the Walnut Diary

It’s a good machine but the manual isn’t, so I wrote down a few points a new buyer should find useful.

NOTE:  Check for updates at the end of the article.  Rod

With a full inventory of shaper cutters and ample time, I decided to fabricate historically-accurate trim for our house renovation project. When faced with the challenge of making the casings and baseboards, I decided that sanding each piece with a handheld sander or driving over each with a floor sander would not pay off in the long run.

The only product which seemed likely to do a competent job on a thousand board feet of stock for trim in the house turned out to be a double drum sander, a sort of thickness planer using long sandpaper belts instead of blades.

I actually found one available used, but the guy wouldn’t sell it until his larger model came in, and Busy Bee Machine Tools in Ottawa put their two models on sale for less than the asking price on the used one, so the task then was to choose between the two models in the same store. This simplified itself quite soon: the more expensive model weighs over seven-hundred pounds and its narrowest dimension is 41″. This precludes installing it anywhere without a wide door and heavy lifting equipment. Busy Bee had one in stock, however. The still massive, but smaller model weighs 500 pounds and was selling so well at its sale price of $1488. that the job was to nab one before the entire Canadian consignment of machines was sold.

Manager Carl Talbot warned me about a couple of things with the machine. Most importantly, a drum sander of this sort requires at least a 2 hp dust collection system or it will instantly plug itself. This meant an expensive upgrade to my current system. He also warned me that the clips which hold the sandpaper make the learning curve on belt installation quite a steep one. Apart from that, he explained, the machines are great, and he can’t keep them in stock.

I’d had dealings with Carl before and I took him at his word. We wrote up the order, including an upscale dust collector with it.

The machine ran well right out of the box, without adjustments.

Reviews on the Internet had warned that a normal heavy cut with a drum sander is about 1/64″. The power feed runs off a 12V D.C. motor, with infinite variations on speed between dead slow and full fast. This system works very well, and Carl told me that it’s an important selling point for this model.

While the 25″ Double Drum Sander should not be mistaken for a thickness planer because of its thin cut, it produces flat, true boards with a consistent texture over their entire surface. It proved particularly valuable on wide, glued-up pieces, and would likely do a fine job on cabinet doors and wooden counter tops.

Tactics for use of the sander:

1. Cut stock to size first. This thing is slow, and the less wood you must put through it, the better. Similarly, the flatter the wood is, the better. A cupped board will keep you busy planning 1/72″ off until you are sick of the sight of its grain.
2. If the machine starts to squeal, that’s the drive belts slipping on the sander drums. Immediately lower the table, allowing the drums to spin again. There’s no real need (apart from operator panic) to shut the sander off. Bring the table back up to where you had it but slow the feed rate until it works properly. This will leave a lump on the board, but you can catch it on the next trip through by slowing the feed down until the obstacle has been chewed up. Don’t worry, you’ll be making several passes with each board.
3. Sand as quickly as the machine will allow. Dead-slow sanding will leave boards less smooth than if a very light final cut is taken at medium speed.
4. The belts gum up all too easily on pine. With many door and window casings I found I had to clean the belt after each board by holding a large crepe block against the rollers. A resinous knot would plug the belt and burnish the remainder of the board. Eventually I selected 100 grit for the rear drum, rather than the 120 which came from the store. The front drum stayed with 80 grit throughout. Plugging was still enough of a problem that I despaired of sanding 16′ pine baseboards and looked for an alternate material.
5. This led to my last two days of work sanding a number of 12 to 14″ wide American chestnut boards recovered from an old granary. Using 80 and 120 grits on the drums, I have found that the belts do not clog with this wood, and the finish is good. I’ve also sanded red oak and basswood with good results.
6. Some adjustment of the conveyor belt is necessary, but it’s not nearly as hard as controlling the tracking on a belt sander. You just twist a pair of Allen screws controlling tension until the belt behaves. If it’s pushing to the right, add tension on the right and let a little bit off the left. It will level out if you don’t over-correct.
7. Carl had warned me to make sure I had enough length on the sanding belts when I cut them. He was right. The length is critical to within ½” if the belt is to fit.
8. Changing belts: What the manual didn’t explain is that the clip next to the little feed motor (I’ll call it the right-hand clip) is rotated forward on a large spring within the drum. Until I had figured that out, things didn’t go well. It wasn’t until I donned a head-lamp, saw the spring, and then pushed the whole mechanism against the drum’s rotation with a large screw driver that it began to make sense. Then and only then did the belt clip line up under the slot in the drum, and I was able to insert the second end of the belt. So you start with the left clip. It’s easy. Wind the belt on until you get to the right side. Pry the large spring mechanism on the roller  so that the right-hand clip is forced back under the slot for the belt. Feed the end down to the clip. When you let go it should grip the belt and tighten it as it rotates forward.
9. When the belt came loose this morning I discovered (again with the help of a head lamp) that I could grip the tag end of the belt down inside the roller with a pair of 90 degree needle-nose pliers and tighten it nicely while I held the clip open with the other hand. That worked. No more problems with belt slackness. Add a pair of offset needle-nose pliers to your tool kit for the machine.

In Summary:

I’m glad I bought the machine, though it’s less versatile and a lot less productive than my planer. It should pay off in the improved quality of the interior trim on the house and later, when it becomes a toy, I will likely build a lot more dressers and armoires because this machine is in my shop and I won’t have to spend hours with a random orbital sander on every project. Even lawn chairs and stairs will have a better surface when they leave my sawdust factory.

Resinous woods will require a lot of crepe block work, but the machine will sand them.

I hope this helps,

Rod Croskery,

Sawdust-Ink

UPDATE: June 10, 2008. Today I finished the stain and varnish on the pine baseboards for the upper floor of the house. The surface which has emerged from the finishing process is better than I have achieved before on pine. It is smooth and consistent, without blotches. I can only conclude that the sander does its job well, even on resinous woods.

UPDATE:  August 13, 2008.  While sanding some old, unfinished pine bookshelves I got fed up with the motor belts slipping and did something about it.  I had to take off four panels and disassemble the depth gauge to gain access to the motor and the drive belts, but once I found the adjustment bolts I realized that they had never been tightened.  With a 12 mm wrench I tightened the double belt to about what I’d use on a fan belt:  1″ deflection with a moderate pressure from a thumb.  That made a big difference in how much I could cut without the belts slipping, though overloading the machine just causes the sanding belts to clog, so it didn’t leave me all that far ahead.

Again, pine calls for a lot of crepe block work, but the finished product looked fine, sanded with 80 and 120 grits.

BTW:  Last month I did a set of bookcases out of basswood as a wedding gift.  The beveled-panel doors trued up very well on the sander.  I took care of the cross-grain scratches at the top and bottom with a random orbital sander.  All of the other wood in the project made a couple of trips through the sander, as well.

It’s earning its keep in my shop.

For other articles in this series check:
https://rodcroskery.wordpress.com/category/renovating-a-stone-house/