Upgrading A Line Trimmer With 3D Printed Parts

Many have complained about the hassle of rewinding their weed whackers with fresh trimmer line. Manufacturers responded by making models with solid plastic blades instead. Some of these suck, though, like this Ozito model belonging to [Random Sequence]. 3D printing was the way forward, adapting the blade trimmer to use traditional line.

The design is simple. [Random Sequence] created a small plastic tab which matches the attachment tab of the Ozito trimmer’s plastic blades. On the end of the tab, in lieu of a blade is a round slot into which a length of trimmer line can be inserted. The trick is to use a cigarette lighter to slightly melt a bulb onto a length of trimmer line so that it doesn’t pull through the slot. Centrifugal force (argue about it in the comments) keeps the line from falling out.

[Random Sequence] prints them in PETG, but notes that the part could benefit from additional strength. They do break when hitting tough objects, much like the stock trimmer blades do. Also, unlike a bump-feed trimmer head, there’s no way to auto-feed more line. Instead, one must simply assemble more of the tab-adapters with fresh line manually.

Overall, though, it’s a great way to fit stronger, more capable trimmer line to a weed whacker otherwise hamstrung by weak blades. It’s reported to work with Ozito and potentially Bosch tirmmers, and parts are on Thingiverse for those wishing to print their own.

Just as string trimmer line was once used as 3D printing filament, you can also go the other way, turning old plastic bottles into trimmer line. If you’ve whipped up your own fun hacks for tools in the garden, don’t hesitate to let us know.

Sound off with your best name for a weed whacker in the comments, too. The Australians may hold the title with “whipper snipper,” but we’re open to other submissions!

23 thoughts on “Upgrading A Line Trimmer With 3D Printed Parts

    1. yup same here, I’m using bike brake cables.
      Ideally not use it when wearing flip flips, or thongs for our Australian friends. Better not wear thongs in the rest of the world either, although in the rest of the world those (don’t) protect something else.

  1. “Sound off with your best name for a weed whacker in the comments, too. The Australians may hold the title with “whipper snipper,” but we’re open to other submissions!”

    My favorite name is “free”, picked up from a curb (3 so far).

  2. The original PivoTrim by Oregon was the best. The patent must of passed it’s expiration date because Oregon left the market and it has been flooded with look a like Chinese copies that stink. They say “fits 98% of trimmers”, which is not true because it does not fit the Ryobi Expand It trimmers sold by Home Depot.

    The plastic pivots do not work the same, not shaped the same, the holes are too small for 0.095 line, it is shaped different, and weighs so much more it actually slows down my 30cc Cub Cadet. I imagine it is unusable on the more common 23cc trimmers. Even worse then that, the lines down break when hitting chain link fence where they would not before. Which was the original reason for buying it.

    The Harbor Freight 80v trimmer and line feeder is actually pretty good compared to others, but, is not close to the original performance and convenience of the original PivoTrim sold by Oregon. Especially if you dislike getting hit and covered with the stuff you are trimming such as ivy and stones since the shield is badly engineered and designed. I know someone that almost lost an eye to a stone to his pupil because he was not wearing safety glasses and a full face shield like I usually do.

    Because the battery powered trimmers operate in the opposite direction of most gas powered trimmers, you can not use a superior designed gas powered shield from the commodity Ryobi on the HF trimmer named to honor their free mason god.

    I posted elsewhere how to adapt the new Chinese copy of PivoTrim to get it to work with the gas Ryobi Expand It trimmers. Basically use HD’s own kit $16 and rob the left handed nuts and adapters that fit the hole of the newer version and use a stand off adapter to get the original height spacing back.

    1. Swap 2 motor leads (2 of 3 if it’s a brushless and you might have to figure out the correct hall sensor sequence too) and suddenly it’s operating in the “right” direction?

    2. “I posted elsewhere how to”

      I’d love to see that.

      I have a couple of those Ryobi electric trimmers and a gas one. I was stuck on gas for years thinking electric wouldn’t have enough power. Finally I got sick of having one item, with such a tiny engine that used a specific mix of oil and gas. It always runs like crap because even if I mix the smallest amount the oil bottle has directions for that is still too much and I can’t use it up before the gas gets old! Then there’s the diaphram in the carb that is always getting eaten and needing replacement, I guess by the Ethanol. Maybe if I drove all the way across the city to get boat fuel… Not worth it!

      So anyway, the Ryobi trimmers. Yah, they work well and are a lot more convenient to use than gas. Except… the directions say they should automatically let out a little line each time the trigger is released. Mine both do the opposite! They suck the line back in. If I don’t reach down and press the button to manually release a little more line each time before I press the trigger it will suck it all the way back in so I have to pop it open to get it back out. Of course about every 3rd or 4th time I do that I end up dropping the spool which then unwinds itself leaving me to re-wind the whole thing. Even worse, sometimes even when I do press the button it sucks the whole thing back in as soon as I start to use it.

      So I’ve been looking at alternative heads to put on one of the Ryobis.

      1. Solution to old gas problem, 2 stroke mower and car.

        Both getting hard to find in California. IIRC the cars are English, so suck at everything but irritating hippies. Lucas electrics.

        They’ll get my 2 stroke mower from my cold dead fingers! It’s great, already 20 MTD mower lives old (possibly 40 MTD mower lives, YMWV, but not in a good way).

      2. There’s a Ryobi head that uses quick change blades that are available as off brand. Mine only lets the line out when the spool is full. The blades are heavier though and will eat through a battery faster. If there was a manual head like on gas trimmers I’d prefer that to having to hit the button whenever I break the string.

      3. Hi,

        This was all I could recover from wherever I had posted, my original links and text have been deleted from the forum(s). Maybe because they contained a link to the Home Depot trimmer head you needed for the parts bag. Anyway, buy the fake PivoTrim, no longer made by Oregon, drill out the holes so they are larger for the 0.090 string, use their supplied bolts, then buy the cheaper trimmer head kit from Home Depot for their parts bag, and assemble in this order.

        The pictures pretty much explain everything:




        Here is the original compared to the clone:


        In the FWIW category the 80V Atlas string trimmer head works well.

        If you wanted to try to rescue the original or copy it, since there is still one pivot not broken, though the bottom needs redone, I could send it to you for the cost of postage, $10 ?. I think it will fit into a small priority box.

  3. Echo makes a great head in which you just stick the string into the two holes and twist. The string gets pulled in and winds itself without the the struggle. https://www.echotools.com/en_us/products/accessories/rl-25 This product is for straight shaft trimmers as curved shaft trimmers rotate the other way. They also sell this product https://www.echotools.com/en_us/products/accessories/trimmer-heads/3-line_rapid_loader in which you have to pre-cut line and insert it into the head. This product works with both the curved and straight shaft models. As far as names for the device it is a weed whip, string trimmer, weedo pronounced weed-oh, and weed trimmer. I worked as a golf course mechanic for about 8 years and hence my knowledge on the subject. One day I was driving the course to look at things and saw one of the workers running for a few feet stopping, weed whipping, running, stopping, weed whipping, and was confused by his actions. I drove over to him and he was chasing and weed whipping a Possum. I put and end to that post-haste.

  4. my line trimmer is designed to let out two strings at once, so winding its cartridge was extra-fiddley. what i did is just took out their cartridge and 3d printed a couple pieces that friction fit into the space where the cartridge used to be, and when they’re in position they pinch a piece of the nylon string in between one of the pieces and the motor spindle. to make sure the string doesn’t walk itself out, i tie a half hitch knot in one side of it.

    the other thing i improved is i bought a giant 855 foot spool of .095″ nylon for only $30. the trimmer originally came with 0.065″, so it’s considerably thicker…i get on the order of 2-4 hours of runtime per 18″ string before it gets too short from running it into rocks and fence posts and things. so i load it 2-3 times a summer. loading it just requires a screwdriver to lever out the piece.

    i’m this because that’s my “time-tested” counterpoint to the concerns i have with [Random Sequence]’s design. where they went for an elegant-looking approach that has the downside of carrying significant force through weak FDM plastic, i instead went for a kind of braindead hack with the advantage that it never carries any force to speak of!

    i haven’t used this “clear” (white) PLA since 2014. it’s an *awful* filament that is extremely brittle and unsuitable for any use. but this part has nonetheless done constant trouble-free duty since 2014, stored outside half the year. all thanks to its extremely unambitious design.


  5. A better hack. Create true and good, bio-degradable trimmer wire. Every day around the world, these machines transform tons of crappy chinese plastics into micro-plastics, spreading them in the environment. That and the use of mineral oil in chainsaws are big problems that most people choose to ignore.

    1. > tons of crappy chinese plastics into micro-plastics, spreading them in the environment.

      Good point, I try to pick up the extra flung pieces when possible, but, I never really though of it as spreading micro plastics everywhere. Unfortunately I am not allowed to have “livestock”, otherwise I would just be as happy trimming everything with a goat.

      I have tried non-petro lube in my smaller chainsaws, but, it overheats the bar. I guess if I get brave enough $ I can try the veggie oil thing that some chainsaw OEMs sell.

  6. I have a few 3d printers but you need to know when to use them. Not in this case (and in many other cases I’ve seen here on hackaday). Like others here I modified my trimmer long ago to use old bike cables when I have them or old clothesline cable or old wire from discarded appliances, etc (ie: use up the junk you have first). Lasts much longer than plastic and junk is free. Create an eyelet on each cable piece by bending the end and wrapping a twist tie or one strand from a stranded copper wire then hold each one in place with a screw or both. Works just fine.

  7. I have learned about Harbor Freight tools from the North Americans on here. Ozito is the Australian equivalent. Future e-waste sold by the containerload from our big box hardware store that has pushed all the local hardware stores out of business.

    Then again, for domestic use, a tool that is rated for dozens of hours is probably suffucient for many summers to come. Just don’t use Ozito tools for your regular job. Of course, I welcome comments and exceptions, fire away…

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