DIY Automated Glass Bottle Cutter

Ever thought that cutting a glass bottle could be so easy? This time, I've created a tool that slices glass bottles in seconds!

How I did it - you can check by looking DIY video or you can follow up instructions below.

For this project you will need:

Materials:

• Heating Element Coil Wire 2kw - Link here
• Microwave Turntable Motor 5/6r/min - Link here
• AC Voltage Regulator - Link here
• Double Rocker Switch - Link here
• Tubular Crimp Terminals - Link here
• Silicone Wire - Link here
• Spiral router bits - Link here
• 9/12/15mm plywood pieces
• CA glue
• power cord and scarp wire piece
• Silicate block

Tools:

• Hacksaw
• 6mm threaded rod
• Tools to cut plywood pieces to needed dimensions
• Drill, drill press and bits
• Palm router with 6mm bit
• crimping tools
• any other various bits and bobs which helps to get job done in the workshop

I started with a 25-millimeter thick slice of silicate block. I needed to get two equal parts, so I marked the middle line and cut with a hacksaw. This material is lightweight and quite brittle, which makes it fairly easy to work with hand tools.

Next, I marked the middle once again and offset the ruler a few millimeters on the side. This is a 6mm threaded rod and it's the perfect tool for the job. By using it as a scraper, I formed a half-round groove along the block. At this point, the threads acted as a file, leaving a perfectly round and even groove.

This is a Heating Element Coil Wire rated for 2kW. The formed groove will accept this coil perfectly by keeping it halfway exposed above the surface. As always, I've left links in the video description for all the main parts used.

One last thing with this silicate block - I need to drill a hole at one end, which will help to manage and connect the heating coil later.

From plywood leftovers, I started to form a holder for those silicate pieces. CA glue was the right adhesive for the job, allowing me to work very fast and accurately.

Its final position should be like this, so by making a few 45-degree cuts on my table saw, I made a simple holder from a scrap wood piece and glued it in place.

The base will be made from 15mm thick plywood. Two narrow strips will act as feet by providing a raised surface in between. The second great feature - they will be a perfect guide for my palm router. With a 6mm spiral router bit, I made two passes until I milled through the plywood. As a result, I got a groove going through. 

The base is ready - let's glue in the V-shaped holder.

In that milled groove, another sliding holder will be fixed. The process is the same as before, pre-cut plywood pieces and CA glue make this progress relatively fast and easy. This thicker piece should slide inside. Before gluing the second guide rail, I added paper on each side. This will act as a shim and ensure enough space inside when the paper is removed. Nice and smooth!

With a homemade router attachment on my table saw, I milled a groove with the same 6mm spiral router bit. I really love the finish which these spiral router bits give. I highly recommend you try them out! 

One more hole was drilled and the holder could be mounted in place. The hardware I’ll use includes a square neck carriage bolt, a washer, and a wing nut. That square bolt part will sit in the groove, allowing it to slide and at the same time keeping it in place while securing with the wing nut.

To keep sliding this newly created part along and parallel to the base, I need to glue a pair of guide rails. I used the same shimmed paper technique because it worked extremely well in my previous glue-up. When the paper was removed, the fitment was spot on! Not too tight, not too loose, and could be moved, literally, with one finger.

Next, I’ll use a microwave turntable motor. I salvaged it from an old and broken microwave, but I also will leave a link in the video description if you want to get it online. My plan is to mount it here and at the same time to keep it sliding up and down. I’ll use this spacer from the previous glue-up, because it has the perfect width. It has enough thickness which allows me to mount it flush with the surface. A quick job at the drill press by changing various forstner and regular bits ended up with this recessed part.

Now all the hole shapes and depth will start to make sense. The square neck bolt will be placed in the deepest hole. It should sit deep enough to give clearance for a microwave motor to be installed flush with the surface. At the moment, one hole is still left unused, but I will come back to it a bit later. Now let's mount the slider in place. 

The last assembly part - a cone-shaped cork from a wine bottle. A hole in the bottom allows it to mount on the motor shaft. And yes, I glued it with an epoxy glue, but forgot to press the record button.

The whole body is ready, the sliding part is fully adjustable, and could be fixed in any position.

Time to get back to the heating element and the other electrical parts. To extend the ends of the heater coil, I’ll use those 14 AWG or 2.5 square millimeters of gauge silicone wire. I chose this type of wire due to its flexibility and great thermoresistance characteristics.

To get a solid connection, I’ll use Tubular Crimp Terminals and a crimping tool. I even tried to pull out the coil wire for testing purposes. Trust me - the connection is reliable and very strong. 

Placed silicate blocks into the holder and wired in crimped silicon wires. It sits quite nicely, but I need to keep the heater coil to follow the groove. I separated one wire strand from the scrap copper wire and adjusted the heater coil position by tensioning it all the way to the bottom. This is important only until the very first heat-up. Then the heater coil will lose its memory and springiness. 

To keep wires nice and tidy, I secured them with wire holders. 

Drilled a pair of different diameter holes in the base for upcoming wire management. I drilled them at an angle for a purpose, which became obvious later.

To control the heater coil, I’ll use an AC voltage regulator. This is quite a cheap and simple device. A pair of wires goes in, a pair of wires goes out, and the control is done by twisting this big potentiometer knob. Secured the regulator to the base and connected the heater coil wires at the output side.

Now is the time to use those drilled holes and wire through a pair of wires. A main power wire, and a thinner wire to connect the microwave motor.

The main power wire already has crimped spade terminals. They are without insulation, so I added heat-shrinking tubing and heated up. Now I merged the main power income wire, microwave motor wire, and additional wire splitter with spade terminals. Tubular Crimp terminal did the job very well! The second microwave motor wire got a spade terminal and insulation too.

To control all electric parts, I’ll use this double Rocker Switch. It has 3 terminals for each button due to the light indication feature. To mount it on the plywood base, I made this simple holder. Managed and connected all spade connectors to the corresponding switch terminals. It is a simple switch, so I don’t think that additional comments are needed here. And the wiring job here was finished by connecting two last wires to the regulator. Proper amount of CA glue fixed button holder in place permanently. 

I left with the last unused wire, which is dedicated to the microwave motor. To connect it, I have to remove the motor. The wire was managed through the premade hole. Naked wire ends were crimped with a pair of spade terminals. Before connecting them - I made a 90-degree bend because inside the plywood holder was a bit of a tight fit. To finish - all 4 fixing screws were tightened in. 

To keep nice wire management under the cover - I used wire clips. I know I know this part will not be visible, but I like to keep everything nice and tidy. 

Final check if my wire management isn't too tight in any position. And it is spot on! 

The final puzzle piece was this Y-shaped plywood holder to catch out all glass parts. I glued it with double-sided tape in case I will need to remove it for better access to the switch or voltage regulator

And this is it, let's test this little machine! The first button turns on the motor. The second one - gives the power to the AC voltage regulator. By twisting the knob, I adjusted the proper amount of power given to the heater coil. In the current setup, this is how it looks fully heated up. I measured with the power meter that in this setting I’m using only 400 watts. Double switch is great because it could be turned on and off with a single finger. Small, but nice detail.

Ok, let’s grab an empty glass bottle and test the performance.

Pressed the bottle on the cone-shaped cork. It has plenty of grip to be turned. Adjusted vertical and horizontal position to achieve the needed angle and cut length. Flipped the first button for the rotation, and the second for the heat. I started with the real rotation speed and later speeded up the footage 9 times.

About 1 minute later I grabbed a glass of cold water, dipped the small brush in, and with the wet part touched the line which was heated. And It worked magically! I’m not kidding - I was more than surprised by this! Cold wet touch was giving that thermal shock at the heated line, which caused it to crack. Evenly heated line ended up with a perfectly round and even crack line. It's just insane! 

I really love those fully adjustable axis which allow me to cut glass bottles in various shapes, like this. This one was quite thick, but the tools worked flawlessly

You know what is more impressive? That it cuts a glass bottle into rings. It could slice bottle after bottle effortlessly.