How to use an orbital sander!

[foxhole]

Worth buying 1/2 dozen interface pads . They go between machine and sanding discs and prevent wear of original hook fastening on sander which are often expensive to replace .
Also provides a little cushioning on uneven surfaces.

5" 125mm Interface Pads Hook & Loop Soft Sponge Pad Polishing Sanding 5-44 Hole | eBay

Material: Sponge. -Hook & Loop patch bottom, convenient to use. -Especially suitable for pneumatic and electric type of self-cleaning polishing machine and grinding machine. -Hole Quantity: 5 Hole / 6 Hole / 8 Hole / 44 Hole.

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[MrsRenovator]

Thanks. I'll do that. I had seen them but thought they were only for if you used the mesh pads. I'll definitely get some now. Thanks.

 

[Justin Passing]

Usually the ones with higher oscillation rate use smaller circles
Keep it moving.

"Kill" the paper before you first apply fresh paper to the wood - that's a light rub over the sandpaper with an old piece of same grade sandpaper. It just knocks the sticky-out bits off which would produce the nasty marks.

They often clog up with paint . If so , roll up a plastic bag very tight and tape it to make a stick. Push it into the paint on the sander - it'll often bring it out.

 

[Notch7]

When I get jutter/dotty-trail marks, does that mean I was going too slowly

Random orbital sanders typically have a 5mm orbit.

Trail marks tend to be a result of bits of abrasive breaking off and cause indentations.

What sort of abrasive are you using?

Judder and difficulty of moving can be related to extraction, sometimes the vacuum can make a sander more stable, sometimes it makes it too “sticky” and difficult to move smoothly.


In terms of use, make sure you start with a grit that cuts, on timber usually that would be 80g or 120g

You can use it flat for general sanding, but for getting rid of local imperfections use one edge of the sander - just put a bit more pressure on one side, don’t lift it up so it’s on a noticeable angle.

I have to say there is a big difference between budget and expensive ROS in terms of balance, I ran a joinery company and we used Mirka air sanders which were extremely well balanced.

 

[^woody^]

If you can see the marks, then the paper may be too course. Start rough, go lighter for the finish. Or too fast, slower speed or movement

Keep the machine moving, check the effects and then go back if need me. Be mindful of sanding more areas for longer than others. Either do the whole piece in several passes, or keep to smaller areas for the same amount of time.

The object is to just steady the machine, not press it excessively, and move it gently and evenly.

Final pass with the grain.

 

[MrsRenovator]

I've got all sorts of grit, from 40 right up to a 240 which I'm unlikely to use. I'm thinking of trying the non-clog-mesh type. (With a saver pad)

Thank you all for your advice. (I had tried looking on YouTube but most of them are American, speeded up and no help at all.)

 

[catlad]

Depending how much you are doing! don't forget the vibration element on your wrist and hands

 

[MrsRenovator]

UPDATE

I needed to sand a small cupboard top today. Even though I clamped it, it still moved very slightly as I sanded. Double clamps, and voila! The sander behaved much better and was far easier to handle. The very slight vibration in the timber was transferring to the sander.

I used most of the advice you all gave. I used a slower speed, I turned the sander to face the other way, I held it with both hands (that helped a lot), I 'killed' the paper, I moved slower but smoothly, not rushing. And I finished off with a few sweeps with the grain.

My mesh discs and saver pad will be here later this week.

And that is why I like this forum.
Thank you!

 

[^woody^]

Teamwork makes the dream work.

Consider one of those foam rubber anti-slip mats sold for under carpets or ornaments. Cheap from the discount stores. They hold workpieces well and don't block the surface like clamps.

 

[Harry Bloomfield]

Consider one of those foam rubber anti-slip mats sold for under carpets or ornaments. Cheap from the discount stores. They hold workpieces well and don't block the surface like clamps.

Good idea - I never thought of that use for it.

 

[opps]

Don’t turn it on unless it’s in contact with the wood or it skips and jumps.

Erm... that is the wrong way around. Sanders should be turned on before touching the surface.

That is pretty much true of most power tools- never start a tool under duress.

 

[Notch7]

UPDATE

I needed to sand a small cupboard top today. Even though I clamped it, it still moved very slightly as I sanded. Double clamps, and voila! The sander behaved much better and was far easier to handle. The very slight vibration in the timber was transferring to the sander.

I used most of the advice you all gave. I used a slower speed, I turned the sander to face the other way, I held it with both hands (that helped a lot), I 'killed' the paper, I moved slower but smoothly, not rushing. And I finished off with a few sweeps with the grain.

My mesh discs and saver pad will be here later this week.

And that is why I like this forum.
Thank you!

Mesh discs like abranet are fine on flat surfaces but avoid using them on edges or they rip

 

[opps]

Thanks. I'll do that. I had seen them but thought they were only for if you used the mesh pads. I'll definitely get some now. Thanks.

I have a Festool RO125 (£550 in today's money). It used to bounce a lot. It took two hands to hold it down. I eventually relegated it to only sanding water based primer on MDF. BUT I used a 10mm interface pad to make it work.

None of my 150mm Festool sanders had the same problem.

One day I lent it to someone, they completely messed up the main pad. I had to buy a new pad. Once I fitted the new pad, the bounce disappeared.

Turns out that the original pad was badly balanced. That may be the case with yours.

Apropos the scratching- as others have mentioned it may be the result of broken grit falling off the paper. All of my sanders are connected to dust extractors- it sucks away any dust and grit.

I decorate for a living- I occasionally have to sand sprayed finishes. I would never consider sanding those without a dust extractor (read: vacuum connected.

BTW, the mesh finishes, such as Abranet, are brilliant, but yeah, if you don't use a thin interface pad, the heat transfer will chuff up your pad.

 

[foxhole]

Erm... that is the wrong way around. Sanders should be turned on before touching the surface.

That is pretty much true of most power tools- never start a tool under duress.

Not true if orbital sanders , there is no duress if you hold correctly .

 

[opps]

Thanks. I'll do that. I had seen them but thought they were only for if you used the mesh pads. I'll definitely get some now. Thanks.

I use the Mirka or Festool saver pads on my festool sanders when using mesh. My 125mm sander has used the same saver pad for about 100 hours of use, it is still fine.