting crimper because I don’t think that is causing your problem.

Yes, I see non-trivial failure rates using our ratcheting crimper as well.

They’re bittersweet because with students who’ve never crimped before, you’re more likely to get a good crimp with the ratcheting crimper.

With experienced members, you’re less likely to get a good crimp vs a manual crimper.

Sometimes if a crimp fails a small tug check, I ask students to re-crimp using the next smaller size down. This works sometimes.

Sometimes there simply isn’t enough wire stripped and pushed through the crimp for it to grab.

Rarely, the crimp connector is rotated too much to crimp properly, or the connector was put in backwards.

Even when all things are “perfect” I see too many failures with the ratcheting crimpers.

Personally, I prefer a set of big set of non-ratcheting pliers similar to your Channellock 909s, what slijin above recommended, or something like this:


Is this what you are talking about: http://www.amazon.com/Ratcheting-Terminal-Crimper-Weatherpack-Terminals/dp/B0027K7AS6? We have some that look just like them that we got at Fry’s. It creates incredible crimps, I’ve used all the other tools described here and I never get as nice and strong of crimps as I do from this tool. When we first got it, it didn’t seem to crimp quite enough, so I adjusted the limit, and since then I’ve never had a crimp fail that had the right size wire fully inserted into the correct size terminal.

Usually failures in ratcheting crimpers occur when the terminal is positioned incorrectly in the tool. I know it sounds trivial but these tools are designed to crimp in particular fashion. The tool sold by MCM for instance requires that the terminal be placed in the tool from only one side. Since these tools are commonly designed for right handed installers, the insulated terminal should be placed in the tool so that the open end is is facing to the left hand. The terminal should be placed in the jaws of the tool so that the insulation is centered in the jaws and that the terminal is facing up (parallel to the jaw face). The correctly stripped wire is then placed into the terminal. If the wire is stripped properly, the end of the wire should be visible protruding from the terminal opposite where the wire was inserted. Then operate the tool and you should have a good crimp.
When the wire is not stripped properly or inserted fully, the crimping action will push the wire out the back of the terminal much like squeezing a banana. If the terminal is inserted such that the seam inside the terminal is not facing the jaw, then the terminal will not close properly on wire during the crimping action and will pull out. On many of the tools I have used, the jaws are marked for the color terminal for which the tool is designed. In general, the colored markings are the side of the tool in which to place the open end of the terminal.
Remember yellow terminals are for #10-#12 wire, blue for #14-#16, and red for #18-#22. It is also important to note that many of the ratcheting crimpers also have adjustable crimp force. If your tool has a small indexed wheel on the side with + and - marked on the tool, simply remove the locking device (usually a small screw), rotate toward the next + mark and reinstall the locking device.
Finally, the Thomas and Betts crimper many of us have received in a rookie KOP over the years is designed for uninsulated terminals when using the dimple part of the tool.