Plastic welding, any tips?

[Golf Houso]

Going to have a go at shaving my front bumper soon, does anyone have any advice, experience or good websites on the subject of plastic welding and/or bumper repair?

Cheers, Branko.

[jasn78]

mate also be interested in this as well

[DMS_Dan]

I tried a few times to fix a splash guard with a soldering iron and a scrap bit of plastic. It held up pretty well but didnt look to pretty. The actual plastic welding tools are pretty expensive i saw it demoed at a trade show, wasnt something i would do without some practice

[Preen59]

Probably one of those things that you should "leave to the professionals"...

Like re machining wheel centre bores.. ;)

[peedman]

Wear a mask.

[thestu]

wow none of those comments were helpful lol

did mickey do his own vr bumper? ask him how his was done :)

[DubSteve]

Its not that hard providing you can do it right lol.

[DubSteve]

did mickey do his own vr bumper? ask him how his was done :)

No that was my bumper lol.

[Golf Houso]

Probably one of those things that you should "leave to the professionals"...

Like re machining wheel centre bores.. ;)

If I wasn't an unemployed student I'd most certainly consider it, but unfortunately thats not the case ;) And besides, if you knew how cheap I got the spare bumper for you'd be doing the same!


wow none of those comments were helpful lol

did mickey do his own vr bumper? ask him how his was done :)

Well, has anyone here attempted it or does anyone have any information available? I'm aware that Raymond has done his, and quite well might I add, weren't you telling me Steve that you were doing some work on your own?

[abreut]

I have done a bit of amateur plastic welding with a soldering iron. I just kind of stitched the joins by dragging material from one part to the other. It helps if the two plastics are similar and some plastics work better than others. Obviously its going to end up being more brittle than original but you're probably not planning on flexing the bumper too much anyway! You'll have to go over it with bog or some other filler to get a smooth finish regardless. I'm not really sure what kind of areas you need to join but you can always use some fibreglass backing/reinforcing behind as well.

[Lorenz]

Ive been having a go at a spare bumper I bought aswell. It was a bit harder than I first expected and time consuming so you have to be patient and expect it to not work first time around! I got impatient and pee'd off so kinda stopped and will have another crack when Im really keen!

I will find the link to a site with a great DIY on shaving a MK3 front bar, he makes it look and seem too damn simple :(

[Preen59]

Well if you want to be tight fisted..

From what i've been told by a guy that's done a bit.. Melt the plastic on the bumper and smell it.. Find another piece of plastic to use as a filler rod that smells the same or very similar when you melt it.

Then you just melt the two edges and push the filler rod in and melt it as you go to bond the two parent materials together.

Easy.. :S haha.


There you go. I was helpful and everything.

[madglf3]

You guys should ask rayray the DIY KING, he did his didn't he?

[Mrk_Mickey]

You guys should ask rayray the DIY KING, he did his didn't he?

Yeah he did, there's a writeup on his blog I think! If he comes online tonight I'm sure he'll see this and (shout for joy...) post the link :nana:


Well if you want to be tight fisted..

From what i've been told by a guy that's done a bit.. Melt the plastic on the bumper and smell it.. Find another piece of plastic to use as a filler rod that smells the same or very similar when you melt it.

Then you just melt the two edges and push the filler rod in and melt it as you go to bond the two parent materials together.

Easy.. :S haha.


There you go. I was helpful and everything.

Bahaha...sounds just like normal welding! Easy! (Wait...I need to know how to do THAT first :duh:)

Yeah I'd love to do some more shaving on my car...it'd be nice to learn how to do properly, too!

[rayray086]

From what i've been told by a guy that's done a bit.. Melt the plastic on the bumper and smell it.. Find another piece of plastic to use as a filler rod that smells the same or very similar when you melt it.

Yep, sounds hicky but that's one of the most important part of plastic welding. Gotta use the same material that you're welding into! A rear bumper for scraps will do well. For DIY plastic welding, it's best just to use it as a way of keeping the panel in position so you can fix the rest of it on permanently without it shifting. Plastic products are created under pressure and certain temperatures so there's no way you can get the same kind of strength.

I just use a soldering iron with a flat-bladed tip. I get decent results by tacking weld points about an inch away from each other so it holds on nicely. I then join the "tack welds" by applying pressure and running the tip right in the middle, going slow enough so it melts it together. Do this all the way around the panel on the front side.

Next is just use a good epoxy bond or fibreglass and work it over the rear. Remember to scuff up the surface for better bonding. Try not to leave any air bubbles/gaps - hot air expands and it could potentially be easier for the bumper to crack later on.

Once that's fixed in place, use plastic filler (I use UPOL's PlastX which I got from VG Autos, pretty much across the road from Seb's workshop) to clean up the front. Plastic filler flexes a lot more than regular filler so it should reduce the chances of it cracking when you move the bumper around. Again, make sure the surface is very well scuffed and cleaned for maximal adhesion.

The bumper I first did was plastic welded the entire way around without any rear reinforcement, with just plastic filler on the front. The bumper's now cracked around the plastic welded part cos it had rubbed against the fence (I fail at driving) and same goes with the rear exhaust cut-out delete as well.

So yeah, just make sure the surface is very well scuffed and thoroughly cleaned before you lay on the epoxy and fillers. It'll help a great deal.

For pic references, search "Joey Russo" in the Mk3 section of the Vortex. You should find a pretty recent topic on a DIY on plastic welding.

[Golf Houso]

Thank you very much for the input guys, some valulable tips there. I've gotten a sheet of a very similar plastic which has a slightly lower melting point than the ABS, which isn't that great but is still ok to work with. I'll start practicing on some offcuts before I attack the bumper :)

Oh and I've busted my VR lip already, I might have a go at trying to fix that first :duh:

[rayray086]

Our front bumpers are PP+EPDM! The grille slats, lower duct pieces and side mirrors are ABS though.

It's not a case of similar melting point either... they may mix around once melted but they might not actually bond together well enough once they reach back to room temperature again! It's all chemistry though.

[DubSteve]

So in turn use front bars on front bars and rears on rears?

[Lorenz]

Rear bars and front bars should be the same plastic, thats what me and Ray have been using :)

[Mrk_Mickey]

So in turn use front bars on front bars and rears on rears?

rears and fronts are fine to use together, it's just the lips/trim (textured) and the front bar accessories like the grilles and stuff that are different materials.

[KI11Z]

WEAR A ****ING MASK!! Unless your a stoner :biggrin: and just practise, i dont think its that hard?!

[Mrk_Mickey]

WEAR A ****ING MASK!! Unless your a stoner :biggrin: and just practise, i dont think its that hard?!

Hah, one of the most important processes! Good boy hahah

Yeah with practice all things become easier. Once you get the hang of something there's noooooo going back!

[mk5 golf]

Hi guys, I've had the front bumper on my black '05 2.0 FSI damaged the other day and was wondering about this plastic welding thing as one of the members here suggested it. I haven't decided yet on whether to replace the whole bumper or just repair the damaged part on lower passenger side. Here are some of the photos taken on mobile:

http://s992.photobucket.com/albums/af50/mk5golf09/?action=view&current=SNC00430.jpg

http://s992.photobucket.com/albums/af50/mk5golf09/?action=view&current=SNC00429-1.jpg

I am not even sure what's under that area and has been damaged/fallen out. That's another thing that I will get looked at but with plastic welding on my damaged bumper, how would the finish look look like in general? Is it like noticeable? And could anyone recommend a good plastic welder in Sydney that they used? I've googled and found some but they don't always deal only with car parts. The bumper itself is in very good condition and so I wouldn't want to spend too much money or use insurance on replacing it. Thanks for any info/advice.

[Golf Houso]

Hi guys, I've had the front bumper on my black '05 2.0 FSI damaged the other day and was wondering about this plastic welding thing as one of the members here suggested it. I haven't decided yet on whether to replace the whole bumper or just repair the damaged part on lower passenger side. Here are some of the photos taken on mobile:

http://s992.photobucket.com/albums/af50/mk5golf09/?action=view&current=SNC00430.jpg

http://s992.photobucket.com/albums/af50/mk5golf09/?action=view&current=SNC00429-1.jpg

I am not even sure what's under that area and has been damaged/fallen out. That's another thing that I will get looked at but with plastic welding on my damaged bumper, how would the finish look look like in general? Is it like noticeable? And could anyone recommend a good plastic welder in Sydney that they used? I've googled and found some but they don't always deal only with car parts. The bumper itself is in very good condition and so I wouldn't want to spend too much money or use insurance on replacing it. Thanks for any info/advice.

Errrggg... I'd just get a new bumper, you could plastic weld a crack together but not reconstruct that, wouldn't be worth the time...

[Transporter]

Hi guys, I've had the front bumper on my black '05 2.0 FSI damaged the other day and was wondering about this plastic welding thing as one of the members here suggested it. I haven't decided yet on whether to replace the whole bumper or just repair the damaged part on lower passenger side. Here are some of the photos taken on mobile:

http://s992.photobucket.com/albums/af50/mk5golf09/?action=view&current=SNC00430.jpg

http://s992.photobucket.com/albums/af50/mk5golf09/?action=view&current=SNC00429-1.jpg

I am not even sure what's under that area and has been damaged/fallen out. That's another thing that I will get looked at but with plastic welding on my damaged bumper, how would the finish look look like in general? Is it like noticeable? And could anyone recommend a good plastic welder in Sydney that they used? I've googled and found some but they don't always deal only with car parts. The bumper itself is in very good condition and so I wouldn't want to spend too much money or use insurance on replacing it. Thanks for any info/advice.

You can try Q-bond, I used it to glue sliding door handle in our house and 5 years later it is still in one piece. You can quickly build up missing bits since it sets in less than 10s.

It is designed for gluing automotive components. I think that the dentists were using it as well, long time ago .

Good product.

[mk5 golf]

Errrggg... I'd just get a new bumper, you could plastic weld a crack together but not reconstruct that, wouldn't be worth the time...


You can try Q-bond, I used it to glue sliding door handle in our house and 5 years later it is still in one piece. You can quickly build up missing bits since it sets in less than 10s.

It is designed for gluing automotive components. I think that the dentists were using it as well, long time ago .

Good product.

Ok.. I've also seen some cracks on bumper being welded on the web but wasn't so sure if it's doable in my case. I just thought it may be worth considering as the bumper is like brand new other than that. I guess I will just find out how much a front bumper costs first.. including spraying and maybe just get it replaced. Thanks for the advice.

Transporter, thanks for the information.

[DMS_Dan]

New bar inc fitting and painting will cost you around $1000

[Jace]

I work for a plastics business.
We use a lot of Loctite products, including their 40X range and catalysts/accelerators.
If you're not afraid to sand and glue and sand some more, and fork out a bit of cash for Loctite products, then you'll be able to get a good DIY job.
I'm not sure about the type of plastic you'd be fixing, But try:
Loctite 401 or 406 as glues, Loctite 7452 as catalyst (spray onto the glue) and some fiberglass matting, to lay over the cracks/breaks.

Tools that will be super handy include:
A dremel
An Air Grinder/File/Sander
Power Sander
Lots of sandpaper (P150, P240, P320, 600/800 wet & dry, maybe 1200wet also)

There's no special skill required. It's easier than you'd think.

Edit: didn't look at your pictures. I assumed it was a clean break for some reason...
Good luck!

[Golf Houso]

Its interesting to see now I'm actually about 80% through my fully shaved and plastic welded front bar on my MK3 considering I started this thread, I'll take a few pics when I get the chance :banana:

[mk5 golf]

New bar inc fitting and painting will cost you around $1000

Thanks for that.


I work for a plastics business.
We use a lot of Loctite products, including their 40X range and catalysts/accelerators.
If you're not afraid to sand and glue and sand some more, and fork out a bit of cash for Loctite products, then you'll be able to get a good DIY job.
I'm not sure about the type of plastic you'd be fixing, But try:
Loctite 401 or 406 as glues, Loctite 7452 as catalyst (spray onto the glue) and some fiberglass matting, to lay over the cracks/breaks.

Tools that will be super handy include:
A dremel
An Air Grinder/File/Sander
Power Sander
Lots of sandpaper (P150, P240, P320, 600/800 wet & dry, maybe 1200wet also)

There's no special skill required. It's easier than you'd think.

Edit: didn't look at your pictures. I assumed it was a clean break for some reason...
Good luck!

Thanks for the information. I think I will give it a miss this time.. there is no way I can make it glossy like new. I am not very good with my hands.. thanks anyway.