Poor drum sander results

[Greg Crawford]

I bought a Performax 16-32 about a month ago, and it seems no matter what, I get bad scratches, even with 220 grit. They're so bad I have to use at least 150 grit on a palm sander and sand a great deal to get them out, which pretty much negates any benefits of the drum sander. I get better resluts straight from my Delta planer. The paper isn't overlapped, it's "Performax" brand (Klingspore), I can't see any obvious rogue pieces of grit or loose threads, and all the paper is fairly new. I've tried light cuts (less than 1/8th turn ~1/128th), slow speeds, angling the piece, multiple passes at the same height, reversing the piece, different angles, literally scrubbing the paper clean, all to no avail. I experienced the same issue on a 37" Supermax in a cabinet shop. Is this inherent to all drum sanders? Woodmaster has a claim to collect the dust at the bottom of the drum. Does this make a difference? Are wide belt sanders any better? Do I need to change something? (I've also reversed the paper). I've seen so many people speak so highly of many different drum sanders, I'm a bit stumped. Thanks for any and all help.

[John Terefenko]

Stop and think what a drum sander does as oposed to a palm sander. It rotates on the same plane at all times and does not ossicilate as a palm sander does. Hiding your scratch pattern. Thus your answer, yes this is inherant to all drum sanders unless it is an ossicilating one. I could not live without my 16/32. It saves so much time and work and yes the final sandinging is done with an ossicilating palm sander but the bulk is taken down with the Performax. Some people get away with a planer and palm sander. To each his own.

[Al Killian]

I have been tolld that if your DC is not strong enough it will couse the board to be rougher? The main use of a drum sander/wide belt sander is to flatten a board out, which can not be done with hand sanders. A guy down the road has one and it leaves the board fairly smooth, only need light touch with the palm sander. Maybe call the tech line and ask them.

[Brent Dowell]

I love my little performax drum sander. I've mainly used it for making end grain cutting boards and it has done a wonderful job getting all those little pieces perfectly flat.

What I did when I got mine was to order a bunch of rolls of bulk sandpaper from 60 grit on up to 220. I hook it up to dust collector and it just hums along, as long as I don't try to hog off too much at once.

I also try to run things through at a a bit of an angle, alternating on the passes.

I've noticed on the lower grits, yes I do get a lot of scratches, but as I work my way up, things disappear.

What grit are you using?

For what I use it for, it's a great little tool.

Not sure if this is any help, but... Good Luck!

[Mitchell Andrus]

Inline scratches are inherent in the straight line nature of the sandpaper's movement against the wood.

It's working as designed. It's not meant to be a finish-ready surface. 95% of the wood I touch goes through my 25" twin drum Powermatic. I've got 120 and 180 grit... followed by pad sanding with 150 and 220.

[Doug Shepard]

...
I've noticed on the lower grits, yes I do get a lot of scratches, but as I work my way up, things disappear.
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That's pretty much my experience too. The scratch lines usually start going away at 150 or 180 grit. Don't think I've noticed them with 220 grit, but I still take a ROS to things I've run through the 16-32 to 220 grit.

[J.R. Rutter]

I'll just echo that scratches are par for the course with drum sanders.

I run 120 / 180 as well on my big Extrema drum sander, then step back to 150 ROS to finish up.

Since I use mine to hit panels right from the clamps with no glue scraping, I just use cheap abrasives from Wooworkers supply (stroke sander belts that I cut to get 2 wraps from). At $8 / wrap, I don't mind changing wraps every 3 kitchens or so...

[Mike Cutler]

Greg.

Is it possible for you to post a pic of the problem? I have a 16-32 also, and have never had "Bad scratches". Mine leaves faint lines in the wood but they clear up with hand sanding.
Post a pic for us.

[Brad Naylor]

Hi,

I use a 36" drum sander every day in my cabinet shop

http://i128.photobucket.com/albums/p166/bradnaylor/Img_0439.jpg[img]

The thing with all drum sanders is accepting their limitations - they are a cheap alternative to a wide belt sander and will never do the same job.

A drum sander is best for levelling a piece of wood or work - such as a panelled door - rather than achieving a finished surface. To this end you are better off working with fairly coarse grits - on my two drum model I use 60 and 80. Finer grades will clog up quickly causing the sandpaper to slip on the wood. The main other cause of slippage is inadequate dust extraction. Unless the dust is sucked away quickly it will gather in front of the drum and get between the sandpaper and the work.

The other thing is to take off only a tiny amount with each pass. I will regularly put a door through 10 or 20 times taking maybe .1mm off each pass. A wide belt sander would do the same job in one pass each side!

Having said all that, for the relatively small outlay, a drum sander will do a great job. Just don't expect it to do the job of a machine costing 5-10 times as much!

You still need a good ROS to finish your job off.

Cheers
Brad

[Don Selke]

I would not be without my Preformax 16-32 drum sander. As previously stated, it is not a finish sander. The maximum grit I use on my machine is 120. I too use my ROS for finish sanding. When lowering my drum I only turn the crank 1/8 turn per pass. You also need to make sure that you have the drum level or parell with the sanding table. I had to make several adjustments before I got everything where I want it. It is not a high dollar machine and you need to know its limitations like all the machinery in the shop. You will never be able to run a piece thru a drum sander and apply stain and a final finish.

[Greg Crawford]

Thanks for all the input. I guess I was expecting finish results from a sander that can't produce a true finish sanded product. It does do a good job leveling glued-up items. As for the dust collection, it's got a 4" hose hooked to a 2 HP Shop Fox that really sucks, and is only about ten feet from the DC. I also only take 1/16 to 1/8 of a turn per pass, and sometimes make multiple passes at the same setting. The drum is set as parallel as I can get it, using a steel straight edge. I'm only using 220 grit, as the coarser grits leave such deep scratches it's not worth using.

I'll have some doors ready to sand this evening, and I'll post some pics of what I'm talking about, but I think I'm just expecting too much.

Again, thanks

Greg

[Chuck Harris]

One thing I have found with my Delta 18/36 is you can't skip grits. If you do the scratch from the coarser grit will show. Mine has been great for finishing panels and getting parts ready for segmented turning.

The combination of a drum sander and a Domino for making wide panels is great.

[John Terefenko]

I rarely go no higher than 180 grit knowing I am going to finish sand with a radom orbital sander with 220 grit. One thing to take in consideration when doing door you will have a cross grain situation so the scratches will show even more. These are used as others have said and you will not get away from a finish sander but just imagine if you did not have one and all the work you would have to do. Good luck

[J.R. Rutter]

The other thing is to take off only a tiny amount with each pass. I will regularly put a door through 10 or 20 times taking maybe .1mm off each pass. A wide belt sander would do the same job in one pass each side!

I am looking forward to a double belt sander one of these years, but this Extrema 37" has been a great stepping stone. It has a 7.5 HP motor, but 10 HP would be perfect...

I normally do one pass per side on mine at 120 / 180. I do sand my panels to thickness before shaping and assembly though. I remove 0.02" per pass. On full 20" + doors, I will take an extra pass on sides where the panel is flush with the frame.

[Greg Crawford]

Sorry for the delay, but I ran into a few snags. Anyway, here are pictures of what I've been getting, both with and without flash. You can see that there are scratches running at different angles from making two passes at different angles, and not just in the cross grain portion. This is from 220 grit with about 1/16th of a turn or less for each pass. Pictures 3 and 4 were after some RO sanding with 150. To me, it would seem that 220 should leave such light scratches that a very quick touch with 150 on any kind of palm sander should take care of them, but these are harder to remove than the machining marks from my planer or jointer. Is this what the rest of you experience?

I guess I need what we all need, a million dollars and a 10,000 square foot shop with 3 phase power.

[Maury Morneault]

Greg,

What you're seeing is pretty typical results from a drum sander. Remember, and as others have said, drum sanders are not intended to be the final sanding, but rather to produce a flat surface and/or uniform thickness.

Also, the more pronounced scratches you are seeing is from the drum sanding across the grain. The number one rule in sanding is to sand with the grain. When you sand across the grain it tears the fibers and would explain why you are working so hard to remove the scratches. As a rule of thumb, I don't send anything cross grain through my drum sander. Instead, I'll send my pieces through (with the grain) to get a uniform thickness before assembling. Then, all that's required after assembly is a light sanding with a ROS.

Maury

[John Terefenko]

That is typical yes. One other thing to make sure of and I bet you are is that the paper is not overlapping and is run at a 45 degree angle when wraped. You can always buy 320 paper and get finer scractches.

[Mike Cutler]

I agree with John. That's about what I'd expect from mine.
The scratches appear to be going across the grain though, and that doesn't look right. Sand with the grain as Maury stated.

[Ed Labadie]

While I've never used a Performax sander, the finish in your pictures looks worse than what I get from my Woodmaster.
After using the drum sander it doesn't take much sanding to clean up the surface, I use the same grit on the rotex that was on the sander for the inital hand sanding.
The scratches will be deeper when you are sanding perpendicular to the grain and when using soft woods.
You might want to call Performax and ask them.

Ed

[J.R. Rutter]

Your pics look typical to me as well. Even a widebelt leaves scratches, especially cross-grain, but does a better job at averaging out the scratch depth. And if it has a platen, the depth is reduced even more. For a truly uniform finish sand, factories use a feed through orbital sander...

For doing assemblies like door and frames, I always run them through at an angle to avoid a dip when the drum comes off of the rail. Step back down one grit to ROS those scratches away.

So think of the drum sander as a great way to level out your joints and get uniform thickness, not as a finishing tool.

[Cliff Rohrabacher]

I have been tolld that if your DC is not strong enough it will couse the board to be rougher?

This is true to the extent that the drum sander was designed to be dependent on DC. Many high end planers are built that way and failure to have DC will give you many little dimples over the board cause they are being compressed by the rollers.
The effect is similar in the drum sander when the thing is incapable of eliminating it's own spent grit it gets trapped and causes deeper cuts. Try putting your DC on it and run it that way.