I’m new to Form (well, new to 3D printing too, but never mind that). I don’t have the printer yet, but have a backlog of projects to break it in when it arrives.
One is an antenna mount. The business end mimics a 1" PVC pipe (not really 1", but I know that. ) and I want to join it to a standard 1" slip x male NPT adapter.
Looking around the forums, it appears that PVC glue won’t melt the resin for welding like it does PVC. Does CA work on both cured resin and PVC? The joint doesn’t need to be waterproof, much less pressure-bearing. It just needs to be mechanically secure.
I would score both surfaces with a 60 grit sandpaper and use an industrial epoxy or Urethane based adhesive. PVC pipe is remarkably Smooth, and CA shears a little too easily from very smooth surfaces.
Its also made of vinyl, Which is pretty inert and hard to bond to- hence the actual melting used by PVC cements.
A good mechanical attachment will be attained when both surfaces have enough “tooth” from fine irregularities that can hold a hardened adhesive filling those irregularities like grout.
Would it be worth it to design in a sort of sawtooth surface on the print (if I can figure out how to do that in Fusion 360)?
No… just a smooth slip joint in the print- the printer will produce some small ridges in the printed part.
but you may have to ream the hole out to accommodate the pvc anyway.
For a really close fit, I would print the part with a hole undersized and drill it out to dimension after post curing.
You could either print a jig to hold it accurately aligned in a drill press… or print a hole undersized to match the pilot bit in hole saw or forstner style bit to align the hole accurately. ( if you can find a bit that pretty exactly matches the outside diameter of the PVC)
Otherwise- just print the hole to dimension- but expect it to come out slightly too small… and use an under dimension wooden dowel wrapped with sandpaper to sand the hole out large enough for the pvc pipe.
Or- you could model several versions of the part- each with a slightly different sized hole… print them all together in one build and find out which one has the best fit- then in future only print copies of the one part who’s hole printed with a good fit.
It’s actually the other way - the PVC is on the outside and the print is on the inside. I dimensioned the print to the exact spec for 1" PVC, which is paradoxically 1.315".
PVC is very difficult to bond to other materials. We have found the best compromise to be PU building adhesive (Its available in a mastic tube from the local builders merchant). Be careful not to put too much on as it foams and expands as it cures. The adhesion to the print and to PVC is incredible (its just messy to use if you are not very careful.
In terms of solvent adhesives the best that we have found for this sort of application is “Tensol 12”, This contains dichloromethane / methyl methacrylate and is fantastic for gluing prints together and for bonding prints to PVC just AVOID the fumes!!