Dual Drum sander build/ help

[Mike Reinholtz]

Matt Armstrong's long and impressive thread of his home made drum sander has me motivated to get back to work on mine. I started gathering materials about a year ago and put it off to complete other projects, time to get back to work on it.

For those of you that have drum sanders and dual drum machines, what do you like/dislike about yours?
Any size concerns or wish it was a little wider? I'm aiming for 38" drums.
On dual drum machines, anyone have grit preferences you use most often?

I will be powering the conveyor with a 1/2HP gearmotor, and have drawn up a powered lift for the bed ranging from 0-12".

Thanks for your time and help!

[Chip Lindley]

Mike, this is a subject that is near and dear to my heart! I mulled over the idea of making my own DDS for far too many years. To say "how far back" I must admit that I was using a Kuster design as my basis. It was perfect on paper, but I lacked the metal-machining capabilities to bring it off. I waited long enough until I lucked into a deal on a nice Woodmaster 3820 DDS. A 38" wide drum can sand most anything you will encounter, except perhaps sections of a huge conference table, or very oversize doors.

I have found that wrapping two grits at the same time serves no real practical purpose. It is a waste of time and energy. If only one pass was needed, it would be practical; but the truth is several passes must be made to level out most panels to finished thickness. I load both drums with 80 grit for initial sanding, to level everything out quickly. 120 grit is then wrapped on for final smoothing. After drum sanding, panels are touched up with a ROS. It works for me.

The Woodmaster DDS, and even the current Grizzly "Z" series DDS have micro-adjustable rear drums. Unless your provide for some adjustment on the rear drum, using two grits together will not work at all. Coarser grit sanding rolls are thicker than finer grit rolls.

Best of luck with your custom DDS! I have no doubt it will be worth the effort, and much cheaper than store-bought!

[Mike Reinholtz]

Thanks Chip, that's exactly what I was looking for! I like the idea of the micro adjust for the rear drum height, I will be sure to add that in. I've been looking for quite some time at the various models out there and none had what I'm looking for at a reasonable price (or at least reasonable to me).

The only major part I have left to decide on is the drive motor. Initially I was leaning towards a 7.5HP motor, but I'm probably heading towards 3 phase because I have a 10KW rotary phase converter. With 3 phase I can throw in a VFD and not only get variable speed but also can program for soft start and lower the inrush current. I set up my shaper and RAS this way and have had great luck with them. I've been searching online and locally and from what I've seen I can get a 10HP 3 phase motor and VFD for less than a single phase 7.5hp motor. My electric panel is in the garage, so running another outlet is easy.

What size motor does your woodmaster have? I've heard people can customize their orders, you ever wish it was bigger?

How is dust collection?

How about table height range?

[Chip Lindley]

What size motor does your woodmaster have? I've heard people can customize their orders, you ever wish it was bigger?

How is dust collection?

How about table height range?

Mike, the Woodmaster has a 7.5hp 1-phase Leeson. A motor sized for adequate power, using the full width of the machine. (something I have never done) Overkill, under normal circumstances, since I do not crowd the machine in any event. Trying to take off too much stock, heats the wrap and risks melting the velcro drum coverings.

Dust collection is good! The internal baffles of the Woodmaster are very effective at channeling dust to the two outlets. (compared to the former Grizzly G1066R which had NO baffles!) I've attached the 3720 directly to a 2hp Delta single stage collector (55 gal. barrel-type) and to a 3 hp. Oneida system.

Table height is fine with me. To be honest, when I'm sanding a batch of panels, attention to the task at hand takes over, and that is the last thing on my mind.

Keep us posted on your progress building your sander. PICS PICS PICS!

[Alan Schaffter]

I like the idea of the micro adjust for the rear drum height

I've been searching online and locally and from what I've seen I can get a 10HP 3 phase motor and VFD for less than a single phase 7.5hp motor.

Mike, micro adjust is essential if you plan to use different grits. Something else to consider is the height adjustment crank needs to be fine as well. The one on my Grizzly 1066 is too coarse and I can typically only turn the handle a 1/4 turn or less between pass with my 24" Grizzly 1066.

I think you will be surprised with the prices of VFD's. They go up dramatically once you get over 3 hp. Just use your RPC to run the 7.5 hp 3 ph motor (you really don't need to vary the drum RPM).

Get an AC powered DC speed controller and a DC gear motor (Baldor, Bodine, Dayton) to drive the conveyor (I converted my single speed converyor to variable speed this way). You should only need a 1/4 - 1/2 hp motor for the conveyor.

I agree with Chip. The conventional wisdom is to put coarser grit on the infeed drum and finer grit on the outfeed. Typically 80/100 or 100/120 (or 150). To work correctly the drums must be accurately set- the outfeed very slightly lower than the infeed.

But, what if you plan, or need, to make more than a single pass and raise the table? I always do!!! You are actually wasting the second, finer grit drum on the first pass- because when you run the stock through a second time, you are hitting the stock with coarse grit again (followed by the finer grit). If you need more than one pass, using fine grit on the first pass is a waste (or using coarser grit on the second pass)!!!

I plan to re-engineer my Grizzly- to allow the use of either drum or both drums on a particular pass and also have the conveyor reverse . Eventually I would like to set it so it will reverse and change drums automatically. My plan is to fabricate a new pair of mounts for the drums- rocker arms that pivot in the middle so only one drum contacts the work at a time. It needs to rock less than 1/4". Actuation with be done by four small, bi-directional, pneumatic cylinders at the ends of the rocker arms that operate on standard shop air. Screws under the ends of each rocker arm will make for easy alignment.

Theory of operation-

Turn on the machine. Flip a switch to select a drum- so only the front, coarse (or rear, fine) drum contacts the work. At the end of the pass I will be able to reverse the direction of the conveyor. The second pass can be made with the coarse drum or if desired flip the switch to select the other fine grit drum.

The mechanics should be relatively inexpensive and easy to fabricate- heavy steel pivot arms with pivot bearings, bearings for the two drums, SMC 110V or 24V solenoid air valves and some Bimba cylinders- all available on Ebay.

My ultimate goal is to be able to automate some functions like automatic reverse via LED sensor. Also, if I select automatic reverse, I want to be able to preselect grits for each pass- Coarse - Coarse, Coarse - Fine, or Fine - Fine.