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Red oak and random orbital sander

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Forum topic by dschlic1 posted 10-29-2019 04:57 PM 527 views 0 times favorited 12 replies Add to Favorites Watch
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dschlic1

463 posts in 2534 days


10-29-2019 04:57 PM

Topic tags/keywords: resource oak sander finishing

I am in the process of building a large circular kitchen table from Red oak. I discovered that when I use a ROS to sand the surface, the ROS cuts the porous grain faster than the non-porous. This results in a slightly wavy surface. When I sand with a belt sander I get a very flat surface.

So I am sanding it with a belt sander up to 120 grit. I am coloring the wood with a water based dye.


12 replies so far

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wildwoodbybrianjohns

547 posts in 111 days


#1 posted 10-29-2019 05:08 PM

Card scraper could sort you out.

Is there a question?

-- Wildwood by Brian Johns: If you tell the truth, you dont have to remember anything (S. Clemens) Edit: Now where is that darn pencil/ tape measure!

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EarlS

3316 posts in 2912 days


#2 posted 10-29-2019 05:17 PM

A wavy surface can be caused by inadvertently rocking the sander which moving it around. I always hold the sander on the side as low as I can, just above the pad that way I don’t put uneven pressure on the top and let the sander float, rather than trying to apply pressure.

I’ve also seen similar problems with a belt sander. It’s all about technique, IMO.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View JackDuren's profile

JackDuren

544 posts in 1524 days


#3 posted 10-29-2019 05:38 PM

If you have belt sanded it flat and with the grain with 120grit, there shouldn’t be a lot of sanding with a ros 100,120 and 150…Your really just eliminating the belt sander scratches and working to a final final finish sand…

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WoodenDreams

834 posts in 475 days


#4 posted 10-29-2019 05:48 PM

After gluing up panels of red oak, I use a portable 4×24 belt sander, using 180 grit. stopping quite often to feel the surface for smoothness and flatness. Able to get a nice flat surface this way. I seldom start with 150 or less grit, unless I sand by hand with and sanding block, and using a card scrapper if I feel needed.

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JackDuren

544 posts in 1524 days


#5 posted 10-29-2019 06:22 PM



After gluing up panels of red oak, I use a portable 4×24 belt sander, using 180 grit. stopping quite often to feel the surface for smoothness and flatness. Able to get a nice flat surface this way. I seldom start with 150 or less grit, unless I sand by hand with and sanding block, and using a card scrapper if I feel needed.

- WoodenDreams

I start at 80 grit if I’m sanding glued up panels. It’s not the grit, its how well you know how to belt sand. I’ve never seen a shop use 180, it won’t sand glue…

View Stephan in BC's profile

Stephan in BC

13 posts in 2278 days


#6 posted 10-30-2019 09:06 AM

A ROS can work fine, but you’ll want to put a hard pad on it. Most come from the factory with a fairly soft pad.

-- Woodworking videos: https://www.youtube.com/AWoodworkersLife

View OSU55's profile

OSU55

2452 posts in 2553 days


#7 posted 10-30-2019 12:15 PM

Use a smoother hand plane if you want a truly flat surface.

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bilyo

910 posts in 1667 days


#8 posted 10-30-2019 03:52 PM

I have not had that experience with hardwoods like oak. But, It has happened with wood like pine where there is a bigger difference in hardness between summer and winter wood grain. Anyway, I suggest that you make sure that the backer under the sandpaper disk is firm. A soft foam pad will be more likely to create the problem you have experienced. The reason that belt sanders don’t have this problem is that the platen is hard and rigid.

View dschlic1's profile

dschlic1

463 posts in 2534 days


#9 posted 10-30-2019 05:03 PM

Thanks for all of the comments. The ROS I have is a cheap, fairly old (5 years) unit and I doubt that any parts for it are still available. My intention for posting was to inform anyone interested what I had found out.

The water based dye I am using says to use a max of 150 grit sanding. So 120 grit should work fine.

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Sark

223 posts in 924 days


#10 posted 11-13-2019 02:37 PM

Agree with Stephan in BC and Bilyo. The pad on the sander makes a big difference…as does the sander itself. Festool sells a hard pad for their ROS which I use when I want to smooth out the surface. The tool itself is smooth as butter. I also have a couple of older Delta sanders which compared to Festool are like chainsaws.

View Stephan in BC's profile

Stephan in BC

13 posts in 2278 days


#11 posted 11-14-2019 12:17 AM



I also have a couple of older Delta sanders which compared to Festool are like chainsaws.

- Sark

Funny because it’s true! :D

-- Woodworking videos: https://www.youtube.com/AWoodworkersLife

View jbmaine's profile

jbmaine

72 posts in 34 days


#12 posted 11-14-2019 01:57 AM

Just as a tip. I’ve built a lot of things from RO and colored them with water based aniline dye. If you heat the dye before applying, it will flow into the open pores more evenly ( something about less surface tension) . You will end up with less of the tiny white bare wood spots.

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