Slice Rocks Like Bread

Back a while...I created my first instructable. It just so happens it was a DIY version of a Lapidary machine. Rock artists: now is a good time to cover your eyes and ears- look away!

Lapidary is essentially the art of working with rocks, minerals and gems. Cutting, faceting, engraving and polishing them to create something that will last a very long time...

I inherited a geode?/agate? rock from my Dad and wondered if I couldn't slice it into thin pieces and use it in my stained glass work. The last photo shows the beginning of my thoughts...a little creative book-matching- it'll look great! Right?! The problem is, when I looked up how to do this, it's not something a DIY'er can do. We are talking HUGE machines running on ALL the volts and amps, filled with oils and coolants and self feeding mechanisms. It just didn't look like I could pull this off. Everything I searched for online showed people BREAKING the rocks open, or cutting very TINY rocks- not slicing large pieces.

I thought that was the end of that, but then again...I'm not one to give up. I am known to employ

• PROCRASTINATION
• PERSISTANCE and
• PATIENCE

NOT in that order and definitely not in equal measure.

Was I able to pull it off? Well yes...but it's complicated. Stay a while and I'll tell you all about it.

One lapidary blade. (mine was MK Lapidary 6" with a 1/2" arbor) and cost around $30.

One wet tile cutting saw...you don't have one? Me neither....!

One DIY adjustable speed lapidary machine: https://www.instructables.com/Rocks-to-Art-DIY-Lap...

Baby oil - to periodically lubricate the blade/bearing surface.

Back when I made this machine I needed to smooth and polish rocks, nothing more, nothing less - and it worked very good for that. Over time I found some other uses for it- like sharpening woodworking tools (bonus!) You'll find that I am usually trying to get things done WITHOUT spending any money, or spending the least possible. You could easily spend hundreds or thousands of dollars on "gear" without ever making anything! Gone are the days where "you can just get this and that at a flea market..."

While brainstorming how I was going to get my existing machine to cut rocks, I contemplated coming out the side of the motor. Kitchen stand mixers have a square hole that accepts all the fancy attachments (like a pasta roller). I thought I would use that area to attach the blade and keep it in a container with water. That way it would be separate from the motor and could be ran through the water for continuous cooling.

The problem was I would then need to build some kind of table that is at a 90 degree angle to the blade, then I would have to come up with a fence. All of this would have to support the rock while it is being cut. I have a condition known among makers as 'IT HAS TO BE PERFECT'. I have let that get in the way of many a project and those projects never seem to get done.

In the spirit of "let's get this done, shall we?" I went ahead and rigged up a plan B. I placed the metal disc underneath the cutting blade and separated them by a washer. That gave me the thickness I needed to slice the rock to the size of my stained glass. The rock would ride on the oversized base plate (sliding on water and baby oil...smooth) and get cut all around through to the center with the lapidary blade. It's a PERFECT PLAN, what could go wrong?

HI! (*future me here*) : Any time I try and side-step an entire industry, it's wise to think..."you are going to get gently...kicked in the shin" and reminded why there is an entire industry that does this stuff.

Remember how I said things need to be perfect for me to proceed? Well, this was me just pushing through to test this out. You will notice my set-up. The machine is outside, on the floor, not clamped or anchored to anything. No comfy seat- just a quick rig with the garden hose into the bucket that will then drip the water onto the blade to keep it cool and whisk away any rock bits.

I gathered up my rocks...a few small ones I found that looked worth cutting in half, and the main event- the 6 inch tall by 4.5 inch wide geode...agate...big rock!

I applied some baby oil to the base plate, blade and rock - and fired that thing up. It was apparent within the first 10 seconds that I was A-OK to turn up the speed on the machine. From my little bit of research and reading- these blades are NOT OK to use on high speed machines like angle grinders or table saws, and need coolant. I mean it says on the label- do not under any circumstance use this blade dry.

Let's just say I started cutting all around the rock and was pleasantly surprised at how well it was going. It wasn't going fast - of course (it is a DENSE ROCK) but it was moving along!

After 30 or 40 minutes of kneeling on the tile I started to get...tired of kneeling on the tile. So I grabbed a nearby bucket and sat on that while I worked on the rock. I realized that I didn't need the garden hose to continuously feed water into my drip bucket because I wasn't using that much. I used a random bolt stuck in the end of the hose and the threads on the bolt acted like a slow feed on the water. The water had to travel around all the machine threads and then it would slowly drip onto the saw. If I wanted a slower drip, I would push the bolt higher into the hose, if I wanted it faster, I would pull the bolt out a little more.

I would periodically check my progress, fight off killer Texas wasps, get a drink, etc...and by doing so the machine was not spinning, but the water was still dripping. When the machine is spinning, water is flung into the catch basin, but when the machine is off, the water flows onto the baseplate, down the shaft, and onto the machine. I tripped the GFCI breaker and had to reset it because of this at one point. I would make sure to move the drip off to the side during those "non-grinding" activities. I may have also spilled water all over me at one point.

I should have been ecstatic with my progress, but I was lacking the PATIENCE piece of the puzzle after close to 2 hours. The paper slid into the rock shows how much rock STILL needed to be cut. It was starting to be difficult to hold the rock that deep into the blade without it wanting to grab and pull away from me. I set the rock down on the tile without being careful and snapped a piece off the corner (shake my head...) So being tired, a little wet (my fault, not the machine) and needing 2 band-aids, it was time to call it a night.

The next day, I decided that I had a deep enough groove to remove the base plate because I suspected the washer between the baseplate and blade was preventing me from cutting deep enough. I did just that and sliced through the rest pretty quick. I then grabbed a few of the smaller rocks and cut 2 of them in half in less than 10 minutes holding them free-hand. I started cutting the third and decided that was enough rock cutting for one weekend.

To be honest, I was amazed how well this worked. If you have an interest in rocks, I suspect you could get a table saw style tile cutter with one of these blades and cut right through any rock pretty quick. If the rock does not have a smooth surface to reference off the table or fence, you can put the rock in a square mold, fill it with plaster of paris, and let it cure. You will then have a perfect cube (with your rock inside) to cut safely on the machine. My machine does not spin very fast so it probably took a lot longer than it should have.

I learned that for my machine, I need to install a rubber "skirt" type washer that will prevent any water from going down the shaft. That will keep all the water in the catch basin where it belongs, even if the machine is not spinning. On the slow setting, I'm sure I could set up a jig to hold the rock in place and walk away while it polishes the rocks without me. The slowest speed is quite slow and there are 5 or 6 speeds to choose from. I'm really happy with how this worked out.

As for the rock, WOW! I got an incredibly consistent thickness of slice. What was most eye opening for me was this particular rock- once I cut off the slice, the deep blue color was almost gone- washed out. It needs the depth that is in the rock to have that rich blue color. When I placed it on the light table to see what it would look like back-lit, it looks dramatically different- it's quite muted compared to the vibrant blue it has normally. Having learned that, I don't think I will use this rock for the original purpose I had in mind.

The journey was well worth it, and I see many more uses for this machine in the future!