Originally Posted by
toyotaguy
whats the washer mod?
From the first post in this thread:
The Bigfoot’s 21mm stroke creates loads of centripetal force at speed, and its spindle bearings allow the backing plate to spin along unabated. Consequently, random rotation of the backing plate should be out of this world! However, a purpose-built shroud not only covers the driveshaft-mounted rotating components, but also slows backing plate rotation via drag-induced friction.
Marco (the Rupes engineer that developed the machine) explained that excessive rotation could cause scouring of the polishing surface if the backing plate and buffing pad were allowed to freewheel spin prior to contacting the polishing surface. He also mentioned that excessive rotation was considered to be a safety hazard in some parts of the world. Understanding his reasoning, I nevertheless decided to install a spacer between the backing plate and mounting pad in hopes of restoring a maximum amount of backing plate rotation.
A metal, plastic, or phenolic washer will work. Cut and sand to size.
The height of the spacer needs to be enough so that the backing plate will no longer contact Bigfoot’s shroud. The spacer shown is approximately 3/16” tall and was taken from a backing plate featuring a 5/16”-24 mounting stud.
The spacer was placed between the backing plate and mounting pad.
The pad still mounts safely and securely. If desired, a minimally longer bolt can be installed to compensate. The bolt is 8mm. The shape of the platform and spacer is known as a Double-D cutout.
The resultant gap is nearly unnoticeable.
With the spacer installed, backing plate rotation and cutting speed were dramatically increased.
The difference was apparent, even when low speed settings were used.
With the spacer installed, backing plate rotation increased immensely. While I was not able to verify exactly how big an increase occurred in terms of backing plate rotation or cutting power, I can say that it was a LOT. My best guess: backing plate rotation increased to 10-14 times per second, and cutting speed increased by about 50 percent.
If a rotary buffer outfitted with a wool pad had any sort of performance advantage over the Bigfoot, the advantage was nearly or completely negated after this easy to implement modification. This newfound cutting power elevates the Bigfoot to superstar status. I hope that Marco will not be overly upset by the addition of the spacer, and I am sure he is aware of the tremendous rotation potential of this machine (otherwise there would have been no need to design the shroud to contact the backing plate). Regardless, I plan on using my machine with a spacer installed.
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