LumberJocks

Drum sander problems creating cupping

  • Advertise with us

« back to Woodworking Skill Share forum

Forum topic by Adrian A posted 1340 days ago 1020 views 0 times favorited 9 replies Add to Favorites Watch
View Adrian A's profile

Adrian A

152 posts in 1536 days


1340 days ago

Dear Woodworking Experts,

I glued up some 2” wide strips to make a 16” wide 36” long Glued up Panel. (making an end grain cutting board).

I then put it in the drum sander to level out the panel and it made it all smooth and level…. So I thought. Upon further inspection the middle was thinner than the edges creating a dished effect across the 16” width.

This doesn’t make sense to me because the drum is flat and if anything you would think one side would be higher than the other side because the drum might be angled, but a dish doesn’t make sense.

Anyone know what could be causing this?

This problem is okay if making a face panel, side grain panel… But when making end grain it causes horrendous problems in the next glueup step.

Thanks


9 replies so far

View childress's profile

childress

841 posts in 2176 days


#1 posted 1340 days ago

I have a performax and the manual says to raise the end of the drum (like a couple thou) if sanding boards wider than the actual drum to prevent this very thing from happening.

I also don’t recommend sanding the edge grain before cutting and re-gluing. I personally don’t believe it leaves a good enough glue joint surface. I’m sure others think it’s ok but I don’t. The board really needs to go through the planer before crosscutting and gluing.

-- Childress Woodworks

View Adrian A's profile

Adrian A

152 posts in 1536 days


#2 posted 1340 days ago

I’m not having problems like the manual shows. I’m only feeding a 16” wide piece but, that 16” piece is coming out cupped instead of flat.

I’d use a planer but my planer is 12.5” wide, not big enough for my 16” wide board.

View Loren's profile

Loren

7443 posts in 2282 days


#3 posted 1340 days ago

Check the platten for distortion. You may be taking off too much
material in a pass. Drum sanding to accurate thickness takes several
passes in my experience with a cantilever drum.

Loose paper in the center of the drum could possibly cause some problems.

You might want to correct the problem with a handplane for now
and try sanding to thickness again working from a flatter panel.

-- http://lawoodworking.com

View rhett's profile

rhett

697 posts in 2301 days


#4 posted 1340 days ago

It sounds to me like you are either trying to remove too much material in a single pass, or your pressure rollers need adjustment.

On my drum sander, the two drums and the feed belt are a softer composite material. With enough pressure, I could imagine they would deflect just enough to produce cup or non flat surface.

-- http://planeandsimpleblog.wordpress.com/

View dbray45's profile

dbray45

2488 posts in 1411 days


#5 posted 1339 days ago

You may want to check both sides for flat. If the whole panel has a bow in it, the rollers will flatten the panel through the equipment and the bow returns on the other side. If this happens, put the panel on another board, put spacers under to bow so the panel cannot flatten and then run it assembly through the sander. I have a board with a whole bunch of machine screws that I adjust to “mold” to one side, run the board a couple of times to make it flat, turn the board over and run that without the “leveling” board.

If you don’t want to go through this trouble, I have run a board about 4 times without changing the hieght, this puts less pressure on the board and tends to flatten things out.

-- David in Damascus, MD

View Adrian A's profile

Adrian A

152 posts in 1536 days


#6 posted 1339 days ago

Thanks for the replys. Let me clarify a little. When the board comes out it comes out cupped but thats not really the problem. The problem the thickness isn’t even acrossthe panel. The middle is not only cupped but thinner in thickness than the the outsides.

View John Ormsby's profile

John Ormsby

1279 posts in 2371 days


#7 posted 1339 days ago

What grit sandpaper are you using. You can start with 60 to 80 grit. Then proceed to finer grit up to about 150. Any more and it will start burning. Finish with a ROS .

-- Oldworld, Fair Oaks, Ca

View dbray45's profile

dbray45

2488 posts in 1411 days


#8 posted 1339 days ago

I would call the manufacturer.

-- David in Damascus, MD

View patron's profile

patron

13020 posts in 1975 days


#9 posted 1339 days ago

i do my wide panels and boards
in multi-passes
just a little at a time
flipping over and over
and end for end
and cleaning the table of sawdust in between
takes longer
but helps with this problem

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com

Latest Projects | Latest Blog Entries | Latest Forum Topics

GardenTenders.com :: gardening showcase