Sanding a mirror surface

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Review by gko posted 06-26-2011 04:24 AM 5139 views 3 times favorited 6 comments Add to Favorites Watch
Sanding a mirror surface Sanding a mirror surface No-picture-s Click the pictures to enlarge them

Bosch 1/2 sheet sander

After using 1/4 sheet sanders or random orbit sanders on my table tops I usually end up with a bit of a ripple when I varnish or lacquer the top. I have a planer but even after planing I always seem to have these slight ripples after sanding. In Flexner’s book he uses what looks like a half sheet sander (can’t confirm, a WC owner borrowed my book I bought from him after telling him how good it was) and a carpenter friend said he really liked the 1/2 sheet Bosch so I took the plunge and bought it.

The good.

It creates an extremely smooth, flat as a mirror surface. I start with pencil stripes on the surface and then sand with 100 grit until it all disappears. If I planed the surface then I just lightly go over with a 150 grit to get rid of the little knife ripples that show up in staining. In the past I found turning the sander at an angle gave me the smoothest surface. Going parrallel always left lines at the edges of the sander. Having the corners of the sander on the sides of the direction of movement feathered the edges. Turning the Bosch at an angle creates a totally smooth surface with no sanding lines. Once totally flat, going through 150 and 220 sands out the previous sanding scratches really quickly. The scratch pattern is excellent for such a large sander but if I want a nearly invisible scratch pattern when staining with pigment I finish with a PC 330 Speed bloc 1/4 sheet sander. Pigments get caught in the tiny sanding scratches and the PC seems to give me the smoothest scratch pattern without going to a Festool. Of course I finish sanding by hand going with the grain but even that requires just a quick light sanding If I’m not staining I’ve gone straight to the finish from the Bosch. Doesn’t seem to make a difference going to the PC and hand sanding if I’m not staining with pigments.

It has a trigger lock that works the way it should, not all work this nicely. Hand grips in the front and back as well as on top in the center. I like to lightly hold it in the center as I find I tend to lean on the front or back grips and have to concentrate on keep the machine balanced between the front and back.

Again the scratch pattern is very nice and with 100 grit I get almost no pigtails. If you stained at this point it would show a little but its nearly invisible. Among my power tools it second to my PC 330 in giving me a scratchless pattern. But it does a better job of giving me a really flat surface to finish on.

The bad

Well, the included dust filter does an ok job but you need an adapter to hook it up to regular vacuums. I ordered the adapter but haven’t gotten it in so I can’t comment on how well it works. An adapter to poke holes in the sandpaper which works well and it looks like the hole pattern would work well with a vacuum. There is a strong ozone odor but it doesn’t bother me much. That’s it for the negatives.

I don’t have a large flat bed drum sander so this is a wonderful way of getting an extremely flat surface. I’ve used it after a planer and hand planning and it easily gets it ready for the stain. I tried messing up a piece of wood with my belt sander and using 80 grit it flattened the surface nicely. It is my go to sander for anything that needs to have a large flat mirror llike surface.

-- Wood Menehune, Honolulu

View gko's profile


83 posts in 4132 days

6 comments so far

View spunwood's profile


1202 posts in 3724 days

#1 posted 06-26-2011 05:07 AM

Thanks. Something to think about.

-- I came, I was conquered, I was born again. ἵνα ὦσιν ἓν

View David Grimes's profile

David Grimes

2078 posts in 3528 days

#2 posted 06-26-2011 07:30 AM

Good review. I have a myriad of ROS, belt and 1/4 sheet sanders (PC, Dewalt, and Craftsman), but not a 1/2 sheet. I have been looking at a positively reviewed 2 amp 1/3 sheet Craftsman at $40, but I see this Bosch is 3.2 amps… pretty strong and is about $135 or so and has 19 customer reviews with all 5 stars (you don’t see that too much).

Tell me… is it balanced and comfortable in use ? Is it heavy / tiring in use ?

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

View gko's profile


83 posts in 4132 days

#3 posted 06-26-2011 09:18 AM

Hi Dave, yes the sander is well balanced and very comfortable. Its so well balanced that I hold the center portion and just let the weight of the sander work the surface. A lot of sanders have a bias towards the handle or to one side. I grab the front and back and put some weight on it if I need to get rid of a lot of material.

I think the extra power is needed on a half sheet sander because there is a lot more area in contact with the wood. With the extra horse power it hardly bogs down with added pressure. I notice on other sanders if the rpms start dropping when you push harder the pigtails become deeper and bigger. Makes getting rid of them more work with the finer grits.

The weight seems perfect, feels light for the size of the machine but yet it has just enough weight that I normally just focus on moving it around instead of trying to keep the downward pressure even. It kind of makes sense that the larger the footprint the more evenly it will sand. It also has a relatively small swirl pattern for its size which hides the pigtails.


-- Wood Menehune, Honolulu

View SchotterWoodworking's profile


113 posts in 3918 days

#4 posted 07-09-2011 03:11 AM

I’ve loved every Bosch sander I’ve used (6”RO, 5”RO and 1/4 Finish). I’ve been eyeballing this one for a long time. Thanks for the great review. I might have to take the plunge too!

View dhazelton's profile


2839 posts in 3185 days

#5 posted 04-05-2012 08:23 PM

I wanted one of those for a refinishing project but it seemed like overkill. The tool store had a 1/3 sheet Makita so I bought that and it was fine for my purposes. It actually has fewer amps than Makita’s 1/4 sheet sander, so it’s not really for heavy paint removal. It would probably shine with fine grit paper finish sanding between coats of varnish or shellac. Still would like the Bosch though….

View gko's profile


83 posts in 4132 days

#6 posted 04-06-2012 12:31 AM

On a glossier surface the little dips and hills are very noticeable and the 1/2 sheet minimizes them. I think the 1/3 sheet should do the job nearly as well. I tend to rub out my finish up to rottenstone and nearly back to glossy so the dips begin to appear. If I go for a more satin look then I just take out my Festool 6” ROS. Btw, I tilt my sander a bit so you don’t end up with the edges causing a sanding line. The are more pronounced on these longer sanders.

-- Wood Menehune, Honolulu

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