Thread: 20 inch Disc Sander

Greetings chaps. Here is a work in progress started about 3 years ago. I intend to make a vice prompted by various thread on this forum. But I needed a largish Disc sander for the pattern work. The Disc is 3/4 " ply with a Velcro disc. Not your off the shelf gear But I tracked down a firm out Dandenong way who supplied the Sticky base and Velcro disks. The table has to be able to be moved away from the disc to put the sanding disc on easily. Technically the pivot point of the table should be on the edge of the table closest to the disc. But because the beastie is used for patten making it has to stay at right angle to the disc. Any draft angles are obtained by using tapered block. First is the front with the table back.Second the side of the beastie showing the direct drive to the disc Third id the dust extraction unit and last is the other side. The dust extraction gear is not complete yet but it is close. Hope this is of interest. Yours 4-6-4

Thats a beast, would be very handy to have a bigger one like that.

Dave

Yes Dave yo can not purchase a sander this big without going into stuff like Wadkin make. Technicly this is for wood but if you pot a metal disk on it and watched for the sparks that could set fire to you then it would work well. Thinking about it the dust arresting gear could be done away with for metal work. If you push too hard then the motor stalls. Yours 4-6-4

Now that is a big beast.....there was a similar sized wadkin where i went to tafe, the way it could turn timber into dust was amazing.....
You can cut steel on any sander with the right paper, but remember that airborne dust and an ignition source is a bad mix.

Do you have a nearby foundry that will pour for you? I need to get a new compound for blondie done but have no idea where.

Leda do a 20" disc sander -
Disc Sanders : LEDA DS-20 DISC SANDER
The only down side is that it is $2376 to buy one. I worked at a place that had one, and wondered why get one so big - but then the senior man in the workshop was a patternmaker.

4-6-4, can you post a pic or two of how the wedges are used? If someone asked me to put draft on a part with either of these beasties, I would have adjusted the table.

Michael

Greetings Chaps. I saw the idea for a home made disc in Fine Woodworker but The RMIT had two of a large size one was a Wadkin which had a Bobin sander on the other end. Now Ewan did you want a Ferocious or non Ferocious foundry We have both in Melbourne but they become disinterested in any thing unusual. Let me know. Michael. The wedges I mentioned are pieces of ply glued together to make piece about 10 inches long and 8 inches wide. Mine were cut under an overhead Router using another set machined by a German patternmaker at RMIT. They are 1, 11/2, 2,3, 4, and 5 degrees on one surface of the block. To get the required draft angle the job is placed on the required block and placed against th disk. Double sided tape can also be used to hold the job to the block. I will take Pics today Yours Rod

Out of interest could someone tell me what advantages one of these has over a belt linisher. I'm curious because i'm never used a disc sander before but have seen them come up quite a bit.

Originally Posted by 4-6-4

Greetings Chaps. I saw the idea for a home made disc in Fine Woodworker but The RMIT had two of a large size one was a Wadkin which had a Bobin sander on the other end. Now Ewan did you want a Ferocious or non Ferocious foundry We have both in Melbourne but they become disinterested in any thing unusual. Let me know. Michael. The wedges I mentioned are pieces of ply glued together to make piece about 10 inches long and 8 inches wide. Mine were cut under an overhead Router using another set machined by a German patternmaker at RMIT. They are 1, 11/2, 2,3, 4, and 5 degrees on one surface of the block. To get the required draft angle the job is placed on the required block and placed against th disk. Double sided tape can also be used to hold the job to the block. I will take Pics today Yours Rod

Hi 4-6-4
That would be "ferocious"....I can cast my own non-ferrous. I know there is a foundry in wagga, Wagga Iron Foundry - Welcome but otherwise i have no idea where to go.

The advantages of using a Disk over a belt sander especial for pattern making the disc has a large table to place the pattern on and if you scribe the line you are sanding to you will see the edge of the line break away and thus you are up to the line. The Belt sander would have to oscillate to give a good finish and the Disc is easier to make in the home shop. I have included a shot of the tapered blocks and the type of overhead router which I used to make the blocks. As I have said the blocks were made from 5/8 inch ply and were double sided taped together to get the angle. I will make you a set if you don,t have the capacity. The overhead router is a real finger biter It was based on a similar type at The RMIT Except the Tech ones were German and did not use a die grinder. There is a vertical height adjustment the 2 inch column at the rear and a fine adjustment on the head. The head also tilts and it has a fence. yours 4-6-4

Thanks for posting Rod. I was picturing a smaller block with a thin edge to it and was wondering how you avoided it potentially jamming things up. One thing that was repeated many times by the fore-mentioned pattern maker was that the table and the wheel had to be really close together and don't even think about doing really thin stuff on there. With the larger (heavier) blocks I can see that would not be an issue.

Not having a 20" disc sander, I'll pass on a set of blocks thanks.

Michael

If anyone's thinking of making a disc sander, I thought I'd mention a source of cheap steel discs: My local steel retailer has a laser cutter and a plasma cutter and has a good supply of circle cut outs in sheet steel, they must make a lot of pipe flanges so the circle of steel goes very cheap compared to normal steel prices. The steel they feed the laser cutter has a clean, flat appearance with no rust, just mill scale and an accurate circle, ideal for a disc sander!. Once mounted you could true up the edge with an angle grinder.

Originally Posted by Com_VC

Out of interest could someone tell me what advantages one of these has over a belt linisher. I'm curious because i'm never used a disc sander before but have seen them come up quite a bit.

When pattern making, you sometimes want a very flat surface, it's almost impossible with a belt sander as it tends to round off the leading edge of the sanded surface, also you get that bump from the old fashioned scarfed belt join once per revolution. My first 9" disc sander had the disc machined for me by a pattern maker: he made the aluminium face rotate true to 2/10 of a thou and I glued the paper on with spray on glue rather than use velcro as the velcro can again cause rounding of the sanded surface. You removed the sandpaper with some turps and a bit of elbow grease.

It was a joy to use, very low vibration just effortless stock removal and a flat surface.

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

Hi 4 6 4,

That's nice! In fact it's so nice that even though I don't have a use for one (yet) I feel the urge to put it on my never ending "to do" list!

Just out of interest, how many horses is that induction motor?

Cheers,

Simon

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 will try that as I use the wood glue method and have 2 discs, one on and one getting new paper. I only have a 230mm discs to suit standard paper, nice and cheap, LOL

Dave