ETS EC 150/5 sanding strategy for plywood built-ins

[escapegoat]

I just took delivery of what these days seems like an exorbitant quantity of plywood for a built-in mudroom project. The sheets are paint grade birch. Imperfections have been filled, but there are some small gaps that need to be addressed.

• Can I start from 180, or do I need to go lower?
• Am I better off sanding all the way up through 220 right up front, while the sheets are flat and unassembled?
• Or, should I wait until everything is assembled? This makes corner sanding more difficult, although I have an RO90 for that.

Thank you for your advice everyone!

 

[mino]

One rule of mine with plywood - first check every surface with light how straight it really us, if there are no drum sander marks etc. etc.

With no wavy marks, I would start with a light sand at 120. But this heavily depends on the material initial state and how flat/smooth I need the result. If you can get to desired end state just with a light sand at 180 and a 220 finish sand, then you hit a jackpot and so go for it!

When you have the space, it is much better to sand before any cuts. You do not need to worry about messing up the edges and sanding a whole sheet is potentially way faster. After cuts, you may still want to give it final at 180 or 220 depending on the project.

If there is no space, ideal is to rough-cut to manageable sizes, sand, final cut, (optionally) assemble, finish sand. But that can be overkill in many cases so best is to test and adapt.

 

[escapegoat]

Thanks! I had the plywood pre-cut into manageable sections so I can easily reach all areas of the panels with a hand sander. I'll take a closer look with good lighting and see if I can get away with starting at 180 or if I need to drop down to 120.

 

[ear3]

FWIW, I usually start off on this sort of plywood at 150.  The one concern with starting off on a lower grit with a sander as aggressive as the 150/5 is burning through the veneer in spots.  Theoretically this shouldn't happen with good quality plywood that has a decently and consistently thick veneer face, but there are always exceptions.  If you're painting it though, this is obviously less of a concern.

I would sand through to final 220 grit before assembly, so that it's just touch up once everything is set up.