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PLA soldering - maybe new technique? Scenery and structures
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New member 19 posts Roger Rasmussen Rogerdat New member 19 posts
Roger Rasmussen Rogerdat

I've been looking around to see if anyone is doing this and I haven't seen it yet, so thought maybe I'd share.  I'm big into designing and 3D printing parts for layout structures, especially where things are more or less modern such as steel building parts, etc.  So recently I've been working on a grain cooperative structure.  I'd made quite a few parts in 3D printed PLA material (the "corn starch" filament), and noticed that it's much easier to print things relatively flat and "fold them up", versus printing taller and removing supports. Then I noticed while working on my P2K GP9 that some of the plastic is "spot welded" together. I wondered if I could use a dedicated soldering tip on my digital iron to do the same thing with printed parts?  The rest is history.

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So with my digital iron, what I've learned is that the smaller the weld, the lower the temperature setting necessary to maintain control of the melting situation. For larger welds, such as when I was reinforcing the roofing on a "metal" structure, I found about 270C to be about right for making a quick, rough joint. These tiny cooperative elevator walkways above, I'm running the lowest setting, 200C.  Dedicate a tip to this, as once they are used on PLA they are way too polluted to go back to regular soldering.

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In the above photo, I'm right on the very tip of the iron to make this tiny handrail weld. I've found this to be crucial. The side of that iron, even at 200C, would destroy that handrail.

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I use this Creality Ender 3 for my PLA filament printing. This is a very entry-level 3D printer that can print near or at 0.2 mm resolution.  Of course drawing the parts shown here in 3D is another matter and for a different entry altogether.

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At the pinnacle of my attempts to do articulate PLA welding, this would be for me the holy grail: a 60 foot cage ladder that can go from the base of the elevator to the top. As you can see, it's pretty spindly. Part of this is due to the fact that the cages are printed flat, and then I must add the curvature by heating them. I've found the best control by wrapping about one brass tube and inserting that into the inside of a larger brass tube, just so much that the cage barely fits in there. I've then tried heating with both a heat gun and also by dipping in boiling water and cooling.  I think the hot water idea is best but boiling is too hot.  I've yet to find just the right temperature. I know you can buy brass etched kits for this, but I just wanted to see how close I could get here at home. Also, I've improved on my welding technique, operating at the very tip of the iron. So I'll probably give the cage ladder another go with hopes of better results. -Rog

 
Rogerdat
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Prof_Klyzlr Moderator 7,956 posts
Prof_Klyzlr

Heat-welding

Dear Rog,

Yes, "heat welding" can certainly work well if one has a dab-hand,
the parts are engineered with a little extra material to act as "sacrificial weld",
and the soldering-iron temps aren't crazy high

Indeed, some old-heads may remember mass-assembling Kadee #5 couplers into their draftgear boxes and heat-welding the box close with the slightest-graze of a soldering iron along the top edges where the lid edges met the box sides...

The tip about "poluted soldering iron tip" is well taken,
but you may find some ppl have concern about heating/melting 3D material of (unknown specific?) chemical composition...

(yes, we might be able to validly say that "corn-starch-based PLA may be safe to re-heat/weld",
but it only takes one modeller who Only hears the incomplete ambiguous "PLA is safe" part of the statement,
tries the technique on a non-corn-starch-based PLA item,
and ends up having an issue,
and things could be a little dicey...)

The results look goreous!

Happy Modelling,
Aim to Improve,
Prof Klyzlr
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eastwind Super User 3,619 posts
eastwind

3d pens

people who create things with 3d pens often use soldering irons to create smooth surfaces, lots of videos on youtube. 

If you print using ABS you can just use a little acetone to weld bits together, since it's dissolving the ABS and causing it to melt together. No heat required. 

You can call me EW. Here's my blog index
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Benny MRH Author 7,142 posts
Benny

....

Brilliant.

Now I need a UV light pen...

--------------------------------------------------------

Benny's Index or Somewhere Chasing Rabbits
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jimfitch Prolific poster 5,288 posts
jimfitch

For us who only remember PLA

For us who only remember PLA as Peoples Liberation Army, what does it stand for in this case?

 

.

Jim Fitch
northern VA
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Yaron Bandell ybandell Prolific poster 1,555 posts
Yaron Bandell ybandell

@jimfitch

Quote:
Polylactic Acid
 
PLA, also known as polylactic acid or polylactide, is a thermoplastic made from renewable resources such as corn starch, tapioca roots or sugar cane, unlike other industrial materials made primarily from petroleum.

-Yaron.
Susquehanna Bridge Build | My Personal Website | Capitol Free-mo
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Prof_Klyzlr Moderator 7,956 posts
Prof_Klyzlr

PLA Disambiguation

Dear Jim,

PLA (Poly Lactic Acid) - all you need to know...

https://all3dp.com/1/pla-plastic-material-polylactic-acid/

Happy Modelling,
Aim to Improve,
Prof Klyzlr
Reply 0
Yaron Bandell ybandell Prolific poster 1,555 posts
Yaron Bandell ybandell

Plastic Welding

@Rogerdat,

I like the technique shown. I knew of plastic welding but hadn't considered doing that with PLA printed items.

I wonder if using some of the woodburning tips could be handy too?

Regarding temperature: since most PLA is listed as having an extrusion temperature of somewhere between 180-210 degrees Celsius (356-410F). I'd be assuming that you'd be wanting to stay close to or slightly under that temperature range. Thinking that staying just below those temperatures would make things soft enough to push around and weld and not get it runny and melt away. Then its up to the soldering iron to keep the temperature in check in the tip. You'd have to account for temperature difference between where the temperature sensor in the tip is located and the actual (lower?) tip temperature as well as any hysteresis in temperature while the iron is going through a heating cycle.

Yet from your experience it seems that even boiling water at 100C/212F can be too much? Guess the total amount of Joules going into the object from heating is somehow at play as well?

-Yaron.
Susquehanna Bridge Build | My Personal Website | Capitol Free-mo
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Juxen Super User 576 posts
Juxen

Wow!

That's an excellent idea! I'll be sure to use this idea soon. Thanks for sharing!
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jimfitch Prolific poster 5,288 posts
jimfitch

Thanks for the info.  Sounds exotic

Thanks for the info.  Sounds exotic

.

Jim Fitch
northern VA
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