Homemade Thickness Sander

[Inklings]

I hope this is somewhat on-topic for a builder's forum. If not, I trust a moderator will move it to a better place, or delete it as inane babbling.

While I would love to purchase a Jet 16/32 sander, it's just not in the budget anytime soon. It looks, however, like I may not have to right away.

I am going to set the Octave Kit to the side for a little while and work up one of these.

I like the idea that you actually use the bed of the device to true up the drum, meaning that there should be a fair degree of accuracy in the amount it takes off across the stock. Holding 3/16" sides, backs and tops flat to the workbench so I can plane them by hand isn't nearly as much fun as I thought it would be.

A friend on mine is a mechanical engineer, and got me a great deal on the hardware. I have a great motor sitting in the workshop that was given to me for a drill press ages ago. If I can find a good source for the hook velcro for the drum, and the loop sandpaper, I think I could be in business. At least enough to take it down within shooting distance of what I can finish by hand sanding.

Or I may end up weaponizing a bunch of MDF discs and sending them through the basement windows.

[stepasha]

I've built that same one. I picked up a piece of granite from a deconstruction store and used that for the bed. The granite is glued to some plywood so that I could install the hinge.

My major criticism of this sander is that the lack of a mechanical feed means a lot of pushing and pulling, and in the end it gives less than perfect results. There are always dips in the wood where I went too slow, too fast, or if the wood itself was just soft in a spot. I use an orbital sander with fine grit sandpaper or a card scraper afterwards to finish flattening it. It has been very useful in working with figured woods. My thickness planer would eat them for breakfast.

This is all just a long way of saying that while I don't love this sander, it has been a total life-saver. If you have a good deal on the parts, I say go for it. If you don't have a good source for the parts, then just save your money for a real thickness sander. Costs often end up higher than you think for projects like this.

As for hook and loop part, I used the Grizzly H5037 Hook and Loop Conversion Kit. Costs around 50 bucks, and it worked well. My drum sander can sand about 18 inches wide, and this kit was more than enough, and probably enough to wrap it again. By the way, I would recommend a thick metal bar for center of the drum sander. You don't want it to deform ever.

[Inklings]

Many thanks - that Grizzly spec will be very helpful. I deeply appreciate your take on the feasibility of the unit, as well.

A friend of mine works for a machine shop, so he can order those parts for me at a deep discount. Granted, I will need to make him some beer - not a chore, all said.

It's good to know what to expect by way of results - thickness it down within a bit, but plan to do the last parts with more control.

I'm using a 1" solid piece of polished steel for the shaft, given similar advice from someone else about the deforming issue. The pillow blocks I'm using are cast, so hopefully it will be sturdy enough.

Great idea on the granite... I may look into that.

[Oliver A.]

Here's one that I made over 30 years ago. (pictured in 2005)



It has automatic feed that keeps the feed rate constant. It is accurate to .1mm I made it when I was still making guitars. When you put guitar tops or backs through it, they stack themselves on the tray in the rear, saving a lot of running back and forth. The feed belt is run by a separate 1/4 hp motor that is connected to a 60:1 gear reducer with stepped down pulleys and then stepped down again from the reducer's output to the roller. I trued the drum by clamping a straight edge across in front of the drum and while the drum was spinning, I slowly ran a router across, using the straight edge as a guide.
It does have some quirks but I only use it once a year or less to thickness mandolin sides so I can't justify spending 2 grand or more on a store bought one that I'm sure would be better.

[kjbllc]

nicely made

[Inklings]

Amazing! Wow Oliver - that is the super-deluxe model! Looks like a large diameter on that sanding drum as well, must stay true quite well. If I may ask - what width do you consider sufficient for your normal guitar backs and fronts? I'm guessing 20" or so, but I suppose it depends on the model. That kind accuracy must mean you can get pretty close to finish size right out of the machine itself.

I have seen few models online that have an automatic feed - afraid that's far out of the range of my engineering abilities. I like the two "hold down" cross members before and after the drum, as well. Are they what moves the piece along, or is the bed itself powered? Great idea for the output tray - must take the calisthenics out of operating it. Am I seeing mortice and tenon joints on the uprights?

I visited your site - Holy Cow! Amazing site, and amazing products. I have to say, it is really an honour to have so many top notch builders willing to offer support and advice so readily on these forums. And, I take particular joy in seeing that you're a Canuck! Do you offer shop tours? That would be worth a drive from Mass, if you do. Congrats on the "new" digs. I hope it's working out for you - looks like a lot of hard work to prepare a space like that, you must be proud of it.

[Oliver A.]

Thanks for the compliments Inklings. I could go and measure the width for you but my recollection is that it is a full 24" wide. The problem with a 15" diameter drum is that it is not as aggressive as say a 6" drum. (The upside is, there are less sandpaper changes.) For that reason, I use a 60x abrasive and for that reason, I leave the sides about .1mm thicker than my desired finished thickness to allow for sanding by hand or a palm sander. I'm not particularly proud of this machine. I built when I was 19 years old. I could do much better today but it works well enough for the limited use it gets these days.
Feed is via a wide "grip top" industrial conveyor belt. The hold down rollers are passive and ensure that the material does not come shooting back into my belly.
The mortise and tenon joints are sorta' fake. They were made by gluing and screwing three pieces of 1 X 3 maple together. At the time, I was much more interested in building guitars than making machinery. I didn't even draw up a proper plan for it. The first version had a manual sliding feed but the plywood "slide" that I used, which was long enough for guitar sides plus my fingers at the end of the pass, was warped and my side sets would end up thinner in the middle than at the ends. That's when I added the auto-feed. Luckily, I made the machine robust enough to accommodate the extra weight. A lot of the parts were scrounged. Some of the pillow blocks and angle iron I got for free through "connections". The feed motor was taken out of an old washing machine that a neighbor had thrown out. If I get around to it, I'll take a photo of the depth-of-cut adjustment. With the 15" diameter drum (which is mostly hollow) and 60x sandpaper, I can only consistently take off .15mm per pass. If I were to do it again, I would put a vertical sanding belt on it with 6" drums. That would make it more aggressive and go even longer between belt changes.

BTW, one thing that I do not see on the plans you posted is a thin rubber sheet to cover the drum. I used 1/16" neoprene with a cloth backing. I was able to use contact cement to glue it to the drum. This little detail will improve the performance immensely and help the sandpaper last much longer.

If you happen to be in the area, I could probably give you a short "tour" of 1/2 hour. You would have to arrange it with me in advance. I don't think that it would be worth a whole trip for you but if you happened to be in the Toronto area anyway, it could be an interesting side trip.

[Inklings]

A full 24" sounds like it would certainly do most guitar backs/tops. Thanks for the information!

Interesting idea with the hold-downs. I've wondered about the design wherein the drum is pushing the work away from you. If you're only taking 1/32 or so at a time, I imagine it's alright if guided slowly.

In terms of the rubber coating - I am wondering if the hook velcro tape would adhere well to it? From what I understand, the velcro does have somewhat of a cushioning effect. As I've looked into this, it does seem to be something people mention as important, as they get inconsistent results with the abrasive glued or stuck to the drum by itself.

I'll look you up if I'm in Upper Canada - thanks!

~Kirby

[Oliver A.]

I'm not very familiar with the hook and loop sanding pads or belts etc. They may have the right amount of cushioning. In my experience, If the backing is too hard IE: sandpaper over wood, the sandpaper will where very quickly. If the backing is too soft, you will loose accuracy and consistency. My machine uses J-weight sanding belt material of a specific length. The two ends are tucked into a slot in the drum. The slot ends in sort of a music note shape and a long, spring-loaded cam holds it in place. I copied the design of the drum from a machine that, guitarmaker Git Laskin, had made in the early 70's.
Having the drum rotate away from the operator may work. It seems counter intuitive but if the work-piece slips, at least it will shoot out the other end. (foam padded wall?)
BTW, I checked my drum, it is 22" wide. Large enough to put a guitar top through sideways, although I preferred to put them through at a 5 or 10 degree angle. Enough so that the grain lines are not running straight into the sanding belt and clogging it up.

[stepasha]

Oliver, I second Inklings' opinion after looking at your site. I'm only in the beginning phases of my instrument-making journey, and it's nice to have people like you showing us what we can achieve if we keep at it.

Inklings, FWIW, I use about 1/4" of reinforced packing tape (the stuff with the white lines in it) wrapped around the sandpaper at the ends to keep it in place. I've never had any problems with the tape coming loose. If you do build it, I would recommend making it about an inch wider than you think you need so that you can put the tape around the ends.

[Inklings]

foam padded wall?

That's the kind of room I'll likely get put in when people start seeing all these crazy things I'm building. Great tip on putting the piece on an angle - wouldn't have thought of that.

making it about an inch wider than you think you need so that you can put the tape around the ends.

I kind of wondered about that. With velcro, I would think that once it caught, the whole shooting match would come unraveled pretty quickly, leading to various bad things.

So nice to know these contraptions can work, and learn from those who have built them!

[Oliver A.]

Here's a photo of the front end the machine showing the depth-of-cut adjustment mechanism.



Turning the center knob, below the belt, rotates two threaded rods equally. The rods push up on the angle iron supports for the table. 1/8th of a turn gives me a 1.4mm rise between the table and the center of the drum and that is all I can skim on an ongoing basis.

[Inklings]

I like the idea of it being supported on both of the in-feed corners. The design I'm looking at has some robust hinges on the out-feed side, but I am a little worried about it staying true to the drum from left to right. Ideally, it will put out a fairly accurate thickness across the plates, so that it's more a matter of finishing the work, rather than correcting it.

- - - Updated - - -

And that is some ORANGE sawdust on the scroll saw. Cedar?

[Oliver A.]

I was concerned with the same thing. The table not staying in line with the drum. Especially if you want to keep the wear on the sanding belt even by feeding stock through on alternating sides. My set-up solves those problems. Luckily for me, my father was a machinist and welded nuts onto the brackets above the sprockets for me. I also have long nuts, used for joining 2 lengths of threaded rod, embedded in the wooden supports.

The dust is Honduras mahogany. I just finished sawing out some inside blocks for mandolin rims.

[Inklings]

Ah, that explains the colour. Very fun! I was given a pre-historic Sears & Roebuck scroll saw that I am powering with the guts of an old treadmill. Improvisation, for the win.

I'm wondering if I could get away with sinking these into the frame. I've used them with thread blocker for kid's toys (put a bolt through the wheel, instant axle). Then use the threaded rod with the dual-drive mechanism you show underneath.

Great ideas, so much fun to build tools. And build things with tools.

[Oliver A.]

The problem with tee nuts is that they are really only good for tension in one direction like on furniture legs where the load is always pushing the tee nut into the wood. They pull out very easily when force is applied in the other direction. I suppose you could put them in the top of your supports but I think they aren't quite up to the task. The nuts I used are readily available at pretty much any hardware store that sells threaded rod, or as some call it, "all-thread". They are approximately 2" long and are intended for joining two lengths of all-thread to create a longer rod. Since the supports that I used were built up of 3 pieces of 3/4" maple, it was easy to embed them during assembly. There are also additional "guides" below the main supports that are made by welding a nut onto a steel plate. If you don't have access to a welder, you can embed nuts of the right size, into some hardwood. The point being to stop the strong tendency of the height adjustment rods from going askew. I'm sure there are many other ways to accomplish this but however you do it, it must be fairly robust or it will not work smoothly.

'good score on the scroll saw. Used tools are generally a good buy in my opinion. (free is best). They are good value and sometimes go real cheap when all they need is a little re-working and cleaning up. The trick is to know what's good and what was junk from the day it was made. I got my "Excalibur" scroll saw from kijiji and I couldn't be happier. They are arguably the best ever made and not easy to find.

[Inklings]

I am beginning to see your point about the in-feed adjustment being a possible weak link in the support of the bed. With a sanding drum vibrating the entire frame, and bearing down slightly on the work, it does make sense to plan to be a bit more robust with the support. I will give it some more thought. One of those projects that gets planned in the hardware aisle of the local hardware store.

I am of your way of thinking entirely on the subject of old tools. In this build, I was given the sander, the treadmill, and the metal stand. Turns out the variable speed control for the motor (left of the cutting bed) is really helpful. It's a delight to cut plexiglass on this for templates.



The hook & loop sanding paper arrived from Grizzly. Pictured in front of it is yet another tool rebuild. My father-in-law had an old belt sander whose plastic frame was cracked. Bench-top belt sander, anyone?



Speaking of the in-laws from NC, they are visiting this week, so one of the kiddos will be in the basement, making the workshop inaccessible after 7pm. So, progress is going to slow for a while.

[Oliver A.]

'looks like a great old machine.

[Inklings]

Updating things here. I have the frame assembled per the instructions, but a little wider to accommodate a 24" drum:



Which brings me to the saga of the disk cutting. Yeah. So. Cutting 5" circular disks - get a hole saw, get some MDF, rinse and repeat, right? Yeah. Not so much.

After burning up a Harbor Freight drill and tripping the breaker with the drill press, I had about 26 of the 32 disks I need. Some were very, very sadly mangled by the wobbling hole saw (long story, stripped shank, etc). So, I set up a jig on the Bandsaw as I had once seen Norm Abrams do. Whipped out the last 6 with perfect edges, no sweat.

Why, oh why, oh why, do we not learn the easy way to do things until 27/32 of the way through?

[stepasha]

I sympathize Inklings. I did say "Costs often end up higher than you think for projects like this." For me it's never for the cost of the things themselves, and always for the costs of the failed solutions. I ended up doing the bandsaw trick as well.

Another thing I did was to cut a 1/4" slot into the side of the center hole of each disk so that I could install a key into the keyway of the steel bar. I think the bar took a 1/4" key.

[Inklings]

I did say "Costs often end up higher than you think for projects like this."

Absolutely true. Still pretty far South of the price of the "real" item. I guess there's no such thing as learning a trade without paying tuition one way or the other. I've never tried the bandsaw circle-cutting thing before, and it does really work a treat.

The steel rod I have coming does not have a keyway - at 1/4", you've got a substantial grip on things, so that would be a great solution.

Turns out the motor I have is a little faster than I thought. It says "3,450RPM" on the label. With that speed, I should nicely be able to launch wood through the wall of my basement, and through my neighbour's as well. My original plan was to step that back by using a 2" pulley at the motor, and a 5" at the drive end. That should give me about 1,380RPM, I believe. Other folks have said around 1,100 is a good number for this, so I'm close. But I'm getting nervous, and wondering about moving to a 1" pulley at the motor, giving me around 690, right? Would that be agonizingly slow?

[Marty Jacobson]

Other folks have said around 1,100 is a good number for this, so I'm close. But I'm getting nervous, and wondering about moving to a 1" pulley at the motor, giving me around 690, right? Would that be agonizingly slow?

Yes, anything under 800 RPM is going to be a little slow. I'd try to get it closer to 1500 RPM, I usually tend to prefer lighter cuts and higher feed speed. You might think that lower RPM would generate less heat, but if you can feed twice as fast and take half the cut, you'll probably generate less heat overall.

[Ron McMillan]

I really admire the ingenuity and industriousness of guys making these tools from scratch, and find threads like this fascinating. Carry on please

[stepasha]

Inklings, what is the hp of that motor? If it's 1 hp or above, I agree that you would be better off going for the 1,380 rpm than 690. I'm no expert in physics, but I would think that either one could shoot something at the wall pretty well if you lose your grip : ) My reason for aiming high is that I would think the higher speed would lower the torque, which can be helpful when you're trying to push/pull a piece of wood through the thing by hand. 690 rpm might work better if your motor is 1/4-1/2 hp.

[Oliver A.]

Here's a link to a commercial machine that has 6" drums and runs at 1,600 rpm. That would make the surface of the sanding drum run at 2,513 FPM.
http://www.busybeetools.com/products...csa-cx504.html

When I calculated the speed of my 15" diameter drum, I aimed at a surface speed of 2,200 FPM because that is what my belt sander runs at. It seems a good speed.
If I were using 6" drums, I would use the speed of the commercial machine which presumably had some decent engineering to determine the drum speed. From my own experience, I'd say that anything from 2,200 to 2,500 FPM should work well.