sanding speed

[Gethenet]

Can someone tell me why it's better to sand at a low speed? I can understand if you were sanding pr or alumilite. ..I would think a higher speed would cause a better chance of " melting" the blank. Is there a good reason for wood?

 

[designer]

Some woods, like hardwoods, will tend to get heat cracks in them. If they do, chances are you will not be able to sand them out completely.

 

[1080Wayne]

As Allen said , plus the higher the speed the farther the dust particles get thrown into the air , which is not good if your dust control isn`t good .

 

[monophoto]

Sanding at higher speed causes heat. That does two things.

First, instead of the abrasive cutting and smoothing the surface of the wood, it burnishes it. That looks fine when the wood is raw, but it changes the way it absorbs finish and can lead to splotchiness.

Second, too much heat can damage the workpiece, especially if there are pockets of moisture within the wood. The heat flashes that moisture to steam which expands and can cause the workpiece to crack if not explode. DAMHIKT.

 

[Jim Burr]

Easy...at lower speeds the paper is more likely to contact all areas of the wood in question.

 

[Edgar]

I use 2200 RPM (4th gear on my 5-speed lathe) for almost everything, including sanding.

As noted in previous posts, you do want to keep heat down. For wood, I use Mirka Goldflex & Abranet with a fairly light touch & keep it moving - generally about 30 seconds at each grit. I like these products because they don't generate as much heat as some products & I can feel when they start getting a little warm. For acrylics, I wet sand with mm sheets (not pads) at the same speed. I can judge heat generation better with the sheets than with pads.

If I had a VS lathe, I would probably slow it down a bit for sanding, but after much experimenting, I've managed to develop a very consistent technique at 2200 that I'm quite happy with.

I do drop to 1st or 2nd gear for drilling & CA finish, but I don't do either of those very often.

 

[Gethenet]

It all makes sense now that others have said it...lol pretty much what I was thinking in me head :biggrin:
I just wanted some opinions on it, cause I don't have a VS lathe at the moment, and if there wasn't a good reason to have to change speeds.....I wouldn't

Thanks guys and gals

 

[butchf18a]

High speed. If you are building up heat to the point of blank cracking or failure, you are applying way too much pressure. A light touch and only a few seconds per grit is all that is needed. If you are sanding down to final size' removing a lot of material, work on your tool technique.

 

[raar25]

Sorry I see it diffferently. RPM is not the measure, feet per second is the real measure to use.Consider I sand at 3500 rpm which is 58 RPS and if your pens is aprox 0.5 inches each circumfrance is only 1.5 inches. Hence you are only sanding at 90 inches per second. This is the same as sanding a 12 inch bowl at 180 rpm (not fast at all) This actually lower than what most power sanders are sanding at. The real solution to not burnishing or overheating your project is "use good sand paper like it is free and discard it often" . So if you ask me, you should use a lighter touch, good paper and crank it up! Oh and wet sand your acrylics and you wont overheat those.

Of course this is just my math, someone else may have different math to offer.

 

[Gizmo3k]

Sorry I see it diffferently. RPM is not the measure, feet per second is the real measure to use.Consider I sand at 3500 rpm which is 58 RPS and if your pens is aprox 0.5 inches each circumfrance is only 1.5 inches. Hence you are only sanding at 90 inches per second. This is the same as sanding a 12 inch bowl at 180 rpm (not fast at all) This actually lower than what most power sanders are sanding at. The real solution to not burnishing or overheating your project is "use good sand paper like it is free and discard it often" . So if you ask me, you should use a lighter touch, good paper and crank it up! Oh and wet sand your acrylics and you wont overheat those.

Of course this is just my math, someone else may have different math to offer.

My worry with these figures is on a 12" bowl, that friction (and thus heat) is spread around the circumference of the bowl. On a pen, it is still concentrated around a diameter of 1.5" - there must be a much greater heat buildup.