For those with double drum sanders

[Alan Schaffter]

Mike
I run 80/120 on mine, front/back.
While it is true that the 80 will scratch up the 120, on multiple passes*, but the final pass through should fine. I can also see how the grits on both drums should work well also.
I don't consider the drum sander to be the final surface prep personally. For me that is done with ROS's at 150/180/220.
Hmmm, maybe I should just use the same grit on both drums.

*This is a point many folks don't realize about a dual drum sander! You waste either the fine grit on the coarse passes or the coarse grit drum on fine passes.

The (only?) benefit to two drums is not having to change grits for the final pass. I came up with a design that eliminated this. I had already upgraded my 24" Grizz G1066 with a variable speed conveyor, but planned to modify the drum assembly too, but never got around to it. Essentially I was going to mount the drums and bearings on a dual rocking mounting plate assembly- plates pivot in the middle. Only a limited amount of rock (1/4' or less) is needed. "Rock" the drum assembly towards the in-feed and only the coarse grit contacts the stock. Rock it towards the out-feed and only the fine grit contacts the stock. Use the coarse grit drum until the desired thickness is achieved (of course drum sanders should not be used as thickness sanders ) and the only marks remaining on the stock are those made by the course grit. Then switch to the fine drum. There would be finely adjustable stops under each end of each mounting plate

Other possible options included, pneumatic vs mechanical drum selection, bi-directional belt motion, automatic direction change, rotating bristle dust brush adjacent to the out-feed drum.