3D Printing Texturing print surface for better epoxy grip

[neil_w]

I was fiddling with my nose cone twist lock design yesterday, and it occurred to me that there was no good reason for me to be providing a smooth flat surface for epoxying to the nose cone. Of course the print surface is never totally smooth, but still.

Is there a particular surface texture that I could add to the design that would be better for epoxy grip? It's not subject to particularly high forces, but if I can make it better why not.

 

[Michael L]

I bought the additional textured plate when I ordered my Prusa i3 MK3s and it leaves a reasonably rough surface. I wonder of there's a way to build roughness into the print. I am a very new 3D printer owner so take this for what it's worth (zeero)

 

[neil_w]

I will be farming out the prints, so my only option is to design in the texture. I was thinking a lattice of fine grooves, or something like that, but I don't know if there's an optimal groove shape or size. It doesn't need to print the texture precisely, just needs to leave it rough enough to enable good epoxy grip.

 

[Scrapmaster87]

See the grooves I added to my top and bottom centering rings on my motor mount. This was my first stab at adding a texture to a printed surface to bonded. The intent of my grooving is for epoxy to get drawn into the grooves as I slide to mount into place or pour epoxy from above.

Im not too much farther along on this topic than you are. If you're bonding your printed part to non-plastic part, then you'll absolutely want greater surface area on your print. If you're bonding 2 printed/ plastic parts. I think you want to be aiming for greater surface area in general (and full contact with your adhesive) rather than just more area on your print. I guess you really should be matching your contact area ratio to the bond strength ratios of the 2 materials you're joining....

Good luck with your twist lock system, I have one of my own for coupling my e-bay to my payload section.

 

[Dugway]

You could always use something other than epoxy. There are adhesives that actually melt the plastic, for PETG I use Scigrip 16 Medium Body. With a 5 minute working time, 10 minute set time, and 24 hour 80% strength time, it's just about perfect.

 

[neil_w]

Well, in many cases I'm gluing to balsa, so plastic adhesives are a no-go.

 

[cwbullet]

Well, in many cases I'm gluing to balsa, so plastic adhesives are a no-go.

Why? I use plastic bonding epoxies with Balsa to plastics.

 

[Bruce]

I was fiddling with my nose cone twist lock design yesterday, and...

I like your idea of a twist lock nosecone. Might you be willing to share more details about it or maybe even an STL file?

 

[neil_w]

Why? I use plastic bonding epoxies with Balsa to plastics.

My apologies, I saw "melts the plastic" and my brain immediately assumed something like Plastic Weld, being unfamiliar with the Scigrip stuff. Sounds like that would work.

However, I already am successfully gluing my existing pieces using regular old BSI epoxy, in low-stress applications. I'm not looking for new glues, I'm wondering whether it is possible to improve epoxy bond strength by texturing the print surface.

 

[cwbullet]

My apologies, I saw "melts the plastic" and my brain immediately assumed something like Plastic Weld, being unfamiliar with the Scigrip stuff. Sounds like that would work.

However, I already am successfully gluing my existing pieces using regular old BSI epoxy, in low-stress applications. I'm not looking for new glues, I'm wondering whether it is possible to improve epoxy bond strength by texturing the print surface.

Ok. I just wanted to understand.

 

[neil_w]

I like your idea of a twist lock nosecone. Might you be willing to share more details about it or maybe even an STL file?

It is reasonably well documented here: https://www.rocketryforum.com/threads/diamond-cutter-build-thread.129671/post-1554266, and here: https://www.rocketryforum.com/threads/biohazard-build-thread.134261/post-1623434.

I also have a little video:

I'm happy to share the STL files if anyone wants. Currently I have it in BT50, BT55 (untested), and BT60. I imagine I should post those in a different thread.