Horizontal stripes with random orbital sander


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Hi. I’ve looked all over the internet and can’t seem to find the answer for this. I have a random orbital sander and anytime I use it I end up with these horrible lines running perpendicular to the grain. This has always been using 80 grit sandpaper. 
 

Would it go away after going up to 120 or above? I feel like it wouldn’t. 
 

1CC7B3D7-AEA0-4084-B8F8-502ECB779300.jpeg

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This typically happens when you're moving the sander too quickly or using too much downward pressure on the sander causing it to dig into the surface rather than letting the tool do the work.  It also might take a while for the sander to remove all the weathered material/stain.  Once down to bare wood though you should see most of the linear scratches disappear but will somewhat visible until you proceed through the grits.  

Another issue might be with the type of random orbit you're using.  If the pad is square/rectangular it can leave linear scratches like this.  However if you're using a circular pad its more likely going to give you swirl marks that will eventually go away to the naked eye the higher grit you go to. 

However, I'm not an expert, but in my experiences this is what I've noticed. Hope this helps. 

EDIT: Stumpy Nubs has a really good video about this. Link below

https://www.youtube.com/results?search_query=so+you+think+you+know+how+to+sand 

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Looks like the horizontal likes that is left over from what ever milling machine the lumber mill used on the board. I find this is somewhat typical from standard construction lumber. It could be the above as well though.

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3 hours ago, Askland09 said:

This typically happens when you're moving the sander too quickly or using too much downward pressure on the sander causing it to dig into the surface rather than letting the tool do the work.  It also might take a while for the sander to remove all the weathered material/stain.  Once down to bare wood though you should see most of the linear scratches disappear but will somewhat visible until you proceed through the grits.  

Another issue might be with the type of random orbit you're using.  If the pad is square/rectangular it can leave linear scratches like this.  However if you're using a circular pad its more likely going to give you swirl marks that will eventually go away to the naked eye the higher grit you go to. 

However, I'm not an expert, but in my experiences this is what I've noticed. Hope this helps. 

EDIT: Stumpy Nubs has a really good video about this. Link below

https://www.youtube.com/results?search_query=so+you+think+you+know+how+to+sand 

Thanks, I checked out a couple of his videos so hopefully it’s one of those things. I do think I was likely moving too quickly and using too much pressure. Going to try again going more slowly and lightly and see if that helps. 

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2 hours ago, Tpt life said:

The lines I see are milling marks. Coarser paper to start would help that. 

 

18 minutes ago, Chestnut said:

Looks like the horizontal likes that is left over from what ever milling machine the lumber mill used on the board. I find this is somewhat typical from standard construction lumber. It could be the above as well though.

Thanks. I was using 80 but may try a 60 and see if that makes a difference. 

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