20" disk sander

[Robert Edington]

Has anyone made a large disk sander? I'd like to make one but I feel the disk must perfectly flat for it to have any viability. I've considered trying to use different materials for the disk but quit, because I feel it would be faulty.
I don't mind mounting it to the lathe, but that creates a problem as well. Trying to find a face plate large enough or building up a from a face plate to support the disk.

Am I making too of this? Should I just make it out of MDF, sand it flat, seal it and forget it?
Anyone done this?
I want this for segmented work, sanding the rings flat as well as the edges.

Thanks for any help and pictures as well.

RP

[Tom Albrecht]

I am curious why you want it so big? I don't do segmented stuff, so I don't know. A 12" disc can get a lot done and would be easier to make.

I use a stand alone dedicated 12" disc sander -- it has a miter gauge, cast iron table, cast iron disc, and the table tilts for angles-- does everything I need for turning and cabinet making.

[Peter Fabricius]

Making a sanding disk for the lathe is relatively simple, in fact make two or three so you can have 100, 150 and 220 grits.
Start with a glue block tapped (with the Beall Tap, 1.25 or 1" X 8tpi for your spindle size, about 4 - 6" X 2" thick will work nicely.
Next Bandsaw cut the sanding disks from MDF, use two thicknesses of 3/4" material. Glue the disk to the Glue block.
On the lathe true up the outside edge and the face.... Glue the sanding disk on and you are ready to sand.
Build a box to fit around the disk for DUST control, vac hose should fit in a hole. The box is also the Sanding table and the top is at precise disk centre.

You mention sanding Segmented rings to size, thickness, and this is a questionable process. To sand the two halves to fit tight is possible but you do loose some roundness, better to make the Seg Easy Sled designed by Jerry Bennet, perfect 360 degree rings in one step glue up.
Flatten the rings (one face) by Hot Gluing to a 12" ??? disk with 1/2" rings scribed into the face for centering. Use a big scraper to face the ring and then move the ring attached to the disk to the Tailstock and press up against the bowl being built held on the Headstock. Let it cure and then remove the disk and face off the ring on the bowl. Repeat for next ring.
Hope this helps.
Peter F.

[Mark Greenbaum]

How about making a drum sander for an attachment to your lathe. Do a google search for "DIY Drum sander on shopsmith" and there's a simply made device that's adaptable to any variable speed lathe.

[Brice Rogers]

I've made a couple of sanding disks like Peter mentioned. It is very easy.

If you are sanding something round (like the bottom or top of a big bowl and you center the work on the spinning axis, it inevitably will start wobbling out of control and try to spin. It is better to sand it off center but you'll need to rotate it regularly as the outer edge is removing more material than the inner edge.

If you are sanding segments individually, you'll want to build some some of simple table.

BTW, on one of my sanding disks (made from mdf), I charged the edge with red rouge. It works very nicely for honing knives and turning tools. The MDF seems to easily accept the charge and I seldom re-charge.

[Reed Gray]

I have seen commercial grade disc sanders that are that size. You could probably buy the metal disc for it and lathe mount it, but getting it to run as true on the lathe as it does on the dedicated machine could be a problem. Only reason I can see for one that size is to make the half sections of a glue up to fit perfectly, and they would be large sections. I would not want to try to get a flat surface for a completed ring on a disc because you have to have the exact same pressure all the way around the ring. A drum sander would work better.

robo hippy

[Dick Strauss]

It is very difficult to get a metal disc that large mounted and balanced so it doesn't vibrate. At 1000 rpms (which is too fast for a sander of this size IMO), you are getting close to the momentum of a tire and rim on a car travelling at 60mph! I've got a 20" aluminum disc with steel mounting plate that my neighbor used to use for sanding. It weighs over 30 lbs and made his lathe vibrate quite a bit when he used it. You may have a very hard time finding someone to turn that 21" disc down to 20" on a metal lathes with a 24" swing aren't real common. You could do it on a Bridgeport with a rotary table but that will be a slow process.

Whatever you decide, be safe!

[Bruce Page]

Can a 20" piece of MDF withstand the centrifugal forces?

[Tim Boger]

Once you've used a sander like this, you'll never flatten a ring any other way.

http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dtools&field-keywords=JET+629004K+16-32+Plus

[Len Mullin]

Yes Robert, you are making to much out of this, do as Peter has recommended and you'll be all set. You don't have to sand the face of the MDF, it is already flat and sanding it can make the surface uneven. I disagree with the others that are telling you, that you should build a drum sander for this purpose. If possible, built it out of 3/4"MDF.
Len

[Bob Coates]

I'll third Peter's post, the only difference is that I use only 1 3/4 MDF. As Len says the MDF is flat and you don't need to sand. I didn't get one of the arbor block glued flat to MDF so it has slight wobble, but is flat. You also want to make a seg easy sled to cut your segments, you will never sand them again. I use 6" strips glued to MDF with 3 M glue.
Bob

[Mark Greenbaum]

https://www.youtube.com/watch?v=Lf2qfOm6bDg drum sander attachment for a shopsmith, easily changed for a dedicated lathe.

[Michael Mills]

If you would consider going a smaller, like 16", you may want to take a look at these.
I ordered the 5/16 X 16-3/4; this gives a little to trim down. I will mount it to a 6" faceplate which I already have.

Shipping was about $12 IIRC.

http://www.sandsmachine.com/alumweb.htm

[Robert Edington]

Thankyou for all your replies. You've given me something to think about. I do have a Performax 1632. I still want to have a 20" disk sander but I'll try to incorporate the drum sander into the process.

RP

[Brice Rogers]

I saw that Steven Ogle has a nice video on both a segment miter sled and a lathe accessory drum sander. Both seem well thought out and well done.

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

I use my home made disk sander for the bottoms of some bowls to remove a spigot. It takes a lot of care to use it and end up with the desired result. But for segmented rings, I think that it would be even more of a challenge getting the two surfaces of the rings absolutely parallel and not lose some skin in the process. The drum sander seems like an easy-to-use tool that would give consistent results.

[Marvin Hasenak]

You can try the giant disc, but you will not be happy with the results. Like what a couple of others said, search "thickness sander plans for lathe". Simple to build and they work. I laminate small stuff, one of my thickness sanders fits on my drill press, got that idea from the penturners.