What grit in radius dishes?

[seeaxe]

Hi all

I have made a couple of radius dishes which I am using for the first time, and so far so good.
I haven't put any sandpaper in them yet and (as it uses a lot) I was wondering what most people use.

Seems to me that most things I would use if for need fairly coarse grit but when working on the box, I wouldnt want it too coarse for fear of putting accidental scratches on it.

Any sage advice??

Cheers
Richard

[Rod True]

80 grit seems to be the most common in use for a radius dish. If you preshape your sides before bending and your tail and head blocks are shaped "close" you could get away with 100 grit.

[jeffhigh]

80 grit and then use 2 layers of paper when you have the top or back in contact . Will stop scratching and avoid contaminating the grit with glue.

[Allen]

I've got 80 grit in mine. I bought 24" floor sander disks. Hard to find in Australia as they don't seem to use them much here.

[Bob Connor]

I use 80 grit as well. I got the big sander discs from John Hall in the States.

www.bluescreekguitars.com

[Rod True]

News papers good as a barrier between the sandpaper and plates, I like to use a piece of construction paper though. It's much harder to tear and you don't get distracted from the personal adds

[seeaxe]

Thanks guys - 80 grit it is, I've got a roll of that so Ill d/s tape it to the dish. Ill get a bit of heavy duty paper or similar (old towel, I think someone mentioned).

Richard

[Paul B]

Yeah you can just glue down strips from a roll of 80 grit. The big disks would be better, so you'll have to keep and eye out for dust etc building under the edges and making a lump if you use strips. I used contact adhesive, worked well.

[Taffy Evans]

Yep I use 80 grit cut from strips or a roll, I glue them down with special disc cement as it allows easy replacement later. I never thought of use large discs
of paper.

[Rod True]

You can also get a wide belt disc and cut out what you need from that. There is a local furnature maker near me who has a 24" wide belt sander and he's given me 80 grit belts after he's done with them. There is still grit enough for my sanding dish (I also preshape my rims which helps with less sanding).

[kiwigeo]

Looks like Im the odd one out..I run 120 grit in my dishes.

[Hesh1956]

I have 120 in my 25' dish and 80 in my 15' dish but I like the 80 grit better and will be replacing the 120 with 80 when the 120 wears out.

Yeah, I'm cheap....

[Craig]

We all knew you were cheap Hesh

I've found 120 to be a bit slow , so swapped to 80 and found that too coarse for my liking . very deep scoring.
I'm using 100 now and find it the best of both worlds. It's quick and leaves a decent finish.
I've used lots of different papers , but invariably end up going back to the garnet ( usually Nortons ). Seems to just keep on keeping on ! . The 4 " strips work for me also.

Posterboard from the newsagent for a working surface on top of the sandpaper . I usually draw the template shape on it . I find it comes in handy.

I bought my top dish years ago as a 33 ft radius , but upon checking it
a few months ago I discovered it's not 33 at all. More like 22' . Made me check my back dish . Sure enough , bought as 21 ' but is actually 17' . I remember when I first got them , there seemed to be a bit of a slight bulge at the rear .They're made from 1 inch MDF and I'm told removing the surface from one side alters some surface tension ,,or something . I gave them a good coat of paint all over to seal them and they have been stable .
Have any of you guys checked your radius' ?. I'm not worried about it at all as they've been doing a good job.

[Kim]

I made my own dishes from 4 x 600mm x 600mm x 38mm MDF off cuts i picked up cheap from a salvage and disposal place. I glued 19mm ply from the same place to the base of each off cut. Yep that's right, each dish is 57mm on the outside edge. Using a circle cutting jig i made for the bandsaw, i cut off the corners to make the rounds. Two 15' and two 25' radii were cut and then they were sealed with heavy cut shellac. 80 grit was glued to one of the 15' and 100 grit glued to one of the 25' with the one of each left plain to be used as glued dishes. More room to store? Slightly, i made a rack that holds them side by side so it is not too bad. Heavy? Yep no doubt, but stable as you could imagine and i 'know' i have a consistent 15' and 25' radii throughout the build.

Cheers

Kim