By Otter
Machine Definition of a Porter Cable 75182
The Porter Cable is described by literature a 3.25 HP Router Motor. It has speeds settings of 21000, 19000, 16000, 13000 and 10000 rpm. In use it seems to stay quite cool while working away, so for a dry cutting environment where I am working wood mostly, I am rather pleased with it. The downside is that there is no data telling what the torque or HP is at the different speeds. I am assuming that the highest speed is the HP, but it is entirely possible that the HP advertized is simply based on power consumption. It is possible within the speed range to have an adaptive system on a brushed motor (which it is) that maintains HP on a fairly stable line through a decent range of speeds, but I have no way of knowing. The literature does indicate that the torque is controlled on this motor, but unless anyone can help provide a few good clues, it seems like I will have a hard time optimizing the use of this motor at various speeds.
Thanks ahead of time for any wisdom or advice provided.
Bob
Eldar Gerfanov (Admin)
I seriously do not know.
But if it is a variable voltage controlled motor, i think it will probably be a safe bet to assume that you have maybe 1/2 the torque at 10000 RPM
I jut do not know. Sorry!
Otter
Thank you for the reply on this one, this is a puzzler.
My best guess from reading all the specs is that I should divide the initial HP rating by 1.4 to get a more trustworthy specification for HP.
Then use that for the top torque.
The literature could be read to indicate that this motor varies it's hp/torque in order to maintain constant speeds. If I assume that this motor always has acess to it's best performance specs it is going to have a magic torque in the low speeds of 1.7 and I really don't see that as likely. If I assume the torque remains constant I get an HP curve that looks close to believable. The problem is that I am really reaching here.
For now I will use these numbers as a guess and try to test this with cheap bits first.
Speed HP Torque
10000 1.10 0.58
13000 1.44 0.58
16000 1.77 0.58
19000 2.10 0.58
21000 2.32 0.58
Bob
Otter
I have been thinking about how to properly determine the characteristics of this motor and here is my current plan.
First I will obtain a large quantity of very inexpensive 2 flute ballnose mills for aluminum. I am going with a 1/8" ball mill hoping that is small enough to break without damage to the collet or bushings on the motor while being large enough to be able to test the torque on the motor. A ballnose in aluminum should do a very good job of showing quality of cut.
I have a supply of 6063-T5 anodized aluminum in stock, so I plan to use this for testing.
Then I plan to cut a pattern with a depth of cut
My pattern is going to be a spiral going one way leading into an "M" shape and terminating in a spiral the other way. This should test all directions of the cut so I can find a feed rate that is ideal at all angles.
After drawing this pattern at increasing feed rates at each motor speed, I Should be able to determine good speeds for fast removal of material and good speeds for best finish.
Last, I will plug the values into HSMAdvisor to reverse engineer a decent model for what this motor should be able to do.
As always, any other ideas or feedback on this would be more than welcome!
Bob