Soldering Question after a recent catastrophe.  - Page 1
Forum section: electronics / projects

author: davelectronic
author_rank: Frequent Contributor
timestamp: May 04, 2021, 12:51:39 am
content: I have been trying to put together an airbrush compressor for a while now, its been over 20 years since i first discovered this type of art medium. So a few might have seen what I've been trying to achieve in previous threads and posts. I purchased a retail silent compressor, but it wasn't so silent, not enough so for apartment indoor use. Then i purchase a pair of identical refrigeration compressors to replace the oil less compressor and motor it came with. Things where going quite well, but i decided it was to heavy to move around with just the feet it had on it 30Kg total weight. Purchasing some suitable caster wheels, i removed the feet, and added the wheels. What i hadn't anticipated is it was slightly top heavy having a vertical air receiver. From adding the wheels, i moved it, and it toppled over smashing both refrigeration junction boxes on the back of each unit.Since then i bought a couple of boxes to try and mount these boxes in place of the smashed junction boxes. But it hasn't gone that well lining up each box to be secure to each compressors steel fixing stand off's. So now i'm somewhere on plan C or D, the latest idea is to mount the control starters off the main compressors housing ( except the thermal protector which will be on the compressors casing ) My question is, can i solder on the 3 pins that terminate out of the compressor housing, then run as short as possible lead to the junction box and the starting relay. I can't see that being a problem, other than i don't know if soldering to the three pins is likely to damage any insulation surrounding each pin. Any thoughts appreciated, and thanks for reading.

author: Nikan
author_rank: Regular Contributor
timestamp: May 04, 2021, 04:53:41 am
content: I have once soldered terminals of a compressor. The terminal was pretty similar from the looks of it.If you are going that route, heat shrinking and strain reliefs are advised, but still not guaranteed to keep everything intact due to the heat applied to those terminals.Other than that... If the terminals have a standard thickness, try searching for a female crimp, that would be the better option, if you are unsure about the insulation around the terminals.Good luck

author: moffy
author_rank: Super Contributor
timestamp: May 04, 2021, 05:28:06 am
content: They look like they are part of a 'seal', I would be wary of applying to much heat. Some sort of female crimp sounds the safest, but I could be wrong about the 'seal' part.

author: davelectronic
author_rank: Frequent Contributor
timestamp: May 04, 2021, 07:11:45 am
content: Thanks for your replies, I did think crimps to try first. But standard non miniature sizes like bullet or recepticle are just still to small. For stain relief or insulation, I was looking at potting with resin. I've found the perfect fit cylindrical mould to glue in place an fill with epoxy or resin. That seemed the safest isolation / insulation from the the live terminals. It's what those pins are set in that l think is the deciding factor, I was hoping that's silicon or glass.

author: SeanB
author_rank: Super Contributor
timestamp: May 04, 2021, 07:35:35 am
content: Molex connectors from PC power supplies have the right diameter sockets, just need to remove them from the socket, and use heatshrink on them afterwards. Otherwise just solder them on, the seal is generally soft glass, which handles heat well.Just remember those compressors do tend to leave an oil mist in the output, and will eventually deplete all the oil from the compressor casing. You probably will want an oil coalescing filter on the output of the tank, along with a second 0.3micron air filter after it, to get the last bit of oil mist out.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: May 04, 2021, 01:42:15 pm
content: Not a clue how they're built, but you definitely don't want to be breathing oil mist (or paint!). Expensive, but the Jun-air "Quiet Air" units are the ticket for this, if you can find a used one. They need filters too.

author: davelectronic
author_rank: Frequent Contributor
timestamp: May 04, 2021, 02:39:00 pm
content: I'm adding a water / oil trap, and there's another another inline to the airbrush. I had contemplated cutting each compressor top half and adding an oil sight glass fitting. Also a seal clamp to hold the top casing on securely. But decided I'd need to cut very precise to achieve this top removal and add a secure seal. Bambi compressors have a removable top for maintenance I think.I though it a task to far, I can gauge any oil loss in the drain process. Also the output airlines are clear braided hose, so I should see if a thin layer makes its way into the receiver. I anticipated a small oil loss anyway, I've got a large barrel syringe and hose to top it up with oil if needed. I might look at experimenting with a non critical compressor to see if I can pull of a neat and tidy cut and seal of the top half of a compressor. Never thought of molex as an option, but it sounds a great idea. Once the pins are fitted with the cable, I was going to wrap them in PTFE tape, and then encase the leads and connections in epoxy or a suitable resin.

author: davelectronic
author_rank: Frequent Contributor
timestamp: May 05, 2021, 12:42:43 pm
content: Thanks all for your help with this issue. I'm going with the molex crimps, had an old molex lead, there sure are a perfect fit. Something I doubt I'd ever have thought of.Be safe out there.