Avoiding burning/striping on drum sander belts

[Andy Pratt]

Discussion in another thread made me think to improve my technique with my drum sander. I have a performax 16/32 with the variable speed belt drive. I bought the machine used in good condition, and purchased a quantity of klingspor sandpaper rolls for it, the kind you cut yourself. I had a few old belts (factory) to make sure I was cutting to the correct size.

Since using it, I've had a recurring problem with the belts burning the wood, and with "striping" occurring well before the belt has met it's useable lifespan. I've done the following things to try to mitigate this:

1. Made sure belts are on as tight as possible, with fairly even gaps between them across the drum. (also started using the tightening key that came with it).

2. Try to always take light passes, (1/4-1/3 handle turn) which allows me to keep the belt speed above the 50% mark, which seems to really help with the burning and reduce the frequency of striping.

3. Always scrape glue off everything beforehand, make sure to feed glued projects at a skew so same part of drum isn't handling all the glue for the whole pass.

Doing these things has helped a good deal, but I still feel like I'm wasting 50-75% of the useable life of my belts. Sooner or later they start a stripe, and it seems like once it's started there is no way to scrape the gunk off the belt well enough to ever get it to function normall again.

What do you guys with drum sanders do to avoid the striping, or do you just find ways to deal with it or clean it up? Could there be something wrong with my tool technique or sandpaper prep that is causing issues?

Also, I believe my drum is a very tiny bit out of alignment (drum is closer to the table on motor side than on the outboard side) if that has any impact on this. The motor side is also the side of the belt that usually has the problems first.

Thanks,
Andy

[Jeff Duncan]

I don't have a solution but a few things to look out for. First if your motor side is lower then it's bearing down on the workpiece more, which of course will cause it to wear or burn faster than the high side. Second, watch the woods your using, I find pitch pockets in woods like maple and cherry to be the cause of most of my few "stripe" problems. Lastly you may have too much pressure going. The performax is a very lightweight machine, you can't really do any heavy sanding with it so be careful how much your working it.
good luck,
JeffD

[Lee Schierer]

Burning on a belt sander results when too much pressure is applied for too long a period of time and the wood chars as a result of getting too hot. Pitch, glue and finish can all accumulate on the belt and create lines that become hot spots. You can limit the accumulation of material on the belt by moving the part being sanded around so it isn't always rubbing on the same area of the belt. Less agressive pressure also works. Pick the piece off the belt periodically and feel the wood. If it is too hot to touch, let it cool down before sanding anymore.

You can also use a stiff wire brush against the belt on the ends of the table where the belt wraps around the rollers and just brush off the material sticking to the belt. Don't wait too long to do this as it won't work if the stuck on layer gets too thick or continuous in length. They also sell rubber erasers that will clean up sanding belts. Again don't wait too long to do the cleaning or it won't work.

Open coat sand paper may work better for your belts.

[Mike Cutler]

Andy

A couple of answers to your points.

1.) Get the sanding strip as tight as possible. Run it for a few passes, then retighten it.

2.) 1/4-1/3 of handle rotation is too much, back it down to a sixth of a rotation max. Rotate the material, end for end, once or twice before changing settings.

3.) Yep, gotta get the glue off.

To get the "gunk" off of the sanding strip, soak the strip in a mild solution of simple green for an hour or two. Then clamp it to a 2x4 to clean it off. I used a soft bronze bristlre brush and piece of wood sharpened like a plane blade.

Your drum may not be off parallel. It could be that the material is acting as a wedge and deflecting the drum up on the outboard side.
To check this, get some chalk and run a piece of MDF through the sander.
Set the drum to just barely touch the MDF, and run it through colored with chalk. You will see where the drum is removing the chalk. Swap the MDF material end for end and pay attention to where the chalk is being removed. It should be uniform, or very close to it.
The material needs to go through the sander a few times swapped end for end. A pencil can be used in place of chalk, I just prefer chalk.

Make sure your feed belt is tight, without binding, and feeding true. Any distortion of the belt will be transmitted to the material.

The Perfomax 16-32 is a very fine light duty sander. It excels at veneer work and smaller material pieces.
It takes a bit of "fiddlin" to get it setup right, but the results are worth it.

[Chip Lindley]

All the above is good advice! Trying to sand TOO much TOO soon is just NOT DONE with any of the drum sanders. It is a long process, but good results can be achieved.

You need to align your drum parallel with the conveyor. Even passes are a must for decent sanding action!

Lastly, you never said what grit belt you are using. I hog off material to achieve a flat surface with 60grit. Then 100g to minimize the grooves with the grain. I never go finer than 100 grit myself. I think its a waste of energy and time to change to a finer belt..The minute grooves from 100g can be sanded out on panels with a ROS quickly. This is my method of sanding on my Grizzly 1066. It has its limitations, but if I work within them, the DS Works For Me!

[CPeter James]

I don't claim to be an expert, but I have owned two double drum sanders and find them to be very useful for some projects. My first was a Performax 25X2 and my present one is a General 15-250. My first comment is that there is a steep learning curve which will involve several wraps of sanding strips destroyed before you get the hang of how to get the wrap the strips just right and how little you really can remove in one pass.

Second, make sure the machine is set up correctly. This is most important. They will work great...when the drums are correctly adjusted one to another and to the table. They will burn and rip the paper if the drums are not right. My new General was used jut once and put aside as not worth the effort. A few hours getting things set correctly and now it is within .002" side to side and the front and back drums both do their job.

For getting dead flat panels, a drum sander is the cat's meow, but it is not a finish sander. A little hand sanding or a ROS after the drum sander is required.

CPeter

[Andy Pratt]

1/6th of a turn is going to be an eternity but I'll give it a try.

Good tip on retightening after the belt warms up, I had read that before and will definitely try it.

Also great to know about the simple green method for cleaning the belts, I've got a few contenders to give that a try on right now.

I've used 36 grit and 80 grit occasionally (one belt of each) and have a huge roll of 150 grit and 220 grit that I've been working my way into over the last few months. Seems like the higher the grit, the more chance of problems with the belt. I've had a lot of problems with the 220 especially, since it seems like there's no thickness to it to prevent one part from slipping over the other on the drum, then it stripes really bad.

I almost feel like picking a grit (150 seems like a good middle ground), getting it on really good and then just only using that one grit for all of my work. It would increase time sanding the things that need more work, but I might not lose time overall compared to frequent belt changes, retightening etc.

Thanks,
Andy

[Jeff Duncan]

Put the 220 grit away, if you really need to sand that fine do so with a ROS. The 150 is the finest you'll want to go and if your doing something that actually requires the removal of stock then 150 is still much too fine.

I use a double drum with a 100/150 combo so I can remove a little stock if needed. With your sander you need to go much coarser to remove material. Re-read Chips advice on grits.

good luck,
JeffD

[george wilson]

I agree,Jeff. The finest I can go is 150 grit,and I only make smallish stuff,like guitar tops and backs. Also,never sand strips parallel to the table. Angle them so the strip doesn't get sanded on 1 little part of the drum. I think too fine a grit is your problem. Another thing: Blue zirconia belts cut A LOT better than the dark brown belts you usually se for these sanders. I have noticed a huge difference on my belt grinder. I am going to get a roll of it for my drum sander.

My drum sander is the 16" Delta. I think it is much more rigid than the Performax. You cannot lift up the outboard end of the sanding head at all. The Performax head is always pretty easy to flex. That's because the head has to be loose enough to slide up and down. The Delta is 1/8" thick steel,very rigid. The table raises,and you can micro adjust the outboard table elevation screws to get a board not even .001" out of even all the way across a wide board. Then,you can adjust the table to gradually taper off to nothing if you want to sand a 36" wide table top. The only problem I have had is the tendency for the wide abrasive belt that propells the wood to sometimes want to go slowly sideways.I have filed down the projecting corners of the steel straps that are at the corners of the table,so the belt on the table doesn't get torn on them when it does deflect. I do not mean to discourage Performax owners,but for prospective buyers,I'd go for the Delta.As for thickness planer type drum sanders,I've had 2. They were both a huge pain to try to get the drum really parallel to the table,and those soft squishy feed belts are not as accurate for sanding as the hard abrasive belt feed. I never did really get mine very accurate. And,the open side belt feeds are much much easier to replace,should they get damaged.

[Tom Cross]

I have the Performax 16-32 and use it all the time. I only use a 120 grit belt. I tried a 150 grit belt and it burned too much, an 80 grit belt was just too coarse and caused too much work with the random orbit sander to remove the scratches. The 120 grit belt has been ideal for me.

All the above matches my experience except I use 1/4 turn all the time and it works for me. I move the pieces around on the drum so I don't cause the belt or piece to get hot.

All in all, I love the machine. It is ideal to remove planer marks and get everything to a uniform thickness.

[Tony Joyce]

The suggestion George made at the first of his message is key for me.

"Also,never sand strips parallel to the table. Angle them so the strip doesn't get sanded on 1 little part of the drum."

Excessive heat build up is what causes burning and destroys belts. Canting the wood going through has helped me to be able to avoid burning with all woods, and especially the exotics. If I get any burning now it's because the belts are worn out. When it starts burning in an area I replace them. I sand from a few feet a day to several hundred feet a day in a millwork shop. Before I started doing this belts were being replaced weekly, now I'm averaging a month or more.

Also with a single head machine the finer the grit the less you can remove per pass.

Tony Joyce

[James Hart]

There was an article in FWW way back that suggested 1/4" plexiglass on edge to remove the shiny stripes. Run the drum slowly.

Have done it carefully dozens of times and it works great.

Jim

[Rob Cunningham]

I've found that light cuts with fast feed gives me the best results. I will rough off most of the material with 80 grit, then go to 100 then 150. Run the parts at an angle so you are not using one area of the drum. I also send the parts through several times before making any height adjustments. Heat build up is what kills the sandpaper.

[frank shic]

i do the same thing as tom and leave the 120 grit on the 16/32 all the time. i use 150 grit on the ROS to finish.

[Andy Pratt]

Thanks for the additional thoughts, I'll probably see if I can sell the 220 grit and use the 150 until it's done, then maybe move to 100 or 120 in the future. I think I'm fairly sold on the idea of just leaving a single grit on it all the time, I'm sick of changing belts back and forth.

Thanks,
Andy

[Chris Padilla]

All good advice. Here is what I've learned sanding veneers of walnut down to 1/16".

The heavier the grit, the easier it is to sand and the less likely to burn.

I do 1/4 turns on my Delta 18-36 and found less burning with 100 grit versus 120 grit. I plan to stick with 100 grit for sanding veneers down nice and even.

How is your dust collection? I have very good dc on my sander...very little dust escapes.

Some parts of the wood might be more prone to gunking up the belts.

Use those sandpaper cleaner bars to clean up the belts every so often.

I always send in my veneers TWICE before changing heights and I flip the veneer around to sand from the opposite direction previously sanded. If I hear significant sanding after pass 2, I'll send it a 3rd time just to be sure.

For the first pass, I run the conveyor belt REALLY SLOW (contrary to some folks who've posted here). The second pass is much faster. My thoughts are to give the belt more revolutions to hog material off but perhaps I don't have heat issues because my DC really sucks in a lot of air and that may keep things cooler. I dunno. The 2nd/3rd passes I double the speed because I know I've thicknessed the piece for the most part.

Slow, steady, and mind-numbing is sanding with these drum sanders but it will provide the best results for you.

[Bryan Cowing]

Take the belt off, you can clean them just like you remove the gunk on your saw blade. I use a liquid soap, some like Simple Green or other type of blade cleaner. Rinse and let dry.

[Phil Thien]

There was an article in FWW way back that suggested 1/4" plexiglass on edge to remove the shiny stripes. Run the drum slowly.

Have done it carefully dozens of times and it works great.

Jim

The cheaper (acrylic, I think) stuff, or the expensive (polycarbonate, I think) stuff?

This sounds like an interesting tip. I'm guessing it is the cheaper stuff, which can melt when cutting it. How does it work? Does it melt a little and then bond to the clog, and then pull it out?

[Byron Trantham]

I have Grizzly's 18" drum sander. It's a beast. I swear I could sand concrete blocks! :cool: That said, SLOW and LIGHT are the orders of the day. Chris pointed out that he passes his through twice at the same height. The manual that came with my sander recommends this procedure. I use it. When I first started using it I would pop the built in breaker because I was trying to take too much off. I figured out that 1/8 to 1/4 turn is all I do without bogging it down. I use a pencil to draw a bunch of figure eights to know when I have "flattened" the board. The pencil marks also show me the progress of the sanding. Once all the pencil marks are gone, I'm done. I use 120 grit and clean the drum frequently with one of those crepe blocks. It's a slow process but worth the wait IMHO.

[Joe Chritz]

I always use stroke sander belts cut down for the sanding belts on my drum sander. They are designed to be cleaned aggressively a few times so I can pull them and scrub or normally just use the pressure washer to blast anything off.

It increases the life by a wide margin.

Joe

[george wilson]

I bought big bunches of 6" wide stroke sander belts.I also plan to cut them to fit my Delta. I really think the blue zirconia belys are the way to go. I move slowly,since I am still carrying home tools,wood,etc. from 23 years of pack ratting from Williamsburg,and putting up ever more shelving to store it. I must have 500' of shelving at least.

When I do get this and some other obligations finished, I'll buy the zirconia belts,and post the results. They work much better on my belt grinder,and not just on metal. A sculptor friend asked me to grind out a piece of bonded marble for him. I used brown aluminum oxide,which only seemed to polish the stuff,which is marble in a resin binder. A blue belt cut it like crazy. That opened my eyes,as all my drum sander belts are the brown ones.


As a last note,if you look carefully at your sanding job,it does make a difference if you run the wood in such a way as to smooth the grain down,not rough it up. Experiment,and look carefully. You may have to use darker woods to see it,but it's there.

[Paul Johnstone]

Put the 220 grit away, if you really need to sand that fine do so with a ROS. The 150 is the finest you'll want to go and if your doing something that actually requires the removal of stock then 150 is still much too fine.

I use a double drum with a 100/150 combo so I can remove a little stock if needed. With your sander you need to go much coarser to remove material. Re-read Chips advice on grits.

good luck,
JeffD

Not to contradict you, but I have a double drum sander as well. The guy at Klingspore told me that off the planer is roughly equivalent to 100 grit.
So, I put 120 on my first drum and usually 180 on the second. I have also done 150/220 and that works fine too

The key is that the finer the grit, the smaller passes you need to make.
I can run a board through 2 or 3 times on my grit combo and with red oak, I don't need to do any ROS, because there's no visible lines.

The key is tiny, tiny bites and setting up your second roller so it is just barely below the first one (I think mine is on the lowest setting)

[Andy Pratt]

What's special about the blue belts that makes them cut so much better? I'm going off a distant memory but I thought they were for non-wood applications(aren't they aluminum zirconia or something), is my memory wrong?

[Chip Lindley]

Paul, the Klingspore rep is not taking into account any planer marks, uneven glue lines, chipout, or any other imperfection which must be sanded out to achieve a nice flat panel. They want to sell lots of different grit sandpaper! I want to flatten panels ASAP! I can hand-sand with a ROS faster than I can change grits on a 2-drum sander. Oh, and I use the same grit (100) on both drums to increase my effective stock removal! With no means to adjust drum height, I have had very *Iffy* results with 2 grits on the Grizz 1066.