Jump to content
UltiMaker Community of 3D Printing Experts

UMO B&B Manufacturing 298MXL025G Replacement Long Belt Set Review

Recommended Posts

Posted (edited) · UMO B&B Manufacturing 298MXL025G Replacement Long Belt Set Review

I suspect that more than a few members here may have older UMs with aging stretched belts and might benefit from my experiences with belt replacements.

I removed my short belt drive mechanisms and replaced them with direct drive over a year ago:


You can checkout the "Made" link in the above page for my photos and notes. After installing the direct drive components, my UM became quieter and it required virtually no belt adjustments. (I re-bent my clothespin spring adjusters once.) I've tried several cool-looking printed manual tensioners, but I prefer the self-adjusting long belt clothespin spring tensioners, barely ever require any manual adjustment or maintenance.

Almost immediately after assembling my new UMO over three years ago, I felt the supplied belts were a touch on the long side. After a short break-in period, the 3 mm screws and nuts in the belt "claws" of the slider blocks ran out of their extremely limited adjustment range. I suspect the screws and nuts were added by UM designers when they discovered that the claw did not result in sufficient tension of the 300 mm long belts and supplies of a slightly smaller belt size were problematic, due poor market availability. Regardless of the reasons for the 3 mm hardware, it is really a poor excuse for a belt tensioner!

Thus I ran perfectly satisfactory, but kludgy-looking, clothespin springs for over three years. Recently, even bending the springs as much as possible, to maximize the tension of my aging belts, resulted in the springs rubbing gently on the UM's frame and still somewhat inadequate tension. (I could no longer "jump" reliably at 300 mm/sec!) I knew it was time to replace my long belts.

Rather than buying 300 mm replacements, I decided to special order 298 mm belts from B&B Manufacturing in the U.S.:


Unfortunately, BBMan charges some pretty hefty extra shipping and handling fees but also discounts quantity buy levels. Accordingly, I ordered 12 belts to more favorably amortize the $17.42 USD shipping and handling charges, which is an outrageous sum for an order quantity that fits in a medium size envelope! The total charges, delivered to my door about two months later, were $63.26 ($15.82 per long belt set), but now I probably have more than a lifetime supply of UMO belts!

The 298MXL belts are the perfect size for use without any extra 3 mm claw tensioner hardware. (The wooden claw part alone results in perfect tension.) The 298 belts were slightly more difficult to install than the original 300s, and they were on the tight, but still acceptable side, in a belt pitch tone test before break-in (I think tone is the best way to check UMO belt tension), but they are perfect after a couple of prints worth of break-in time:


(I don't know why UM doesn't emphasize the above method, because any belt tension evaluation that is based on belt deflection depends on providing a known and standard pull force on the belt!)

I expect to get maximum service life from these belts, because no extra tensioner is needed initially, as it was with my original UMO 300 mm belts. I'll probably add my clothespin springs again, when necessary, for set and forget convenience, but the original 3 mm claw hardware could also be used to extend my 298 mm belt service life beyond what it can accomplish in tensioning the original belts too.

Edited by Guest
  • Link to post
    Share on other sites

    Posted · UMO B&B Manufacturing 298MXL025G Replacement Long Belt Set Review

    Interesting video. I'm definitely going to look at my printers later tonight to check the tension.

    Thanks for sharing and for the possible replacement source.

    Did you look at replacing them with the original one from fbrc8?


    Would probably have been less expensive.

  • Link to post
    Share on other sites

    Posted (edited) · UMO B&B Manufacturing 298MXL025G Replacement Long Belt Set Review

    Did you look at replacing them with the original one from fbrc8?


    Yes--most definitely! I've purchased parts from fbrc8 and it is an excellent vendor. I was very pleased when fbrc8 got a contract with UM Ltd. to be a support partner in the USA.

    Yes--fbrc8 would have been cheaper in the short term, but I don't need the short belts in the set and assuming that I keep my UMO for a long time or another direct drive UMO mod'er needs only a set of long belts, I think the B&B belts will work out to be more economical in the long run. They fit better than the original belts initially and have more room to stretch with any given tensioner. They fit so well that, hopefully my machine will not need any belt tensioners at all for a long while.

    Also, I probably could have continued to use the old belts with some other type of manual adjuster that could take up more of the slack, but clothespin springs are my favorites. They are "set and forget" and they feature a fairly wide adjustment range too. However, I can think of a couple of non-spring adjusters that might be able to take-up even more belt slack.

    On the other hand, the tooth spacing is continually increasing when belts age and stretch, so maybe a new tensioner would not have re-enabled 300+ mm/sec jumps for me, which  helps with stringing and hairs in nylon prints.

    Edited by Guest
    • Like 1
    Link to post
    Share on other sites

    Create an account or sign in to comment

    You need to be a member in order to leave a comment

    Create an account

    Sign up for a new account in our community. It's easy!

    Register a new account

    Sign in

    Already have an account? Sign in here.

    Sign In Now

    • Our picks

      • Here it is. The new UltiMaker S7
        The UltiMaker S7 is built on the success of the UltiMaker S5 and its design decisions were heavily based on feedback from customers.
        So what’s new?
        The obvious change is the S7’s height. It now includes an integrated Air Manager. This filters the exhaust air of every print and also improves build temperature stability. To further enclose the build chamber the S7 only has one magnetically latched door.
        The build stack has also been completely redesigned. A PEI-coated flexible steel build plate makes a big difference to productivity. Not only do you not need tools to pop a printed part off. But we also don’t recommend using or adhesion structures for UltiMaker materials (except PC, because...it’s PC). Along with that, 4 pins and 25 magnets make it easy to replace the flex plate perfectly – even with one hand.
        The re-engineered print head has an inductive sensor which reduces noise when probing the build plate. This effectively makes it much harder to not achieve a perfect first layer, improving overall print success. We also reversed the front fan direction (fewer plastic hairs, less maintenance), made the print core door magnets stronger, and add a sensor that helps avoid flooding.

        The UltiMaker S7 also includes quality of life improvements:
        Reliable bed tilt compensation (no more thumbscrews) 2.4 and 5 GHz Wi-Fi A 1080p camera (mounted higher for a better view) Compatibility with 280+ Marketplace materials Compatibility with S5 project files (no reslicing needed) And a whole lot more  
        Curious to see the S7 in action?
        We’re hosting a free tech demo on February 7.
        It will be live and you can ask any questions to our CTO, Miguel Calvo.
        Register here for the Webinar
          • Like
        • 7 replies
      • UltiMaker Cura 5.3.0-Alpha 🎄 Tree Support Spotlight 🎄
        Are you a fan of tree support, but dislike the removal process and the amount of filament it uses? Then we would like to invite you to try this special release of UltiMaker Cura. Brought to you by our special community contributor @thomasrahm
        We generated a special version of Cura 5.2 called 5.3.0 Alpha + Xmas. The only changes we introduced compared to UltiMaker Cura 5.2.1 are those which are needed for the new supports. So keep in mind, this is not a sneak peek for Cura 5.3 (there are some really cool new features coming up) but a spotlight release highlighting this new version of tree supports.  
          • Like
        • 16 replies
      • New here? Get ahead with a free onboarding course
        Often getting started is the most difficult part of any process. A good start sets you up for success and saves you time and energy that could be spent elsewhere. That is why we have a onboarding course ready for
        Ultimaker S5 Pro Bundle, Ultimaker S5, Ultimaker S3 Ultimaker 2+ Connect.   
        They're ready for you on the Ultimaker Academy platform. All you need to do to gain access is to register your product to gain free access. 
        Ready? Register your product here in just 60 seconds.
          • Like
        • 14 replies
    • Create New...