Radius Dish Question

[needsmorecowbel]

Hey guys I'm just about to start making up some dishes (finally)
I'm going to use the lazy susan method and create a whole bunch of lovely MDF dust.

Should I be using a bowl and tray bit or a round nose bit when the router is in the cradle?

Thinking of starting with three dishes:15, 20, 25. Might even give Graham's method a go

[Kim]

If you have a bowl/tray cutter in your arsenal then use it. If not it won't really matter as you will clean up with a bit of sandpaper anyhow, I made 4 dishes and cut all of them with a 1/2" straight bit.

Cheers

Kim

[simso]

I use a radius bit

[kiwinoz62]

Hi,
I used a straight bit, but more important, wear the correct PPE, lots & lots of dust.
Better yet, use a dust extractor, vac.

[needsmorecowbel]

What radius were your dishes Kim? Is it good to have a range say 15-30 (15,20,25,30)? Yes MDF is horrible stuff and the appropriate safety precautions will be taken.

[Dominic]

I got myself a nice 1/2" shank bowl bit for this and it made a mess. Tended to lift the dish and the finish was horrible. Most sucessful was like Kim using a smaller straight bit.

The typical lazy susans are pretty crappy and you'll get a bit of wiggle around the centre which will also result in a bumpy finish. I installed a steel pin in the middle and put 4 adjustable wheels from a sliding door I had lying about around the edge. This spins true and all i have to do was bump the router foward a bit each time and not let the dish spin too fast and i got very accurate smooth dishes.

You've also got to back you dishes before you start (if you are using one sheet of mdf) because they will start warping as soon as you cut them and you'll end up with a larger radius once you flatten them out. I use 15mm ply.

I set mine up with dust extraction and I didn't get any dust in my workshop.

Good luck
Dom

[Kim]

I cut 2 x 15' and 2 x 25'. One of each is bare MDF sealed with shellac and the others are fitted with a 600mm sanding disk for cutting the rims and liners in etc. Mine were all made the same day with the same jig, all from 32mm MDF with 19mm ply bonded to the back side to keep them stable...heavy but they make killer frizzbies....literally...the radii took about 10 or perhaps 15 min each to cut ready for sealing.

My jig was a simple dual sled arrangement that carried the base of my old hack 1/2" Makita snugly on twin rails bearing the appropriate radii screwed into place on a frame clamped in place above the disk and adjusted so the cutter would 'just' kiss the outer edge of the disk.

The disk were all cut from 600mm x 600mm x 32mm off cuts obtained from a scrap and salvage place for about $5 each, same deal with the 3/4" ply backing. Because I made my own circle cutting jig to make the disks, each was left with a 1/4" hole dead centre.

This hole was used to position each of the disk for the cut. The router was cobbled up with a festools CT22 dust extractor so there was not very much free dust at all during the cuts. Cutting was a straight forward affair because the disks were placed on a melamine panel through the centre of which a 1/4" bolt had been secured. This bolt was not only used to position the disk but also worked as an axle upon which the disk was at first rotated into the cutter by hand until app 25% of the cut had been made.

By this time there was enough depth of cut to provide the toque to rotate the disk automatically so that the job then became one of using my knee as a brake to slow down the feed rate as the cutter progressed through the job and sped up the disk....no need for a lazy sue me thinks because you could find yourself tilting the Earth off it's axis should you allow the RPM's to get too high.

Cheers

Kim

[Allen]

I used a 1/2" straight bit. Cleaned up with a bit of sandpaper pretty easy.

Use a dust extractor if you've got one. Don't even think of using the vacuum. It will kill it in minutes. I did mine outside on the driveway with a dust extractor and still managed to cover the surrounding houses in a layer of dust.

[Dominic]

Use a dust extractor if you've got one. Don't even think of using the vacuum. It will kill it in minutes. I did mine outside on the driveway with a dust extractor and still managed to cover the surrounding houses in a layer of dust.

You guys have got to get a cyclone for your vac.

Heres mine and it works brilliantly. Cheers Dom

Shopvac 002 (Custom).JPG (101.1 KiB) Viewed 10035 times

[simso]

Nowadays, I use the cnc router, set it forget it, 10 minutes later finished. Man, modern technology is soooo sweet.

[needsmorecowbel]

Good call with the lazy suz. Perhaps it would be easier to just use a central pin from the underside of the dish (that does not go all the way through and misses the router blade of course). The pin would allow the dish to spin on the workbench but clamping it off would prevent the spin and there would be no issues with tilt. Registration would be the main issue