Broke An Old Tool

[Jim Frye]

I broke the shield on my favorite string trimmer the other day. I'm really bummed about it too. A bit of history, if I may. Back in 1995, I purchased Ryobi's new four stroke string trimmer, the 990R. This trimmer also had the ability to use attachments designed for the power head. The line was called "TrimmerPlus" and I quickly bought additional attachments for it. The 990R lasted a little over 15 years before the cam on the little OHV motor wore out. The repair would have cost more than a new one. By that time, Ryobi had sold their outdoor tool line to MTD, so I bought their four stroke version with the brand name TroyBilt, which came with a string trimmer attachment. The attachments used the same form factor, but was renamed "ExpandIt". The new power head lasted nearly another 15 years when it developed carburetor issues. That power head got replaced with a Ryobi 40 volt unit, which came with another string trimmer using the "ExpandIt" accessories. Now the reason for my dismay. I still use the original string trimmer head from 1995 because it has a larger shield and a larger, easier to refill spool. The later two trimmer heads are vastly inferior to the thirty year old one. The shield is in several pieces where it mounted to the trimmer body, so I looking to rebuild the shield with CA, epoxy and additional plastic.

[capncarl]

You can make one out of a frisbee that will last another 15 yrs. They don’t have to look like Darth Vader’s chin guard.

[Jim Frye]

Gave the cast aluminum trimmer housing a couple of applications of Dawn Powerwash, let it sit overnight and the 30 years of chlorophyll washed right off. Trip to the hardware store tomorrow for some thick CA glue and some epoxy and I'll start the rebuild.

[LCHIEN]

It's gonna be built like a tank with reactive armor and weighted down and beefed up with Jim's exclusive epoxy-lead filling.
I hope he's been eating his Wheaties to lift it and I fear for the weeds.

[Jim Frye]

OMG! I've been exposed! The parts that broke do have a shallow recess on top and after I get them back together, I was planning to fill the recess with the epoxy/lead mix to further hold things together. It won't be very thick. I measured it at 11/64" deep, so not much added weight.

[leehljp]

I am not totally skillful with it yet but plastic welding is very beneficial, and even in my less than perfect plastic welding skills - I can plastic weld and get stronger joints far more often than I can with most plastics with epoxy or super glue.

https://www.amazon.com/Upgraded-Plas...1zcF9hdGY&th=1

https://www.amazon.com/s?k=plastic+w...ps-ranker_1_15

[Jim Frye]

I've seen these. Many years ago (late '70s), SWMBO accidentally backed into the snowblower in the garage and cracked the plastic housing in several places. I had heard of plastic welding and used a 130 watt soldering gun and some plastic sprue from old model car kits to "weld" the housing back together. It wasn't pretty, but it worked for many, many years, and saved us a bunch of money in parts.

[leehljp]

"It wasn't pretty, " - That is where my skill level is in with plastic welding, but it does work.

[capncarl]

Another alternative? Clean it up and fiberglass and glass cloth it over .

[Jim Frye]

Absolutely, but I have all of the glues and plastic on hand and no fiberglassing stuff.

[Jim Frye]

Step One. Glued the broken parts back onto the main piece. I used Gorilla gel CA as there were some gaps from the breaks where the plastic stretched before it broke. I cleaned up the areas with a sharp knife and joined things back together. Interesting thing with the Gorilla glue. The instructions state to vigorously shake the bottle to mix the glue and then tap the capped tip sharply on a hard surface to load the glue into the tip before removing the cap. Turns out a lot of customers don't follow the instructions and claim the glue doesn't work.

[Jim Frye]

Step Two. The lead shot/epoxy infill. The mounting holes were taped over to prevent the shot and epoxy from running out of the cavities. May have to do a follow up epoxy application as there was a wee bit of leakage through a couple of pinholes in the gel glue joints.

[Jim Frye]

Step 3. I spent most of the day researching prescription insurance since our current provider just told us the premiums would be DOUBLING for next year. According to the carrier, it's due to the increased costs from tariffs. All carriers have doubled their prices for 2026. Anyway, I drilled out the three mounting holes in the shield from underneath so I could use them to drill out the add on plate I will add to the underside of the shield to reinforce the mend. I made a paper template and will use it to cut the plate from some 7/64" thick plastic I have as leftover from the shipping materials from my electric riding mower.

[LCHIEN]

Nice repair job. Good for another 20 years... may outlive you.

[Jim Frye]

Step four. The plastic backing piece was cut 1/4" wider on the convex side and the backside was tapered to mate with the shield to further reinforce the repair. I bonded the backing piece to the shield with e6000. This glue cures somewhat flexible and I thought it would provide some vibration protection. All of the edges were cleaned up with files and sandpaper and the mounting holes were drilled out. The shield was mounted with new, longer bolts as the mounting base on the shield is now thicker. While I as at it, I sharpened the line cutter, and re-lubed the gearbox. Maybe the rebuilt trimmer will outlast me.