Practical TIG Welding: Sharpening Tungsten and Stick Out
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Sharpening Tungsten and Stick Out
06.36
| 00:00 | - The tungsten is one of the most critical components of TIG welding and as we've already learned, its job is to direct the arc onto our workpiece and when correctly sharpened, it will provide the level of control we need for accurate welds. |
| 00:13 | Given that the tungsten has so much influence over the finished weld, it makes sense that we need to ensure that our tungsten is correctly sharpened at all times. |
| 00:22 | You'll also find that particularly when you're learning, you'll frequently end up inadvertently touching the tungsten into the weld pool which will require your tungsten to then be resharpened. |
| 00:33 | Keeping things clean and contaminant free is important in the sharpening process so having a grinding wheel dedicated to sharpening tungsten and nothing else is a great way to prevent contaminants from being introduced to the tungsten. |
| 00:46 | The tungsten needs to be ground longitudinally which means the grain structure created by the grinder will be in line with its length. |
| 00:53 | What I mean by this is that the tungsten needs to be held pointing at the grinding wheel and then tilted up to the desired angle, not horizontally across the grinding wheel. |
| 01:03 | Getting the angle of the tungsten right by hand can be a tricky process but with practice and believe be you're going to get a lot of it, you'll find it becomes second nature as you gain experience. |
| 01:16 | When you're just getting started, it's going to be hard to judge the angle by eye and we'd suggest using a protractor to mark out your desired tip angle on some paper and then comparing your results to this as a guide. |
| 01:28 | Also don't beat yourself up too much if your angle isn't exactly right, there's enough flexibility here that if your angle is a few degrees off, your weld is still going to be just fine. |
| 01:40 | In the majority of DC welding we do, the desired angle of the tungsten point should range from 30 to 45°. |
| 01:47 | We've added some recommendations around this angle in the material specific section of the course and you can refer to that for more detail, however 30° is a good all round angle for most instances and it's what you'll likely be using in most cases. |
| 02:03 | The same is true for AC welding aluminium but it is common for AC welding to ball up the tungsten tip as we've already learned, although this will be a factor of your AC balance setting. |
| 02:15 | Because of this characteristic, a wider angle such as 45° is acceptable for AC welding. |
| 02:22 | In general, a sharper tungsten angle tends to result in a more narrow, focused arc whereas a wider angle will produce a wider arc that can be better suited to welding thicker material where we want more penetration and a wider weld profile. |
| 02:37 | For this reason, we'd recommend that you experiment with some scrap material and test for yourself to see the effect of changing the tungsten angle. |
| 02:46 | Taking the very end off the point of the tungsten once it's been sharpened will improve the arc shape and this also reduces the chances of the tungsten becoming included in the weld pool. |
| 02:57 | We only need the lightest tough on our bench grinder to remove enough of the sharpened tungsten tip. |
| 03:03 | Around half a mm or 20 thousandths of an inch on a 30° sharpened tungsten is sufficient. |
| 03:09 | It can be common for fabricators to use a linishing wheel or even an angle grinder to sharpen their tungstens and while this is better than nothing, it will be more likely to introduce contaminants into the tungsten from previously ground materials. |
| 03:23 | This is why we strongly recommend investing in a dedicated bench grinding wheel for your tungsten. |
| 03:30 | Given how often you'll find yourself sharpening tungsten, it's also worth doing a few all at the same time so that you can keep a packet of pre sharpened tungsten in your pocket, allowing you to quickly swap them out while you're in your weld position and then you can resharpen between welding sessions. |
| 03:47 | Dedicated tungsten grinders are available from a range of manufacturers which take the guess work out of the process as well as producing a consistent and guaranteed angle every time. |
| 03:58 | They use a diamond wheel and an adjustable angle to cut, grind and flatten tungstens. |
| 04:03 | These are a worthwhile addition to your tool box, however we'd still strongly recommend you become proficient at manually sharpening your tungsten first since you're not always going to have access to a dedicated tungsten grinder in every situation. |
| 04:17 | Once we've got a freshly sharpened tungsten, we can insert it back into the torch and set the stick out length. |
| 04:23 | This is the distance that the tungsten protrudes from the gas cup or nozzle and the only limiting factor to this length is the shielding gas coverage that's required in order to cover the arc and the resulting heat affected zone. |
| 04:37 | This has a direct relation to the size of the cup as we detailed earlier in the gas lens and cups module. |
| 04:44 | The rule of thumb for DC welding is that your stick out length should match your cup diameter. |
| 04:48 | So for example, if you're using a number 10 cup, then you should have a stick out length of 16 mm. |
| 04:56 | We don't require large stick out length for AC welding due to the smaller nozzles and a reduced need for shielding gas flow when working with aluminium. |
| 05:05 | For the majority of AC welding in motorsport, a stick out length of 6 mm or a quarter of an inch, will allow access to most weld joins. |
| 05:13 | Motorsport fabrication can present some pretty interesting welding situations and having a sharpened tungsten at the correct stick out will help with directing the arc where you need it but sometimes this just isn't enough. |
| 05:25 | On face value, you'd probably think that welding around corners isn't possible but actually it is. |
| 05:31 | Tungstens are extremely brittle and can't be bent at room temperature but if we heat the tungsten we can actually put a bend in it to allow us to weld where we wouldn't be able to with a regular straight tungsten. |
| 05:43 | To bend the tungsten, we need to clamp it and heat it up until the bend area is glowing, this heating process also needs to occur under the shield of argon gas. |
| 05:52 | The easiest way to do this is with your TIG torch supplying the heat and shielding the heated area with argon gas. |
| 05:59 | As the tungsten begins to glow, we can keep some pressure on it with a pair of pliers until it starts to bend. |
| 06:05 | Once it does, we can then get the bend we require in the tungsten and let it cool under the cover of argon. |
| 06:13 | Once the bent tungsten is inserted back into the TIG, run a few test welds just to ensure that the argon still adequately shields the arc completely as it'll no longer be in the direct path of the gas flow. |
| 06:26 | Using a bent tungsten can allow you to weld some previously unweldable parts and doing this can come in very handy. |
