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I picked up an old delta/rockwell buffing arbor outfit a few days and I have been building a pedistal and motor mount for it. I have two motors that I could use for it, a 1 horse 3000rpm, and 1/3horse 1750 rpm. I opted for the 1/3 horse motor because 3000 something rpms just seemed way to high. I ordered the 12" wheels and compound from stewmac and I am just about ready to go but I don't know what my final rpms at the buffing wheel should be. once I know the desired range I'll be able to select the right pulley for my motor. the pulley on it right now essentially puts me at 1:1 and it seems like it should be a bit slower, but I have not used a buffing outfit like this before so I don't know.

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~shad peters

http://www.flickr.com/photos/petersinstruments/
http://petersinstruments.blogspot.com/
http://petersinstruments.com/

Torque is good, RPM's not so much.
Wish I had an exact answer for ya.

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"Act your age, not your shoe size" - Prince

You know, I can't seem to find any buffer that has an RPM lower than 1200's. I think it's because they use an induction motor so the speed is dependent on the power line frequency... I suppose moving the machine to Europe where they use 50 Hz would slow it down... otherwise the only way is to pulley it or use a VFD to control its speed.

I am wondering about using a drill press as a buff because it spins at just the right RPM (or at least it can be made to spin at the right RPM), the machine is always there, so I think maybe it might not be such a bad idea until you manage to build a buffing machine with the proper RPM. The problem is finding the proper mandrel for it...

Can someone kinda give me some info on how to set up a buffer? I got medium and fine Menzerna compound, but I can't find the kind of buffs that Stewmac and others sell, all I managed to find is a very soft but thin (about 1/8") soft cotton spiral sewn buffs. I got 4 of them and ganged it together but the thing is real floppy and relied on the centrifugal force of the drill press to keep it stiff.

Should I go ahead and buy the buffing wheels from Stewmac because they're about the only one who has what I needed...

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Typhoon Guitars
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The RPM depends on the diameter of your buffs. What you are looking for is ~1200SFM or 1200 Surface Feet per Minute max for lacquer buffing. You need to calculate the circumference of your buffs from the diameter (you do remember your Jr. High School math, right? ) so you know how many inches or feet it is around. Then determine how fast to spin it to get in the 900-1200 SFM range. Once you know the RPM of the buffer shaft you can select the pulley ratios for the motor you have or get a proper RPM motor to match your sheaves.

FWIW,
Alan D.

1200 SFM on a 12'' buffer wheel sets the RPM at 382 RPM. Seems quite slow to me since mine is set at 1750 RPM (5497 SFM)

The formula I used is this one: SFM / (2 x PI x radius) ---radius being in feet

Maybe I'm mistaking somewhere though... Or maybe my buffer spins way too fast!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

The reason that i went with the 1750 rpm motor is becuase that is the same speed that the stewmac setup runs off of so I figured it must be possible to get it into the ball park using pulleys. I suppose to get in the 350-400 rpm range I would need to run a 1" pulley on the motor ( if I can get one that small, prob more like 1.25") and probably a 4-5 inch pulley on the arbor?

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~shad peters

http://www.flickr.com/photos/petersinstruments/
http://petersinstruments.blogspot.com/
http://petersinstruments.com/

I am using 12 inch buffs, and run at about 1200 rpm or so ... it just feels right - 1/3 hp, so it will slow down if I lean in too hard.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Correction: mind runs as about 1200 RPM, such as Tony's. (and not 1750 RPM as I mentioned in my first post)

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

12" buffs, 750-1000 rpm buffer shaft speed for lacquer works well. Just don't apply to much pressure or burn through can happen, keep the guitar moving too.

I use a 1/3hp motor with no issues. 2" pully on the motor 4" pully on the buffer. for 860+/- rpm at the buffer shaft.

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thanks everyone. I got a 1 3/4 inch pulley for the motor and left the 3.5 inch one on the arbor and it seems just right.

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~shad peters

http://www.flickr.com/photos/petersinstruments/
http://petersinstruments.blogspot.com/
http://petersinstruments.com/

The issue is surface speed and torque which determines frictional coefficeint. Any given compound will perform best on a certain surface with a certain friction.

One formula to calculate surface speed is......diameter (in inches) times rpm divided by 229.2, which equals surface speed in feet per second.

The Stewmac system works beautifully. It would be quite difficult to burn through a finish with this system set up properly...yet the medium and fine Menzerna compounds cut rather quickly. One important point about torque. If there is too much torque at the contact point then the wheel will not bog down under the load. THIS is how you burn through a finish....by having too much torque at the surface so excess friction doesn't overcome the motor's torque. The Stewmac system allows belt tension to be adjusted such that the wheel will stop under too much load. So...I consider the Stewmac system a model application. The Stewmac system is......a 730 wheel rpm and a 14" buffing wheel.

730 x 14 / 229.2 = 44.58 feet per second.

40 - 50 feet per second is what your shooting for....along with the abilty to adjust belt tension.

Of course, one can learn do a lovely job buffing with any kind of setup but learning to avoid burnthrough on an overpowered system is a completely unecessary learning curve. Buffing nitro is quite simple if you get the speed right and can bog down the wheel by using too much pressure. Get something together that uses a belt to drive a shaft, gets the surface speed right, and also allows a belt tension adjustment.

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