ProperWinder Thickness Gauge

I designed this to hold one of those cheap thickness gauge tools you can get on Amazon (link below) so that it can measure the thickness of filament being extruded from my Filastruder rig and spooled up by my ProperWinder. It can certainly be used without those things on some other machine, but may need a minor remix for mounting it. This one is designed to screw into one of the M10 threaded holes on the PTFE carrier from the ProperWinder.

To build this you will need:

• cheap thickness gauge as shown
• two R188 ball bearings
• two PC-M10 Passthrough PTFE couplings (festos)
• some PTFE, 4mm OD, 2-3mm ID
• some M3 screws and washers and at least one M3 square nut.

Here's a link to the ProperWinder, if you haven't already printed on:

https://www.printables.com/model/251029-properwinder-filawinder-kit-upgrade

If your thickness gauge cannot provide enough pressure to keep the ball bearings pressed against the filament, then you might want to use some small o-rings, or even some knotted rubber bands around the heads of the screws that hold the bearings in place. If that causes too much friction on the sliding bearing mount, and lubricating the rails does not help, there are screw holes on the back that can be used to put another rubber band on to help even out the pressure on the sliding bearing mount. Do whatever you can to ensure that it moves smootly and maintains pressure on the filament, which should be cool enough not to compress by the time it gets to this gauge.

Note that the PTFE couplers can only be fed from the top, so plan your guide tube installation accordingly. This can work in conjunction with the loop of PTFE used to create tension for the ProperWinder, but it may be enough by itself. Make sure you aren't overloading the ProperWinder by creating too much tension. Eliminate the PTFE loop if you think there's too much.

Assembly:

• Dislodge the sliding bearing mount using a screwdriver through the hole at the tapered end if your print does not move freely. A drop of plastic safe oil or grease on the runners will help with smooth motion. Make sure it slides freely back and forth before proceeding.
• Install a PTFE passthrough coupler on the separate coupler mount. You will probably need to use a wrench to get it fully seated. This will plug into the main body later.
• Cut a point on a short piece of PTFE (or the loop of PTFE) for the entry guide and insert that through the top of the coupler. Push it through until the point of the cut is a few mm above the coupler.
• Install R188 ball bearings onto each of the mounts using an M3 bolt and washer. The bearings should spin freely.
• Install the upper PTFE passthrough coupler and cut a point on another short piece of PTFE. 
• Insert the PTFE into the upper coupler, point-first/down, just to the bearings, but not pushing them apart. 
• Test the path with a piece of filament to ensure that everything moves freely.
• Install an M3 square nut into the slot below the gauge mounting hole
• Slide the sliding bearing mount so that the bearings touch and hold it in position.
• Retract the thickness gauge and “measure” the C-shaped post. Use an M3 bolt and washer to secure the gague in place, shifting one way or the other as needed so that the sliding bearing mount can still move to the right a few mm.
• With the bearings touching, zero the thickness gauge.
• Press fit the lower PTFE coupler into the slot, making sure the coupler is on the top and the pointed tip of the PTFE is not quite touching either of the bearings. This should be a solid interference fit, but if your print is loose, run an M3 bolt through the hole below to lock the pieces together.
• Screw the entire thing into one of the PTFE coupling holes on the ProperWinder PTFE loop holder. I found that it's easiest to screw into the plate before installing the other PTFE coupler into the plate, or the plate onto the wall mount.

Fusion360 and STEP files have been provided for easier remixing to improve the models or adapt it to other machines, such as the Artme3D v2 filament extruder. I'd love to see some remixes!

Here's a video showing the diameter being measured in real time, as if it were during an extrusion process.