This short video from [ProShorts 101] shows us how to build a variable speed disc sander from not much more than an old hard drive.
We feel that as far as hacks go this one ticks all the boxes. It is clever, useful, and minimal yet comprehensive; it even has a speed control! Certainly this hack uses something in a way other than it was intended to be used.
Take this ingenuity and add an old hard drive from your junkbox, sandpaper, some glue, some wire, a battery pack, a motor driver, a power socket and a potentiometer, drill a few holes, glue a few pieces, and voilà! A disc sander! Of course the coat of paint was simply icing on the cake.
The little brother of this hack was done by the same hacker on a smaller hard drive and without the speed control, so check that out too.
One thing that took our interest while watching these videos is what tool the hacker used to cut sandpaper. Here we witnessed the use of both wire cutters and a craft knife. Perhaps when you’re cutting sandpaper you just have to accept that the process will wear out the sharp edge on your tool, regardless of which tool you use. If you have a hot tip for the best tool for the job when it comes to cutting sandpaper please let us know in the comments! (Also, did anyone catch what type of glue was used?)
If you’re interested in a sander but need something with a smaller form factor check out how to make a sander from a toothbrush!
I cut up sandpaper with wrecked scissors, like the pair that someone apparently tried to cut wire with or the pair I dropped and bent the tip of one scis so I ground them down like kids’ safety scissors. There always seem to be awful scissors around for free. But a utility knife seems at least as good because it’s so easy to swap the blade when it’s finally ruined.
Fold and tear along a sharp edge also works pretty well with the paper-backed coarse stuff.
On my bench I have wrecked wire cutters and wrecked tweezers. I mark them as such by taping some green and gold electrical tape on the handle. When I find myself with the need to cut sandpaper I guess I will add wrecked scissors to the list! :)
Would a hard drive have the torque to really grind or would one have to let the object “float” and wait for it to get ground down right?
If you could find an old 5 1/4″ full height drive, that’d probably have plenty of torque. They sound like a jet engine when they power up.
Also maybe replace the platters with a single heavier metal disk, to act as a flywheel once it gets up to speed.
I tried it a long time ago and it was pretty useless, but I just used the original motor driver. This one uses an RC ESC, so maybe it will produce a bit more torque. It’s still a tiny motor though.
I “cut” sandpaper by creasing it on my drill press table edge, paper-side on the table, then just tearing it. Perfect straight ‘cut’, and no abrasive touches anything.
Good idea! Of course in this case we need circular cut outs which makes things a bit tricky. If it was me I would probably use a craft knife and cut from the back paper side… I think this is one of those problems where every solution has some sort of drawback…
That glue looks like Fevicol 15 Fevibond rubber cement.
Thanks for the tip! I found it for sale at Amazon. Gonna get a tube to try it out. Other glue which I discovered lately is B-7000 from AliExpress: https://www.aliexpress.com/item/1005007671330956.html also a friend has recommended Gorilla Glue: https://www.amazon.com/dp/B08XW9YB66
My preference is to use hot glue for this.
To replace the sand paper, you just heat the whole disk and then peel of the old, add some more glue and put on a new sheet of sandpaper.
This works best if the disks are removable and you have a few of them. You can then replace the paper on two disks, and clamp them to each other to make sure the paper stays glued flat to the surface.
I do have some real doubts about using an old HDD for this though. The motor does not have enough power for most of the sanding jobs. Maybe it’s enough for tiny works such as parts for scale model building. But I would not even attempt grinding an axe with this myself.
If you could attach a 3″ diamond grinding disk to the spindle or top platter it might be good for fine honing of carbide lathe tools.
Yes I think that would be a good solution and a useful tool.
Someone in the YouTube comments suggested a possible improvement by gluing velcro to the platter so the sandpaper can be easily replaced when needed.
My thoughts exactly. (I mean, independently, not the actual YouTube comment)
My experience with velcro sanding stuff is that it gets clogged up and increases my cursing and sacrilegious profanity.
I use a laser cutter. I have templates for all my sanding tools. Works great for the fuzzy backed velcro paper as well.
I wish I had a laser cutter! And a CNC machine. And a 3D printer. I am stuck in electronics land due to space constraints… for now.
Velcro probably has too much “give”. Anything you sand is going to end up slightly convex because it will cause the sandpaper to flex.
I generally just fold, crease and tear to get straight “cuts”. If I actually have to cut it I’ll score the paper backing. Once the paper backing is scored it tears off pretty easily.
Hmmmm…I’ve recently become interested in gem cutting and have been eyeing some lapidary tools, but I may just order some diamond paste and see about repurposing one of my old hard drives to see if it would be a viable alternative. I am curious as to whether the torque output on a 3.5” HDD would be sufficient. I’ll also have to figure out how to waterproof it.
If you end up putting this together be sure to write it up and let us know!
I cut sandpaper with a #10 blade in an X-Acto knife. The blade lasts for several tens of cuts before I have to replace it.
Ah, that’s what I was looking for, the voice of experience. Thanks for letting us know! If I find myself needing to cut sandpaper I think this is the tool I would use for the job.
I usually use a cheap-as snap knife, preferably one that’s nearing snapping time and cut gently from the paper side. Usually cuts enough that it makes perforations enough to easily pop out or tear the line without completely destroying the cutting edge
Hard to take anyone making a grinder seriously when he doesn’t know how to use one. You grind toward the edge, not away from it like he’s doing in the picture.
Tough crowd! :) Can you link us to a video that demonstrates correct technique?
Not a video, but text and pictures:
https://www.popularwoodworking.com/techniques/sharpening-for-woodturners/
Thanks for the link, but that’s for a grind stone, not a disc sander…
And that invalidates the build how exactly?
So you “know better”, doesn’t mean you have to post about it, at least not in that manner.
You can actually sharpen scissors by cutting through fine-grain sandpaper.
Interesting!
That’s a popular myth. Cutting sandpaper won’t make your dull scissors sharp. It’ll just remove some of the roughness and actually dull the cutting edge. It’ll cut better than it did before the sandpaper trick, but it’ll get worse each time.
Look up how to properly sharpen scissors with a whetstone. It isn’t all that hard – if you can sharpen a knife you can sharpen scissors.
No, not really. You can remove the dings and rolled edge on the cutting edge that way, but that isn’t “sharpening.” It is still dull, it just doesn’t snag as badly.
Sharpening scissors isn’t that hard, but cutting sandpaper won’t do it.
I sharpen household scissors and garden shears using diamond “whetstones.” There’s a world of difference between sharpened scissors and ones that have been “sharpened” by cutting sandpaper (or aluminum foil.)
I made one of these a while ago, just using the original hard drive board. Turns out old ~40gb HDDs just start to spin as soon as you give them 5 and 12v on the molex. (Some don’t restart spinning after a stall though).
I just put a 5v regulator on the side and now I can just supply 12v to it.
I really want to hook it up to something and check its SMART stats, lol. I’ve been grinding stuff for years now. I was not expecting it to last this long.
some years, huh? Impressive! I don’t know if you were just kidding about the SMART stats or not, I’m not sure what might be possible there…
Made the “same” 18 years ago in Metku.net. Good ideas never die it seems! ;)
https://www.youtube.com/watch?v=_4KCu8EAHsY
lol, awesome! Love the low res video! :)
That PCB need some protection from chips or it will short out very quickly.
skipped through the video to answer my question: he drives the motor using what looks like a brushless speed controller from an rc airplane.
i like the shape of this tool, with the recessed grinding surface. a little less scary than like putting your angle grinder in a bench vice :)
i am sure there are a ton of uses for this sort of tool but i am skeptical of using it specifically for sharping like chisels and stuff because the outside is moving so much faster than the inside. seems like it will tend to grind your things at an angle?