Buffing wheel diameters

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JimGo

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OK, I'll admit right off the bat to being a buffing novice. Why would I want to use an 8" wheel to buff a pen, rather than a 3" or 4"?
 
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BRobbins629

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Probably for the same reason you carry an Emperor - bigger is better.

But glad you asked. I am soon to be in the market for a buffing system and would love to hear the real answer.
 

btboone

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There's no real reason other than it will take a lot longer to wear down an 8" diameter one than a smaller one. It's all about the surface speed. If it goes too fast, it will melt plastic and get bits of compound caught in the finish. I personally use a worn down one around 4" or so when doing pens or wood inlay rings. Because my buffer runs at a fixed speed, the surface speed at the wheel diameter is less, so doesn't burn my parts as easily.
 

JimGo

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Originally posted by btboone
<br />It's all about the surface speed. If it goes too fast, it will melt plastic and get bits of compound caught in the finish.

Interesting point Bruce. You'll get more surface area going past the pen/ring/whatever on an 8" than on a 4" or 3" (on a per-revolution basis). Maybe it's just that is speeds up the buffing? It will probably also increase the friction, which means more heat.
 

Jerryconn

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I use the buffing system that PSI sells and am very happy with it. I think they are 4" wheels. I like it because it has a small footprint. I have just about stopped using MM on the lathe, after going over the CA finish with 400 grit sponges I pull the mandrel off the lathe, buff with tripoli, white diamond, then wax and its done.
 

ed4copies

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OPINION: (NOT SUPPORTED BY FACT)

First, the larger diameter does create higher speed (this is a fact), so it buffs better (this may not be a fact)

Second, because the same spot is hitting the pen less often, I would think it dissipates heat and therefore causes LESS heat in the pen

Third and most important: Experience tells me it does a good job, but then I have never used a 4" wheel.

Wasn't that helpful?????[B)][B)][B)]
 

JimGo

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Originally posted by ed4copies
<br />First, the larger diameter does create higher speed (this is a fact)...
<br />
OK Ed, just because it was YOU that posted this, I'm going to call you on your purported fact. Technically, the entire wheel moves at the same speed, at least when measured in RPM's. When you're measuring feet of surface area that pass a given point per second, then yes, the 8" wheel moves faster.
 

ed4copies

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JimGo,

Don't take my word for it. Do a little experiment.

Mount about a 14" piece of really hard wood on your lathe, start up the lathe at full speed, PONDER.

Now, do the same with a pen blank (1/2" diameter) PONDER again.

QUESTION: WHICH ONE WAS MOVING FASTER?????? (in YOUR opinion)???
 

JimGo

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Originally posted by ed4copies
QUESTION: WHICH ONE WAS MOVING FASTER?????? (in YOUR opinion)???
<br />

The jury said, in their most enlightened tone, "neither". As they observed, with my lathe set at 300 RPM's, both the pen blank and the 14" bowl blank moved at 300 RPM's. [:D]

But we digress...anyone have any other reasons why I might want an 8" wheel instead of a 3" or 4"?
 

btboone

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Jim, that's where the whole concept of surface speed comes in. The cotton at the end of an 8" wheel hits the surface at twice the speed of one at 4" diameter. (Think of it this way: The entire circumference of the buff hits the pen every RPM.) Because you can have different diameters on a given RPM, this is really the only way to know. The same thing holds true for machine tools like drills. A larger drill needs to spin slower to get the same surface speed at the tips as a small one that spins faster.
 

Jerryconn

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Look at the circumference of a 4" circle and a 8" circle if you could break the line and lay it out flat for each circle you would see that the line from the 8" circle is considerably longer The distance around the 4" circle is approx. 25.1" and around a 8" circle it is approx 50.3". for a piece to travel around the different diameters in the same time (RPM) the feet per minute has to be higher.
If you are interested take a look at this link:

The only other reason I can offer for a smaller diameter wheels is cost for the wheels and for the motor to drive them. If I were polishing bigger, heavier items I may also want bigger wheels and a bigger motor to turn them. Another justification for bigger might also be to get done polishing faster.
 

JimGo

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Originally posted by Jerryconn
<br />For a piece to travel around the different diameters in the same time (RPM) the feet per minute has to be higher.

Agreed - I was just giving Ed a hard time!
 
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