Random orbital sander query

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PostPosted: Wed Sep 08, 2021 3:24 am
Gents

Looking at picking up a 3m 150mm pneumatic random orbital sander and notice they have various models with 2.5mm / 5mm / 8mm orbit.

Is one orbit more suited than an another for prepping body panels for paint or is it a personal preference thing?

Main use will be prepping bare metal panels for epoxy and maybe rough up cured epoxy for primers, will block sand the primers.

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Adam

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PostPosted: Wed Sep 08, 2021 8:15 pm
The larger the orbit, the more aggressive the action.

So, for prep work, the 8mm is better suited.
Chris



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PostPosted: Wed Sep 08, 2021 10:07 pm
Thanks mate.

Do you know if there is a functional difference between the 6-8inch DA sanders with the lever on the back and the palm sander variants?

Image


Image


I have had the one like the top picture in the past, but picked up a cheap 6 inch palm sander but found it didn't rough up the bare metal as well (but I thought it might have been caused by the soft backed intermediary pad that came with it).

Looking to get a nice commercial grade one.



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PostPosted: Thu Sep 09, 2021 2:47 am
Anyone ever used the electric version of the orbital sander that airvantage / mirka deros etc sell? They sell for a premium but the lower noise output would be a big plus.

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PostPosted: Thu Sep 09, 2021 7:40 am
Don't get confused between a random orbital (RO) sander
and a dual action (DA) sander.
They are two completely different types of sanders.
JC.

(It's not custom painting-it's custom sanding)



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PostPosted: Thu Sep 09, 2021 5:51 pm
If I strip the paint with paint stripper / strip disc, is there any reason (apart from efficiency) that I can't prep body panels for epoxy by block sanding by hand as opposed to using an air / electric sander?

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PostPosted: Fri Sep 10, 2021 8:13 am
As long as exposed metal is clean, dry and has a scratch
it's ready for epoxy. Doesn't matter how you got there.
Keep in mind "clean" means no residues remaining from
anything, especially paint strippers.
Even city water leaves residue if left on to dry.
JC.

(It's not custom painting-it's custom sanding)



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PostPosted: Fri Feb 11, 2022 1:19 am
Gents

Apologies if this is an ignorant question, but these tools are expensive enough that I don't want to waste money on an incorrect purchase...with regards to roughing up bare metal for epoxy / body filler etc...aka 80g to 240g kind of work...

Was looking at buying a Shinano SI-3100 7mm orbit sander (pictured at bottom)...as its specs say only 75db and low cfm use...but I do like the feel of the palm sanders.

Would a Rupes SKORPIO III Palm Sander with a 9mm orbit like below perform the same as the Shinano? Both are dual action, but do the different designs perform the same and it is just the orbit that matters or is there other intrinsic differences in the different designs?

The rupes also has a 6mm orbit that may have a bit more versatile use

Image


Image

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PostPosted: Fri Feb 11, 2022 12:07 pm
The top one looks like a random orbital, the bottom one looks more like a
DA (dual action)
DA's are much more aggressive than RO's.
DA's spin faster in a elliptical pattern,
RO's spin slow and orbit (vibrate), giving a finer finish.
Check the nameplates or specs and watch for number of orbits per minute (RO)
verses revolutions per minute (DA)
That's the difference.
There's some really good electric RO's out there, there are palm sanders and there are
"right angle" sanders which orbit less and spin faster making them a little more
aggressive than the palm ones.
I use an electric right angle one for dry sanding clear coat and it works great.
I use the palm ones for woodworking, and even have one that's cordless.

I don't use a DA (air) much anymore, when I need something real aggressive, like paint removal I find a rotary buffer with 80 grit works better.
JC.

(It's not custom painting-it's custom sanding)



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PostPosted: Fri Feb 11, 2022 6:29 pm
Thanks mate, I think I have been misunderstanding that despite both of them having "orbits" per se, that does not equate to the same thing.
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