20" Disc Sander Recommendations

[John Halsted]

I'd like to buy a large disc sander and it seems 20" is the most accessible large size before things scale out of reach and/or become a restoration project.
Seems every tool maker has a version of a 20" disc sander. I'm pretty certain I do not want the very closed down boxy style like Grizzly has. I like having it more open like the pedestal ones because that makes it easier to work around. Plus if you can expose the whole disc that's great for bowls.
Jet, Laguna, Powermatic, Dayton, Baileigh, etc... all have similar looking pedestal 20" disc sanders. It is also pretty common to see a 2hp 1 phase version and a 3hp 3 phase version.
There are almost no reviews out there for disc sanders, so I'm hoping I can get some pointers here.
One thing I've noticed is that some manufacturers use rather small dust collection ports (like 1.625") whereas others have 4". I'm thinking that the former is designed for metal work and the latter for wood. I'd be doing both, but mostly wood.
Regarding the 3hp motor options, I'm always attracted to more power but I only have single phase, so I wondered about buying the 3ph and adding a VFD (something I've never done but basically understand). That would also give me reversing and braking, which would be great.
Regarding overall quality, since I can't really find reviews my next best gauge is looking at the weight of the machine and assuming that heavier is better.

Any tips would be greatly appreciated.
Thanks!

[Robert Hayward]

I have a DS20, for a little over a year. I am a hobby woodworker and a hobby metalworker and use the sander for both. The machine is built like the proverbial tank and needs a 30 amp 220 outlet. When I first got it I thought I would use it on an existing 20 amp outlet. No go, breaker trips on startup and I had to add a new circuit. The machine takes six or seven seconds to spin up to speed. Might not sound like much time but is an eternity when you are standing there with a piece of wood in your hand. It is common for me to let the machine run for an hour or two at a time to avoid waiting for the spin up. It also takes right at 18 minutes for the disc to stop spinning once the switch is turned off. It has a brake but still takes a couple minutes to stop that heavy steel disc. That is unless you lean hard on the brake handle which I do not do.

Dust collection is pretty good using my Cflux3 collector. Very little dust hangs in the air. There is actually a breeze coming out of the machines dust port while the disc is spinning. If I am doing one or two little pieces I stick the ShopVac hose in the flex hose I leave attached to the sander. Otherwise I hook up the big collector.

Machine is really smooth while running with no vibration. Discs are $10 and up each. Grizzly/ShopFox has them on Amazon with free shipping if you have Prime. These work good for wood but lose cutting speed quickly with metal. Cubic zirconia works better on metal but the cost is way more. Thought I wanted to be able to reverse and almost went with the 3 phase model. Have not missed not having reverse. For disc speed just move closer to the center of the disc for a slower speed, if you piece is small enough that is.

[Philip Glover]

I have a Jet 20" which I think is from the early 90's. I bought it used last year on ebay for $375. I had been looking for several years for a larger disk sander.
It is 2hp, single phase. It weighs about 375 -380 lb. The motor was replaced by the previous owner with a new Jet motor. This machine will eat wood if need be - it's very powerful.
When I first started it there was some wobble in the disk. I removed the sandpaper and checked the runout; it was 0.012" at the outer periphery of the face. That is TOO MUCH in my book.
I found out how to true the disk on Old Woodworking Machines. After some fussing about I got it down to 0.004" runout. This is as good as this machine will ever be.
I have found that I never use the outer 1 1/2" of the disk, so the small of runout doesn't matter anyway.
The large table is a real luxury. The ability to reverse direction is a plus depending on the part to be sanded. Reversing the direction may help disk life.
i bought two sanding disks from Supergrit. They are an excellent company to work with.
If you make a lot of curved parts, as I do, you will find that a larger disk sander is indispensable.

Regards,
Phil

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[Bill Dufour]

three phase and a vfd will give you variable speed, slow start, power braking etc. If you have a rotary converter many use a sand as extra idler motor for running bigger motors.

[Mark Gibney]

I've had a 20" disc sander for several years, but I'm thinking of selling it. I don't use it as much as I expected I would.
To those of you who use them, for what do you mostly use it, and how often?

[Alex Zeller]

I made a 20" disc for my lathe. This gives me the ability to adjust the speed and to reverse. I find being able to do both is very useful. When the sandpaper is new it will eat right through the wood and slowing down the speed helps control it. As the paper gets some wear on it going in reverse allows me to use the back side of the grit that hasn't lost it's edge yet. If I was buying a new one I would get a 3 phase and add a VFD. I occasionally see them used on Craig's list so you may want watch to see if one turns up. I've only used Kliingspor sanding disc, which have worked well for me. But they cost twice what the Grizzly disc cost.

[John Halsted]

Thanks for the responses everyone. It sounds like 2hp is nothing to baulk at, but I still have trouble turning away from a 3hp option even though I'd have to make a little project of the VFD.
I'm eying this Laguna model: https://www.acmetools.com/shop/tools...disc3ph3hp-020
500lb, 3hp, and a 4" dust port.

How much work is the VFD adaptation? Would I abandon the microswitch in the foot pedal brake or include it somehow?

[Philip Glover]

More power is always better!
I say go for it.
Adding a VFD is straightforward. Where to to mount it is more of an issue than the wiring. There is usually some programing involved with a VFD and it will be easy in this case.
I do not see a reason the footbrake switch should be an issue.

Regards,
Phil

[John Halsted]

Will I be able to run the 3hp 3ph motor with VFD on a 20A 240v breaker?

[Robert Hayward]

Will I be able to run the 3hp 3ph motor with VFD on a 20A 240v breaker?

Probably not.

I also looked at that Laguna sander when I was shopping. I could not find it in stock anywhere back then though. I also could not find it on Laguna's web site. Notice that it is currently not available for order online at Acme.

[John Halsted]

I saw the note on Acme's site saying it was not available for online orders, but it does let me add it to my cart.
I emailed them earlier today asking if it can be purchased. I was more worried about the other thing you just pointed out - the item cannot be found on Laguna's site.

[Mark Gibney]

My 20" disc sander is single phase 2 hp, and there is no way it is underpowered.

I was looking for a 3 hp because my metal working neighbor recommended that, but I found a 2 hp and it is more than enough power to do anything I've ever asked of it.
If you could run 2 hp comfortably on your current electrical system then it might be something to consider.

[Robert Hayward]

My 20" disc sander is single phase 2 hp, and there is no way it is underpowered.

That is my experience also. Once up to operating speed it would take a lot of force to slow that steel disc even with 2hp. The plate on mine is just a tad under 9/16" thick. Difficult to measure with a sanding disc attached but I believe it is 35/64" thick X 20" diameter. A lot of inertia/momentum in that spinning disc. Way different than my old Rikon 9" disc/belt sander with a tiny little motor. Chamfering the ends of dowel rods would slow that one down.

[John Halsted]

I've yet to own a power tool that I couldn't bog down and therefore wish I had more power.
I slow down and can even stall my 4hp bandsaw all the time, but maybe that's because I use it like a sawmill...

[Matt Day]

I’ve got a 20” State. Excellent machine. I use it for many little things around the shop, for wood and metal. For instance, today I used it to trim some 2x4’s to fit the stake pockets in my trailer. Quick and easy. Also used it to bevel a 1/2” pipe before threading.

It takes 16 minutes to spin down. It’s on a VFD and it’s nice to keep it slow for fine work when needed.