Do big slabs tumble okay?

[RockingRuralMo]

I have a big tumbler with 8 gallon and a 12 pound drums, and a small 4lb vibratory.  I've always used my slabs for cabochons in the past, but some people have asked for polished display pieces and I kind of want to try making some.  I was thinking of trying to tumble a batch of slabs that are around 4-5 inches in diameter.  Would that work?  Would they break?  I've seem small "slabettes" tumbled before and they come out okay.  Will bigger pieces be more prone to breaking?  Which equipment would you use?

[dshanpnw]

You sure can tumble slabs. Be sure to include some media, ceramic cylinders, or smaller rocks to keep them from sticking together. Do you have the Lot-O vibe? Will the pieces fit in the opening? If the rocks you are tumbling have a hardness of 6-7 and about 3/16" thick they shouldn't break. I've tumbled a lot of slabs and they come out very nice.

[victor1941]

RockRuralMo, I use a UV-18 vibe and can tumble slabs that are good size as long as they don't jam and tumble freely. I totally agree with dshanpnw that one should use plenty of media, filler and grit for each cycle and fill after each cycle to maintain the volume with previously tumbled material. I would also call Shawn at The Rock Shed for advice since I think he uses the larger tumblers.

[HankRocks]

I have successfully tumbled larger slabs in a Model B rotary tumbler. As victor1941 and dshanpnw mentioned, I use a lot of scrap smalls to facilitate the grinding and polishing as well as cushioning with more surface contact points. I usually reduce the amount of grit a bit as it does not break down as fast. 

Just put a batch together and started it yesterday of 3 1/2 to 4 1/2 inch slabs, about 35 or so. I will be starting another batch today or tomorrow of larger 5 to 6 inch slabs, probably about 25 or so. 

One thing to keep in mind if the slab has fractures there is a chance they will break along the fracture.

Good luck
Henry