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Episode #50: Two-Stage Drum Sander
Get plans for this project here!

TRANSCRIPT:

 

S- I can think of at least ten things I'd rather be doing than sanding, eleven if you include things that aren't done in the workshop. So I'm always looking for a new machine to make the job easier. What's the most useful sanding machine known to mankind? You guessed it, the drum sander, a tool with a heritage that stretches back to antiquity. When great explorers such as Gilligan and the Skipper encountered the aborigines of coco-maka-laca… they found them sanding their coconut drums with one of these workshop wonders. They're the pride of the professional shop designed to make wood thinner, flatter and smoother, with minimal cost beyond the at least $700 initial purchase and the expensive, difficult to find replacements belts. Now that I think about it, they aren't very affordable at all. Which is why I decided to build my own.

M- This isn't the first time Stumpy's built a drum sander. In fact, we made one almost two years ago on episode #34 of this show. More than a hundred thousand people watched that episode, and hundreds of them have built Stumpy's sander. So you may be asking why we're talking about making a new one. Seriously, why are we talking about making a new one?

S- Because I can make it better.

M- You mean with a feed belt?

S- Among other things, yes. This one will have a feed belt.

M- Finally, some common sense! You see, I used to work in a pudding cup factory watching a long line of empty cups ride on a belt into one side of a machine and come out the other end as delicious snacks. It was so simple! I think we need more of that in our workshop.

S- While I've never been against pudding, a conveyor belt is not an easy thing to build into a homemade drum sander.

M- Matthias could do it.

(INTRO)

S- A drum sander might be a great tool to have, but it's not an easy one to build. That is unless you know how to do it. I've built five of them, and not all of those worked well. It took a lot of time to refine the design so that all the features I wanted worked properly. So if you're thinking of building one, you'll want to pay attention for the next few minutes as Mustache Mike and I tell you everything you need to know about drum sander building.

M- That way you'll avoid making some of the costly mistakes that Stumpy made. And boy did he make a lot of costly mistakes. I mean, who uses a Pringles can for a sanding drum?

S- They don't need to know about that. Let's just start with the basics

S- (MUSIC) A drum sander is essentially a box. Four sides, a top and a bottom. The trick is in how those parts interact with each other, but we'll get into that later. For now, concentrate on getting your sides square and true.

M- You're saving a lot of money already by making this machine yourself, so now's not the time to cheap out on the materials. A good cabinet grade plywood will stay flat and last forever. You'll only need one sheet of it, depending on how many cuts you screw up.

S- Let's talk bearings. A drum sander must have good ones to work properly and last longly. They'll be spinning as fast as thirty revolutions a second in a dusty environment. I've tried the cheap ones. I've even tried the bronze sleeve bearings. They won't last. Find a good sealed set at a parts dealer or an online supplier. The good news is you don't really need a specific size. Get what you can get and build your sander around them.

M- Actually, the size of the bearing does matter. It has to fit the shaft.

S- You mean the size of the shaft doesn't matter as long as it fits the bearings.

M- The outside diameter of the bearings?

S- No, that has to fit the flanges.

M- Do the size of the flanges matter?

S- Not as long as they fit the bearings.

M- So the inner diameter of the bearing doesn't matter as long as it fits the outer diameter of the flange and the outer diameter of the shaft doesn't matter as long as it fits the inner diameter of the flange?

S- No, the inner diameter of the flange has to fit the outer diameter of the bearing and the inner diameter of the bearing has to fit the outer diameter of the shaft. It's all very simple. Find some bearings, then choose a shaft to fit inside the bearings, and then a flange to fit over the bearings. Or you can also make your own out of hardwood.

S- While we're talking shafts, let me tell you what I've discovered. A plain steel rod works great. But it's difficult to mount the drum to a smooth shaft. After my first few sanders I learned to use a threaded shaft. You'll see how that all works later, we're getting ahead of ourselves, we've still got some building to do.

(AD)

S- So, what do you use to make a drum? On my first sander I made a bunch of MDF discs that I glued together into a big log. This is the most common way to make a homemade sanding drum because MDF has the same density throughout.

M- Medium density.

S- Yes, that's why they call it MDF. Solid wood is too inconsistent making it difficult to balance the drum. All but the expensive plywoods may contain voids which will throw you off too. So MDF is pretty much perfect. Which is why I don't use it anymore. Instead I use good old 4" PVC pipe, the thick stuff, not the sewer pipe.

M- Sewer pipe would make crappy sander.

S- PVC works well because it's already the right size and shape. But that's not all. The inside is also as empty as someone's head, and we've got to take advantage of that. You see, I don't want an ordinary sanding drum, I want one that's removable. Why you ask? It's all about price and convenience. I'll let the stash cover the price bit.

M- Most homemade drum sanders use hook and loop sandpaper. It works well, but it's difficult to find and expensive. Stumpy's last sander used the same sanding rolls that commercial units use, which are more economical, but still a little bit pricey and no easier to find.

S- So I asked myself- "Self, why not use those 6" sanding belts you can buy in the box stores?"

M- What was your answer?

S- I high fived myself and had a cold one because those belts are cheap, easy to find, and very durable. The problem is, how do you stick them on the drum?

M- That's a head scratcher.

S- Spray glue. Spritz it on, wrap the belt around and it stays as tight as my waistband after dinner. Which brings us back to the removable drums. It would really stink to have to peel that paper off every time you wanted to change grits. So, I made three drums, each with their own grits of paper. Instead of swapping paper, you swap drums. And the hollow inside of the drum is a perfect place to build a detachable drive mechanism, which I'll show you in a minute. First, we need to discuss drive belts.

M- I used to work in a pudding factory…

S- We already herd that one.

M- Your head is a pudding factory.

S- Drive belts are few and far between on homemade drum sanders, and for good reason. Actually, I don't really know the reason because they're really awesome. They can be intimidating, which is why I never made one before now. But I saw a replacement belt for a Jet sander in the clearance section of my local woodworking store and decide it was time to put on my man apron and face my fears.

M- If you don't have a local woodworking store with a clearance section that just happens to have a drive belt in it, you can just buy one online. Again, the exact size doesn't matter. You can modify it to fit your homemade machine.

S- The key is getting it to track correctly. Professional drum sanders have little adjuster bolts on each side which allow you to stretch one side of the table or the other until the belt runs straight. So that's what I built into this one. I doubt anybody will be cranking this thing at a thousand RPM or anything, so steel spacers will serve as inexpensive bearings. Now let's move on to the top.

S- The last time I built a drum sander I made it so that the top of the drum was accessible. As far as I know, I am the only one to ever design a 2 in 1 drum sander, and it just makes sense to me. Why should the bottom of the drum do all the work? It's really nice to be able to pass a work piece across the top of the drum for a quick sanding. But I found a flaw in my first version.

M- Say it isn't so!

S- Because the center of the upper table is cut out, over time the table itself bowed. If you built one of those sanders there's an easy fix, which I am incorporating into this sander from the start. I attached 3/4" angle iron to the front and rear edges. This keeps is flat, even under load. I'm also adding aluminum inserts along the drum. I'm not sure if those are necessary, but they look cool.

M- The heart of any drum sander is the motor. Which one should you choose? A general rule for any homemade drum sander is the bigger the better. At least 1HP, 1 1/2 is better. Fine grit sanding isn't very demanding, but you'll need a lot of power with the course grits, especially with wide work pieces. And what about speed? Motors generally fall into two categories- 3700 RPM of 1750 RPM, or threabouts. In this case, the rule is the slower the better. You don't want your drum spinning a 3700 RPM. The problem is, most motors you find at flea markets and yard sales aren't slow speed. The motor Stumpy is using came from an old table saw, which is faster than 3700 RPM. The solution is to use as small a pulley as possible on the motor's shaft, and as large a pulley as possible on the drum itself. In this case we're using a 1 1/2" pulley on the motor, and a 5" pulley on the drum. If you calculate the circumference of each pulley and figure in pie and all that, you'll find that the difference in pulley sizes slows the drum down about 75%-ish.

S-Mmmmmm, pie… So, now you've got the basics of not just this sander, but any homemade drum sander you may want to build. Let's see how all those features come together right after this.

(AD)

S- So the sander is finished and I couldn't be happier with it. Let's go for a tour.

S- The table tilts to adjust to the thickness of the work piece, all the way up to 4" thick. In order to accommodate such a wide range without having to push your work piece up a steep slope, the table's pivot points are also adjustable. The top setting is the one you'll use the most, for stock 3/4" and thinner. There are three more settings for thicker materials. On the front of the sander is a simple micro adjust mechanism with a quick release feature. This allows you to take off a very small amount of material with each pass.

M- The hand crank feed belt is a great addition to this sander. It makes it a lot safer and easier to feed small parts beneath the drum, and it helps you feed longer pieces through at a consistent speed. That's important because any pause in the feed rate can create an uneven surface.

S- Running work pieces beneath the drum is a great way to achieve a perfectly flat surface with a consistent thickness. But it's even faster to sand work pieces on the top of the drum. Having access to both the top and the bottom of the drum makes this sander way more versatile than any other design out there.

M- When it comes to changing paper grits, it couldn't be easier. Pop off the front and loosen the stop. The entire drum slides right off the shaft. Slip a new one on and a pair of drive pins engage in the rear. By swapping drums rather than the paper itself, you have the option of using inexpensive and easy to find sanding belts rather than the pricey hook and loop paper. And it's actually faster to swap drums than it is to peel off the paper and re wrap the drum every time you want to change grits.

S- These 6" sanding belts last a long time, but eventually you will have to change the paper. Depending on what strength of spray glue you use, it may be as simple as peeling it off. If you have trouble removing it, use a hair dryer or a heat gun and it should be no problem at all. If you get glue buildup over time, clean the drum up with a little hand sanding, maybe once a year or so.

M- Since drum sanders create a lot of dust, Stumpy designed the structure of the sander itself to funnel the dust to the back where it can be collected with a 4" dust collector hose.

S- One thing that was very important to me in this design was to make everything adjustable. If the drum isn't aligned with the tilting table, you can adjust it's angle in all four directions with set screws in the front. If the top table is out of alignment you can make an adjustment to on the side beneath the hinge. Of course the tracking of the feed belt is adjustable using the bolts on each side, and the height of the upper table is adjusted with a pair of set screws as well.

M- Looks like you thought of everything.

S- Well, there's always ways you can improve any project, and you may decide to design your own sander from scratch. I hope the information we gave you in this video helps you along the way. But if you want to save yourself a lot of time, energy and expense, consider picking up a set of plans for our sander over at Stumpynubs.com. They should be available in a day or two and will include cut lists, dimensioned drawings and step by step instructions complete with photos to guide you along the way. It looks like an intimidating project, but it's really easy to build with our detailed plans.

M- And while you're there be sure to check out all of the other projects, articles, tool reviews and other woodworking goodness.

S- It's a great place to sit back and have a cold one, because you've earned it my friend!

 

 

 

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