I have a dumb question.

[Randall Clark]

When I am using my Milwaukee ROS on my white oak garden bench that I am making for my beautiful wife, how do you tell when the sanding disk is used up and needs to be replaced? Is it the "feel" of the paper? Is it the reaction of the sander? Thank you in advance for informing the ignorant. Is there a standard rule?

[Kyle Iwamoto]

There are no dumb questions. Inquiring minds want to know.

I use mine until they no longer cut in a reasonable time. I know that's WAY too long. But I'm a cheapskate and hate to throw out a disc that is still somewhat working. I'd also like to know how others measure when to toss the disc.....

[paul cottingham]

How about when you start thinking "I wonder if this would go faster with a hand plane?"

[ray hampton]

the few times that I use a disc , I use each disc until it came off of the backing plate

[Eric DeSilva]

There are no dumb questions. Inquiring minds want to know.

Oh, there are dumb questions... Like why it is that every time I remove a used sanding disk, I feel compelled to throw it in a box instead of throwing it away. I really have no idea what I think I'm going to do with those.

[daniel lane]

Oh, there are dumb questions... Like why it is that every time I remove a used sanding disk, I feel compelled to throw it in a box instead of throwing it away. I really have no idea what I think I'm going to do with those.

No, no...that's a good question.

[glenn bradley]

As Kyle stated; I am quick to change paper once it stops working as I expect it to. If you find yourself going over an area again and again, that is a waste. Overusing your abrasives gives you inconsistent results and makes your grit changes less effective. I figured out a long time ago that trying to stretch your abrasive dollars was a false economy. It wastes your time and give poor results. Formula - $150 worth of White Oak + 53 hours of my time versus a 50 cent piece of sandpaper = hmmmm.

[Ken Fitzgerald]

Another consideration. I have a couple of the crepe abrasive cleaners I find extremely useful. Often, just cleaning the sand paper will extend it's life.

[glenn bradley]

Another consideration. I have a couple of the crepe abrasive cleaners I find extremely useful. Often, just cleaning the sand paper will extend it's life.

Ken is dead-on. I use them regularly; they work very well.

[Van Huskey]

+1 on Ken's point, the sander sitters make that easy and pay for themselves.

I suppose it is a feel thing for me and I am bad about being cheap and pushing it, which as has been pointed out is often false economy.

[Jim Matthews]

Paper is cheap, time is expensive.

When you don't see dust, change the pad.
I hand scrape with a cabinet scraper until I think I'm close then sand with a cork block @ 220 grit.

The dust fills in divots where I need to scrape a bit more.

ROS are a nuisance, in my basement shop.

[Steven Hsieh]

When you press the sander too hard.

[Myk Rian]

I figure if I start with a 120 disk and keep using it, it'll wear down to eventually being 400 grit, and then 1000.
No need to change it until the next sanding job. :rolleyes:

[John Lanciani]

4 to 5 minutes, seriously. Most people tend to go way too long before changing. I'd rather waste a little bit of money instead of a ton of time. I can make more money but I can't turn back the clock.

They don't call sandpaper a consumable for nothing...

[Peter Quinn]

Depends. At work where somebody else provides the paper, about every 2 minutes. Ok, not always quite that quick, but pretty often. Where you start grit wise has a lot of bearing on what you will see and feel. I usually start at 100 grit if the objects have been machine sanded, 80 grit if not, unless the wood is something particularly soft like butternut. You can see mill marks disappear, feel minor surface irregularities diminish, etc....then suddenly it starts dragging, your 80 grit has become 120 grit or worse, its time to change. Each grit gets rid of the scratches left by the previous, as you see them go and feel the surface improve its time to switch grits. If you are still moving around a piece and the surface isn't improving, I like to change the paper.

At home I use a festool sander with Rubin paper, so the equation is different. First the vacuum helps prolong the life of the paper considerably. At work I sand in front of a huge evacuation fan which takes the dust away from the user, but does't pull it away from the paper, so it dies much quicker. And the Festool rubin paper is made for sanding raw wood, its one of the best sand papers I've used. When using cheapo paper I simply don't get the same life. Third factor, the festool paper is expensive, and when I'm paying for it, I'm going to squeeze every drop out of it. So when a piece of 80 grit stops being effective as a first stage, I pull it off and save it. When I jump up to the next grit, back goes the used 80 grit which is now approaching 100 grit. I use that as a segue into the next grit. But I never push a piece of paper past its effective limits. Refer to Glen's fine equation , IF COST OF LUMBER + VALUE OF LABOR / COST OF PAPER >1, then the paper is worth a small fraction of your total investment and should be treated accordingly.

[Rod Sheridan]

Hi Randall, you take the mass of the sawdust produced in grams per minute and multiply by by the inverse of the grit rating of the sandpaper divided by the janka hardness of the wood.

This yields some meaningless result, however it sounds official. :-)

You will notice the sander removeing less and less material as the paper wears, this will change how the sander reacts to the wood, the sander appears to glide easier as the paper wears out.

As others have said, change the paper frequently, probably in the 2 to 3 minute range.............Regards, Rod.

[Metod Alif]

When I am using my Milwaukee ROS on my white oak garden bench that I am making for my beautiful wife, how do you tell when the sanding disk is used up and needs to be replaced? Is it the "feel" of the paper? Is it the reaction of the sander? Thank you in advance for informing the ignorant. Is there a standard rule?
I scribble a few (use light touch) pencil lines, and see how fast they erase. Experiment (start with a fresh disc) a bit, to get a feel. Using a worn out sandpaper wastes a lot of time (which becomes more rare as one gets older...:mad:).
Best wishes,
Metod

[Prashun Patel]

I really appreciate this question. I was always told - like many say below - "when it doesn't work like it's supposed to." But the degradation is for me always so gradual that I can't tell. I still don't have it figured out. My general rule of thumb would be to use 2 discs of the starting grit on a garden bench, and then 1 of every higher grit.

The key to success IMHO is not in the frequency of paper change but in making sure I don't skip grits. Also, resist the urge to press down. It's bad for everyone: you, the sander pad, and the paper. And never tip.

[Ben Hatcher]

I think Wood magazine did a study on abrasive life a while back. They found, if memory serves, that the material removal rate is fairly constant for the first 5-15 minutes then starts to drop off fairly quickly and that the "as it wears it turns into the next grit" to be untrue. I generally use a pad for about 15 minutes and toss it, though I'm certainly guilty of keeping a stack of used paper for sanding back finishes, removing paint, drywall mud, rust, and the like if I know I have a project like that coming up.

[Ron Natalie]

I was going to lament that there is no 6" Sander Sitter, but they recently announced one. There's a couple of listing for it on Amazon with "notify me when available" links.

[Larry Browning]

Paper is cheap, time is expensive.

Being a hobbyist gives me a little different perspective. Materials(wood, sandpaper, stain, finish, etc) are expensive, I want them to last as long as possible. So the longer something takes the less money it cost me. When I finish one project, it just costs me more money to start another.

I'm jus sayin.....

[Jim Rimmer]

I think Wood magazine did a study on abrasive life a while back...and that the "as it wears it turns into the next grit" to be untrue.
I was really surprised to see so many comments on the idea that the grit changes when the paper wears out. That is jut not right. You have the same grit with the individual grits rounded off. The grit doesn't change, the sandpaper just becomes less efficient.

[Mike Heidrick]

Another consideration. I have a couple of the crepe abrasive cleaners I find extremely useful. Often, just cleaning the sand paper will extend it's life.

++++++++++++1

[Van Huskey]

I was going to lament that there is no 6" Sander Sitter, but they recently announced one. There's a couple of listing for it on Amazon with "notify me when available" links.

Highland has them in stock, or did.

[Richard Dragin]

You should change it sooner than you think. They wear out fast and will waste time. If you find sanding boring and laborious as most of us do, changing disks will shorten the process.

Skipping grits? Does that mean, you have to use every one a manufacturer offers? I go from 100 to 220 with nothing in between. I spend half the time (or less) with grits after the initial grit.

Quality paper is the key. I prefer Industrial Abrasives Rhyno disks (hook & loop) but have never heard anything bad about Klingspor. 3M and Norton are over rated based on my experience and leave a lot of swirl marks.

[Prashun Patel]

Different strokes for different folks. I use the rhinos on yr recommendation. Am pleased. I am probably just worse at sanding than most. I have probs when I skip from 80 to 120. If I'm not feeling lazy I prefer 80 100 120 150 180 240 320 (tel:80 100 120 150 180 240 320) 400 for turned work. Flat seems more forgiving to go from 100 to 150 to 240. This is just what works for me.

[Brian Kent]

I am curious about sandpaper differences. I use Mirka disks (5" Bosch ROS) and sand until the grit has come off of the paper on the edges. This is also on a white oak garden bench, and there are a lot of places that are not just flat panels. Lots of curves and breaks.

Using other brands of sanding disks the grit stops cutting before it is worn off of the paper With Mirka I just look at it and when the edges are worn off, I toss it. I don't know which is better, grit that wears out first or grit that comes off before it wears out.

What kind of paper are others using?

[Brian Kent]

[QUOTE=Rod Sheridan;1935813]Hi Randall, you take the mass of the sawdust produced in grams per minute and multiply by by the inverse of the grit rating of the sandpaper divided by the janka hardness of the wood.

This yields some meaningless result, however it sounds official. :-)

Don't forget to divide by the square of the oil content.

[Rich Engelhardt]

how do you tell when the sanding disk is used up and needs to be replaced?
A few years ago I rented a U-Sand floor sander to refinish some hardwood floors.
The U-Sand is a large heavy machine with four 6" ROS underneath.
I started sanding using 36 grit disks and it became immediately apparent I had grossly underestimated the sheer number of disks I would need.
The base of the machine is roughly 14" by 14", and I could only get about three times the width of the base out of each set of four disks.

Removal of the old finish dropped off noticeably after that. I tried to extend the life of the disks as much as possible, but, after doing 3X the area of the base of the machine, the amount of time required to remove the same amount of material increased by a factor of nearly 10 times.

As I worked up through the different grits, the life of each disk got greater and greater.
80 grit would sand roughly 10X the size of the base of the machine.
120 grit would sand nearly half of a 12 X 15 living room
180 grit would sand the entire living room plus the 4' X 12' hallway.

It was hardly any sort of scientific experiment - but - it was a real eye opener to me as far as the useful life of a sanding disk.

The one thing that impressed me the most out of that experience was the condition of the 36 grit disks after they had "worn out".
It was impossible to look at them or feel them (to see how "sharp" the teeth were) and tell them apart from a set of new out of the package disks!

As the grits became finer, the wear on the disks became more noticeable to both the eye and the touch.

Since that time, I've started changing disks on my 5" ROS a lot more often.

A real wild card is also the hardness of the wood being sanded.
The first time I used the U-Sand, I was doing Red Oak floors.
A month ago when I used a U-Sand I did White Oak.
My figures for the White Oak are roughly half of what they were for the Red Oak.
However - there were a number of other factors with the White Oak floors that affected disk life.
The majority of the floors there were old 1.5" wide boards that had curled up a bit.
There was one section of new 2.5" wide flooring 8' x 8' that I had just installed.


I think Wood magazine did a study on abrasive life a while back...and that the "as it wears it turns into the next grit" to be untrue.
My experience w/the U-Sand yielded the same conclusion.
Using a "worn out" disk on a previously sanded area did not remove any of the scratch marks left by a good disk - which is pretty much the whole object of using progressivly finer grits.