Filament tension sensor by tetroboylp

Last crawled date: 4 years, 1 month ago

This is a very simple design with a potentiometer, a spring and two bearings to detect the tension of the filament. It is designed for 1.75mm filament, but that is adjustable by the U groove in the bearings. I'm going to use it as a part of a filament winder for my upcoming filament extruder.
I have included all the files so you can edit it as you wish. In the .dwg file I have included is a part to use when your filament is 45mm above the plate, but mainly you probably want it higher, so in the .dwg file and in .stl files there's a design for filament 50+mm above. You can adjust the height with two M3 screws or threaded rods. Sky is the limit.
If you want to make your own bearings like I did, I included the .stl file for printable bearings with U groove. For one, you're going to need 10pcs of 4.5mm steel balls (BB gun ones do just fine) - they are actually 4.3mm in diameter. This ball bearing has 25mm OD and 5mm ID. For more info about these printed bearings and instructions about assembly, check out my design:https://www.thingiverse.com/thing:4266295
Parts:
1x Potentiometer (resistance value doesn't really matter as long as it can be precisely read by Arduino. I'm using 10k one.)
2x short M5 screw (16-18mm if your bearings are 6mm in height)
2x bearings with inner diameter of 5mm. Preferably, you want a groove on the OD. OD doesn't really matter since you can adjust what you want with the M5 screw holding the spring. They should spin very easily.
1x Spring - it is designed for a spring with 5mm diameter and 15mm height. I'm not sure about the thread diameter, sorry. Height of the spring doesn't really matter, though, 20-30mm should be better than a 15mm one (so you have higher sensitivity - higher precision)
1x M5 screw to hold the spring. Length depends on what bearings you use, what tension range you want to measure and so on. I used 24mm long one, but I might change it for a different one after I test it on my filament extruder.
4x M5 nuts. Two for two bearings and two for the M5 screw holding the spring (one might be enough, but I want to be able to adjust the spring height anytime, so I used two)
2x M3 threaded rod or M3 screw. If you use a threaded rods, you need two M3 nuts for each of them to attach them to the base plate (bottom part). If you use a screw (I myself used M3x40mm), you only need one for each screw to tighten it to the bottom part. If by any chance the M3 rod/screw is loose in the middle part, go ahead and use two more nuts for each rod/screw to attach it firmly to the middle part.
M3 nuts - depends on how many you need to use...
3x 2.5x12mm countersunk wood screw to attach the thing to a wooden plate or wherever you want it.
Watch the video: