Before Christmas when I was using my drum sander for making gifts I decided to take it apart after Christmas for a little tweaking.  When I got it the table needed to be made parrellel to the drum (fixed), I found out that it works better with a dust collector attached (so far), but the biggest problem is that the drum is about 10 thousandths out of round on the outside end.  This makes a vibration when used on that end, and it doesn't allow the full use of the sandpaper around the drum.  This is what it looks like right now.

 

My plan is to take the drum to my cousin and have him remachine it, reinstall it and tune everything up.

 

Paul, did it shake when it was new.  If it didn't, it may just need new bearings.

The inside of the drum also gets somewhat filled with dust that will cause it to vibrate. I clean mine out pretty regular and it makes a difference.

couldn't you glue sandpaper to a piece of MDF and pass it under your paperless drum? My thinking is this would sand it round and make it parallel to the table at the same time.

Hey ron, yes it vibrated on the one side since it was new.  It doesn't have very many hours on it.  I put a dial indicator on it when it was in one piece and there was 10 thousands difference in the diameter on the outer side.  Before we turn it we'll chuck it in the lathe between centers and double check with another dial indicator to see, but I feel confident that thats what the problem is.  I don't think its sawdust in the drum John, my drum is sealed on both ends with a steel plate that holds the aluminum drum to the shaft.  John there is too much material to take off with just sandpaper.  The best way to fix it is to turn it on a metal lathe. The table is adjustable itself to be able to make it parrellel to the drum.  Thanks for the thoughts, will keep you posted what happens.

Sounds like you may have a bent shaft Paul.  I agree with indicating it between centers to figure out what the root cause is.

Great post Paul, good to see some active users on the Grizz drum sanders, besides the vibration, how does the rest of the sander perform?

It doesn't vibrate when running without a load.  If you pass a board through closer to the inside or the middle there is no to little vibration.  Its only when you pass a board through on the outer end that there is a vibration.  Its like its only sanding about half the time.  The sandpaper shows that too. The other "bigger" problem i have had with it is that it would all of a sudden get a burn streak in it for no apparenent reason.  I fought with this, when it would burn, scrape the burn stuff off, use a crepe block on the paper and try again.  Sometimes it went alright for awhile then i'd get a burn somewhere else.  My thought on this is, mostely i was using the supplied dust collection bag with the sander when it would happen, i think that there would be maybe some globs of sawdust or residue from the crepe block that would fall onto the drum and cause the burn.  Lately i've had a better dust collector hooked up to the sander and it seems to be pulling the sawdust out better.  I've also not had any burning issues so far since i tried this.  Time will tell.  The other issues that i have delt with is the platten being parellel to the drum and the tracking of the feed belt.  Both issues can be fixed with some adjustment.  Overall i think it will be a good sander once i have the kinks worked out of it.  I also was going to talk to John Moody about his sander and see what he is doing with his to try to trouble shoot it.

I've noticed that my jet will burn if I'm taking too heavy of a cut. it seems that the sawdust can't clear fast enough and clogs the paper. 

John, how heavy of a cut do you usually take.  I understand that the wider the piece, the less of a cut.  Mine has a variable speed on it from 2 to 12 fpm.  Ive been able to take about 1/128 up to about 6" wide at 12 fpm, then at 10" slow it down to about 8.

I got my sander drum back from the shop this afternoon.

When we chucked it between centers, the shaft was good and you could see definate runnout on the open end of the drum.  So we machined it true, the bearings were good also.

 

Sander completly reassembled and tuned up.

The test runs that i did showed a huge difference in the sanding on the open end.  Also it appears that the sandpaper is being used all the way around the drum.  My test runs consisted of a 6" wide piece of hard maple, 6 fpm, and about 1/128 of an inch cut.  I'm also going to continue using a bigger dust collector on this sander it see if that takes care of the burning.  I am also open to any feedback anyone else has using a drum sander.  Thanks, Paul

Paul, glad you got it working but I have a couple of questions.  How many thousandths did you have to turn off to get it true and how thick is the wall on the drum now?

Hey Ron, I think we took off about 20 thousandths.  I believe there also was a taper to the drum from side to side.  Not really sure how thick the wall is now but I believe that there is plenty of meat there.

Just a little more feedback Paul for the fine tuning, you can scribble a bunch of pencil lines the entire width of the board and see if they disappear equally after running it through your sander, learned that little trick with my Performax fine tune instructions.

Also the main reason paper gets those burn streaks is the grit being used at the time, and of course the type of wood being used.

If you are getting a lot of burn streaks on your paper it could be you are using too fine a paper with too heavy a cut.

Soft woods hate fine drum sander paper, hard woods love it with light passes. The softer woods will streak the heck out of your paper, especially pine.

.020 is just a skin cut Paul.  Y'all did good and it clearly was the right thing to do.

I find on mine when I get to the 120 grit paper I have to do lighter sanding. Which of course it should be as you are at the finishing stage. I find when I am sanding cutting boards, the cherry is the worse to build up on the paper and burn. I just got a new hood for mine with a 4" dust port instead of the 2 1/2 that came on the Performax. I think pulling that dust away as much as possible will help. I also keep a gum eraser there and clean the paper regular to remove any build up.

 

The drum on my performax has the open drum and veins running through it. It can get dust in the drum between the veins and cause it to vibrate.

 

Looks like you solved the problem with yours and should do really nice now.

I usually take a 1/8-1/4 turn on a 5/8" x 18 shaft not exactly sure how that measures out thickness of cut

On the top of mine, it says a 1/4 turn is 1/64 of an inch. I usually move it about an 1/8" or less when I get to the 120 grit paper.

Hey John and John, Ive been turning mine about 1/8 of a turn or less, one complete turn = 1/16 for me.  So John do you mean 1/8 turn or 1/8" more turn.  Thanks.

1/8" more turn.