Widebelt Sander Gets Straightened Out
I went shopping for new tools last year after my fire. One of my best finds is a 36″ AEM (now TimeSavers) widebelt sander, affectionately known in the shop as the “FriendMaker”. It is a 20hp wood-eating machine that is in great shape for its age. I would say it is perfect, or at least now I would. The only problem that I found after I ran it was a groove or three in the front sanding drum. I didn’t know a lot about this sander and told myself that it would be alright if the drum wasn’t flat because the platen, which is a flat bar that presses the sandpaper to the wood would smooth things out. And it did (kind of), when it wasn’t falling apart.
The platen is a piece of aluminum about 37″ long and 1-1/2″ wide. It has a piece of stout felt attached to it that is covered with a separate piece of graphite fabric. The graphite reduces the friction and allows the machine to apply pressure to the backside of the sandpaper without burning through everything. The sander had the platen in it when I got it, and I assumed that it should be in there all the time, so I used it all the time. I was getting decent results, even with the grooves in the front drum, but I was going through graphite and felt quickly. I had to baby the machine and the graphite was still wearing out. I finally broke down and called TimeSavers to talk to a tech guy.
The good news was that the tech guy knew what he was talking about. The bad news was that he assumed I did to, even after I told him that the machine was new to me, that I had never used it or one like it before and that he should assume that I knew nothing about it. It took me close to a half an hour of going back and forth to finally figure out that it isn’t necessary to use the platen all the time. If I wanted, I could run it without the platen. Well, now I was listening (not that I wasn’t before). Turns out that the platen is for finish sanding and shouldn’t be used to take off more than .005″ at a time. It was for smoother grits, like 150 and up. The platen spreads out the sanding pressure to keep the sanding scratches from going too deep. Good to know.
Now things started to make sense. I had read that my sander could take up to 1/8″ per pass on rougher grits. That was a crazy number compared to .005″, and I am all about crazy. If I could take that much off at a time it would be a real game changer for me. The problem I faced with my new aggressive sanding technique was that the front drum, which is rubber coated, had those grooves in it that I mentioned earlier. Smaller pieces could run through and avoid the bad spots, but bigger pieces couldn’t. And many times the smaller pieces would drift into the zone with the groove and come out with high spots. I wanted to fix it, but it looked like a daunting task. There is no obvious way to get the drum out, and I had heard that redoing the drum would cost thousands. As much as I am all about crazy, I am also about cheap. Thousands for a resurfaced drum was not in the cards for a machine that I got for $2,500.
So, I coasted. I used the sander almost every day and tried to avoid the bad spots. I even put the platen in when it was vital for the part to be flat. No matter how careful I was, parts would still come out with hidden ridges, the sneaky kind that only show up in the finish, when you want them the least. I kept coasting until, out of pure coincidence, the guy that sold the exact machine to the original owner stopped by my shop trying to sell me new machinery. He asked me how the sander was working, and I told him about the drum and the grooves that were ruining my life. He casually mentioned that I could “dress the drum” if there was enough of it left. He took a look at it and assured me that I could fix the drum on my own. All I had to do was search the internet for info and videos on “dressing the drum”.
Searching I went. No videos. The only thing I found was one posting on WoodWeb about how to dress the drum. I was really hoping for a video because I wasn’t in a hurry to destroy the drum and mandate the purchase of a new one. However, the one posting was all I could find. I read it and it made sense, so I stopped looking and decided to give it a whirl. It ended up being quite easy and intuitive. I just never would have thought of sanding the rubber drum on my own, but once I knew it was an option it all made sense.
Because I couldn’t find a video on how to do it I decided to make my own. I’ve been wanting to start making videos because I think the videos can be a lot clearer than still shots. I don’t like seeing or hearing myself, but I decided it is something I just need to work through. So, here it is, my video on “Dressing the Drum on a Widebelt Sander” (just click the photo of the sander below). Next up is a full-time, non-judgemental cameraman.
The premise of the whole event is that a flat board covered with sandpaper is sent through the machine (with the sanding belt removed) and sands the rubber drum smooth. It starts with a new 36 grit sanding belt and a piece of 1/2″ thick MDF with radiused leading edges. The width of the MDF is determined by the throat opening of the machine and what is the widest piece that will fit through it. In my case, it is about 39″ wide. The length of the MDF is based on the width of the sandpaper minus 2″. The minus 2″ is so the paper can completely cover the two radiused edges. My paper is 37″ wide, so the MDF is 35″ long. The new sanding belt that is applied to the MDF runs at a 90 degree angle or perpendicular to the way it normally runs. Doing this allows the MDF to be a little wider than the drum and to be sure the drum gets completely sanded on each pass. The key is to have a wide, flat, consistent-thickness sanding block to send through the machine. After the MDF and sandpaper are cut, apply the sandpaper to the MDF with spray adhesive (3M SUPER 77) and trim everything flush.
I was instructed on WoodWeb to use a high feed speed, low grit and very shallow cuts since the rubber could just melt instead of being sanded. It didn’t take long. I took light passes and was done way before I got the video shot. In all, I only sent the MDF sandpaper block through 10 times to remove the 1/16″ deep grooves.
Now, I use the drum all the time and never use the platen. I consistently and confidently take of 1/16″ or more per pass (even on wide stuff) with the 36 grit and 1/64″ with the 100 grit. It is amazing how different my life has been since I “dressed the drum” on my sander.