Table Saw Disc Sander

Intro: Table Saw Disc Sander

A disc sander is a must for any shop! They make quick work of shaping and smoothing stock. Getting the most out of your shop tools can often take you down paths you didn't know existed. If you can't afford a disc sander or dont have the means to make your own, this simple table saw version might be for you. The usable space on the disc is less than a standard disc of the same size, however if you are limited on shop space this may be just what you need.

STEP 1: Tools and Materials

Materials:

• Sheet Metal
• Sandpaper
• Spray Paint

Tools:

• Dividers
• Metal Punch
• Angle Grinder
• Drill Press
• Step Drill
• Lathe
• Bench Grinder
• Metal File
• Utility Knife
• Table Saw

STEP 2: Draw Circle

On a piece of scrap sheet metal, mark the center of where your circle will be. I have a 10 inch table saw so I made a 10 inch circle. Punch the center of the hole. With your compass, scratch the circumference of the circle.

STEP 3: Cut Circle

Using an angle grinder, cut the circle out. Be careful of the sharp edges.

STEP 4: Drill Center

Secure the disk to the drill press and drill a pilot hole through the center of the disc (where you marked with the punch). Drill the final hole size of your arbor (probably 5/8 inch in the US). Be sure that there is clearance under the disc for the drill bit to go without drilling into the drill press table. Depending on the thickness of your plate, you may need to flip the disc over to drill the other side.

STEP 5: Grind the Disc Round

On the lathe, turn a support to hold the disc on the bench grinder. Turn one end the same size as the hole through the middle of the disc.

Cut the support so the shoulder of the support is the same height as the tool rest on the bench grinder.

Unfortunately I never made an instructable on my lathe tool sharpening system which is what makes this step work. You could probably set up a holder of some sort to clamp down to your bench next to your bench grinder. All it needs to be able to do is be adjusted to grind more or less off the outside of the disk.

Once mounted, turn on the bench grinder and rotate the disc grinding off more and more until it is perfectly round.

STEP 6: Smooth Edges

The edges of the disc are going to be rough and sharp. Using a metal file, break the edges to prevent possible cuts in the future when handling the sander.

STEP 7: Paint

Degrease the disc and apply a coat of paint to prevent rust.

STEP 8: Apply Sandpaper

Remove the paper backing from the sandpaper and place the disc on it. Cut the outside of the sandpaper off with a utility knife. Trace the outside of the arbor washer and cut on the outside of the mark. This will give clearance around the arbor. Test to verify that there is clearance around the entire washer.

STEP 9: Mount Disc Sander

Insert the disc just as you would any saw blade following your manufacturer's instructions and connect your dust collection.

You can mount it with the sandpaper facing either direction if you are using it at 90 degrees. If you plan on using it at an angle, be sure that you are sanding on the upward facing side. You do not want to trap your piece between the table and the sander.

Always sand on the downward cutting side. This will be the side closest to you when using the table saw normally. This will keep your workpiece firmly on the table.

STEP 10: Get Sanding!

This is a fairly easy project that can save some space if you don't have a dedicated disc sander. Clearly this will never be as good or versatile as a stand alone sander, but will work in a pinch. With the higher RPM (3600 for my table saw) be careful to keep fresh sandpaper on it as worn out paper can easily cause burn marks. If you do not have the tools or time to make this, you can purchase one instead for around $20, but what's the fun in that? :)

Share a picture of your homemade disc sanders in the comments. What strange and interesting uses do you have for your shop tools?

Comments

[twhite101]

I might also be good to 3D print the table insert so if the disk comes in contact, the damage will be to the plastic insert and not the original metal insert for your saw blade.

[Errol1951]

On my way to the workshop now to make one thank you

[BirgitJansen]

Oh my god, why didn't I think of that. Here I am trying to find an affordable disc sander while the solution was right there in front of me! But it got me thinking. Could one modify an old/dull table saw blade? Somehow grind down the teeth and adhere the sandpaper? Hm, I have to work on that idea! But thanks for the instructable, great idea!!

[allangee]

You can add a thin piece of plywood on top of the blade with a slightly smaller diameter so it sits inside any raised teeth. A little bit of adhesive to hold it flat against the blade... the center bolt will ensure it doesn't fly off. Once it's mounted to the blade, I'd run it in the table saw and "sand the sanding disc" with sanding block to ensure it's smooth. Then apply the sand paper. Depending on how thick a disc you can fit, you can make it double-sided -- coarse grit on one side, fine on the other.

I remember my dad used to pop a grinding wheel in his table saw for tool sharpening back in the day.

[allangee]

Or just use a thick piece of plywood and skip the saw blade.

[BirgitJansen]

True, but would be nice to take advantage of the center of the blade to secure it safely and firm in the table. (kind of lazy thinking, I know ;-) )

[allangee]

Lazy people come up with the most efficient methods!

[Errol1951]

when I was doing my trade training as a Fitter a very good tradesman told me the best tradesman was a lazy one because he want to only fix it once and not having to continually return and fix it over and over

[GTO3x2]

I find that resourceful rather than lazy. For occasional use, it's brilliant, IMO. A hand belt sander mount works well too.

[JohnC430]

now why didnt anybody else say that. throughout reading these suggestions i was thinking the same thing. i suppose it may not be strong enough and can split apart and perhaps do some bodily damage? maybe plywood would work?

[allangee]

Wooden airplane propellers seem to do just fine. Have also seen wood blades on homemade blowers.

If you wanted to get fancy, you could put a motor speed controller (like a ceiling fan one) between your table saw plug and extension cord to drop the speed. NOTE: Not a dimmer switch... a motor controller. The dimmer switch is cheaper, but works differently and can kill your motor over time.

[JohnC430]

The grain of the wooden propeller is along its length. in this case, you will always have the centrifugal forces pulling the wood apart. The only way it could possibly work is with plywood which has layers so there is always something holding the grain together.

Yeah maybe you can reduce the speed so the force is lower after all it is mV^2 so reducing the rpm by half (which will still allow it to work as a sander), will reduce the centrifugal force to 1/4th

[lr10cent]

You could taper the back of the plywood so it's thin at the edge. That should reduce the load considerably, while leaving it strong where it needs to be.
Let's look at the forces involved. Say you have a 6 foot airplane prop turning at 2500 rpm. Acceleration is v^2/r, or at the prop's tip, over 200,000 ft/sec^2, or around 6400 g's. If you had a 10 inch disk on a table saw, going 4,000 rpm, then the outer edge would be experiencing about 2300 g's. Furthermore, since the prop is bigger there's 7.2 times as much wood. So the wood at the center of the prop experiences about 20 times the stress that the wood at the center of the disc does. If I was going to do a formal calculation, there would be some more steps, but this gives a very rough idea of the magnitude of the forces.
Stress is probably on the order of 100 psi*, while most reasonably dense woods can take several thousand pounds of stress parallel to the grain. So stressing at 45 degrees, which is the worst case, is still going to leave a good safety factor.

*My calculation from the formula in Engineering Toolbox, and the stresses given by an on-line calculator I found, are both this order of magnitude, though they don't exactly agree.

[JohnC430]

Thanks for the explanation and the calculation. i always wondered about these forces but never knew how to calculate them.

[Knex_Obsessed]

at the high rpms of a table saw, I would highly recommend avoiding wood as it will probably fly apart

[KevinW65]

I have seen people use plywood or mdf on bench grinders to sharpen knives and have had no problems at all and my bench grinders spin faster than my table saw.There are also cardboard disks you can buy for bench grinders...just a thought is all.

[jimmcneil2]

this guy used more skills making this than someone who just said "well i'll just cut out a piece of plywood"

my father ran the model shop at Harvard observatory, he was working on a piece for NASA and one of his machinists suggested using a "tire rim" as the hub for the equipment they were building, my father told him

"we're the model shop at "Harvard Observatory", we build one of a kind things for government agencies and you expect me to go to NASA and tell them we're using a tire rim for their multi million dollar project? we'll never get another contract from NASA or anyone else, ever again."

my father would hire this guy

[tomatoskins]

As someone currently studying mechanical engineering, I take that as quite the compliment. :)

[GTO3x2]

If it really does the job well and it's much more inexpensive, then why not. Model shops, AFAIK, are mock-ups anyway -no need to waste time on uncessary efforts.

[sgbotsford]

Will plywood reliably take being spun at 3000-5000 rpm? If your disk has a void on the interior you might get an unexpected surprise down the line.

Maybe use thin baltic birch and put a layer on both sides of the blade and epoxy it in place. Make the birch disks slightly larger than the disk to hide the teeth?