Official Luthiers Forum!

I've got a small problem with this sander that I'm sure someone has figured out. I've used it quite a bit with no problems, but now that I am sanding a spruce top, it sands a little deeper at each end of the drum where the sandpaper attaches and is not quite as tight against the drum as elsewhere on the drum. The drum is dead level, and it is not a problem with drum alignment; just 1/2 to 3/4 at each end of the drum. I've tried to tighten up the sandpaper at the ends, but can't get it perfect. I tried it on a sheet of mahogony, and it is barely noticeable on the harder wood, nothing that wouldn't disappear with finish sanding. But on the soft spruce, it is more noticeable.
Any ideas?
thanks, Mike

Find a way to attach your paper tighter, you may need to trim it a bit. Take lighter passes. Most of the time you don't even need to lower the drum, a few passes at the same setting will get you there and smooth things out.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Take the paper off the right side of the drum (as you face the front) and clean the take up lever/spring clip area (inside the drum) and spray the springs and moving parts well with a dry lubricant. It should move easily. It's normal to get stretching/slipping of the abrasive over time and it will loosen on the drum and need to be adjusted. I normally put a piece of regular duct tape on the back of the last 2" of my abrasive to help prevent slipping and tears.

I have had same problem, especially with the coarser grits. What I found helped was -
1) Fit abrasive as tight as you can
2) Run drum, do a light pass on a full width (10" board) and check there is still space between each wrap (realign/run again if neccessary) then retighten abrasive, seeing where the abrasive goes into the "slot" at each end. Then mark this point.
3) Take out abrasive one end at a time, and fold it, creasing at the point where it goes in, or just a hair before where it passes into the slot and fit back into the tensioning mechanism.
My idea was to make a sharpish right angled crease in the abrasive before reinserting it. This avoids having a "hump" in it when it passes across the edge of the slot due to the stiffness of the abrasive..
Worked for me, now part of the routine for changing abrasives

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Thanks guys! I really appreciate the quick, useful replies. I used all the suggestions, and I think they all helped. The two that appeared to do the most were:
1) crease the paper where it enters the drum. That was the only place my paper wasn't tight, and I just wasn't able to get it all out. The crease at that point almost totally gets rid of the hump at that point. Interestingly, the instruction manual shows that same hump when it shows you how to load the paper!
2) take multiple passes at the same light setting. this indeed helped in smoothing things out.

I also noted a significant improvement when I supported the soundboard more conscientiously level - I don't have outfeed/infeed extenders. I'm a little puzzled, because I can see why it would reduce snipe, but I can't see why it helps in keeping the outboard end of the drum from gouging a little. It definitely helped though.

Anyway, thanks for the help; I was really getting frustrated..
Mike