Introduction: Fixing a Harbor Freight Vibratory Tumbler
I bought a Harbor Freight Vibratory Tumbler on a trip to the US. I quickly became disappointed because it fell way short of expectations so I applied a little simple physics to fix it and I now have a great Tumbler. In production it would have cost no more to implement than the original flawed design.
Vibrating Tumblers of this size operate on the principle that a rotating offset mass fitted to an electric motor will generate out of balance rotating forces on the motor and whatever is attached to the motor. In the case of these tumblers a bowl is attached to the motor and the whole assembly is spring mounted to a base to allow the assembly to vibrate.
Tumblers have several uses such as de-rusting fasteners, polishing various items, deburring machined parts etc. To cover the range of uses there are many types of media available ranging from Walnut shells to extremely aggressive abrasive. In addition, some work is done dry and others wet. You can see that there are numerous options
Step 1: The Working Part
Here is a photo of the bowl loaded with some abrasive media for de-rusting steel parts. The idea is that the bowl will get agitated in a circular fashion tumbling the parts to be cleaned or polished with the media. This is not a fast process and can take a few hours, but it works unattended so the time factor is rarely a problem.
The second picture shows some typical work that I give it. These are parts for a radius gauge (check that out in another of my instructables) which I tumbled to remove machining marks and deburr the edges.
Step 2: Bottom View
These two photos show how the offset mass is attached to the spindle of the motor. The support springs are visible in the second photo.
As soon as I opened the bottom and saw this, I realised why the machine did not work well. Situating the offset mass at the bottom was poor design. In the video that I have linked to below I have shown how to easily move the mass up between the motor and bowl which you will see makes a huge difference.
Step 3: The Movie
The very nature of this machine and the simple fix that I applied are dynamic and require a video to show how the device and fix work and the difference that the modifications made. In the video I show how the fix was implemented and I show the theory behind it with demonstrations.
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