RepRap Foot Vibration Damper
by Conseils, published
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Any vibration isolation system will have a specific damping factor, stiffness and natural frequency. Such parameters can readily be calculated and modeled if desired. Your arms and body are in fact dynamically adjusting the effective stiffness so are quite effective. Additionally you have (probably) removed the element being excited by the vibration source (printer).
I suspect the trade offs in this design is the requirement to support the mass of the printer versus the material configurations spring stiffness. Obvioulsy PLA is readily available in this instance.
At one extreme of design, the support will be too stiff and provide no isolation but resist permanent deformation. At the other extreme the plastic permanently deforms up to the point of failure thus provides no isolation. The design seems to have found a reasonable compromise (see note in the TIPs section).
Elastic bands (Natural rubber) will provide good damping but will have to be arranged so as to not be overly compressed or stretched by the mass of the printer. So I would anticipate quite a few will be required! Additionally they may provide better Noise Harshness characteristic as their performance, dependent on configuration, will no doubt be better than plastic alone.
That being said, please look carefully at the photograph. It's not obvious but the black material under the printer is a 3mm thick piece of rubber vibration isolation matting. This, on its own, was not sufficient! The legs are significantly better, certainly from a subjective perspective.
Typically low cost vibration dampers consist of elastomer in shear or compression with the elastomer bonded to some form of bracket. The issue for us would be we have a very 'limited' range of elastomer stiffness, so are reliant on geometry configuration. This creates a number of related engineering challenges in the design. Some examples http://www.isotechinc.com/vibr...
My best low cost, available alternate solution would be a washing machine anti vibration sheet.7 mm thick, http://www.amazon.co.uk/First4...
If you really want quiet, then you would probably get better performance with the vibration feet plus sound absorbing foam surround. It looks like an egg box pattern but made in foam. 25dBa reduction can be achieved. see http://uk.rs-online.com/web/c/...
Hope this helps and was interesting.
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Vibration from movement of the system is transmitted through the feet of the device. In my particular installation Huxley #710 is located on a box 1.5mÂ² covering the stairs below. The resultant chamber underneath acts to resonante, amplifying the vibration into a rather loud drumming.
The addition of the vibration damper significantly reduced the noise levels from the device!
Two additional extrusions have been added to retain the anti vibration feet on the bottom of RepRap Pro device such as Huxley #710. This means that for cleaning and servicing the feet stay in place when Huxley #710 is moved.
To enable the changes to the original model, it was converted from STL to STEP and then modified. You can find the modified STEP file here as well as the un modified file.
A description of how to do this for yourself can be found here
Make sure that your settings are sufficient to create solid walls. There is quire a surprising mass on each foot and they need the stiffness created from both walls well attached to each other. Additionally with time there will be permenant deformation if the walls are not attached which is likely to lead to failure. The orignals are now 8 months old and still work perfectly other than constantly falling off when I need to move Huxley #710 for cleaning and maintenance.
Sample Part Manufacturing Technical Documentation
Printer : Huxley #710 (RepRap Pro)
Firmware : Marlin 1.0.0 RC2 - 28 November 2012
Software : RepRap Pro Software 811708f - Pronterface
Material : PLA - Faberdashery
Material Dia. : 1.75 mm (Msd 1.80 mm )
Nozzle : 0.50 mm
Layer height : 0.30 mm
Layer width : 0.6 mm
Extrusion T : 205 C
Bed T : 60 C
Feed Rate : 28 mm/s
Perimter rat. : 0.5
Cooling Fan : Yes
Bed material : Borosilicate Glass
Design For Manufacture Parameters - Not applicable to derivative item
Model : Absolute dimensions
Scale : 1:1
Holes : Yes
Layer height : 0.30 mm
Layer width : 0.6 mm
Over hangs : No
Support : No
Function: Model Fix up
Tool: NetFab Studio Basic
Function: STL - STEP
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