project: lowering flowrates for dual shield flux core
Posted: Sun Aug 25, 2019 8:59 pm
So ever since I learned about dual shield flux core, I had this nagging suspicion. The larger flowrates "required" by some literature might be due (in part) due to the very long CTWD necessitated by the DSFC process. With 0.045" E71T-1C/1M, the process needs about ¾ - 1" of "stickout" from the tip, so I could definitely understand needing upwards of 40+ CFH to make sure the shielding gas covers the spread considering that most MIG guns either have the contact tip flush or just slightly recessed; so the nozzle orifice itself is anywhere from 1" to perhaps 13/16" away if it happens to have a recessed tip. So I thought, what if the nozzle was simply longer, to the point where the nozzle orifice was approximately 3/8" away from the weld joint, similar to what on would use with short-circuit MIG with typical wire diameters? Would it still "work"? I'm only a hobbyist, so "work" has a looser definition for me than a professional, so what they heck, try it out.
So I got bought some extra nozzles, chucked them up in the lathe sliced them up to make a predetermined nozzle length (in order to "bury" the contact tip with a huge recess) and cobbled together a longer frankenstein nozzle to try out.
Here you can see my standard nozzle (the nickel-plated copper one), and the new mega nozzle. 82.2mm vs 92.5mm. With this setup, I only need 3/8" - 7/16" stand-off distance from the nozzle to the work. First try with only 27CFM of C25 worked great. Close enough to really cut down the shielding gas use, but far enough that it doesn't obstruct the view.
![Image](https://drive.google.com/uc?export=view&id=177QTude5XgZIwsqG-zEPyi9-LFsnEVsq)
I basically took a cylindrical nozzle, and took off a length, and attached the top of standard conical nozzle so as to have them meet on the flat part and not the taper, and just spot welded it all the way around. Didn't use any filler or anything, just autogenous tacks all the way around. It just needed to not fall off.
![Image](https://drive.google.com/uc?export=view&id=1796qwsaxva_MYoiXzAP7RuCH_-vGk5zI)
Other than the nozzle getting hotter because it is closer to the arc, worked out great for me. I guess if I feel really ambitious I could add water-cooling to the nozzle to wick-out the heat, but that will be a project for another day.
So I got bought some extra nozzles, chucked them up in the lathe sliced them up to make a predetermined nozzle length (in order to "bury" the contact tip with a huge recess) and cobbled together a longer frankenstein nozzle to try out.
Here you can see my standard nozzle (the nickel-plated copper one), and the new mega nozzle. 82.2mm vs 92.5mm. With this setup, I only need 3/8" - 7/16" stand-off distance from the nozzle to the work. First try with only 27CFM of C25 worked great. Close enough to really cut down the shielding gas use, but far enough that it doesn't obstruct the view.
I basically took a cylindrical nozzle, and took off a length, and attached the top of standard conical nozzle so as to have them meet on the flat part and not the taper, and just spot welded it all the way around. Didn't use any filler or anything, just autogenous tacks all the way around. It just needed to not fall off.
Other than the nozzle getting hotter because it is closer to the arc, worked out great for me. I guess if I feel really ambitious I could add water-cooling to the nozzle to wick-out the heat, but that will be a project for another day.