Use finer and finer grit sandpaper? Use a good brand of paper helps with grit consistency. Aren't we talking about small curved areas. A regular ROS will get al the other areas.Originally Posted by Richard Coers
Member
Use finer and finer grit sandpaper? Use a good brand of paper helps with grit consistency. Aren't we talking about small curved areas. A regular ROS will get al the other areas.
Member
With flat work, the surface I start with is generally a bit smoother than what my bowls are. Most of the time I can take a card scraper to the wood, then use a ROS with finer grits, in the 220 or so range. If I was to sand out a sculpted chair seat, hopefully I would be able to start in the 120 grit range, but that would depend on how good or bad of a job I did with the sculpting. Chisels? Router? In some cases, it may just take the card scraper. The circular scratch patterns are no more difficult to remove than the straight ones. Mostly sand till you get ALL of the previous grit scratches out before moving on to the next grit. Good light. Good glasses. You can vary the scratch lines to kind of go with the grain depending on which part of the pad you are using. When you get past 220 grit, you are pretty much polishing rather than sanding.
robo hippy
Contributor
I know you specified an electric sander but Woodturners Wonders has a pneumatic unit with modest air requirements.
Specifications:
5/16 x 24 thread female mounting hole
3 CFM's of air at 90 PSI
3mm Orbit
1/4 inch air input (works with our Snubber Hose)
Weight: Just under 1 lbs.
Compatible with 1", 2", and 3" sanding pad holders
Ken has two ROSs listed on the site.
Last edited by Richard Dooling; 10-31-2019 at 1:32 PM.
RD
[OP]
Contributor
Here is a chair I made which shows why my 6" ROS is too big.
The back is first bawnsawn, then shaped with a 4" right-angle grinder with a structured-carbide disc and then with 4" sanding discs. Eventually I want to finish sand, but when I put the 6" ROS on the concave areas, it barely touches at the edges of the sanding pad. A 5" sander would be better, I think a 3" sander would get in there even better.
On the seat, I rough shaped it with the 4" grinder with the Arbortech 3-tooth disc, and then used the same progression of sandpaper on the grinder. To finish sand I again used the 6" ROS, but it rests on the seat edge while I'm trying to get down in the scoop. Again a 5" would better, but I think a 3" sander is really what I should be using.
chaircurves.jpg
Moderator
If you already have a 6, then it makes sense to get a 3". The 'lip' of the scoop is really hard to define crisply. Have you tried scrapers there?
[OP]
Contributor
Some traditional chair designs want a crisp edge for the scoop -- Windsors for instance. But for this modern chair, I don't see the need for a crisp edge; there isn't another sharp edge anyplace else on the chair.
Contributor
read my post above
Moderator
I take your point. What I mean is that even on chairs where I don't have a sharp or crisp edge at the scoop, it's hard - after the carving wheel - for me to flatten the divots right near the edge of the scoop. So, the edge can look uneven near the edges. I am not deft enough to use a sander to get all the marks out there, and find a scraper to be handy.
BTW, Very nice (as usual) chair.
Moderator
I use ROS 1", 2" and 3" on woodturnings such as platters.
As for the drill recommendation, no comparison. The ROS gives me far better surface with no detectable scratches. After turning and hand scraping, I usually start with 320 paper and sand to 400 or 600.
Jamie, I see you are not considering a pneumatic sander. Too bad, since there are some good ones at reasonable prices. What I like best about the air-operated sanders is the size and weight is smaller since there is no electric motor. My favorite one says it uses 8 cf/m but I prefer running these sanders at a slow, gentle speed so the air use is a lot less than wide open.
grex_ROS.jpg
Sorry, I've never used an electric one with small disks.
JKJ
I have a 3" variable speed pneumatic random orbital from WoodTurnersWonders that I have been very happy with. I have only used it in finer grits, 220 and above. It seems well made, ergonomics are good, cost around $125 (I think mine was a bit less some years ago when I got it)
Moderator
One nice think about the Woodturner's Wonders sander, at least the one I have, is the pressure air limiting valve - I set it to run slowly and use only a small amount of air with a full trigger pull. The think is very light weighh and works incredibly well. Always it use it off the lathe with fine grits, after hand scraping
Kristina_IMG_20171212_094320_580-1.jpg
Of course, it's pneumatic which Jamie wasn't interested in. I and students get so much use from this that if I didn't have a suitable air compressor I'd consider getting one just for te sanders.
JKJ
Last edited by John K Jordan; 11-08-2019 at 7:48 AM.
Contributor
Interesting thread. I have a metabo but I hardly ever use it. I have a Fein (corded) and Makita (battery_) multi tools they oscillate, but are not random orbit to my limited knowledge. I also have a Milwaukee off-set drill (corded). I used to get the Micro Max catalog, but never looked for small sanders since I do have a Dremel. I do have a proxxon mini belt sander that I use on small stuff. Don't make my mistakes though. Sometimes I buy specialty stuff and then discover that it's not what a really needed after all.
Project Salvager
The key to the gateway of wisdom is to know that you don't know.______Stan Smith
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