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| Open HV Probe 40kV |
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| beanflying:
Funny I watched Dave's video #85 again this morning as it came up in a search. People are worried about PLA and this one is maybe a touch less safe out there for the masses to watch :o I have no qualms about the maker of it being safe after seeing what else he plays with but it lacks for most. I will grab some dope at some stage but opt for an epoxy clear coat over the hot end of the 40kV probe based on that. Also checked and based on your videos there is plenty of diameter for a secondary thin wall PLA/Kapton Taped inner tube for the Resistors and any above ground terminations to sit in the tip barrel (14mm bore but fitted with a 13.5x12.7 wrapped tube). Just reprinting some bits including the handle after increasing the thread pitches on the parts so they screw together without needing any post processing. Shown in the photo is four parts screwed together. Other than removing the Brim (Flashing) from the prints they are as the came off the printer (Ender Pro). |
| vk6zgo:
Back in the day, EHT probes were quite expensive, & the users paid due care & attention to the use and storage of them. For this reason I would trust an old HV probe. (After, of course, checking it thoroughly for physical damage.) Most of the old style ones are made from hard polystyrene, which, if looked after well, maintains its voltage rating over many years. I do remember seeing one probe machined out of solid Perspex, but that was an outlier. Most HV probes were used to look at TV set EHT, which although it has lots of voltage, cannot source enough current to do much harm. Transmitter HT supplies are another kettle of fish, but most full size TV or Radio Broadcast Tx have their own built-in metering for such supplies, so even at such a site, the HV probes didn't get that much use. 3D printed devices are not as homogenous as cast or extruded plastics, but whether that is a problem, or not , I don't know. |
| tautech:
--- Quote from: beanflying on April 22, 2019, 04:24:02 am --- Also checked and based on your videos there is plenty of diameter for a secondary thin wall PLA/Kapton Taped inner tube for the Resistors and any above ground terminations to sit in the tip barrel (14mm bore but fitted with a 13.5x12.7 wrapped tube). --- End quote --- This is key IMHO ^^^ The handle should just be a vessel to enclose the construction of safe innards. If, and only if the printed materials can be proven to be safe against leakage or flash-over may they be used in any insulation capacity. We can never be sure someone with the printer files and a printer won't use an unsuitable filament. :scared: |
| beanflying:
--- Quote from: tautech on April 22, 2019, 05:39:51 am --- --- Quote from: beanflying on April 22, 2019, 04:24:02 am --- Also checked and based on your videos there is plenty of diameter for a secondary thin wall PLA/Kapton Taped inner tube for the Resistors and any above ground terminations to sit in the tip barrel (14mm bore but fitted with a 13.5x12.7 wrapped tube). --- End quote --- This is key IMHO ^^^ The handle should just be a vessel to enclose the construction of safe innards. If, and only if the printed materials can be proven to be safe against leakage or flash-over may they be used in any insulation capacity. We can never be sure someone with the printer files and a printer won't use an unsuitable filament. :scared: --- End quote --- All things are possible you and can now get fairly easily get Conductive PLA https://www.proto-pasta.com/pages/conductive-pla laced with Carbon. Anyone making an electrical safety probe with it would truly deserve their Darwin Award :palm: There is other options out there but Styrene (ABS, HIPS etc) or PLA are clearly the better and easier to use options. With switching to a secondary tube it is in theory possible to remove the metal tip from having direct contact to the outer shell as it could be mounted onto a stronger inner tube without major changes. A flanged end at the rear of the inner sleeve would hold it in place then carry the probe tip forward. It would only need the first two tip sections modding to make this possible. BUT The downside to this is it would allow the possible ingress and entrapment of liquids or dirt between the inner and outer unless maybe a teflon encapsulated o-ring or seal of some sort was added. Adding more parts with finer tolerances and complexity would maybe not increase overall safety. Like replicating all the parts used in Joes probes it pushes the design beyond most or you may find people cutting corners :-// Sample Inner sleeve done and wrapped with Kapton, I will drop the diameter another 0.4mm so a second or third layer can be added easily. New Handle section is on the printer with the PCB mounts and latest revisions. Will be in Clear PLA as I am short of Black at present. |
| 0culus:
Nice work, bean! Reading over the conversation in this thread, I gotta agree with bean that open designs are overall better. Idiots will be idiots, so let's stop wringing our hands over what they might do. If it's not playing with large electrical potentials, it will be high powered fireworks, thermite, binary explosives, dumbass lifted pickups, and more. So, put proper disclaimers with it and if someone does something stupid, it's their own damn fault. I'd far rather have open and accessible designs than none at all. |
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