It depends upon what I am sanding, but usually when it seems more like it's polishing instead of removing material.

Most of my sanding is done by hand.

To answer the question : When to change sandpaper?

         Some sandpaper comes with a marker and changes color when worn. Finkat is one brand. There is no definitive line on when paper is worn out so there has to be a judgement call.

           One way to tell is look for a dust stream coming off the work. When hand sanding this method is difficult to observe. If no dust results then is it time to CHANGE.

           Another way is that that defect you are sanding is not changing. I may be time to CHANGE.

           The one I like to use is feel. Feel the wood NO that is subjective . Feel the paper and then feel a new piece from that you be the judge. It may be time to CHANGE.

           There is that old saying "use sandpaper like it belongs to someone else". Your time is valuable so why waste it saving a 10 cent piece of sandpaper. Also remember fresh paper cuts better . Some believe old paper worn from 120 is now 150 . This is a fallacy as the determining factor is the size of the grain  on the paper itself these do not fracture evenly and as they break down they will not give a even transfer to the next higher grit. And then the fact that there will be many fewer grains on the paper when worn.

         

I change sandpaper when I get to 2 points.  Either it is not effective or the grit has lost its edge.  I will feel of a new piece and the old piece and if I determine that the one in use is insufficient, toss the old one.  

 

One thing that I love on my Shopsmith, there is a sanding disk.  When it gets full of dust, there is a cleaner like an old eraser that we used in mechanical drawing many years ago.  But, rubbing it on the sanding disk while it is spinning, it cleans.  It does not restore the grit, but it does extend the life of the paper.  I have tried using that cleaner on regular sandpaper, but I don't have the same success.  

21 hours ago, FlGatorwood said:

I change sandpaper when I get to 2 points.  Either it is not effective or the grit has lost its edge.  I will feel of a new piece and the old piece and if I determine that the one in use is insufficient, toss the old one.  

 

One thing that I love on my Shopsmith, there is a sanding disk.  When it gets full of dust, there is a cleaner like an old eraser that we used in mechanical drawing many years ago.  But, rubbing it on the sanding disk while it is spinning, it cleans.  It does not restore the grit, but it does extend the life of the paper.  I have tried using that cleaner on regular sandpaper, but I don't have the same success.  

You know they make those for all tablesaws. I have one for mine but never use it anymore since got the Ryobi ROS. I also made one for lathe when I did a little segmenting.

22 hours ago, FlGatorwood said:

I change sandpaper when I get to 2 points.  Either it is not effective or the grit has lost its edge.  I will feel of a new piece and the old piece and if I determine that the one in use is insufficient, toss the old one.  

 

One thing that I love on my Shopsmith, there is a sanding disk.  When it gets full of dust, there is a cleaner like an old eraser that we used in mechanical drawing many years ago.  But, rubbing it on the sanding disk while it is spinning, it cleans.  It does not restore the grit, but it does extend the life of the paper.  I have tried using that cleaner on regular sandpaper, but I don't have the same success.  

I tried as well. Same result.

Thank you, Gerald.  You taught me something else.  

I also like to stop the lathe and hand sand horizontally, before switching grits. My lathe has reverse, but I found that switching from forward to reverse doesn't matter much since it is still sanding in the same direction if that makes sense. 

I just ordered this today.  I've been using a 2" sanding kit from Sorby with velcro but on my big 18V standard drill.  This should make it easier to handle I think.  I'll let you know.

 

36 minutes ago, Jim from Easy Wood Tools said:

I just ordered this today.  I've been using a 2" sanding kit from Sorby with velcro but on my big 18V standard drill.  This should make it easier to handle I think.  I'll let you know.

 

I've always had issues with power sanders even with the lathe spinning.  Although that cordless one looks tempting tempting.  Let me know how you like it. I may wind up picking one up. Hand sanding is starting to become well dreadful LOL

Edited September 1, 20205 yr by AndrewB

10 minutes ago, AndrewB said:

 Let me know how you like it. I may wind up picking one up. 

Will do!

On 8/27/2020 at 2:09 PM, PatriotWoodturning said:

I also like to stop the lathe and hand sand horizontally, before switching grits. My lathe has reverse, but I found that switching from forward to reverse doesn't matter much since it is still sanding in the same direction if that makes sense. 

I use same method. Works well.

@Jim from Easy Wood Tools I have a Jobmax corded I use mostly but also have a cordless. I always felt the battery did not last long enough.That is a nice looking unit. Does it come with two batteries?

8 hours ago, Gerald said:

Does it come with two batteries?

Just one.  I've found this new generation of lithium ion batteries perform very well.  We shall see...

The problem I've always had with any cordless power tool is the battery life.  I usually wind up buying 20 volts which probably is my main issue with that alone.  But I buy for what I can afford at the time.  So that is the main draw backs of battery operated tools.  How ever I do have a little battery powered cordless drill thats a 20 volt has done quite well.  Even when the drill has been left out in the shop over night and in the colder air.  But most of my sanding for now has been done by hand the disc sander did not work out that great.

My sanding technique is born out of years of being broke and trying to get the last drop of sanding out of the sand paper. Fortunately these days economics are a little better but I still stick to the old routines. My favorite paper these days is the 3M Pro with the sticky back. When I am sanding flat stock I tend to use multiple orbital 1/3 sheet sanders ( the $15 versions from HF) to eliminate changing paper and go through the grits up to 320 and then do hand sanding. When I am finished with the project I tend to change paper and throw them into a paper bag. That bag of used paper becomes my stash for turning. The most common mistake I see in turnings is the lack of hand sanding, resulting in the finished product having the visible sanding grooves. I will start hand sanding somewhere around the 180-220 grit, reverting back to 120 for rough spots. Since I use natural oil finishes to build up to a gloss finish I tend to polish the wood as far as I can get it before I apply the finish. If the wood is hard enough I will go all the way to 8000 grit, but usually stop at at 1000. 
Paul

Since I'm just so keen on hand sanding, I don't really mind it any more I just picked up two of these assorted Turners Sandpaper Abrasive 5 Roll Assormtent from Home Depot.... Ordered it online of course.  But 1 inch width by a 20 foot roll???  I mean I couldn't pass this offer up.  So much cheaper than what I've been doing for purchasing sand paper.  Either way they will be nice to have when I get them... Unfortunately they wont get here until the 17th.  Oh well.  Sand paper shortage SOLVED.

https://www.homedepot.com/p/POWERTEC-Turners-Sandpaper-Abrasive-5-Roll-Assortment-4RA2100/309855301

@Jim from Easy Wood Tools, how did that cordless sander from Rikon work for you?  I'm sure you must have posted your review someplace, right? I must have missed it.

On 10/16/2020 at 4:11 PM, PostalTom said:

@Jim from Easy Wood Tools, how did that cordless sander from Rikon work for you?  I'm sure you must have posted your review someplace, right? I must have missed it.

No...  You haven't missed a thing.  Ordered early September, still on backorder (no warning when I ordered it)

Expected ship date is end of October.  I'll let you know

OK.  Thanks Jim.

Found this article on sanding grits.  Thought it might be useful.

 

https://www.sandpaper.com/articles/abrasive-grains-everything-you-need-to-know-to-choose-the-right-one/