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Topic: Vacuum pump on a cheap solder sucker iron (Read 193 times) previous topic - next topic

DocStein99

I've been using the good-old Radio-Shack style desoldering iron, and want to upgrade.  So I hooked up a little fuel filter to a hose, attached to a small vacuum pump.  It actually worked, until I started losing suction between the hot iron tube, where my rubber hose merged onto it, become warped on heat.

I was wondering if anyone here had a creative simple idea(s) I am stumped.  What can I use to air-tight merge this hot metal tube to this plastic filter - that WON'T warp / melt under that heat?

pert

Silicone tubing is good up to 500 F. If you need a little higher temperature you could use a bit of PTFE (AKA Teflon) tubing, which is good up to 550 F, as a buffer but it's not very flexible so you wouldn't want to use it for the full length of the hose.

DocStein99

What is silicone tubing generally used for ?  I can't see them stocking it at a hardware store.

pert

They use it on aquarium air pumps. You can buy it from many different online sources. One thing to consider is that it's available in a variety of hardnesses and wall thicknesses, which will determine the flexibility of the tubing. A lower durometer will mean that the tubing gives less resistance to you moving the iron around but will also make it more prone to collapsing under vacuum and kinking. The aquarium tubing will likely not advertise the durometer rating. Although likely not the best available price, I have purchased some silicone tubing from McMaster-Carr specifically because they stock a range of durometer ratings and I was looking for the softest possible silicone:
https://www.mcmaster.com/#silicone-hose/=18x3d4y
I'm sure there are other sources, including eBay. I've also purchased tubing from usplastics.com in the past, I think that's where I bought my PTFE tubing. In the end I found that the latex surgical tubing was the most flexible tubing available and gave up on my search for a silicone tubing replacement. This was for a completely different application (glassblowing) where heat resistance was a desirable feature but not essential. The latex is certainly not very heat resistant.

DocStein99

I do not need the whole line to be heat resistant, just the part where i couple the metal pipe into the solder filter.   For a filter, I have a small plastic fuel filter, with steel wool inside, (instead of the actual fuel filter material which is some kind of plastic that would melt).

The hose from my vacuum pump to the rear of my filter, is from a medical nebulizer, and is plenty flexible.  The plastic filter capsule does not transfer heat, so I can use any hose out the back of it.

It worked great for 10 minutes, until the solid solder particles jammed my pre-filter pipe.  The molden solder cooled and solidified right where the vacuum leak happened. 

Come to think of it....  The original red rubber hand pump made a perfect seal, and did not transmit any heat.  I guess i could use that, except I dont know how i could seal it back together if i cut it open, to make a filter out it and fix the vacuum line out the back.   

I can call in favor to my friends at hospital to find that rubbery flexible laytex hose material.  You gave me some good ideas with the glass blowing, since those pipes get very hot and those rubber tubes work perfect.

pert

The part of the blowpipe where the hose attaches doesn't get hot. It's only hot on the other end. The reason a heat resistant blowhose is desirable for that application is because the length of the hose tends to inadvertently come in contact with hot glass, tools, or flames from time to time. Actually there's a rubber boot that goes over end of the blowpipe, then a metal swivel that allows the pipe to rotate without twisting up the hose, then the hose is attached to the swivel.

MarkDerbyshire

Neoprene tubing.  I use it on Rc plane smoke systems where the inlet is on the exhaust

avr_fred

Silicone tubing of the appropriate diameter, sold by the foot (or meter), can be found in any good hobby shop. It is used for fuel tubing for the engines on r/c planes, cars and boats.

Neoprene will work as well but I think you'll find silicone is more flexible and has a higher stretch ratio. FWIW, all of the key, hot contact parts in my Pace 1k$ desoldering station are silicone. The long vacuum tube is neoprene but it's not in contact with hot parts, it's isolated by a solder receiver tube, which is glass. There is optional silicone one is about 10x more than the glass one. In twenty years, I've only broken one glass tube so that's what I stick with.

Here's an exploded view that might give you some ideas on how the professional devices are built. Note there are two filters in the vacuum line to prevent the fumes from destroying the vacuum pump (items 28,30 and 31). The other key part is the "S" baffle inside the receiver tube (27). It prevents the solder from collecting on the filter (28).

http://www.gsaservice.com/PACE_SX-70_Desoldering_Handpiece_Spare_Parts.pdf

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