Anyone have any experience with "plastic welding?"

[MOWboss]

I keep trying to improve my scratch building proficiency. I've been experimenting with incorporating dissimilar plastics like Styrene, Sentra and "kit plastics."
It seems there are so many types of plastic used now that glue ups become a chemistry lesson. I like using Sentra (for strength) and Styrene (for style).

I use the term plastic to include the synthetic alphabet soup of material that is made available to modelers today.

Glues and solvents don't seem hold well between one plastic and another. It seems the only alternative is to "weld" these plastics together since all these types of material have heat as a common denominator.

Curious if there are some recommendations, alternatives or insights about this or a similar products.

 

[bnsf971]

The plastic welding I'm familiar with is of the "spin welding" variety. It works very well for plastic fittings, but for my model trains, not so much.

 

[Mixed Freight]

The Harbor Freight unit looks to be an industrial-sized type of plastic welder, and may be a little too big for smaller modeling work.

In lieu of that, you may wish to try using a good, variable rate soldering iron, and simply use the hot tip to move along and create the weld. Use a "filler rod" of plastic (which could be simply cut from either of the plastics you wish to weld). I'll admit that I've never tried this, but it may just work.

Or another idea, just mix too different solvents together in a 50/50 ratio, and apply that to your glue joint with two dissimilar plastics. Maybe that would work, also? Just be careful if mixing solvents, as I'm not a chemist, and don't know what harm (if any) this might create.

 

[MOWboss]

I agree the Harbor Freight unit seems a bit large but I put it out there as an example.
I did order these two items to try out. The UV glue kit has always impressed me.
I also want to use the welding iron to "dent" the sides of gondolas and hoppers...

 

[logandsawman]

When I want something to stick better, I usually glue with CA and follow up (after it is done setting) with JB weld epoxy. Many, if not all, of my buildings are reinforced with JB weld; whether wood or plastic, this epoxy is not fussy.

For hobby uses, it looks like a little overkill to do the plastic weld.

My opinion, Dave LASM

 

[dgrafix]

Depending on the plastic i either use 2 part epoxy (works on pretty much everything) or superglue. I use Patex "no-nails all materials clear" (not the regular) for fixing my XPS foam boards, that is a winner (although you need some weight and/or screws to get the best stick on that). If sticking plastic to wood, wood glue works well too, but sucks for plastic to plastic as it needs air.
Problem with using heat or melting solvent on many plastics is you loose material, either to the sticking to the knife or running/deflation, especially if if it is expanded in any way, like with foams. For non-expanded/extruded styrene i would use the standard Airfix type glue, but this will melt it to some extent.
For gluing of small stuff then i would probably choose super glue + baking soda (makes it much stronger), if the piece was not to be stressed/vibrated/moved too much, or a 2 part epoxy if it needs to be stronger applied with a toothpick. Putting some micro scratches in the surfaces to be "married" helps massively. I use a tiny fine metal file to do this, it has a similar grade to a nail file or emory board which also works.
I would say the best plastic "welds" are chemical, unless using a laser or something very precise.

 

[MOWboss]

Depending on the plastic i either use 2 part epoxy (works on pretty much everything). I use Patex "no-nails all materials clear" (not the regular) for fixing my XPS foam boards, that is a winner (although you need some weight and/or screws to get the best stick on that). If sticking plastic to wood, wood glue works well too, but sucks for plastic to plastic as it needs air.
Problem with using heat or melting solvent on many plastics is you loose material, either to the sticking to the knife or deflation if it is expanded in any way, like with foams. For non-expanded/extruded styrene i would use the standard Airfix type glue, but this will melt it to some extent.
For gluing of small stuff then i would probably choose super glue + baking soda (makes it much stronger), if the piece was not to be stressed/vibrated/moved too much, or a 2 part epoxy if it needs to be stronger applied with a toothpick.
I would say the best plastic "welds" are chemical, unless using a laser or something very precise.

Thank you.... Brilliant! Never heard of super glue and baking soda. Just watched a couple of You-Tune videos and I'm blown away with the strength, speed and versatility of this combination. Plus all the material is sitting on my shelf...
This link was particularly informative;

 

[dgrafix]

Thank you.... Brilliant! Never heard of super glue and baking soda. Just watched a couple of You-Tune videos and I'm blown away with the strength, speed and versatility of this combination. Plus all the material is sitting on my shelf...
This link was particularly informative;

Cyanoacrylate in superglue reacts with bicarbonates to create polymer chains that are very strong. If you lightly file your surfaces and rub the bicarb in them before gluing then nothing is taking that apart, short of destroying the stuff that is glued together.
Just be really sure you want it before "sticking" it
PS do some experiments first to get a feel for it. Also know the reaction can get hot if a large area is being done (not catastrophically but it could maybe burn your fingers, not tried touching it, but it does smoke so assume there is some heat there).

 

[Mixed Freight]

Problem with using heat on many plastics is you lose material.......................................................

That's why when heat-welding plastics, you use a filler rod. You can run a weld bead on solid plastic just like running a bead on steel. And like welding metals, a filler rod is almost always a necessity for plastics too.

This of course refers to solid plastics, and not expanded foams, which are a different animal altogether.

Heat-welding plastics for smaller modeling work is normally not the best option in most cases. But in some cases, it may rank up there as a darned good way to go.

 

[dgrafix]

That's why when heat-welding plastics, you use a filler rod. You can run a weld bead on solid plastic just like running a bead on steel. And like welding metals, a filler rod is almost always a necessity for plastics too.

This of course refers to solid plastics, and not expanded foams, which are a different animal altogether.

Heat-welding plastics for smaller modeling work is normally not the best option in most cases. But in some cases, it may rank up there as a darned good way to go.

Very true , especially any large scale (and of couse this works only properly with thermoplastics that will accept the filler)
Although i still prefer glue on smaller scale stuff. I am curretly working with N so glue is the only way to fly as 1mm = 16 centimters
PS: i have experimented with those kodak 3D print pens, talking of melt-material feed.. the jury is still out on that one. It certainly has potential i am just ot yet sure what for or how . It is a lot hotter and can be much more precice when used as "hot glue".