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will a drum sander push a bowed board flat like a thickness planer will when it goes through?

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Forum topic by Jimothy posted 10-21-2021 11:56 PM 466 views 0 times favorited 7 replies Add to Favorites Watch
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Jimothy

85 posts in 2227 days


10-21-2021 11:56 PM

Topic tags/keywords: drum sander thickness planer bowed question trick wood tool skill

Basically, I have this old glue up that has bowed over time because I never attached it to aprons. I know you can run a bowed/cupped board through a planer and the rollers will press it down with enough force that it can still produce a decent cut, I know it wont be perfect and it’ll spring back once the cut is finished, but you get my point. It will be good enough for me to be be able to bend back into place when attaching to the aprons.

This is only for myself so don’t go off on me about the customer haha, and so I was wondering, does a Drum sander do the same thing as a planer in terms of the forcing the board down flat as it runs through? I’m not exactly sure the mechanism it uses on a drum sander. I know theres a conveyor belt and a sanding drum above it but is there something to apply downwards pressure on the board? I will have access to one starting tomorrow and I just wan’t to know what I’m getting myself into.

Thanks


7 replies so far

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jonah

2258 posts in 4585 days


#1 posted 10-22-2021 12:17 AM

Planers won’t really force a board flat. If it’s cupped along its length, it’ll just pass through the planer and you’ll end up with a slightly thinner banana.

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Loren

11314 posts in 4934 days


#2 posted 10-22-2021 12:24 AM

Some thickness sanders have hold down rollers on them. I’ve never used one with those but even with them I doubt they will push cup out of your boards. Prepare yourself to spend a lot of time standing around watching the sander as you move incrementally through the cup on both sides. If you have a jack plane it would be way faster to hog off the waste before using the sander.

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Jimothy

85 posts in 2227 days


#3 posted 10-22-2021 12:29 AM

unfortunately the boars are not thick enough that if I plane the bow out I’d be left with no material. My other option is to somehow keep them forced flat when I run them through….


Some thickness sanders have hold down rollers on them. I ve never used one with those but even with them I doubt they will push cup out of your boards. Prepare yourself to spend a lot of time standing around watching the sander as you move incrementally through the cup on both sides. If you have a jack plane it would be way faster to hog off the waste before using the sander.

- Loren


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Loren

11314 posts in 4934 days


#4 posted 10-22-2021 12:46 AM

Your option is to rip, joint and glue them then.

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jonah

2258 posts in 4585 days


#5 posted 10-22-2021 01:13 AM

If there’s not enough material to plane them flat, then how precisely would a sander or planer flatten them even if it did behave as you said?

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Lazyman

8260 posts in 2674 days


#6 posted 10-22-2021 01:21 AM

+1 on rip, joint and re-glue; however, if they are that thin, you may be able pull the panel flat to the aprons with clamps and fasten them down as long as the aprons are wide/strong enough to not flex under pressure. Battens on the bottom may help too. Just make sure that the battens are attached with elongated holes to allow for wood movement. I would try clamping it flat and see how much tension it takes. How thick is it and how much did it warp? I assume it was perfectly flat at one time?

Also, sometimes you can reflatten a panel with a little heat on the convex side and moisture on the concave side. I have had luck laying a panel concave side down on the lawn in the sun to flatten a panel. The sun will dry out the convex side a little while the ground will add just a little moisture to the concave side causing the panel to flatten. It doesn’t take long, especially on a thin panel so keep an eye on it and don’t lay the panel on a bench top overnight afterwards because it will cause it to cup again. Attach it to the aprons and battens right away, put some thick stickers under it so it can breath or lean it against something so air gets to both sides. If the bottom is not finished, this can contribute to cupping so make sure that you get some finish on the bottom ASAP to even out moisture differences between the top and bottom surfaces.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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Jimothy

85 posts in 2227 days


#7 posted 10-22-2021 02:41 AM

With Battens/ apron they get pulled completely straight


If there s not enough material to plane them flat, then how precisely would a sander or planer flatten them even if it did behave as you said?

- jonah


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