Building a 30" disc sander

[Dennis Nagle]

Well, I decided to build a 30" disc sander. I found a faceplate for an old Oliver 66 lathe to use as a hub. It is 12" across, 3/4" thick, takes a 2" x 6tpi shaft, and has 12 holes already drilled in it. I'll use those to screw on a 30" x 5/8" disc.

I have a 1hp R/I motor to drive it with for the time being.

[Ole Anderson]

Hi neighbor!

What rpm is your motor? I wouldn't want to spin a disc that big at 3500 rpms, 1750 would be more appropriate. Are you going to attempt to attach the faceplate directly to the motor shaft or are you going to make up a shaft with pillow block bearings? If you do the latter you can belt drive it and change disc speed by varying pulley sizes.

[John McClanahan]

Even a 1725 RPM motor will spin a 30" disk way too fast. You will need to spin the disk at about 800 RPMs. That will yeald 6,200 SFPM.

John

[Dennis Nagle]

I looked up the speeds of a 30" disc sander over on Vintage Machinery and Oliver runs their 30"er at 1200 rpm so that is my target. Yes I will use Pillow blocks, shaft, and pulleys. Off hand I can't remember what the rpms of the motor is, but it is only 1hp and that seems to small, but fine for prototyping and prove-out.

[Kyle VanMeter]

Dennis,

I have a disc sander for de-burring metal parts, and it has a rim speed of about 6,400 surface feet per minute.

I can not use it on wood because it is too fast. It will get the wood hot, and the surface will burn in a matter of seconds. You may want to consider a pulley configuration that will get you between 3 to 5 thousand SFPM at the rim. That is much more ideal for sanding wood.

Yours will be spinning above 9,400 SFPM, which will really be cooking!

I'd attach a 30" disc of MDF to your behemoth lathe, glue some scrap widebelt sandpaper to it, and run it through your speeds. That way you can see what speed will work best before investing in pulleys, mounting hardware, etc..


Kyle VanMeter

[Dennis Nagle]

That is a great idea Kyle.

[Matt Meiser]

Sounds like a step-pulley setup like a drill press would be ideal for multi-material use.

What are you going to use for a disc? Remember a heavy disc will have a flywheel effect. Might be good for keeping it going if you bog it down, but keep in mind that also means its going to take forever to stop, especially if something goes wrong.

[David C. Roseman]

Dennis, out of curiosity, what are you planning on sanding with that bad boy?

David

[Brian W Smith]

David,I'm with you on the curiosity.

30" disc sander and I'm thinking 2" chrome moly,and building that tube chassis the wife wants for her Sube(just kidding)?

[Greg R Bradley]

My 20" 2hp would coast for a loooooong time.

It ran 1200rpm and was perfect for its intended use on metal. 1200rpm on 30" seems too fast to have much use.

[Dennis Nagle]

Some of my bowls crack when they dry, I want to be able to cut the cracks out, sand both sides, or maybe add in a piece, then glue them back up and turn them. My lathe can turn 30" bowls so I want to be able to accommodate that size.

Here is a video of what I am talking about.

https://www.youtube.com/watch?v=GNFKXhRh7Ss

[David C. Roseman]

Ahhh, yes. That's a great application for your project. Now I think I want one too!

Thanks also for the link. For some reason I'd not come across Frank Horwath's videos before. He really keeps things moving. Very professionally done.

David

[Dennis Nagle]

I think Frank is in the animation business in some fashion. I like all of his work and REALLY like his shop.

Also, I am gearing this to run at 800 to 1000 rpm. I think it could handle running faster, but I don't want to have to think about burning the wood.

[Rollie Kelly]

Why not power it with a 3 phase motor and VFD, this way you can take advantage of variable speed and braking.
Rollie

[Dennis Nagle]

I'd like to do that, but at this point, I have most of the pulleys needed. I like the idea of breaking too. THis thing could spin for ever with its weight.