the other pc

Dec 20th, 2006, 10:10 AM

The Porter-Cable 7428 rotary buffer is a fine machine and is currently available at very good prices.

MaximusZTS and Mike-in-Orange both have PC7428s and the question of their speed came up. The buffer is specified as being adjustable from 1000 RPM to 3000 RPM. The speed setting dial is marked from 1 to 6.

It would be easy to assume that speed varies linearly between the specified values with dial setting but electronic motor controls don’t always work that way. So we decided to have a look.

A sample set of two isn’t statistically significant but the data is still useful for these specific machines and may be useful for other owners of the 7428 if PC’s (Flex division) manufacturing is highly consistent.

MaximusZTS’s buffer is called machine “S” while Mike-in-Orange’s is “M”

We took two sets of readings on each. Along with the measurements the chart below also includes the average of measurements for each machine, the range (max-min) and the range expressed as a percentage of the average. Also included is the average, range, range expressed as a percentage of the average, standard deviation and standard deviation expressed as a percentage of the average (coefficient of variation) for both machines combined.

The data was all taken under no-load conditions.

http://archive.meguiarsonline.com/forums/photopost/data/500/measured_data.jpg

That’s it for now, we’ll have a closer look at the data soon.

PC.

MaximusZTS and Mike-in-Orange both have PC7428s and the question of their speed came up. The buffer is specified as being adjustable from 1000 RPM to 3000 RPM. The speed setting dial is marked from 1 to 6.

It would be easy to assume that speed varies linearly between the specified values with dial setting but electronic motor controls don’t always work that way. So we decided to have a look.

A sample set of two isn’t statistically significant but the data is still useful for these specific machines and may be useful for other owners of the 7428 if PC’s (Flex division) manufacturing is highly consistent.

MaximusZTS’s buffer is called machine “S” while Mike-in-Orange’s is “M”

We took two sets of readings on each. Along with the measurements the chart below also includes the average of measurements for each machine, the range (max-min) and the range expressed as a percentage of the average. Also included is the average, range, range expressed as a percentage of the average, standard deviation and standard deviation expressed as a percentage of the average (coefficient of variation) for both machines combined.

The data was all taken under no-load conditions.

http://archive.meguiarsonline.com/forums/photopost/data/500/measured_data.jpg

That’s it for now, we’ll have a closer look at the data soon.

PC.