Thread: 20 inch Disc Sander

Originally Posted by 4-6-4

Greetings chaps It interesting reading the threads. The mention of sticking the discs on the sander brought to mind a method I developed on the Sanders at RMIT. The method
they used was to use the white PVA glue to fix the sanding disc on. This was a drama when changing the worn out disc. Lots of Elbow grease involved. So after the old disc was removed I spun the disc and cleaned any bits off with a chisel which was reserved for this job. I then applied floor wax to the disc. While it ran at low speed I wiped the wax off. This left an extremely thin layer of wax on the disc. The white glue was applied and the disc was clamped overnight. This was a twin Disc machine so both discs were done at the same time. Next morning both discs were refitted and I was back in business. All that was needed to remove the disc when it was worn out was the cleaning chisel under one edge an the disc came off easily. The cleaning and wax treatment was repeated. I never in the two years at RMIT did I have any problems with discs coming off. I have used the Velcro before in pattern making and have no had any trouble with sanding up to an edge. Yours 4-6-4

I'd been reluctant to use a chisel on an aluminium faced disc, and the guy I gave the sander to, did actually gouge the once accurate but soft face all over with a chisel and it was never the same again. I'd forgot to tell him to just leave the disc face down on a folded rag soaked in turps and the contact cement would turn to a jelly after a day or so and peel off. A bit of clean with a rag and it was ready to go again. It's good that you don't have any curvature problems with your velcro backing, it may be a function of the grit size and type of sandpaper. I also use the disc with zirconia cloth which is not ideal for wood as it tends to clog when old but is also great for deburring/fettling aluminium castings with a bit of stearic acid wax lube. I found as the sandpaper wore out it would start making a very shallow curve on wood as the force required to sand on the disc increased.

I'd heard some foundries had a disc sander large enough that the disc went into the concrete floor, i.e. over 2 metres diameter. They didn't bother having sandpaper on the middle for a large circle as it was too slow to sand effectively. They were large enough that if you had an accident it could kill you if you got wedged between the floor disc and the hole in the floor . The largest one I've seen so far under construction is from memory 36 inches diameter, the disc is off a broken Wadkin and is made from cast iron and balanced, it's been fitted to a tapered roller spindle and frame off an industrial spin drier and when we get around to it an Ebay 15Hp three phase motor via belt drive.

Wimmera jack: I have heard of a 12" aluminium sanding disc face and rim trued up with a sharp wood chisel after fitting to the sander spindle, it took some steel nerves to do.

Originally Posted by Graziano

I'd heard some foundries had a disc sander large enough that the disc went into the concrete floor, i.e. over 2 metres diameter. They didn't bother having sandpaper on the middle for a large circle as it was too slow to sand effectively. Large enough that if you had an accident it could kill you if you got wedged between the floor disc and the hole in the floor . .

Off topic but there was a post on PM in the antique section about machines in wales (by Asquith, as so many of the interesting ones are) It wasn't a HUGE lathe but it was built in situ and the faceplate went down into the floor so the center height wasn't so far of the ground. Only good for flywheels and other short stuff, but a neat trick all the same.

Dear Simon I commiserate as I also have a to do list. John As Graz sais that to do the wax thing may not be the best idea on an aluminium Disc. I only did it on a steel disc. While I was at RMIT I turned up some 20 inch Cast Aluminum Discs for the teachers who had thiere on home shops This was dome on a Macson lathe in their metal shop.I might add that the chisel cleaning method does need a degree of care. I would hate to have some one using this method to have the chisel leap out and bite some one. Talking about big discs I once saw an article in Fine Wodworker of a place in the states which turned OVAL frames for mirrors and pictures on a wood lathe They were on small either. Thake care 4-6-4

Originally Posted by Wimmera Jack

I just use a piece of particle board bolted to the face place of my wood lathe. Trued it up once it was on the lathe.
Base was made the same size as the grinding discs used by shearers for sharpening their cutters and combs. (12") They come in a couple of grits. I also use the same glue they use, and when the disc is worn, just peel it off and re glue the new one on. Clamp over-night usually with another circle of particle board and some G cramps.

Available at your local farm supplies.

Have made a base plate that just fits into a tool rest.

Cheers
John.

I have several of these disks lying around and a grinding unit sitting on top of a big Red Gum post in my implement shed. Flat belt driven. The bearings are very basic. These ones are 14 inch diam. By pure coincidence I made a 14 inch melamine chipboard disk many years ago to fit on my wood lathe the same way. It got a lot of use. Best thing I have seen to dress chainsaw bars.

A friends wife decided to have a cleanup as part of a breakup while my friend was away at work. Most of my lathe was there as he was helping me improve it and it disappeared.

I bought a GMC lathe for $50.00 a couple of years ago and after then finding a decent priced Nova 3000 decided to use the GMC for a sander. The disc would not quite fit. Still deciding what to do for the long run.

Dean

Here's a photo of the disk sander project I've done some work on, it's not mine unfortunately. It uses one of two cast iron discs salvaged from a destroyed Wadkin disk sander and the four legged frame and spindle bearings off a commercial laundry spin dryer that had recently had new bearings fitted. It'll have inverter drive for the 1440 rpm motor to give a nice slow ramp up to full speed and also for variable speed for different jobs. I didn't measure the disc diameter but if you estimate the spacing of the rings at 2cm against my calibrated thumbnail then it's about 30 inches. I may have to see what he wants for the second balanced iron disc and spindle.

Greetings Chaps. Now Graz that is what I call a Disc Sander. How is the table moved away from the disc to place the sand paper on it. I would have preferred a larger table and once again I would Velcro it if it is to be used on woo. The Velcro sticky base and the 30 inch sanding disks may be a bit of a problem. But If I was in Queensland I would defiantly be interested in the other disc. I saw a n aluminium disc used in na article in Fine Woodworker mad many years ago. This would work if the ally was turned true on the edge. Yours 4-6-4

Originally Posted by 4-6-4

Greetings Chaps. Now Graz that is what I call a Disc Sander. How is the table moved away from the disc to place the sand paper on it. I would have preferred a larger table and once again I would Velcro it if it is to be used on woo. The Velcro sticky base and the 30 inch sanding disks may be a bit of a problem. But If I was in Queensland I would defiantly be interested in the other disc. I saw a n aluminium disc used in na article in Fine Woodworker mad many years ago. This would work if the ally was turned true on the edge. Yours 4-6-4

Hi 4-6-4, the table has a bolt at each end that allows the table to be removed for changing the paper but glueing it on evenly is going to be fun as the disc can't be removed, a coat of spray adhesive on both surfaces should do the trick if trapped air can be avoided. The sheet aluminium disc on my first sander started at 8mm thick but moved around during machining until it was about 5mm thick after both sides were faced off due to surface stresses. It was better for the motor startup as the low mass spun up a lot faster than my current 12 inch steel disc.

When I made the 14 inch disk sander I mentioned in post #20 I used 6 inch wide strips of sandpaper stuck on with contact adhesive to the melamine surface. It worked fine. Got to get around to making another one soon.

Dean

Greetings Chaps. Thanks for the comments I was laying in bed the other night ( I do a lot of thinking in the horzontla Position) and for the life of me I could not think of where I obtained my original velcro discs. I have enough to get by on but a few more would not hurt. I have a feeling that my supplier was out Dandenong If anyone knows where to get more I would appreciate it. Yours 4-6-4

I am making a 30 inch disc at the moment using a Wadkin disc and a C & H variable speed 2hp motor.Fabricating the frame from heavy angle with a narrow fixed table using taper boards for draft when required.
It is being made as compact as possible to fit next to the Wadkin bobbin I have.
I have a spare disc or 2 one is 32 inch from memory the other a 30 inch Wadkin.
I'll put them in the classifieds when I get back from Canada late July.
H.