Plastic welding rods

[43rdRecceReg]

Has anyone here experience of using plastic welding kits as an alternative- or supplement- to abs cements, and superglues? Lately, I've seen kits on sale on Ebay and Amazon (for use with soldering irons or heat guns) and quite a few videos on Youtube illustrating plastics being repaired, or formed, by using ABS and PP rods with ordinary soldering irons. Looks like a great way of bonding styrene to me, and has potential for creating real 'welds' on tank chassis edges...or reinforcing the hulls internally.. I'm not a scratch builder- yet- but I imagine this could be a useful alternative to bonding with glues, and might help around the problem of shear under load...
Curiously, I found an earlier thread where 'riggy15' was using a soldering iron and a strip of plastic (the 'rod') in a Tamiya rebuild project.. and it struck me as a smart idea.
It's worth a look.. as he's definitely no slouch when it comes to throwing bits together...
viewtopic.php?f=21&t=14323&p=137666&hil ... ld#p137666

[ausf]

The problem with using heat is depth of penetration. You'll never get the heat as deep as a thin cement.

Styrene and ABS (using the proper glue) are bonded with their solvent by actually melting the surfaces together chemically. They dissolve the mating surfaces together (unlike CA).

Mechanically melting is the same idea, just not as effective since the heat destroys the area while hot then quickly dissipates. It doesn't get the chance to bond as well as glue and if you penetrate deep enough, you're going to disturb the surface.

I use highly controllable soldering irons with needlelike probes to bond 3D printed pieces. It works, it's just a lot harder than glueing, but there isn't a good glue for PLA.

Technically you could hold two pieces of styrene over a candle then stick them together too, but why?

Are you having problems with traditional glues?

Not all ABS cements are alike, maybe you have a sup-par one. MEK or MC based are the best. If anyone is concerned with health issues, the solvents aren't that friendly to your liver, but melting styrene and ABS is worse and burning it is extremely toxic (just ask your neighborhood firefighter).

[43rdRecceReg]

Interesting, and thanks,Ausf.
Finding the right glue/ bonding agent can be frustrating sometimes, and it appears trial and error is the only effective means of finding what works...
Having seen videos lately of repairs to all manner of plastic parts, from bumpers to can tops, I wondered whether precision plastic spot welding might be more effective in scratch building
sometimes than bonding agents.... (tacking panels together for instance- prior to glueing, or maybe in reinforcing seams with layers of matching plastic)..Health and safety issues aside, yep, and I see they both have potential downsides.. I thought plastic welding might be a means of creating stronger joints than by using solvents to melt surfaces together..as the latter thins the surfaces being joined, where the former builds on them...in principle at least... As you say though, plastic welding with heat and rods is probably a lot trickier. Maybe even a way of courting disaster... It's always worth exploring other avenues sometimes, though i think..

[ausf]

I use three plastic glues for everything I do whether PS or ABS.

My main is Testors Blue. It's a semi non-toxic, semi thick that I use on almost all styrene. It sets up in about 20 minutes and gives a great bond over an hour or two. Being thicker and not too hot, it stays where you put it and slowly melts the surfaces together.

Second up is Tamiya Extra Thin. It's Methyl Chloride, a little higher on the toxicity level. It's water thin and really sinks into every crevice. It bonds styrene or ABS and both together. Strong and quick, but since it's so thin and evaporates so quickly (a sign being volatile and toxic) you may need to reapply. It's my go to glue for very fine detail work or large joints like a wing edge where the slightest melting damage would be evident.

Third is PlastiWeld. It's straight up MEK. Extremely toxic but super hot. It evaporates in seconds as soon as you crack the bottle. As a matter of fact, if you don't seal it perfectly, the next time you reach for the bottle on the shelf, it might be empty. I keep it in a sealed bag. I use it for ABS to ABS. It'll work on styrene, but it's like using a sledgehammer on a thumbtack.

I could see tack-welding with soldering iron, or even melting mounting tabs from a piece like a pioneer tool on the inside of a tank in a pinch.

[maxmekker]

great write up ausf. toxic and strong yes, but I do love the Tamiya E T cement.

[43rdRecceReg]

A really thorough analysis of options, Ausf, as well as the pros and cons of of specific bonding agents. You really know your stuff..and how not to inhale too..
Cheers..
But- out of sheer curiosity- I might have a go at tacking on scrap plastic, to see if it helps.. and I'll certainly seek out the Tamiya formula you recommend.