X-Bearing Friction Test with experimental results ufodoctor3, April 12 th , 2019 1. Introduction to the Problem Many forum colleagues complain the x-bearing of the JGaurora5 3D printer. With perfect cleaning and lubrication of the x-rods the printing works fine, else the moving extruder will rattle and the upper printing layers provide an x-offset up to 5 mm. 2. Investigation of the Problem With an auxiliary friction test device (Fig.1), connected between the base unit and the tower the x-friction can be investigated at reduced torque to find out, where the x-rod needs to be polished or cleaned! Force Sensor: Mechanical spring scale Current Sensor: Sparkfun Digi-Key 1568-1882-ND 400mV/1A (DC up to 80 kHz) Fig. 1: Friction tester device Fig. 2: Test with Current Sensor Sparkfun Fig. 3: Test Setup Base Unit and Tower disassembled A: Base Unit JGaurora B: Friction Tester with Current Monitor by Sparkfun C: Moving Extruder on x-rod With the reduced x-stepper torque (by the test device Fig.1) the non-perfect areas of the x-rod can be located by a rattle noise. These x-areas need to be polished! Comment: Starting this friction tester before every printing and hoping not to observe “rattle”, the system is OK!
Transcript
X-Bearing Friction Test with experimental resultsufodoctor3, April 12th, 2019
1. Introduction to the ProblemMany forum colleagues complain the x-bearing of the JGaurora5 3D printer.With perfect cleaning and lubrication of the x-rods the printing works fine, else the moving extruder will rattle and the upper printing layers provide an x-offset up to 5 mm.
2. Investigation of the ProblemWith an auxiliary friction test device (Fig.1), connected between the base unit and the tower the x-friction can be investigated at reduced torque to find out, where the x-rod needs to be polished or cleaned!
Force Sensor: Mechanical spring scaleCurrent Sensor: Sparkfun Digi-Key 1568-1882-ND400mV/1A (DC up to 80 kHz)
Fig. 1: Friction tester device Fig. 2: Test with Current Sensor Sparkfun
Fig. 3: Test SetupBase Unit and Tower disassembled
A: Base Unit JGauroraB: Friction Tester with Current Monitor by Sparkfun C: Moving Extruder on x-rod
With the reduced x-stepper torque (by the test device Fig.1) the non-perfect areas of thex-rod can be located by a rattle noise.
These x-areas need to be polished!
Comment:Starting this friction tester before every printing and hoping not to observe “rattle”, the system is OK!
3. Improved Test Setup
Fig. 4: Improved Test Setup for x-bearing friction investigations1: Base Unit JGaurora2: x-Friction Tester, Switch 2x68 Ohm serial3: Tower JGaurora4: Extruder5: Mechanical Force Sensor 0 to 2 N6: IPhone with RTA App Sound Recording7: Temperature monitoring of the Serial 68 Ohm Resistors. Temperature increase by 30 Deg Celsius within 7 Minutes8: Current into the x-Stepper Motor9: Power Source 230 V AC
Fig. 5: X-Bearing Friction Tester1: U-sheet JGurora, 2: Original Bore D3.2,3: 2-Pol Switch, 4: Alu Heat Sink 10x10,5: Resistor 68 Ohm 11 W
1 2 3 4 5 6
7 8 9
U-sheet 68x30x15JGaurora bottomrear view
X-bearing tester
Normal 16 N
Test 7 N
68 E11 W
CableEP-09-0064-3
Maleto BaseJGaurorarear view
Femaleto X-StepperJGaurorarear view
E1+E1-E2+E2-
redyellowblueblack
E1+E1-E2+E2-
20 mm 150 mm
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4. Experimental Results
The main source of x-bearing friction is DIRT at the entry ports of the upper long x-bearing!
Fig. 6: Cleaning the entry ports of the x-bearing
1. Extruder2: DIRT at the entrance of the x-bearing port3: Cotton wool stick, moisten by Isopropanol4: Toothed belt, perhaps with dirt, too
Please examine this entrance port with magnifying lens with adequate illumination!
Fig. 7: Sound Spectrum with normal full current 0.5A, Force 1.6 N
Fig. 8: Sound Spectrum with reduced current by friction tester 0.34A, Force 0.8 NLess sound if well cleaned!
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5: Discussion and Conclusion
- This friction tester provides a better understanding for the“vibration problem” of the x-bearing
- The original and the replacement x-bearings by AliExpress are sub optimal, but appropriate for this low cost 3D-Printer, but only with perfectly cleaned x-bearings and rods!
- If the entry ports of the upper x bearings are not cleaned, you will notice higher vibrations also at reduced currents with the x-friction tester.
- The main advantage for replacing the x-bearing is the fact, that you insert a new CLEANED bearing, which will operated for a short time nicely¨!
Our advice:
If you notice a “vibration rattle problem of the x-bearing”, please start with the cleaning the entry ports of the upper x-bearing (Fig.6), after that cleaning and lubrication of the rods.
