Sanding after hand planning

[Bacms]

I am building my knockdown workbench and have assembled and flattened the top where I am now ready for finishing. However, there is still a lot of places where I can see planing marks and was thinking of hitting those with a ROS before applying Osmo. Is this a good idea or is there a better approach to achieve this?

Also if I go with the sanding approach which grit should I start with? I am worried about going to aggressive and ruin the squareness and the flatness of the top/aprons.

 

[ED65]

Do you have any scrapers? They can level a surface better than sanding with a random-orbit would. Quite possibly faster too.

But this is a workbench so having the surface absolutely flat isn't an absolute priority. You know what really old benches tend to look like? That dinged, gouged and saw-marked surface doesn't seem to prevent those benches from working the way their users need them to.

Also if I go with the sanding approach which grit should I start with? I am worried about going to aggressive and ruin the squareness and the flatness of the top/aprons.

Coarser than you'd think is likely the answer, but depends on the depth of the marks.

No point in starting at 80 or 100 if your planing ridges are only hundredths of a mm in height (a few thou in old money).

 

[custard]

Do you have any scrapers? They can level a surface better than sanding with a random-orbit would. Quite possibly faster too....

...No point in starting at 80 or 100 if your planing ridges are only hundredths of a mm in height/quote]

This is poor advice.

If you value your thumbs don't use a scraper for levelling a large surface like a workbench!

And if you're concerned about planer marks then use your ROS, and you absolutely want to start with 80 grit. For a workbench you may choose to finish at 80 grit or, if you're really looking for something super-duper then 120 then 180, followed by Osmo, but it's not really necessary.

 

[thetyreman]

don't worry too much, it's going to move anyway, doesn't matter how flat you get it, you'll need to re-flatten it a few times

 

[Bacms]

Thank you, everyone, for the very useful replies. Guess I will give a go at 80grit then