Author appears to have concerns about the belts working out of the top of the housing, but is seemingly ignoring the four existing screws that could be used to fasten a top plate to prevent this?
The simple elegance of the integrated timing belt loopback fastener
11–20 of 32 posts
Re: The simple elegance of the integrated timing belt loopback fastener
#12That center pin looks fragile, especially if it's printed along Z axis. How about printing teeth that'd mesh with the belt?
It looks like the pin doesn't take much load. It looks like the pin holds the teeth open, while the load is on the shoulders of the entryway.
Re: The simple elegance of the integrated timing belt loopback fastener
#13This is why I thoroughly enjoyed building my Prusa as a kit. You see little tricks like this, including this exact one. Or how they embed threaded nuts, or how the print is shaped and oriented to be made without supports, etc. Building the prusa saved a bit of money, but was also a crash course in how to design.
Re: The simple elegance of the integrated timing belt loopback fastener
#14That center pin looks fragile, especially if it's printed along Z axis. How about printing teeth that'd mesh with the belt?
If you printed teeth, you'd have to make sure the teeth in the top loop are precisely aligned in relation to the teeth in the bottom loop based on the length of the belt, right? That seems like it could be limiting
Re: The simple elegance of the integrated timing belt loopback fastener
#15Author appears to have concerns about the belts working out of the top of the housing, but is seemingly ignoring the four existing screws that could be used to fasten a top plate to prevent this?
or, if you upped the pin diameter, you could thread a hole through the pin and throw a washer on top
Re: The simple elegance of the integrated timing belt loopback fastener
#16Also works well with a zip tie or 2. The belt holds itself in place as long as the tension is there.
Most of my old printers still use this method on them. [1] You can also use another ziptie as a tensioner.
[1] Very old example. https://flic.kr/p/db51Ue
Re: The simple elegance of the integrated timing belt loopback fastener
#17Author appears to have concerns about the belts working out of the top of the housing, but is seemingly ignoring the four existing screws that could be used to fasten a top plate to prevent this?
or, if you upped the pin diameter, you could thread a hole through the pin and throw a washer on top
Or just forego the pin and put a countersunk machine screw, washer, and nylock nut in it's place.
Re: The simple elegance of the integrated timing belt loopback fastener
#18That center pin looks fragile, especially if it's printed along Z axis. How about printing teeth that'd mesh with the belt?
Printed teeth are weaker than the belt's own teeth. Conversely, with this design the center pin could break loose and the belt would still hold, because the pin just has to stop the loop from fitting through the slot.
The pin doesn't even need to be captive, if you tug on the belt it'll jam in the slot kind of like a climbing nut in a crack.
Re: The simple elegance of the integrated timing belt loopback fastener
#19That center pin looks fragile, especially if it's printed along Z axis. How about printing teeth that'd mesh with the belt?
A small bolt could easily replace the pin, this would also allow a washer to be added preventing any chance that it working loose.
Re: The simple elegance of the integrated timing belt loopback fastener
#20This is indeed a very elegant fastening method. I wouldn't be surprised if the designer of that CNC machine borrowed it from the popular Prusa MK2 3D printer, which uses a very similar design for its Y-axis belt: https://help.prusa3d.com/guide/2-y-axis-assembly_79992#81120
It's been a standard method for decades. Theres a lot of cases where even the center post isn't required as the zero radius 180 won't fit back through the slot.