Plastic Welding

[BIGBUCK]

Hi all
Has anyone ever plastic welded a saw?
I have a 372xp that is broke rite behind the front mount.
Is it fixable?

 

[caotropheus]

Probably yes. I do not know exactly what part of the saw you want to weld, or if it is made out of plastic, but yes you may try to weld plastic. If you want to weld plastic, first of all, clean thoroughly all your parts with hot water and detergent and after that with some solvent, then weld the parts in place with a soldering iron. After that, you need to reinforce your "welded" part with a "sandwich" of metal net of some kind. Cut a patch of net that covers the plastic component you just welded and with the soldering iron warm up the net and embed it in the plastic. Repeat the same operation on the other side of your plastic component. It should work out. The metal net I usually use is used as window screen against insects.

Don't forget to post pictures!

 

[kodiakyardboy]

Harbor freight used to sell one. I have used it a lot and it works really well. It comes with brass screening for reinforcement, and several different types of filler rods. Get yourself a kit if you don't want to wreck it. I have done the soldering iron method and have found that if you don't add filler, the repair won't hold as well. I have fixed ATV fenders, my plastic utility wood hauling sled, my kid's glasses, the door handle on my truck, and part of my boat dash. One use on an ATV fender would save you enough money for 6 of those welders.

 

[jmarheine]

I have done a repair on my dad's 372 in the exact same place as yours. I used both screen and filler material for this repair. You will need nylon filler material. My repair has seen some hard use and is holding up well.

 

[Hddnis]

I've done a bit of this and just finished learning even more about it for an upcoming project. You need filler material, most chainsaws use nylon which is one of the harder plastics to weld. They also use glass fiber for greater strength, usually around 30% by volume. Metal screen works, but makes a repair bulky and the screen can break from flexing. You can use fiberglass to reinforce your repair, but it is harder to work with than screen. Several feet of nylon filler rod is avaiable on ebay for about $20.00 shipped. The proper filler rod greatly increases the ease of repair and overall quality. A plastic welder with the right tips makes a huge difference; it should also have a temp control so you don't burn the plastic.

Like welding metal it takes practice and more practice.


Mr. HE

 

[MCW]

I've had the tank on one of my 7900's plastic welded after it split. Black nylon filler rods were what was used and although the colours don't match it has worked a treat. There are a few different plastics used in saws by many accounts so ensure the right filler rod type is used.
As Mr HE mentioned above fibreglass filler may be necessary if it is a higher load point.
Luckily I have a couple of mates that do this, one with a heat gun worth about AUD$700 + filler rods (who fixed my 7900) and the other with a full industrial plastic extrusion unit worth about AUD$8000 that feeds plastic rod in from a roll (like a MIG welder).
I think it would be cheaper and better to get it fixed professionally using the right equipment and tools rather than try to do it yourself but thats just my opinion.
Good luck mate.

 

[john inglis]

it may not be that relevant to this thread but i have used plastic cable ties as filler on many occasions with few problems , i have also found that the most reliable filler is usually a strip of identical plastic from another identical item , this applies to all weldable plastics , bumpers , saw covers etc . in rural australia its a little difficult to get some supplies within a reasonable time so sometimes it requires a little suck and see . if it works , great.

 

[kodiakyardboy]

it may not be that relevant to this thread but i have used plastic cable ties as filler on many occasions with few problems , i have also found that the most reliable filler is usually a strip of identical plastic from another identical item , this applies to all weldable plastics , bumpers , saw covers etc . in rural australia its a little difficult to get some supplies within a reasonable time so sometimes it requires a little suck and see . if it works , great.

Yes, if you are unsure what kind of filler to use, you need a piece of the same material. I did this on my utility sled, just cut a few strips off the top rail where it didn't matter. The commercial welder units are way easier to work with than the old soldering iron is. My friend bought a kit from ebay and it works quite well too.

 

[volks-man]

it may not be that relevant to this thread but i have used plastic cable ties as filler on many occasions with few problems , i have also found that the most reliable filler is usually a strip of identical plastic from another identical item , this applies to all weldable plastics , bumpers , saw covers etc . in rural australia its a little difficult to get some supplies within a reasonable time so sometimes it requires a little suck and see . if it works , great.

agreed.

i have used an old wood burning pen with great results. though my repairs have been on cracked tanks, not outright broken-off peices.

 

[thomasjf]

The filler I use for my saw repairs comes from a identical damaged donar part or from some place on the saw where strength is not important. Color and material are a perfect match.
I like the welded stainless screen for reinforcement, run it on the diagonal.