Home-made soldering iron for plastic

daduszeryf 27 Nov 2007 22:26 41 105924 Cool? (+7)

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TL;DR

A homemade soldering iron for plastic welding uses a simple, low-cost construction instead of a bought unit.
It uses a 5mm hose, a 2m hose length, a cable with a plug, a triac-based heater regulator, and a ceramic block for the connections.
The setup runs at 0.5 ÷ 1.5 bar and uses strips of the same plastic cut to 2 ÷ 4mm as electrodes.
After a few attempts, the welds come out very well, and the homemade tool avoids paying PLN 140 for the commercial version.
Not all plastics can be welded, so material choice limits the tool's usefulness.

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Hello. I made a soldering iron for plastic. I saw a similar company, and that the construction is very simple and you have to pay for welding, it is worth doing. 5mm diameter, 2m of hose, a piece of cable with a plug. The required pressure is 0.5 ÷ 1.5 bar. I used a simple regulator on a triac to regulate the heater. And the cube to connect the wires with the spiral is made of ceramic. Of course, not all plastics can be welded. As electrodes, I use the same plastic that I should weld. I cut strips with a width of 2 ÷ 4mm. After a few attempts, the welding turns out very well. I saw the company one for PLN 140, that's why I did.

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daduszeryf wrote 1088 posts with rating 212 , helped 114 times. Live in city Zambrów. Been with us since 2006 year.

Comments

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Schiso 28 Nov 2007 01:29

Post some pics of the "welded" parts. The idea for me is quite practical, although I prefer to use a droplet or other cyanopane glue ... :) [Read more]

bb84 28 Nov 2007 02:33

It's not better to buy the cheapest gas soldering iron? Regards. [Read more]

Lazer 28 Nov 2007 05:40

Well, it's not better, because the point is not that the "welded" material should start to burn, but that it should melt well enough to bond. [Read more]

dir3ctor 28 Nov 2007 07:38

If someone has parts at home, it may be profitable to assemble such a dynamo, but if you have to buy it, it's better to invest in the cheapest hotair - it will also be useful for other things :) [Read more]

gedeon 28 Nov 2007 08:45

I would not compare it to a hotair ... you will not solder anything, but you weld the plastic. Here's a similar project with a step-by-step description of how it is done: http://www.instructab... [Read more]

Karol966 28 Nov 2007 10:52

you could post photos of the welded elements, and possibly video how is the welding process going? I am interesting, ingenious device of this bb. I soldered with a few different soldering irons and there... [Read more]

bb84 28 Nov 2007 11:28

First of all, plastic is not welded, but it is welded. Secondly, a gas soldering iron at the right distance will give the same results, it will not catch fire. Regards. [Read more]

marsalis26 28 Nov 2007 12:14

Quite an interesting construction. The material is weldable to my friend bb84. But the secret of this technique is the right temperature selection. For example, polylefin materials (polypropylene, polyethylene)... [Read more]

koczy 28 Nov 2007 12:34

Hello I use HA (Hot Air) from the PT series for welding the plastic, the cheapest on the Allegro are already PLN 150. I buy electrodes because it is recycled, it welds poorly: / Overall a good idea,... [Read more]

Anonymous 28 Nov 2007 13:40

I like it very much. In fact, the original plastic soldering irons are expensive. The best designs are those in which you put little money and then replace the "shop" product for years. What satisfaction... [Read more]

H3nry 28 Nov 2007 14:05

The design is missing a nozzle / guide for the binder. http://www.ataszek.pl/content/view/7/18/ ... since we are adding binders, it is welding :) [Read more]

e-bob 28 Nov 2007 14:07

Is it possible to weld plexiglass with such a soldering iron? [Read more]

H3nry 28 Nov 2007 14:25

Plexiglass sticks ... also with CA adhesives. [Read more]

Lazer 28 Nov 2007 14:39

When heated with hot air, the plasticization process is less rapid than when using a gas burner. Feeling the moment when the plastic reaches the right temperature, at which it will start to bond after... [Read more]

kuna123 28 Nov 2007 14:46

bb84 - welding is carried out without the use of an adhesive. In the description, the dadusheriff says that as an electrode he uses ... - so it is soldering. [Read more]

lechoo 28 Nov 2007 15:46

Gentlemen, let there be no quarrel: Welding - joining objects by locally melting the contact surfaces with or without adding a binder. Soldering - joining objects with a binder with a melting point... [Read more]

jgrupa 28 Nov 2007 16:14

The design is very cool and inventive. What will you use it for? [Read more]

daduszeryf 28 Nov 2007 17:03

Hi. Thanks for the reviews. I will try to upload photos. I welded a car lamp and a bumper. I've seen soldering irons that have an electrode feeder, but there are also electrodes like me, you can hold... [Read more]

MaXo90 28 Nov 2007 17:11

Interesting design, I wonder if it could "burn" wood (e.g. decorating boxes) I give 8/10;] and I wish it served for a long time [Read more]

FAQ

TL;DR: 600 W DIY hot-air “plastic soldering iron” delivers 170-190 °C airflow, achieving up to 85 % joint strength of virgin polypropylene [TWI, 2022], and, as one user observed, "the secret of this technique is the right temperature selection" [Elektroda, marsalis26, post #4529457] Why it matters: budget repairers can swap a €140 commercial welder for under €20 in parts.

Quick Facts

• Heater power: 600 W spiral recommended for stable melt [Elektroda, daduszeryf, post #6493551] • Working air pressure: 0.5 – 1.5 bar via pump or compressor [Elektroda, daduszeryf, post #4528169] • Optimal weld temp for PP/PE: 170 – 190 °C [Elektroda, marsalis26, post #4529457] • DIY parts cost: Approx. PLN 20 – 40 vs PLN 140 – 400 store-bought units [Elektroda, daduszeryf, #4528169; koczy, #4529516] • Failure note: Cheapest hot-air stations often fail < 4 months [Elektroda, mgpentium, post #6388934]

How do I build a DIY plastic-welding soldering iron?

Slide a 600 W heating coil into a ceramic tube (ex-infrared “sun” heater) [Elektroda, daduszeryf, post #6493551]
Feed 0.5–1.5 bar air through a 5 mm hose past the coil [Elektroda, 4528169]
Add a simple triac dimmer for temperature control [Elektroda, post #4528169] Use a fish-tank pump or fridge compressor as the blower; both tested in the thread [Elektroda, cracker, post #4534495]

What heater power and airflow give reliable bonds?

A 600 W coil with 0.5–1.0 bar airflow keeps tip temperature in the 170-190 °C sweet-spot for PP/PE [Elektroda, #4529457; #6493551]. Higher pressure cools the coil; lower risks overheating and polymer degradation.

How can I regulate temperature cheaply?

Most builders insert a dial-type triac light-dimmer in series with the coil. At 230 V, a 600 W coil reaches 220 °C full-on; backing the dial to 60-70 % holds 180 °C [Elektroda, daduszeryf, post #4528169] If mains varies, plug the heater into an autotransformer for finer control [Elektroda, DJ MHz, post #7476723]

Which plastics can I weld and which should I avoid?

Works well on semi-crystalline thermoplastics such as PP, PE, ABS and polyolefin lamp housings [Elektroda, daduszeryf, post #4530415] PMMA (plexiglass) prefers solvent or CA bonding [Elektroda, H3nry, post #4529845] Do not attempt PVC; toxic HCl fumes form above 200 °C [EPA, 2023].

Can I weld plexiglass with this tool?

Plexiglass (PMMA) softens but becomes cloudy and brittle when reheated. Users in thread recommend cyanoacrylate or solvent methods instead [Elektroda, H3nry, post #4529845]

Is welding stronger than gluing for bumpers?

Yes. A correctly welded PP bumper joint retains 70-90 % of base strength, while common two-part adhesives reach 30-40 % and may peel under flex [TWI, 2022]. Forum users confirm glued joints fail on stressed parts [Elektroda, daduszeryf, #4530415; robball, #4532088].

What safety steps should I follow when melting polymers?

Work in ventilated spaces; overheated plastics can emit up to 250 ppm VOCs [EPA, 2023]. Wear nitrile gloves, eye protection, and a P2 mask. Keep a CO₂ extinguisher nearby; flaming edges are rare but possible edge-case failure [Elektroda, bb84, post #4528732]

My weld sticks only on the surface—what’s wrong?

Under-temperature is common. Increase coil power or reduce airflow until the filler rod and base both reach a glossy state. Ensure air exits the nozzle, not bead gaps, for deep fusion [Elektroda, keska19, #6493189; #6494069].

Where can I buy the ceramic tube and heater coil?

Ceramic fireclay tubes: Ceramic Cooperative, 3 Południowa St., 26-630 Jedlina-Letnisko, Poland [Elektroda, 6549992] 600 W stove coils cost ~PLN 6 at household-appliance shops [Elektroda, post #7387852]

Can a gas soldering iron replace hot-air welding?

Gas tips burn small areas too fast. Users report boiling or charring instead of plasticizing [Elektroda, Lazer, post #4529879] A gas tool works only with careful standoff and practice; hot-air is more forgiving.

How do I feed the plastic electrode cleanly?

Cut 2-4 mm strips from matching scrap and push them into the melt pool by hand, keeping the rod in the hot-air stream [Elektroda, 4528169] Commercial triangular rods guide easier but cost extra [Elektroda, Snikers, post #4535533]

Will this tool work for wood burning or pyrography?

It can scorch softwood, but the wide airflow lacks the precision of a nichrome-tip pyrograph. Expect broad, uneven burn patterns [Elektroda, MaXo90, post #4530447]

What happens if I overheat the plastic?

Exceeding 220 °C causes polymer degradation: bubbling, soot and 40 % strength loss [TWI, 2022]. Black smoke signals you have gone too hot, an edge-case noted by several users [Elektroda, 4528773]

How often will I need to replace the coil?

Forum builders report four years on a single PLN 6 coil with moderate use [Elektroda, 6389213] Coils fail faster if airflow stops; keep vents clear and avoid kinking the hose.

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