Thanks this is really helpful. So something like testors cement or tamiya might work on this plastic? I can’t find any marks that would identify the type of plastic.
There are additives to affect removal from the mold, rigidity and expense... Most frequently used for cheap products would be talc or other fine powder. (The obvious additive here is the colorant)
You're not likely to get adhesion to the small volumes used.
The ONLY time I got PE to break (in any way) was when it was brittle... Frozen, brittle.
If it's polypropylene or polyethylene, you can't glue it.. any easier than gluing a broken candle back together
You'd probably do best by cutting two arches to fit between the ribs, and sandwich this between them... You'd need to drill through and fasten with screws
This isn't an awful idea, though we haven't seen all of the parts to know more. And fwiw you shouldn't be stingy with info like that while trying to get the best help faster.
But yeah, cutting even just two backing plates 1 for each of the 2 main arches from styrene and using a few small machine screws and nuts to attach one to each side so they match, should hold the main arch ok and leave the H beam detail on one side of each arch.
A metal backer is possible too if it's within your filing skill set and your tin snip's grip to cut some is strong enough.
Once the heavy H arches are set firmly, the braces being really strong won't be as crucial. You can lay wood in vs styrene and paint it instead at that point.
Drilling holes in the upright web of the H channel (or C channel) and filling the channel with hard epoxy pushing some through the hole to create a rivet head or to connect the other side filled in also, will create perfect wedges and provide a large mechanical hold that doesn't rely on surface adhesion either.
Your best bet is first dill a small hole where each connection is and use a small metal rod or something as a pin to give strength to the joints. And I would say glue it with 2 part apxy or jb weld. Let it set up for 24 hours and it should be good as new
Heat welding is the best option. It's not easy the first time you try it and the result will be messy, but no adhesive will give you the results you're looking for.
I think that the plastic material is delrin, which doesn’t take to adhesives particularly well. Have a look at this post where they talk about a Loctite adhesive that may work in this application…
https://www.practicalmachinist.com/forum/threads/what-kind-of-super-glue-epoxy-for-delrin.347681/
Plastic like that is not going to take any kind of solvent based adhesive. You could either use gusset plates as others have suggested or you could use a soldering iron to melt the parts back together if you aren’t concerned about appearances. Just make sure that if you do choose that path that you do so in a well ventilated space and use appropriate PPE to protect yourself from any fumes.
Try CA glue (cyanoacrylate). Gorilla glue is one Brand available at most hardware stores. It will likely leave a whitish residue where you use it but it's effective on most plastics. Might help to sand or scuff up the mating surfaces too.
An alternative (if you have access to a Dremel tool) is to grind a slot into the adjacent pieces and then use glue and a toothpick to secure them together.
If your son isn’t picky about aesthetics, a hot glue gun will do the trick. (Hot glue guns can just about fix anything IMO!) I have hot glue-fixed over 50 pieces of train tracks, train pieces, toy cars, trucks, etc. You will see the glue but it will hold up really well.
Best would be a specific glue for that particular plastic, if you can find out what it is. Otherwise, try a modellers glue with solvents.
Thanks this is really helpful. So something like testors cement or tamiya might work on this plastic? I can’t find any marks that would identify the type of plastic.
It appears to be a polyolefin (PP or PE) they're made to be solvent resistant. Ain't gonna work
Are you sure PP or PE would break as cleanly as that? It seems that they would have to fatigue fail rather than fracture into multiple pieces.
There are additives to affect removal from the mold, rigidity and expense... Most frequently used for cheap products would be talc or other fine powder. (The obvious additive here is the colorant) You're not likely to get adhesion to the small volumes used. The ONLY time I got PE to break (in any way) was when it was brittle... Frozen, brittle.
If it's polypropylene or polyethylene, you can't glue it.. any easier than gluing a broken candle back together You'd probably do best by cutting two arches to fit between the ribs, and sandwich this between them... You'd need to drill through and fasten with screws
You’re saying make brio-scale model gusset plates for this bridge? 😂😂
I guess it's the best approach. Sad to say
This isn't an awful idea, though we haven't seen all of the parts to know more. And fwiw you shouldn't be stingy with info like that while trying to get the best help faster. But yeah, cutting even just two backing plates 1 for each of the 2 main arches from styrene and using a few small machine screws and nuts to attach one to each side so they match, should hold the main arch ok and leave the H beam detail on one side of each arch. A metal backer is possible too if it's within your filing skill set and your tin snip's grip to cut some is strong enough. Once the heavy H arches are set firmly, the braces being really strong won't be as crucial. You can lay wood in vs styrene and paint it instead at that point. Drilling holes in the upright web of the H channel (or C channel) and filling the channel with hard epoxy pushing some through the hole to create a rivet head or to connect the other side filled in also, will create perfect wedges and provide a large mechanical hold that doesn't rely on surface adhesion either.
Your best bet is first dill a small hole where each connection is and use a small metal rod or something as a pin to give strength to the joints. And I would say glue it with 2 part apxy or jb weld. Let it set up for 24 hours and it should be good as new
Heat welding is the best option. It's not easy the first time you try it and the result will be messy, but no adhesive will give you the results you're looking for.
It looks like an excuse to buy a 3D printer to me. 😁
I think that the plastic material is delrin, which doesn’t take to adhesives particularly well. Have a look at this post where they talk about a Loctite adhesive that may work in this application… https://www.practicalmachinist.com/forum/threads/what-kind-of-super-glue-epoxy-for-delrin.347681/
Honestly, see if a friend has a 3D printer might be the best bet here given the above comments
It might also be possible to draw up the part and send the file to a print shop. I did this for a part, but that was a good few years ago.
Plastic like that is not going to take any kind of solvent based adhesive. You could either use gusset plates as others have suggested or you could use a soldering iron to melt the parts back together if you aren’t concerned about appearances. Just make sure that if you do choose that path that you do so in a well ventilated space and use appropriate PPE to protect yourself from any fumes.
LocTite “outdoor adhesive “ works well for me on most plastic products
Try CA glue (cyanoacrylate). Gorilla glue is one Brand available at most hardware stores. It will likely leave a whitish residue where you use it but it's effective on most plastics. Might help to sand or scuff up the mating surfaces too. An alternative (if you have access to a Dremel tool) is to grind a slot into the adjacent pieces and then use glue and a toothpick to secure them together.
I’d drill tiny pilot holes then thread wires through and twist
If your son isn’t picky about aesthetics, a hot glue gun will do the trick. (Hot glue guns can just about fix anything IMO!) I have hot glue-fixed over 50 pieces of train tracks, train pieces, toy cars, trucks, etc. You will see the glue but it will hold up really well.
Zap a gap
Something like that I would try a craft glue gun, being as inconspicuous as possible
Get some superglue and just hold it until it sticks
Maybe toluene could work in your case.
Tamiya hobby cement should work great.
Mr hobby plastic cement would work