What size of "Orbit" should I buy on an Air sander?

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Forum topic by PPK posted 02-23-2017 06:55 PM 1221 views 0 times favorited 6 replies Add to Favorites Watch
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1175 posts in 980 days

02-23-2017 06:55 PM

Topic tags/keywords: question style sander pneumatic finishing

I’m looking to buy a 5” random orbital air sander. I have used them in the past, and I know the basics – you need a good, large air compressor with a supply of dry air. I know they use a lot of CFM. I’ve got both. What I DON’T know is what size of “orbit pattern” to get. I’ve got my choices narrowed down to Dynabrade, Mirka and 3M. I’ve used the 3M before, and was happy with it, as well as a Porter Cable. Both were good, but didn’t last terribly long. (about a year)

So, the three brands above all list the orbit size ranging from 3/32” to 3/8”.... What should I pick? I do mostly cabinets, and have been getting into furniture more. I’d use this for the last grits – 120 and mostly 220 grit. I’ve got the Porter Cable “grinder” (right angle) style sander that I use for any aggressive sanding/leveling of joints, so I won’t really be doing any heavy sanding with the air sander.

Any imput is appreciated. Thanks!

Oh, and finally, I hate sanding. So I want to spend the least time sanding, and get the nicest swirl-free glass smooth finish as fast as possible! Just in case that has a difference on anyone’s input!

-- Pete

6 replies so far

View Loren's profile


10477 posts in 3818 days

#1 posted 02-23-2017 07:14 PM

I think smaller orbital patterns are used more
for finishing finishes, varnished table tops
for example.

I think a larger orbit is more useful for aggressive
removal of wood.

I only have one ROS I use for everything and when
I sand finishes I usually do it by hand.

Sanding and finishing are certainly not strong
skills for me though. If you really want to improve
in those areas to save time, there’s a lot to learn.

View jbay's profile (online now)


2733 posts in 1070 days

#2 posted 02-23-2017 07:39 PM

I have the Mirka 5” with a 3/16 orbit.
I like it a lot.
I still can put 80g on it and it’s aggressive enough when you need it,
I mostly use it for 150 and 220.
On occasion I will use 320 on primmer/undercoating before top coating.

-- “Hanging onto resentment, is letting someone you despise live rent-free in your head.” (Ann Landers)......

View cabmaker's profile


1740 posts in 2979 days

#3 posted 02-23-2017 10:21 PM

If those are your options go for the 3/32

If your doing cabinet work and some furniture you will never need the 3/8

View Tony_S's profile


938 posts in 3253 days

#4 posted 02-24-2017 10:53 AM

3/16 is the best middle ground imo.

I can’t speak for the Mirka personally, but I’ve never heard or read anything but good about them.
I’ve got 7 or 8 Dynabrade’s in the shop ranging anywhere from 2 to maybe 15 years old….they are bullet proof.
As you’ve said, good dry air(critical for any air tool) is key….and as many times as I’ve bitched at the guys in the shop to oil them regularly, I’d truly be surprised if any of them see oil more than once a month.
Other than regular pad replacement which is normal for any brand, and replacing a couple of springs and o rings on some of the older ones, never had a single issue with any of them.

-- It is the mark of an educated mind to be able to entertain a thought without accepting it. Aristotle

View PPK's profile


1175 posts in 980 days

#5 posted 03-03-2017 05:16 PM

I went with the Dynabrade 5” Spirit model, in the 3/16” orbit. Tried some 3M ceramic (purple) disks on it last night, and it worked great. Sure is quiet. Looking forward to sanding a little more now… ;-)

-- Pete

View GR8HUNTER's profile


4898 posts in 883 days

#6 posted 03-03-2017 06:26 PM

3/32 WOULD work great on stained doors …and the other would work well with painted doors ….Dynabrade is a fabulous sander …. GOOD LUCK :<))

-- Tony---- Reinholds,Pa.------ REMEMBER TO ALWAYS HAVE FUN

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