# Why is my drum sander leaving these lines in my cabinet doors?



## SweetTea (Aug 5, 2016)

My first foray into owning an using a drum sander. I picked up a Delta 31-250 and replaced the conveyor belt and loaded it up with 80 grit sandpaper, which I am affraid is too course. I am trying to feed some newly built cabinet doors into it and am getting these lines on the rails only. Which as you know are going cross grain. What am I doing wrong here? Solutions?


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## distrbd (Sep 14, 2011)

You can try taking off less on each pass,or change the grit to 120 but your best bet is to use your random orbital sander after the drum sander and sand the the whole thing to a desired smoothness.
It is very common to use a ROS after the drum sander .


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## AandCstyle (Mar 21, 2012)

Sweet, if the doors are already assembled, there is no way to avoid cross grain sanding when using a drum sander. It will be a real challenge to remove those scratches with a random orbit sander even if you start with 80G. You would also have cross grain scratches if you had started with 120G (or even 180G) in the drum sander, but it would have been somewhat easier to eliminate with your ROS. I'm sorry that I don't have a silver bullet for you.


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## SweetTea (Aug 5, 2016)

Well the whole reason that I want to put these cabinet doors through the drum sander in the first place is to true them up and get them perfectly flat. I don't mind going back over them with the ROS a few times, I just want to make sure they are perfectly flat.

These scratches are a result of the 80g sandpaper. You guys think that I would get the same scratches with 150g or maybe even 180g? What is the most optimal sandpaper to use in a drum sander for sanding, and truing up raw cabinet doors and face frames?


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## JBrow (Nov 18, 2015)

SweetTea

I find that I get good drum sander results when flushing up panels using 80 grit Mirka paper (I think it is F weight paper). I purchase mine from Woodmaster, but I am sure it is available from other vendors. The slight scalloping that is suggested by the photos is not present when I flush up panels. Perhaps there is a difference in the way I operate the drum sander versus the method you are using.

When the drum sander first entered the work shop I was getting results similar to those shown in the photo. I could run my hand over the surface and could feel a slight waviness in the surface, and slight scalloping was visible under the right lighting. After changing my method, I concluded I was trying to remove too much material in one pass.

My revised method is to first send the panel through the drum sand while adjusting the height of the conveyor until the drum just begins to remove material. Since initial contact with the drum occurs somewhere near the center of the panel, I run the panel back through the sander at this initial setting once more.

Then the drum is re-adjusted to remove 1/64 inches. The panel is then run through at this setting multiple times until minimal material is removed on the last pass (about 5 - 10 times). I then make another 1/64 inch adjustment and continue the repetitive sanding and adjusting until the panel is complete. The other practice I follow is to remove most of the dust that may lie on the panel when it emerges from the sander before running the work piece through again. My feeling is that even with good dust collection, the dust on the surface can limit the cutting action of the paper.

Once the panel is sanded at the drum sander, I switch to the Random Orbital Sander and sand through the grits to my final grit.


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## Nubsnstubs (Aug 30, 2013)

Hey Sweety, you need to go through the grits to get satisfactory results. Eighty grit is too course for finish sanding. Read the next paragraph. Also, you have the same scratches on the straight grain that's not very visible until you apply finish, so you're going to have to orbit sand the whole door frame and panel if it was sanded at the same time.

When I build doors, I always build them 1/16" thicker than the finish size. I then take them to a friend that has a Timesaver sander. He starts with a 60 grit belt, one pass each side, then to 80 grit each side, 120 each side, then finish at 180. Thirty doors takes about 1 hour, and when I bring them back to the shop, I sand them with 120 grit with an orbit sander. All scratches disappear. That's how I do it and been doing it that way for thirty years.

I worked for a guy to help him out about 10 years ago who had one of those sanders that take the long strips of sanding media that wraps around a drum/bar/roller?. What a pain in the butte to change grits. I ended up using it just to rough sand pieces to get the wood to the same thickness before detailing. Never did I use it for finish sanding…........... Jerry


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## wapakfred (Jul 29, 2011)

That's life with a drum sander. It will do what you want (the perfectly flat thing) but they are not finishing sanders…and 80 grit is way too coarse except for the roughest work. I typically used only 120 grit (sometimes 150) on mine. More coarse does what you are seeing, finer grits get clogged too easily.


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## AZWoody (Jan 18, 2015)

I agree on the grits as others and use from 120 to 150 and you also have to make sure you feed it slower the higher the grit you go.

Also, as someone else mentioned, on your last depth setting, you should do multiple passes making sure it's offest on each pass. That will help get the final pass much more even.

When you do sand with the ROS, I usually start with 1 grit rougher than I have on the drum sander. If you run 150 on the drum sander, then put 120 on the ROS. If you try to run the same grit, you will spend a long, long time trying to get rid of the lines.


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## bondogaposis (Dec 18, 2011)

When you feed a whole a panel door, you are always going to get scratches on the cross grain portion(rails) that you will have to sand out either by hand or w/ an ROS. Make the job easier and use a finer grit.


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## 000 (Dec 9, 2015)

> When I build doors, I always build them 1/16" thicker than the finish size. I then take them to a friend that has a Timesaver sander. *He starts with a 60 grit belt*, one pass each side, then to 80 grit each side, 120 each side, then finish at 180. Thirty doors takes about 1 hour, and when I bring them back to the shop, I sand them with 120 grit with an orbit sander. All scratches disappear. That s how I do it and been doing it that way for thirty years.
> 
> .............. Jerry
> 
> - Nubsnstubs


Sounds a little rough and unnecessary. 
I have a wide belt and I Never have had to use 60 grit for a door! (Maybe sanding down a slab, but never a door)
(How bad are your doors to start?) :>/


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## Underdog (Oct 29, 2012)

Those cross grain scratches are normal with 60 grit. 60-100 grit is used for stock removal only on a hard drum. 120-220 grit is used for finishing passes on a softer drum.

We always make our doors 1/16th oversized thickness as mentioned above. When sanding we use a wide belt drum sander with two heads, and we use a grit sequence of 80/120 for rouging passes (stock removal), and 120/180 for finishing passes. On the roughing passes we take as much as .015-.020" (usually less) at a time until both sides are level and and flat. For finishing passes it's maximum of .005" passes to get all the rough scratches out. And lastly the platen is engaged and a last pass of .003" is taken to polish out anything remaining.

If we were doing it "by the book" then we'd probably start with 100/120 and then go to 150/180 so as not to skip any grits.

The principle is the same as with any sanding. Start with the coarse grit and work your way through the grits. 
And do not, under any circumstances, try to take more off than the grits will handle.


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## SweetTea (Aug 5, 2016)

Ok guys, I will try lighter passes. What is the most optimal grit sand paper to use for flattening out cabinet doors? I don't mind having to do some work with the ROS. I am thinking that I should get either sone 150 grit, and/or some 180 grit. Will 150g or 180g be ok to use for making the doors perfectly flat?


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## AlaskaGuy (Jan 29, 2012)

I have a baby wide belt sander (Bridgwood 16 open end sander). For cabinet doors (and a lot of other stuff) I never use anything but 120 girt followed up with 120 and 150 grit ROS. I can't imagine going through the grits starting at 60 girt.


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## wapakfred (Jul 29, 2011)

I wouldn't go that high (150), like I said, 120 was about all I ever used though I did keep some 150 on hand just in case.


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## splintergroup (Jan 20, 2015)

I always start coarse (80) to get things flat and within 0.075" of my final target. Depending on the wood, I'll go 120 then 180 for the final pass to the target. Several final passes without changing the drum height, angle/offset the panel each time. Finally a ROS starting one or two grits below where you stopped with the DS (see that you eliminated the 'lines' in a strong side light). For 'artwork' type stuff, I'll go all the way to 220 on the DS, it makes the finish sanding much easier.

It takes less than a minute to swap belts on my DS.


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## Underdog (Oct 29, 2012)

I repeat:
For stock removal (flattening, leveling, or just stock removal) use 60-100. I'd personally start with 80 or 100 in your case, and then

For fine sanding and polishing use 120-220. In your case I'd probably use 150 and then orbit sand with 180.

Anything finer than 180 tends not to stain well.

So start with 100, bump to 120 or 150, then orbit sand with 180.


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## AlaskaGuy (Jan 29, 2012)

With decent blades in you planer and joiner the finish should alredy be better that what you get from 60 or 80 grit paper.

With good stock prep, and accurate cutting of parts and accuracy in cutting the cope and stick cuts I can't see where there is a need to grid a door flat to the extend you need these heavy cutting sandpaper grits.

When I make doors there pretty darn flat to start with and most just need to go through the sander to clean them up and bit and flatten minor misalignment where the cope and stick come together and take care of the minor scalloping you get from all and jointer planers.


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