Post by jamesp on Nov 21, 2017 7:23:13 GMT -5
At a lazy 30 RPM with a 6 inch diameter barrel that holds 7 pounds of Mohs 7 rocks I have found rock size is key to slurry management.
Just look at a range of sizes 1/2" to 2.5" rocks to cover a common range of sizes of rocks commonly tumbled.
Consider slurry management based on the size of rocks you are tumbling.
If you tumble 1/2 inch stones coarse SiC will take a long time to break down. Grind rate is extremely slow.
If you tumble 1.5 to 2.5 inch rocks coarse SiC will breakdown quickly. Grind rate is fast.
If you tumble 1/2 inch stones the slurry lasts a long time because the grind rate is slow and stays an acceptable thickness.
If you tumble 1.5 to 2.5 inch stones the slurry lasts a short time because the grind rate is fast and the slurry thickens quickly.
Overdosing with coarse SiC makes a poor quality slurry. It makes excessive gas too.
Sorting should be not be necessary, if the shape of the rock is unacceptable for tumbling then don't tumble it.
High conductivity colloidal clay makes the best slurry for large SiC 30-46-60 or bigger #8 and #16 grit sizes.
High conductivity(a pet peeve of mine using white clays and kitty litter) ?
Muddy rivers will tell you where high conductivity(often colloidal) clay can be found.
Clear rivers are usually low conductivity sand bottomed. Sand particles fall to the bottom quickly.
Red clays are almost always high conductivity and you will find the muddiest rivers in the world are stained red.
Because iron is common in soil and iron rich clays have high conductivity which allows the river water to carry many times more particles.
Making the water heavy and thicker which in turn allows them to carry heavier particles.
Your rotary tumbler is no different than a fast moving muddy river. Heavy muddy water will carry larger grit particles and spread them into your rocks.
Sticky high conductive clay will also suck your rocks together and increase grind forces as they rotate. Try pulling your boot out of wet clay.
More on high conductivity soil/clay:
Central Florida is covered with a thick 100+ feet of sand. Building codes require 2 or 3 eight foot long ground rods driven into the sand for grounding lightning.
Recent central Florida building codes have required the entire footing it have metal in them to dissipate lightning in the low conductivity sand.
On the other end of the spectrum is the 50+ feet deep Georgia clay in central Georgia dissipates lightning easily with a single 6 foot ground rod.
The red clay easily conducts the lightning with minimal metal contact and bleeds it into the ground.
Effect of floods in sandy lands and red clay locations:
a) Sand rarely comes out of the river banks and deposits on the flood plains. Maybe on the fastest flowing rivers... Sand does not suspend in water well.
b) Muddy rivers will deposit feet of clay particles in flood plains. Often killing entire floodplain forests. The clay rich water will also carry sand to aggravate the situation.
Case in point -
The Chattahoochee River flowing next to my house. Often listed as the top 5 most polluted rivers. Not my man made pollutants.
But by sediment pollution. Clay run off from the massive construction projects in the Atlanta area. The Chattahoochee used to be a beautiful Appalachian river.
Deposits of sediment ranging from 1 to 20 feet thick has killed about all of the old growth hardwood forests causing the river banks to wash into the river.
Highly conductive colloidal clay soil was the down fall of the Chattahoochee.
Just look at a range of sizes 1/2" to 2.5" rocks to cover a common range of sizes of rocks commonly tumbled.
Consider slurry management based on the size of rocks you are tumbling.
If you tumble 1/2 inch stones coarse SiC will take a long time to break down. Grind rate is extremely slow.
If you tumble 1.5 to 2.5 inch rocks coarse SiC will breakdown quickly. Grind rate is fast.
If you tumble 1/2 inch stones the slurry lasts a long time because the grind rate is slow and stays an acceptable thickness.
If you tumble 1.5 to 2.5 inch stones the slurry lasts a short time because the grind rate is fast and the slurry thickens quickly.
Overdosing with coarse SiC makes a poor quality slurry. It makes excessive gas too.
Sorting should be not be necessary, if the shape of the rock is unacceptable for tumbling then don't tumble it.
High conductivity colloidal clay makes the best slurry for large SiC 30-46-60 or bigger #8 and #16 grit sizes.
High conductivity(a pet peeve of mine using white clays and kitty litter) ?
Muddy rivers will tell you where high conductivity(often colloidal) clay can be found.
Clear rivers are usually low conductivity sand bottomed. Sand particles fall to the bottom quickly.
Red clays are almost always high conductivity and you will find the muddiest rivers in the world are stained red.
Because iron is common in soil and iron rich clays have high conductivity which allows the river water to carry many times more particles.
Making the water heavy and thicker which in turn allows them to carry heavier particles.
Your rotary tumbler is no different than a fast moving muddy river. Heavy muddy water will carry larger grit particles and spread them into your rocks.
Sticky high conductive clay will also suck your rocks together and increase grind forces as they rotate. Try pulling your boot out of wet clay.
More on high conductivity soil/clay:
Central Florida is covered with a thick 100+ feet of sand. Building codes require 2 or 3 eight foot long ground rods driven into the sand for grounding lightning.
Recent central Florida building codes have required the entire footing it have metal in them to dissipate lightning in the low conductivity sand.
On the other end of the spectrum is the 50+ feet deep Georgia clay in central Georgia dissipates lightning easily with a single 6 foot ground rod.
The red clay easily conducts the lightning with minimal metal contact and bleeds it into the ground.
Effect of floods in sandy lands and red clay locations:
a) Sand rarely comes out of the river banks and deposits on the flood plains. Maybe on the fastest flowing rivers... Sand does not suspend in water well.
b) Muddy rivers will deposit feet of clay particles in flood plains. Often killing entire floodplain forests. The clay rich water will also carry sand to aggravate the situation.
Case in point -
The Chattahoochee River flowing next to my house. Often listed as the top 5 most polluted rivers. Not my man made pollutants.
But by sediment pollution. Clay run off from the massive construction projects in the Atlanta area. The Chattahoochee used to be a beautiful Appalachian river.
Deposits of sediment ranging from 1 to 20 feet thick has killed about all of the old growth hardwood forests causing the river banks to wash into the river.
Highly conductive colloidal clay soil was the down fall of the Chattahoochee.