Raychem VC 5300 Heat Gun, made in West Germany, 1970's-1980's

[nevetslab]

Finished Heater Coil assy, hi temp insulation, mesh screen for Heat Gun

Finally finished restoring this heat gun! The Hi Temp Mica paper arrived last month, and today, the Stainless Steel fine mesh screen material arrived (23AWG, 0.085" square pitch) which the gun didn't have when I began rebuilding it, though my other one does. Had to cut that material into a circle, using the cutter punch from a 1" Greenlee Conduit Hole Punch as a template....just happened to be the right size to fit into the tapered flange end.



The heat gun pulls the same AC Mains Current/Wattage as my other working Raychem VC5300 (903W/7.65A @ 117VAC), it still having the original heater assembly after all these decades (bought new in 1975). It was an exercise in searching out the materials for the coil wire, how to wind the coil, find the high temp insulation material, then find the stainless steel mesh without having to buy a huge sheet of it.

[nevetslab]

Kanthal A1 Wire arrived, heater coil formed & wound

I must have missed this listing yesterday while I was at McMaster-Carr. I just ordered a 2ft length of stainless steel #2-56 threaded rod, OD of 0.086" for use as the winding core from them for winding the 24AWG Kanthal AF wire in making the replacement heater coil. Rats. I just purchased some high temp mica paper, offered for use as replacement material inside heat guns thru Amazon.com.

[ATTACH=CONFIG]54368[/ATTACH] https://www.amazon.com/Maslin-Temper...ag=d_2b_a_p-20

I'll be able to salvage the high temp core from the heat gun, and have found some high temperature ceramic adhesive suitable for repairing the break in the core. I'll see how the core stands up, once I've removed the old heater coil and grind away the overspill from the previous glue job.

If this mica paper doesn't do the job, I'll obtain some of this material you found.

I had considered the alternate core forms we've seen used in hair driers and other replacement heater assemblies. Those, however, leave you with the mechanical interface problem that was solved by the original heater core. This second heat gun doesn't have the original mesh grille on the end of the gun's nozzle, but, not really a problem, as I always have the reducing nozzle in place.

This morning, after removing the old coil from the coil form, and spending the time to cut, scrape & file off the epoxy overspill from the coil form, I got it down to the bare surface. The Kanthal A1 wire arrived at that point, so I stopped to contemplate a winding tool that would set a fixed spacing between coil turns on the 2 ft long #2-56 threaded shaft, which would be chucked into my variable speed drill motor, with the other end sitting inside a small dia brass tube as an end to a poor-man's winding lathe. After coming up with a concept, I cut off a 2" length of Delrin round stock I had on hand, put it in the vise to machine two flat's on one end, then squared one side up, and drilled a 0.093" dia hole thru the width. Then, drilled a 0.028" dia hold spaced in from the edge to form a steady 0.040" space between core coils during the winding operation. I had to file an angled relief on that side to allow the wire to wind onto the shaft. I gave that a try, and as crude as it was, it wound an evenly spaced coil wrapped around the long threaded shaft. The first coil broke when the wire hung up on the end of the first layer, so wound it off that long mandril, and measured the resistance, it being about 10" in long. 11 ohms already. OK, seems like the 0.040" spacing is too tight. No matter, pulling on the coil from both ends, it stretches out just fine.

So, wound another one, it being way too long as it turned out. Using the ohmmeter, I found where it would be 15.6 ohms, and cut the coil there. Then, spent time stretching the coil, keeping it evenly spaced, until I had 22" of coil length, having found the length factor earlier with a similar dia cable wrapped around the core.

The rest was pretty easy....though the hardest part was getting that wire wrapped around the cheeze-head screws of the terminal pins in the base, without breaking anything.



Now, just waiting for the mica paper insulation material to arrive. This would have been easier with a NOS replacement heater assy, but, not as much of a challenge. The Kanthal A1 wire cost me $4, free shpg, the long Stainless Steel #2-56 threaded rod, along with a bag of mating nuts and washers was only $5 (shpg was extra, but having bought materials for the shop, that was billed to those monthly expenses). The insulation material was about $14....it being the most expensive item. I still haven't received a quote on the NOS heater The Dude found listed on someone's website. So, getting close. I found JB Weld has a product called ExtremeHeat, good for 2400 deg F/1300 Deg C for $10 and bought some of that in case the core breaks open again during use, it having been glued together with JB Weld before checking it's temperature rating.

[nevetslab]

This place says they have one (down the page a bit), but you have to email for a quote and who knows what they'll charge for it.

https://www.store.crimptools.com/ind...display&page=8

Nice find! I sent the RFQ......hope it was sent, as there wasn't the usual response one sees on a website after poking their Send button.

I bought one of those inexpensive heat guns like you found on ebay....so far, just have used it for heat shrink applications. I did find ebay had replacement heater elements for them, and ordered one. https://www.ebay.com/itm/For-GJ8018-...8AAOSwAuNW6Td1

[nevetslab]

the resistance wire frames were (and still are) mica, the more flexible material lining the barrel could be silica fabric, which Mcmaster C sells in small quantities, not too expensive
[ATTACH=CONFIG]54362[/ATTACH]
Adhesives are an issue though, silicone could survive but is a piss poor glue.

I must have missed this listing yesterday while I was at McMaster-Carr. I just ordered a 2ft length of stainless steel #2-56 threaded rod, OD of 0.086" for use as the winding core from them for winding the 24AWG Kanthal AF wire in making the replacement heater coil. Rats. I just purchased some high temp mica paper, offered for use as replacement material inside heat guns thru Amazon.com.

https://www.amazon.com/Maslin-Temper...ag=d_2b_a_p-20

I'll be able to salvage the high temp core from the heat gun, and have found some high temperature ceramic adhesive suitable for repairing the break in the core. I'll see how the core stands up, once I've removed the old heater coil and grind away the overspill from the previous glue job.

If this mica paper doesn't do the job, I'll obtain some of this material you found.

I had considered the alternate core forms we've seen used in hair driers and other replacement heater assemblies. Those, however, leave you with the mechanical interface problem that was solved by the original heater core. This second heat gun doesn't have the original mesh grille on the end of the gun's nozzle, but, not really a problem, as I always have the reducing nozzle in place.

[The Dude]

This place says they have one (down the page a bit), but you have to email for a quote and who knows what they'll charge for it.

https://www.store.crimptools.com/ind...display&page=8

[Bloomfield]

If you have a ceramics/ pottery supplier nearby it could be worth a look. Some of them carry supplies for electric kilns such as nichrome wire and probably some hi-temp adhesives. They would likely sell in small quantities too.

[tedmich]

the resistance wire frames were (and still are) mica, the more flexible material lining the barrel could be silica fabric, which Mcmaster C sells in small quantities, not too expensive

Adhesives are an issue though, silicone could survive but is a piss poor glue.

[g1]

Wouldn't the same type of insulator from a hair dryer work? Lots of them around thrift stores here for very cheap.
Or would they not be sufficient temp.?

[nevetslab]

classic heat guns!

modern ones sometimes do better heat control, I'm getting one of these at work
German Steinel HL 2020 E Professional Heat Gun, digital control (in 10F steps) from 120-1150F
the gun alone is $220, but for some reason the Silver kit (which includes plastic welder tip, case, SMD air tip etc) is only $169 on my Amazon, go figure
https://www.amazon.com/Steinel-Profe...06XDCYRQ5?th=1

I've always admired the Steinel heat guns, as well as the Leister products. I think it was The Dude who had come across a really inexpensive probe-like heat gun with a collection of nozzles for use on SMD devices. I bought one just to have a look, it being only $36, free shpg out of China. I also tracked down a replacement heater assy for it while still available.

This current project is one of those that seemed like there would be a simple solution. Would have been simpler if I had hi temp adhesives on hand, and hadn't managed to damage the insulating hi temp film lining the insides of the housing in close contact with the heater assy. I think I can wind a new heater from the Kanthal AF wire that's inbound (though we'll see on that!). Trying to find a suitable and purchasable insulation film to replace what was on the insides of the nozzle housing is what's challenging me now. I did find some hi temp woven ceramic cloth material good to 2600 deg F (from Cotronics), but, it doesn't look like something I can purchase in very small qty. Kapton film doesn't seem like it has high enough temp range.

The material lining the insides of the housing seems like its a mica-like product...1 mil thick, cracks/tears like mica or perhaps muscovite, but, where to buy it in 2" wide x short length is the problem. Not like I don't have a working heat gun that's been with me since the 70's.....I just hate being defeated by one.

[tedmich]

classic heat guns!

modern ones sometimes do better heat control, I'm getting one of these at work
German Steinel HL 2020 E Professional Heat Gun, digital control (in 10F steps) from 120-1150F
the gun alone is $220, but for some reason the Silver kit (which includes plastic welder tip, case, SMD air tip etc) is only $169 on my Amazon, go figure
https://www.amazon.com/Steinel-Profe...06XDCYRQ5?th=1

[nevetslab]

Nevetslab, if you're going to heat epoxy, wear your resperator. Nasty fumes.

Starting over with this heater element, and with the insides of the nozzle-housing that contains this heating element on the heat gun.

I've identified the heater coil material.....Kanthal AF (Fe-Cr-Al) Iron-Chrome-Aluminum alloy, 24AWG, which has a resistance of 2.069 ft. The coil assy on the other heat gun is about 13 ohms. That works out to be around 6.3 ft of this wire. I haven't been able to find any pre-wound Kanthal AF coil wire having this small OD as used, but have found the wire itself, not too expensive. I suppose I can give a try at winding a new coil around a 0.080" OD shaft....which doesn't sound like a lot of fun. The length of the coil, having used a similar dia cable wound around the coil form was about 2.4 ft in length. I know winding that 24AWG wire into a 2ft+ coil, with some length for the straight-wire ends to attach to the pins will be accumulated in winding the small dia coil, but somehow winding up 3 times the length into that small OD coil seems wrong. Won't know until I try, I guess.

ADT2001_12_17_KAF_ENG.pdf

Once the existing 'repaired' coil is removed from the coil form, I can scrape away the excess Epoxy, leaving what was used to bond the two halves together. And, as Juan said, that bond will no doubt fail if I can get this new heater coil created. I didn't even stop to check what the temperature rating of JB Weld was.....550 deg f max, so yes, that WILL fail.

Putting that fish paper inside over the 1 mil thick flexible Mica (or at least that's what I assume it is), since there was already damage to that material from when the heater failed, removing the fishpaper, which had an adhesive backing, that ripped out one layer in the process. There was still another layer of that material, which appeared to have some sort of bond to the steel housing. So, this has turned into a can of worms.

Looking down the throat of my working heat gun, it's coil assy is glowing red hot, so there is serious temperature on the inside surface of the housing, which has to be insulating the housing from the line-voltage potential that's on the coil itself. My initial browsing on the internet for flexible mica hasn't been encouraging.

[ric]

I was only guessing as to what the tan-colored form is made from. It cracked cleanly in two up near the top, and, I just took a chance with the JB Weld Epoxy.

The Fish Paper was a thought, though I wasn't able to find any flame rating on it. It is at least easy to remove, and I did find a source for sheet Mica...3" x 4". The inside surface of the housing for this heater assembly lines that surface. I saw some damage to it, so that was just a first attempt. I had only briefly powered it up, but, just didn't feel secure in blindly using it.

Onward with the search for materials. I believe there are some resources for coil-wound NiChrome wire similar to what was used in this assembly. Thanks.

Nevetslab, if you're going to heat epoxy, wear your resperator. Nasty fumes.

[nevetslab]

Sorry but neither JB Weld nor fish paper are up to the task.
The first one will first become so weak as to crumble if subject to pressure or vibration, the second will plain catch fire.

Maybe you can recycle and adapt a hair dryer element, although those are lower powered; count on, say, new high being equivalent to old low, and so on.

Still useful for some tasks.

Form where wire is wound will probably Mica or Micanite instead of Ceramic but that may hold anyway.

You might make a functional resistor winding standard Nichrome wire around a knitting needle to make the basic spiral resistor and then wind it around the heat resistant form.

Or maybe somebody makes a similar heating element you can kludge in there.

I trust your McGiverish abilities

I was only guessing as to what the tan-colored form is made from. It cracked cleanly in two up near the top, and, I just took a chance with the JB Weld Epoxy.

The Fish Paper was a thought, though I wasn't able to find any flame rating on it. It is at least easy to remove, and I did find a source for sheet Mica...3" x 4". The inside surface of the housing for this heater assembly lines that surface. I saw some damage to it, so that was just a first attempt. I had only briefly powered it up, but, just didn't feel secure in blindly using it.

Onward with the search for materials. I believe there are some resources for coil-wound NiChrome wire similar to what was used in this assembly. Thanks.

[J M Fahey]

Sorry but neither JB Weld nor fish paper are up to the task.
The first one will first become so weak as to crumble if subject to pressure or vibration, the second will plain catch fire.

Maybe you can recycle and adapt a hair dryer element, although those are lower powered; count on, say, new high being equivalent to old low, and so on.

Still useful for some tasks.

Form where wire is wound will probably Mica or Micanite instead of Ceramic but that may hold anyway.

You might make a functional resistor winding standard Nichrome wire around a knitting needle to make the basic spiral resistor and then wind it around the heat resistant form.

Or maybe somebody makes a similar heating element you can kludge in there.

I trust your McGiverish abilities

[g1]

I would look at older clothes dryer elements (and repair kits for same).