Large Rock Production Line

[HankRocks]

(This is some thinking out loud about an tumbling idea I have)

I have been wondering about how to polish more larger rocks in the 1 to 3 pound range. Putting 2 large rocks in the same barrel or hopper has been an issue with them fighting each other and the tendency to beat up other smaller rocks in the load. Contemplating firing up a still in the box Lortone 33B acquired from one of my regular Show customers and my Mini-Sonic 3 - 4lb hopper to create a large rock production line. All of the large pieces will have been coarse stage finished in one of the Model B's. Planning on using the 33B for 600SiC, 1 rock of each of the 2 barrels.. The pieces will have been shaped in Coarse and I am hoping they can go straight to 600 SiC. Have tumbled rocks before skipping 220 SiC stage and not had any issues, plus the large pieces should be more than ready for 600. 

After the 600 SiC run they will go each into a dedicated hopper on the Mini-Sonic for the Pre-Polish and Polish runs.

I have a decent stockpile of Coarse Tumbled larger rocks as I use them in my normal Coarse runs to improve grinding, the heavy hammer effect as I call it. Advancing them past coarse has been an issue as stated above.

Will also look to shorten the stages. Being large rocks I am thinking that they will need less time, say 600 SiC goes from 7 days to maybe 5 days or even 4. The Mini-sonic should be faster than rotary for Pre-Polish and Polish.

Also I have about 5+ gallons of polished Pea Gravel/small scraps that I will add to the batches with the large piece.

The only down side I see to all of this is 4 or 5 extra barrels/hopper to clean out every 5 to 7 days. Then again with tumblers, going extra days when schedule gets busy is not an issue in tumbling.

Henry

[victor1941]

I think JamesP is an expert in this area.

[fernwood]

jamesp want to check in here?

[jamesp]

Go for it Henry. You have the same philosophy I have. A
All kinds of problems with more than one rock banging around.
Impact marks can remain even after finish steps and left after polish.
Love doing the big rock tumbles.

Coarse grind:

Using one barrel for each large rock was the only way I could tumble five 1 to 3 pound rocks at a time.



These are sleeved double thickness sch 40 PVC barrels and they only held 5 pound each due to the double thick walls.
Five clean outs every week required.

This was one of the bigger rocks done and it was shaped at 80 rpm:



One thing I found was that hard agate 'media' like pet. coral or hard agate about 1 to 1.5 inch average size coarse shaped the 1 to 3 pounders much faster than pea gravel. And the big rock also shaped the smaller rocks much faster - cool.

1 to 1.5 inch hard agate 'media'. Typical milkshake slurry that was maintained.:



Also, with one big rock and all the rest small 1/1.5 inch rocks the barrel could turn fast like 80 rpm and no damage would occur causing some really fast grinding and really fast grit breakdown. Instead of cleaning out every 2 to 3 days due to the high speed grit breakdown I would simply add a half dose of coarse grit every 2 days and had to pour off some slurry and add water to avoid the slurry getting too thick when adding the half dose. Total clean out about every week.

Here are the list of differences with a 2 pound rock in a 5 pound barrel with smaller 1/1.5 inch tumbles:
-the smaller rocks shaped much quicker
-the big rock shaped unusually fast(it helped to grind bad spots during the tumble)

-the coarse grit broke down much quicker requiring more doses of fresh grit
-being able to increase the rotation speed to 80 rpm since no bigger rocks were banging against each other(which made the above 3 points happen faster) Even at 25 rpm it was a much faster grind with that 2 pounder in the mix. Call it a the super grinder rock.

Some rocks had to be ground just to fit thru the 4 inch hole. The red and green jasper would not take a wet shine. It was softer than the other rocks on this post.:



Or sawn in half:




Finishing:

Instead of running a 220 step in the rotary I ran an SiC 500 step in the vibe but only after letting the coarse grit run a full week in the rotary for a full break down. I used 100% quartz pea gravel and due to the weight of the big rock rubbing against the pea gravel it did SiC 500-AO 220-AO polish quickly.

I could finish two big rocks at a time in most cases with a split vibe hopper, or a longer rock in a 14 pound hopper:

This hopper has a divider welded into it splitting it:



This double hopper did fine but the mouth's were a bit small for bigger rocks:



This 14 pound hopper would do up to a 10 inch long rock(never did such):



Since I stole these out of your backyard(the moss came from the Zapata Tx McDonald's landscape bed don't tell) 1 to 2 pounds:

solid moss:



Texas wood ball:



Texas palm with fractures darn it(this was a Native man's scraper until the grinder hit it):



A discus ground from a cobble. Fungus ?:



A big thanks to roy for some of these fine fracture free rocks. It's not easy to find bigger rocks with no fractures.
Roy - was it you or Tony that sent me these rocks ?

[HankRocks]

That McDonald's Moss belongs in a Museum somewhere!!

I have managed to build up almost a full bucket supply of South Texas River cobbles. They will be prime candidates for this adventure.

Thanks for the info. The opening on the 4lb Mini-Sonic will be the real limiting factor. If a rock goes more than about 2 1/2 pounds and depending on shape it probably exceeds the mouth limit of the hopper.

[jamesp]

The limitation of the Mini-Sonic hoppers was a surprise.
A rock 2 1/4 x 2 1/4 x 3 inches @ 1.3 pounds would get jammed consistently in the Mini-Sonic hopper even when running pea gravel. This fact pushed building the larger all steel divided hopper out of an 8 inch section of 6" diameter pipe with two 4 x 4 inch top openings. The same 6" diameter thin wall steel pipe was used to mount the Mini-Sonic hoppers inside of for a clamping device. But the Mini-Sonic barrels are about 5/8 inch thick so they have about a 6 - 5/8 - 5/8 = 4 3/4 inch inside diameter. The difference in 4 3/4 to 6 inch inside diameter made a big difference in allowable rock size.

The 4 x 4 inch opening in the vibe hopper matched the 4 inch entrance hole in the PVC barrel.

Don't you have a large UV ?

If getting serious about rolling big rocks a longer 6" pipe with 4 compartments for 4 rocks would work on the Vibrasonic. It has the capability to shake it.

This is the 1.3 pound rock. Hope this helps.



PS I had problems getting a wet polish on a large obsidian and even large jaspers that must have been about Mohs 6. Oh and a large rhyolite that seemed Mohs 6. Frustrating.

[HankRocks]

I do have a UV-18. Just didn't want to use it to polish just one big at a time. Wonder what might happen if I put 4 or 5 bigs in it with all the rest pea gravel sized, already polish rock. I am afraid there will still be skirmishes. Might try that.

Initially I will stick with my original plan and just do 1 to 2 pound rocks that will fit in the mini-sonic and will not jam in the hopper. The more rounded a piece is the less likely it will jam. Elongated pieces of Petrified Wood are definite jam candidates. I definitely have pieces that will need a larger hopper.

One thing I think I notice is I can run bigs in coarse with other rocks and they seem to play nicer. I do add 2 cups of slurry at the start in the 15 pound barrel. As has been noted in the past, the big rock(hammer rock) seems to aid grinding on the rest. I just don't like taking them past coarse in the rotary with other rocks.

Something to ponder on my morning walks.

[HankRocks]

Started my larger rock production work process 12 days ago. Two pieces of Petrified wood just went into Polish stage in a 10lb mini-Sonic hopper. Will check at 4 days(daytime run only) and see how they are doing. Both pieces were run multiple times in the model B until they were approved as candidates for this new process. They are being run with previously polished pea gravel and very small scraps to remove all big to big hits. 

Will post pictures in 4 or 5 days.

Henry

[aGates]

Jul 10, 2022 16:16:32 GMT -5 HankRocks said:

Started my larger rock production work process 12 days ago. Two pieces of Petrified wood just went into Polish stage in a 10lb mini-Sonic hopper. Will check at 4 days(daytime run only) and see how they are doing. Both pieces were run multiple times in the model B until they were approved as candidates for this new process. They are being run with previously polished pea gravel and very small scraps to remove all big to big hits. 

Will post pictures in 4 or 5 days.

Henry

I very much appreciate this update! Look forward to your results. Love your curiosity and willingness to share. I too am curious as well.

[rockbrain]

I hadn't seen the Mickey D's moss agate before. That's an incredible piece and what an amazing shine you got on everything!