How to shrink heat shrink tubing?

Geeezus, all this waffle - one huge thread to avoid buying a heat gun! A cheap one will do, fifteen quid, that`s twenty bucks, and you can use it for other stuff like paint stripping. Why piss about with hairdryers, dodgy modified soldering irons or gas lighters when you can get the proper tool for so little money?

Ron(UK)

If you do a lot of desoldering/salvaging with one I would recommend one that uses a ceramic matrix for the heater, the cheap ones use mica. At the moment of pulling an IC from the board , with nozzle necessarily close to other side, it often bangs the nozzle. My heatgun probably done a few hundred hours , if not a thousand , over 20 years, is a Bosch with ceramic so an easy job to repair breaks in the element with some ex-Nicad battery strip crimped over the broken ends.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Because the OP doesn't use heat-shrink materials on a regular basis, and even 15 quid isn't justifiable. I waited years to buy one, and got it only because it was $10.

But I agree in principle -- too many UseNet questions are elaborated to absurdity. The Yiddish words are "tsimmes" (stew) and "megillah" (a long, drawn-out story).

The ones for heat shrink do not have enough flow for paint stripping. I got to use a Makita gun when I was doing a floor, removing melted rubber mat. it had a continously variable heat control, like a triac controlled system with a heat knob on the back. Thats still too much air flow for shrink.

greg

Yeah, thanks for saying that, Ron. A room full of so-called professionals and they're all cobbing together makeshift tools. I've got three different heat guns at work, and they're all in the over $100 range. For a homeowner who uses shrink tubing once per year, I can see the toaster or bic lighter approach, but for someone who makes money with his tools, shit, buy the damn tool already.

I can see that a paint stripper gun may be a bit on the large side for some things, although it's never worried me. RS components do one specially for this job - smaller and less powerful than a paint stripper, but much more expensive. Part Number 545-137

--
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    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

It's funny - I much prefer a butane lighter over an electric heat-gun. It takes very little practice to get it right, it's quicker, easier to carry, and you don't have to go looking for places to plug in the heat gun back behind the equipment racks.

The power switched popped out 3/16" when I pressed it (2 samples), and the diode in series with the heating element is a 1N5408, rated for 3 amps average. The heater draws 8A average on low.

So my question is, how long will this 3A diode last?

Then why did you buy one? Mine is fine, and I just picked one off the shelf, yesterday. I already have an old B&D, and a five year old HF heat gun. The case on the B&D melted when I had to preheat some 1.5" copper pipe while assembling the cooling system on an old TTU-25B UHF TV transmitter. I also needed an acetylene torch & a 175W Weller iron to remove some damaged copper pipe from some custom 30 year old brass fittings RCA used in that transmitter. The HF has been used to remove floor tiles, on heat shrink, and to expand metal castings to remove bearings.

Where is the 1N5408 diode? It isn't listed in the parts list or shown in the drawings:

How long to you use a heat gun per application? Can you read a datasheet, or only skim one? That 3 A rating is for continuous duty at a high operating temperature, not intermittent. The peak current rating is 200A. The case would likely melt before the diode would fail.

I've seen four 1N4004 diodes in a bridge, in series with the heater in a hair dryer to power the dc motor on the fan. Are you claiming that a tool like that can only provide less than 120 watts of heat?

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

Well, each to his own. We do production work, so I'm not sure the lighter would be appropriate for doing 400 pcs. of shrink at one setting. It's nice to set the gun on its built-in flat back, nozzle pointing straight up, and use it hands-free for extended periods. Another drawback I see to the lighter is, how do you get the flame to point down when you're working inside a chassis?

No, with the *automatic* Sunbeam toaster you could stick a chopstick in and push the bread sensor rib and it would go down automatically. You only had to push it down at first. It would stay down for a while after that and the only way to get it to come up early was to unplug it. Although the absence of bread might have some effect on how long it stays on. Since I never figured out how the toaster worked, the one with no handle or lever at either end, and I didn't measure the timing, I was never sure. (Measuring the timing would have required eating the toast!)**

Actually I may use that distance when I use kitchen matches. I haven't been doing stuff for a few months and have already forgotten.

What does it matter if it blackens anyhow? Is it just appearance and a "professional job" you're concerned about? No one sees most of my heat=shrunk areas.

**We had a Sunbeam *automatic* toaster for about 40 years, and my mother used it maybe every day of those 40 years. Just put the bread in and it went down. It broke once after about 10 years, didn't stay down long enough (or too long), even after adjusting the knob at the end, I took the cover off, and it took me at age 14 about 6 hours to get it back on. It was one piece for both long sides and the top in between, and it was spring steel of some sort, and I couldn't push it tight enough with one hand to put a screw in with the other. I tried tying it with an extension cord and twisting to make it tighter. Finally I noticed a square hole next to each screw hole and realized a narrow screwdriver in the hole could be a lever to pull the two holes into alignment. Then it took 10 minutes. I'm sure that's how it was assembled in the first place.

When it was apart I just couldn't figure out what decided when it would go back up. There was no bimetal strip. There was a 1-inch square of grey metal, about 3 mm. thick that had something to do with it, that I think controlled it. Was that bimetal inside? If it moved at all, it wasn't much, because I couldn't see anything move. But I did eventually find a screw on the bottom that adjusted the time, and that's all I was supposed to fix. Turns out I didn't have to take the cover off to turn the screw. :()

When it broke 30 years after that, I also couldn't figure out how it worked, and couldn't fix it. I think then it wouldn't go down at all. I never could determine what normally made it go down. The whole device is a mystery. It may be in the basement, but my mother a"h has passed away.

I don't want to join in a dickwaving match here but I use a Steinel 1500 watt heatgun for all heatshrink work. I`ve owned it for maybe... 15 years, I forget, It's one of those tools that is so useful, I seem to have always had it.

When I was more active I made many many multicore cables for pro audio work. I use the same gun for both multi core cable over an inch in diameter, tails and singles. I never noticed a problem with the gun being either too powerful or physically too large.

I made a little deflector attachment from sheet aluminium for when I didnt want too much heat going where I didnt want it.

Another use for a decent heatgun is reflowing solder joints on whole circuit boards, it`s amazing how often a good going over with a heatgun gets a board working again.

I guess if I wanted a very small heat gun, I would buy one of those micro blowtorch gizmos which use a BIC Lighter. As it happens I have a Weller gas powered soldering iron which has a heat blower nozzle attachment which is good for reflowing work.

Ron(UK)

I bought the HF heat gun yesterday, and it has a manufacturing date of Jan, 2010. Here's a photo of the inside, showing the 1N5408 diode across the two poles of the switch:

The switch popped out because the lower locking tab was squashed and couldn't lock. I think there's a bridge of small diodes at the end of the fan motor.

Doesn't the continuous amp rating for a diode apply for any load lasting more than something like one 60 Hz cycle (or half-cycle?). I normally run a heat gun a lot longer than that, ;) maybe up to 2 minutes at a time.

I've seen that in a lot of imported equipment, not just in tools. :(

There were none external to the motor in mine. Just two 1/8" fastons that plugged onto the end of the motor.

Have you used it for that two minutes? That should answer your question, and show that it takes more than two minutes to damage it. :)

It takes time to heat the junction in the diode. The heat is produced only when forward biased, and is from the forward voltage drop, times the current flow. The higher the current, the faster it heats. Since a heat gun usually gets very intermittent duty in low heat mode, it works.

If it can handle a couple 200 amp half cycles while charging an electrolytic in a piece of electronic equipment, it can handle the extra current for the heating element even though it is above the 3A continuous rating.

It looks like the motor is run from a tap on the heating element. There is no schematic in the manual. I only saw the one diode, across the switch in mine. Also, how often will you use one on low heat? I rarely do, usually only when I accidentally hit the wrong end of the rocker switch.

BTW, if that diode fails, all it will do is make it run at full heat in either 'ON' position.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

And there you have it. I work with cabling in a TV station, requiring no more than a dozen pieces done at any given time, and you work with small wiring inside a chassis on an assembly line, doing hundreds. Each function has its own equipment needs.

But a butane lighter - especially the "jet" types that behave like tiny brazing torches - will flame downward well enough, unless they're built to draw fuel only while upright.

I removed the "Hot air" tip from a butane soldering iron once, and found it even faster than the lighter, but it required more care in use. If one tipped it the wrong way, the flame would flare due to it drawing liquid instead of gas butane.

I used a lot of clear heatshrink to label cables for TV stations and CATV headends. I preferred to label it before it was inside a rack, whenever possible.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

Well, if the diode fails in short mode, you will have only high heat. If it fails in open mode, you'll have a switch that is off-off-low!

I'll bet customers will either not notice that the gun always puts out full power (diode shorts), or they won't care that it doesn't work at low heat (diode opens). I checked a few different items, including some cheapo PC power supplies, and couldn't find any where the diodes were underrated so much

I bought this heat gun to desolder surface mount stuff, and it seems that its low setting puts out temperatures closer to what hot air soldering equipment does.

Indeed - whenever possible. That's how I put in the replacement Production switcher, after all.

When the cable is to be run through the length of the building, through tight support brackets already crammed with cable, it is sometimes best to run one cable at a time and then label each when finished. Heh, time for a little walk down memory lane...

Ah, the weeks I spent pulling obsolete cable out of that installation, trying to make room for new cable... Whoever had worked there before me had left quite a lot of work undocumented... There are few greater sins.

My Chief Engineer cracked up when I mentioned that "there is something fundamentally wrong with any job that requires knee pads and a squeeze-bottle of (cable) lube."

Still, by the time I was finished, the digital stuff was in and the analog stuff (at least that which we no longer needed) was out. I even built a set of shelves in the basement to hold the obsolete analog equipment we hadn't sold or scrapped yet, and I carried the stuff down and filled those shelves.

It was an interesting two years at that station, and then they laid off more than half the staff, myself included. Ah, such is life.

Those cables were installed well, labeled well, and documented well. And a lot of equipment that wasn't working, was, by the time I was done.

And now I'm a college student on the Dislocated Worker plan.

I imagine I'm in good company here.