What is the best RPM for sanding a bowl?

[Odie]

For me, it keeps getting slower and slower.

For about the past 10 years, my best sanding speed has been about 250 RPM.

=o=

 

[Don Wattenhofer]

You should note that it is more than RPM since the surface speed is greatest at the largest diameter and will decrease as you work closer to the center.

 

[Odie]

You should note that it is more than RPM since the surface speed is greatest at the largest diameter and will decrease as you work closer to the center.

OK, that's a fair statement, Don.....

I avoid turning bowls less than 6" diameter, and I seldom have the opportunity to turn bowls over 12", or so. Outside of that perimeter, I would adjust the RPM to suit.

Generally speaking.......about 250 rpm is best for me.

=o=

 

[robo hippy]

For my warped bowls, I do power sand, and since they are warped, I sand at about 10 to 15 rpm. Can't keep the abrasives on the wood at higher speeds. This speed is slow enough that I can see my wood as it turns rather than being blurry. I do find it interesting that Tomislav sands at about the same speed he turns, and so does Richard Raffen. For a long time, it has been considered slow speeds were better. I think this was more because the abrasives, is spun too fast, would not be able to really dig in and cut. I do keep my finger about half way down on the trigger of my angle drill. This does have the added benefit of the bearings lasting several times longer than if I am running at full speed. Most lathes won't go down to less than 50 rpm. My Vicmark 240 does, and I had my Beauty reprogrammed so it would go down that low. My Beauty is so old, it has 3 speed pulley ranges. I use it mostly for sanding now days since I can keep the hood on all the time, and the hood can't be left on if I am turning.

robo hippy

 

[Richard Coers]

RPM of the lathe or the sander?

 

[John Walls]

Depends. Power sanding, course through fine grit, I'll start slow usually under 50. As grit gets finer, speed goes up, usually finishing around 2-250 rpm.

Hand sanding, course usually the same slow speed, the finer the grit, the faster I go up to around 300. On both, always by hand with the white 3m pads, I'll run up to 1-1,200 rpm if I'm going for a final touch/polish.

 

[Odie]

RPM of the lathe or the sander?

I almost never use power sanding on the exterior of my bowls, so the "sander" would be me....and that would be zero rpm!

I do use power sanding on the interiors of my bowls, and 250rpm works there the best, too.....also at about 250rpm.

=o=

 

[hughie]

RPM of the lathe or the sander?

Much depends on 'how' you sand. I use both power and inertia, along with hand. So I use zero, slow speed as Odie mentioned and the actual speed here varies due the hardwood I use. Too much speed here develops heat and with some hardwoods a glazing effect. Then we have inertia which predominates in the final stages, as in my humble opinion produces the finest surface.

 

[Vincent Vogel]

It all depends on what I'm sanding. A once turned bowl that is dry and warped lathe speed is about 50. I use a Milwaukee 12 volt drill and a small random orbit sander. I run the drill or random orbit about 1/2 speed. I use the drill for 150 and 180 and random orbit on grits above that. If a twice turned bowl that's round lathe speed is about 150 for either sander. If I'm hand sanding lathe speed is about 250. That's what works for me and I lighten up or slow the lathe down if I start feeling heat through the paper. I've never tried an inertia sander.

 

[Curt Vogt]

When sanding harder more solid woods like rosewoods, the speed can make a huge difference. The factor that can ruin the project is heat.
When I first started out, I learned this from experience. The completed project would develop microcracks all around the surface.
If a rosewood or other wood is sanded at high-speed, heat can be a problem compounded by the oils in the wood that tend to clog sandpaper.
Applying too much pressure while sanding can prevent the sanding dust from moving away from the project and clog the paper.
Of course the heat becomes trapped there and then the friction of the material there makes it even worse.
I like to explain sanding as trying to glide over the surface. Not being heavy handed to get it over with as soon as you can...
You do totally love the sanding portion of your projects... don't you?

There are a couple things to prevent this.
- slowing the lathe speed
- reducing pressure on the sanding material so it can work correctly
- removing the sandpaper from the project often and knocking the dust off the grit
- using your sandpaper sheet in a single layer between your fingers and project. If it's hot, you're stressing the wood surface
- move the sandpaper around and don't concentrate on one spot for a long time

The woods I usually deal with are all kiln dry or at equilibrium to the environment. Sanding on a wet wood can develop
heat on the surface where it dries the wood too fast compared to the rest can cause stress fractures. That's a whole big
can of worms too.