drum sander problem/question

[Russ Ambrose]

picked up a used drum sander (Performax 16/32) recently, but am experiencing a problem with it that is (at least for somebody with no previous drum sander experience) a real head scratcher. whenever i run anything through it, i get very noticeable lines at various spots across the width of the material. the lines run in the same direction that i'm feeding the material and run the entire length of the material. this happens with the lightest of passes using brand new sandpaper. i feel really stupid, but i'm old enough that i'm used to it. any thoughts or suggestions are appreciated.

[John TenEyck]

My first guess is that the sanding strip is overlapping itself where you are seeing those lines. Take a look and make sure that's not the case. You didn't say what grit you have on it, but drum sanders can leave really deep scratches with the coarser grits. That tends to be more uniform than what you are describing, though.

John

[Nick Decker]

Yup, sounds like overlapping to me. If so, the added problem is that the overlapping edges will very quickly fray and the sanding belt will be ruined.

It's a rookie mistake that nailed me, too. You'll quickly learn to keep the strip tight while wrapping it onto the drum, and to leave a small gap in the spiral.

[Matt Day]

And if this just started after working okay, the paper likely stretched/settled into place and needs to be tightened up and realigned if necessary.

[Bill Adamsen]

Russ ... indeed an overlap if a new roll.

If you haven't looked into it already, long rolls of any specific grit are convenient and cost-effective. I get mine from Industrial Abrasives with aluminum oxide grit on cotton/poly backing. I'm sure there are other suitable suppliers. I have settled on using two grits - one really - 80 grit. The 80 grit I buy in the 52 yard roll and 120 grit in the 25 yard (it has been there for years). I precut all the lengths and tapers, rollup, label and store so they're ready to go. I've never had much success with the finer grits and just go straight to the ROS. I'd be curious about the grits others use with that machine.

This is the description from the operations manual for the 22/44... "Continue to wrap the abrasive in a spiral fashion by rotating the drum with one hand and guiding the strip with the other (Figure 13). Successive windings of the strip should be flush with previous windings without any overlap.:

[Tim Bueler]

Russ ... indeed an overlap if a new roll.

I'd be curious about the grits others use with that machine.
:

+1 on that it sounds like an overlap(s).

Bill, I have a DDS225. Use P120 on the front and P180 on the back and sometimes have the rear roller raised all the way up. It only takes about 15 seconds to lower into place. Use a thickness planer for heavier/rougher cuts. ROS to finish up and take out cross grain scratches.

[Mike Wilkins]

You didn't state if this is a raised dark line or a gouge in the wood. If it is dark, you may have pitch build up in one spot. Found this out the hard way by running some pine through my drum sander as a first test when I got the machine. Hard stuff to remove; the soft wood allowed pine pitch to build up in one spot.
If it is a gouge, you may have an overlapping belt or a piece of grit in one spot.
Change the paper as a test to see if that is the culprit.

[Kerry Wright]

+1 for pitch build up. I just had this exact same thing happen last week.