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| Crimpers for automotive |
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| Siwastaja:
--- Quote from: nctnico on March 13, 2024, 11:09:26 pm ---You missed the point where ratched crimpers have eccentric pivot mechanisms so you can build up the required pressure manually without needing a pump action tool (like a hydraulic crimper) to amplify the force from you hands. Just take a good look at a professional ratched crimper and you'll see that for each 'click' the jaws close less while the (angular) movement of the handles for each 'click' stays the same. --- End quote --- What makes you think I missed this? This is exactly why I mentioned that non-ratchet tools are significantly larger and more inconvenient to carry around and use: the handle length has to be dimensioned for the peak pressure, and then the total movement range must be larger because unlike the ratcheting version you described, die movement is linear to handle movement, so for anything larger you need two hands. But inconvenience and not working at all are two separate things. From photos alone, I can't say if Engineer tools are good or not. But they are primarily for very small crimps so I have no reason to doubt their usefulness. We already saw that your calculation of 100kg of force was off by a factor of approximately ten. Sure, even with 10kg they are not convenient, but this amount of force is not impossible to produce, and if you mostly use them for smaller connectors than what you used for this calculation, I don't see a problem. |
| Berni:
Non ratcheting crimpers are fine on some kinds of connectors. IWISS brand tools from AliExpress are a very good deal for what you get for the price: https://www.aliexpress.com/item/1005002766345160.html The ratio between the crimp tool and handle is large enough to produce plenty of force to properly crimp the smaller wire gauge crimp pins. These simpler tools are cheap and since you crimp wire and insulation separately they are very flexible in what they can crimp. So 2 different sizes of these will crimp just about anything, from tiny 1mm JST to big automotive connectors. For the larger gauge wires >1mm2 the force requires starts getting pretty high so for those you really want to squeeze down as hard as you can both hands to make sure it is a good crimp. You can pick up 2 crimpers for 50 bucks easy and you are set. Only get fancier ones if you do a lot of crimping. And yes i do pull test the connectors by grabbing it with pliers and pulling hard (before even crimping insulation), it takes an unreasonable amount of force to separate them, at what point the wire itself breaks or the connector pin rips apart. For large gauge wires, i don't have enough physical strength to reach the failure point by just pulling it with my arms. So my advice is <1mm2, use regular pliers like crimpers. For wires <8mm2 you want to use racheting crimpers to avoid having to whale on the handle like a gorilla. For things bigger than 8mm2 use hydraulic crimpers. The big long handle mechanical crimpers for large gauge wires are crap (they don't make good crimps and it is a workout using them with how much force is needed) If you need hydraulic crimpers for some big wires the chinese can get you one for like 100 bucks, i have a set and it handles 75mm2 wire just fine. |
| tooki:
--- Quote from: nctnico on March 08, 2024, 07:27:59 pm ---So no, I'm not mixing anything up. Just take a ratcheting crimper and notice how the amount of travel of the jaws is reduced for each 'click' the jaws close further but the travel distance for the handle stays more or less constant. There is also a typical difference between the cheap Chinese crimpers and the professional ones. The professional ones typically have a much more sturdy construction (more steel plates in parallel or thick solid steel) compared to the cheap crimpers. --- End quote --- You’re still confounding things. Yes, nearly all ratcheting crimp tools use more complex mechanisms to give a large mechanical advantage. But a crimp tool with complex mechanisms for large mechanical advantage can be made without a ratchet. There are crimp tools like that. Ratcheting does one thing, and one thing alone: it ensures you don’t release before a full cycle has been completed. No more. No less. If, as is the case in many cheap Chinese crimpers, a full cycle doesn’t produce the right force or the correct dimensions, the crimp will still fail. |
| tooki:
--- Quote from: shabaz on March 10, 2024, 07:50:05 pm ---A pull test will confirm the huge difference between a non-ratchet crimp result, and one done with a ratcheting crimper. You can do that test using a tool that looks like a luggage weighing hanging device, but one that stores the value. After seeing the difference, you won't ever want to go back to non-ratchet (apart from non-critical use like prototypes for lab use). For automotive, I'd be really unhappy to know if the engineer used a non-ratchet crimper. --- End quote --- While nearly all good crimp tools have a ratchet, so do many cheap ones whose crimps fail. The ratchet only ensures a full cycle has been completed. The rest of the tool design is what actually determines the quality of the crimp. (If you were to take a good tool and remove the ratchet, it would continue to make good crimps, as long as the user always squeezes all the way.) |
| tooki:
As for whether a crimp creates a cold weld, or is simply gastight: I think it depends on the type of crimp. Indent crimping (as used in military and aviation/aerospace connectors, among other things) are definitely supposed to produce a cold weld. On the other hand, insulated terminal crimps (the ones where you crimp the plastic collar), I don’t think those ever produce a cold weld. Gastight if you’re lucky. (Actually luck has nothing to do with it: like all crimps, success hinges on using the correct match of terminal, wire, and tool.) |
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