MadaboutKitcars

Not related to Tribute's fine offerings but I have twatted the bumper on the Mighty Merc driving slowly into an unseen raised kerb. I don't really want to replace the whole thing because of one small crack but it won't glue shut.

I have seen some videos of guys using soldering irons and similar to 'weld' broken bumpers together.

Anyone tried this?
Hints and tips if you have please.

Photos to follow of my attempts, possibly followed by buying a new bumper

I did some repairs to cracked motorbike fairings using a soldering iron and some cable ties as the solder haha
if you do it from the back you can use the cable tie to bond everything together, have a practice on some scrap plastic to get a feel of the depth you will need to melt to get the bonding secure

Could you not add fiberglass on the inside of the crack or is the point to have a go at plastic welding?

You'll need to key up the bumper to give the fibreglass something to stick to. It's one of the few things it won't stick to, unlike skin and hair!

Apparently the stuff they make bumpers of is really difficult to get stuff to stick to it. Superglue and epoxy don't do a thing apparently.

I am hoping that the melt weld with additional ABS filament from my 3D printer will work. I then need some plastic filler and paint the area.

Worse case is I replace the bumper which is where I am now.

Will plastic filler have the same not-stick properties of GRP resin? If it's only a small crack, is it maybe worth (at least) getting a quote from a pro repair place?

With the same proviso- test on something else or an unseen area first- OSMA waste pipes are sometimes glued with a solvent based liquid. Too much and you'll have a sticky mess on the drive and a fully frontal nude Merc...

Google: SAFETY DATA SHEET OSMA SOLVENT CEMENT NO.2

You will need one of those soldering irons designed for plastic welding.
The hardest thing is finding the right plastic welding sticks, you will need to buy a range, then it is trial and error.
The end result will not be as strong and will look a bit of a mess from the inside, but will retain flexibility.
If you are going to do it, practice on some scrap first, it isn't easy.

Might get it done properly then

Have you considered a kit like this one?
https://motornuts.co.uk/pbf-kit

That is like what I was going to use after fixing the cracks. Still need to weld the cracks shut first though.

A local body shop won't charge a lot of you take along a bumper and get them to weld it, especially on a Saturday morning with cash.