Whats the best way to join bumper plastics ?

[MONSTER 0NE]

Hi im thinking about modifiying a front bumper from a different motor on to my van, but am wondering whats the best way to join different bits of bumper together after ive cut it to fit, any info would be appericated ?

[rover]

well AlanN seems to do very well with plastic welding so I reckon he's your man on this one

Rover.

[AlanN]

Ive been lucky so far and I did have a practice first. What I found is you must have a really close fit between the parts your trying to weld, if theres a gap, wider than 0.5mm then it will just seperate and you end up with a melted hole. Its just so much easier to join the parts in a nice flowing motion. When something didnt fit too well, I made some welding rods!!! Thin sticks cut from the same plastic, which I would feed into a joint just like solder, it worked so well. Im thinking about moulding some over riders from a MK4/5 in to a MK3, just as a an experiment at a later date... When someone donates some scrap ones.
I decided to bolt the spoiler onto the bumber so I can remove it easily... plus I didnt fancy welding a 5ft line
I used a soldering gun, but the only problem with them is that you can't hold the trigger for too long, but the plastic pools up lovely. A teflon variable temp soldering iron would the best thing to use, not one of those silly 17 watt jobs, but you have get by with what you have. I also used a paint stripper to soften the plastic to bend, fold and mould it around the ends
I think the key at the end of it all, is to use the Isopon bumper fill, none of these jobs would be possible without it.
Oh! one other thing, reinforce everything on the back, cut strips and weld them over the joints on the back if you welding in anything large like over rider-sided, as it will crack. I look forward to seeing your project bumper.

[MONSTER 0NE]

cheers for the info alan and so do i

[AlanN]

Dont forget the camera

[bazw]

the plastic weld (glue) you get in builders merchants for plumbing is supposed to work on dash and bumper plastics but i have not tried it yet

[AlanN]

It worked great on the grill, which I think is cPVC, the same as plumbing plastics, but didnt work on the bumper which is Polyethelene. I did try a few different glues from work as we use several different types of plastics and formed foam. I didnt try araldite as it sets hard, but maybe good to join parts that are out of sight...
Im having a little problem with the welding on one of the collars I have made... It has a re-occuring crack which maybe where the collar is still under tension and is trying to straighten itself out Im going to try and reweld it over the weekend.

[Jezclayton]

Polyethylene needs to be welded, forget about glue. What you require is some polyethylene welding rod. Some UK suppliers to try are:

Glass Aid
Unit 1, 9 Airfield Rd
Christchurch
Dorset, BH23 3TG
Country Code: UK
Phone Number: ( ) -
Fax Number: (011)441202484316
email:
Website:
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Smart Express
Unit 4 Dundas Spur
Copnor
Hants, PO3 5NX
Country Code: UK
Phone Number: +44 2392 621800
Fax Number: +44 2392 621808
email:
Website:
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WOW Automotive UK Ltd
The Unit 79A Meadow Rd.
Early, Reading, Berkshire, RG6 7EY
Country Code: UK
Phone Number: 078-108-90220
Fax Number:
email: markbirdseye@tiscali.co.uk
Website:

If you do an internet search under "weld polyethylene" you will find a wealth of useful information.

Regards

Jez