Can you glue rigid PLA to flexible TPU and get a bond that holds when you twist or bend it? That is the question behind this MakerBuildIt test. I took five adhesives, joined the two materials, and put the cured bonds through our hand-operated twist and snap tests.
Loctite Super Glue and Y’all Can DIY were the only two adhesives to pass both tests. J-B Weld for Plastics and Loctite Vinyl, Fabric & Plastic passed the twist test but failed the snap test. DAP failed both in this round.
The materials and test setup
For the rigid side, I used turquoise Anycubic PLA. For the flexible side, I used black Levemaker TPU 95A. The point was to test a mixed-material joint, rather than assume a glue that performed well on PLA-to-PLA or TPU-to-TPU would give the same result here.
Every adhesive was given its full stated curing time before testing. This round used two checks:
- Twist test: could I twist the joined pieces apart by hand?
- Snap test: could I bend the assembly enough to break the bond or the printed material?
I did not use a force meter for this video. The results are observations from these hand tests, with no measured breaking loads or numerical strength ranking.
PLA-to-TPU glue results
| Adhesive | Twist test | Snap test |
|---|---|---|
| Loctite Super Glue | Pass | Pass |
| J-B Weld for Plastics two-part epoxy | Pass | Fail |
| Loctite Vinyl, Fabric & Plastic | Pass | Fail |
| DAP super glue | Fail | Fail |
| Y’all Can DIY | Pass | Pass |
Loctite Super Glue and Y’all Can DIY: joint winners
Loctite Super Glue held through both the twisting and snapping attempts. Y’all Can DIY also held in both tests, continuing its strong showing from our earlier TPU testing.
Based on this round, I called those two a tie for first. These were the two I would choose from the five tested for this particular material combination. Other adhesives may work as well or better; this test only compares the five shown in the video.
J-B Weld and Loctite Vinyl, Fabric & Plastic: twist passes, snap failures
The J-B Weld sample had some epoxy outside the joint. I noted that I may have applied too much. It survived the twist test, but the joint separated during the snap test.
Loctite Vinyl, Fabric & Plastic had done well in our TPU-to-TPU test, which made it an interesting contender here. It also held during twisting, then failed during the snap test. That change is why testing the actual pair of materials matters.
DAP: a result with an application caveat
The DAP glue was thick, and the parts had shifted somewhat during bonding. It failed the twist test, with a little PLA breaking away, then also failed the snap test.
In fairness, I noted during filming that I gave the DAP sample an extra twist. That makes the handling difference worth keeping in mind when comparing its result with the others. It still did not pass either test in this round.
Watch the full glue test
Glues and filaments used
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- Loctite Super Glue
- Y’all Can DIY glue
- J-B Weld for Plastics two-part plastic epoxy
- Loctite Vinyl, Fabric & Plastic
- DAP super glue
- Anycubic PLA — turquoise
- Levemaker TPU 95A — black TPU used in the test
Have you glued TPU to PLA, or joined another pair of 3D printing materials? Let us know which adhesive you used and how the bond held up.