Thread: Sanding fast or slow?

SLOW! Most definitely.

Sandpaper is designed to work at relatively low speeds... even a belt-sander doesn't operate as fast as most turning is done. Fast speeds only clogs the paper faster, reducing it's efficiency and creating excess heat... and excess heat damages both the paper and wood.

Consequently, sanding at slow speeds usually gets the job done faster!

All that my "learned" friend said above. Well, Andy and I are probably more in a master-pupil relationship, but never mind.

Aside from slowing the speed down, watch for heat. As will all woodworking, a good rule is 50% turning (or joinery) and 50% for finishing - mostly sanding, filling etc.

And the harder the wood, the more you need to watch for heat. Our hardwoods DO NOT LIKE HEAT. Use your fingers. Hot fingers means you need to stop and take a break.

Faster sanding speed = less control = cracking.

All of this new writing style of mine is to avoid being verbose. (Is this one OK, Calm?)

And I will not re-read to check for typos, so don't bother with any criticism.

Large diameter, slow..... smaller diameter a bit faster.
Jim

Then there is "" fast and "normal" fast.

Pressure makes heat. Faster with light pressure, slower with heavier pressure. Sometimes zero rpm for grinding out a bad bit of tearout. But then I'm the only one that gets tearout.

All good advice. I tend to slow the lathe down for sanding but also think Texian's advice is worth considering. The pressure one uses on the paper is just as important as the speed. So, just like grinding tools on a spark grinder, light pressure is what is needed when sanding. Let the paper do the work.

Definitely slow , I normally sand around the 300 to 500 rpm mark, with the occasional with the grain rub {while stopped this allows me to cool it down and clear the paper and the paper seems to last longer } Micromesh is always slow and wet { I think it gets a smoother finish that way } the only time I fast sand/polish is with EEE from Ubeut or Tripoli Powder . my idea is that I don't really care how long it takes . I want a finish I am happy with

Here is an instructive table table that shows the linear speeds in m/s for different diameter objects turning at different RPMs.



Belt sanders generally operate with linear speeds of between 4 and 8 m/s linear speeds. The figures with red backgrounds show the RPM/diameters that definitely exceed the belt sander values. But don't forget that most belt sanders have a very large areas of paper and a mechanism to remove the dust so the paper doesn't clog. If using a small area of paper this means you need to reduce the rpm even further.

If in doubt just start on the slowest speed and work upwards.

....... slow is fine but how about using a inertia sander? They depend on the drive of the work piece to effect the sanding process. I find that they need speed, in fact all the more the merrier.

One of the current design trends is toward open type of sand paper ie Astra dot, single and double etc. As far a I can see this is to open up the sandpaper to allow self cleaning to be more effective.

I use Noritake sand paper with its single and double dot design, in lower grades ie 60-80-120 etc as speed is required for my inertia sanders, the cleaning aspect is well taken care of due to in part the dot design and the spinning action of the sander.

On higher grades with out the dot design clogging is definitely a issue. But again the action of the sander greatly assists in the cleaning of the paper, so I tend to do it all at speeds over 500rpm.

Power sanding I drop the speed down or even stop the lathe and rock the job back and forth as I sand . But the sander it self is going at high speed especially if your following the Raffan method of using a 4"disc grinder.However most of my power sanding is done with a variable speed pistol drill of which I vary the speed according the problem at hand. But still with a tendency toward higher speeds for faster removal.


These days I rarely do any hand sanding on the lathe. Using higher grades, say 320 and up power sanding and inertia sanding will produce very good results, better I find than any other method I use.

Originally Posted by hughie

....... slow is fine but how about using a inertia sander? They depend on the drive of the work piece to effect the sanding process. I find that they need speed, in fact all the more the merrier.

Oooer! There's always someone who wants to throw a spanner in the works!

But really an inertia sander is sanding at much slower speeds than it appears... It's sanding not at the feet/yards/miles per minute the timber is turning, but at the rate of the angular displacement of the head in relation to the timber. If you do the maths, it's quite slow... about belt-sander speeds.

Originally Posted by brendan stemp

All good advice. I tend to slow the lathe down for sanding but also think Texian's advice is worth considering. The pressure one uses on the paper is just as important as the speed. So, just like grinding tools on a spark grinder, light pressure is what is needed when sanding. Let the paper do the work.

I try to never press on where the paper is cutting. When possible, I hold the two ends and sand using the middle, or I fold the paper to stiffen it up and use it like a stationary flap sander.

Pressing on the paper at the point of contact can clog the paper right quick, with the paper stationary. I've been experimenting with drawing the paper under the point of contact, with light finger or thumb pressure, so it acts a little like a miniature belt sander. It seems to work better this way, at least sometimes.

Cheers,
Joe

Ok guys , what direction to sand ?

uphill , downhill, center to edge , edge to center , up and down , side to side ... ?

Same direction as with the tools ?

The only time I hand sand is on spindle work (which I don't do very often), so will leave the comments on hand sanding to those with more experience with that.

My experience is mainly with power sanding on bowls and the like. My preference is to wind the speed of the lathe up as fast as the piece will safely go and to run the power sander on full revs, BUT work with a light touch. The relative speed would be about 3,000-5,000rpm.

Unlike hand sanding, the area of contact between the sandpaper and wood is constantly changing and as a result there is less heat buildup than might be expected. The air cooling effect of the spinning disk probably also helps.

I can only remember causing fine heat cracks once, in a piece of Flinders Ranges Corkwood (Hakea ednieana), which must have been still green. Should have left it another five years, but it was such lovely wood I couldn't resist it any longer and it did make a rather specy exhibition piece. Don't think anyone noticed the few fine cracks....

Some woods are more inclined to clog abrasives than others. If they do, I just clamp one of those abrasive rubbers near the lathe and power sand that as required.

.....

Nice one Jock, another dimension......

GC