Gas Powered Blender of DOOM

I really like making cool machines.
One time I was trying to blend some almonds into almond butter. I put them into my cheap 30$ blender and started it. Almonds were blended into pieces, but after about 10 seconds, as the almonds started to thicken, my blender just stopped. And I was without my almonds.

I told myself into making a very powerful blender. But I did not have an appropriate electric motor for it, so I came across the idea to make a gas powered one. It will be strong, portable and it could be used off grid to make pancake mix :D

Watch this video to see how it works(feel free to hit the LIKE button):

And here is a video describing the build process:

In this instructable, I will further describe the details of the build.

I was looking for specifications of 1k$+ industrial blenders to see what makes them great and I found out the following:

- strong-ass motor

- strong-ass blades

- big-ass bowl

- metal coupler gear between the mixing cup and the motor (cheap ones use rubber ones)

- high blade rpm speed (18k-25k rpm) for blending everything into a smooth smoothie

I wanted to use a 2 stroke grass trimmer engine for this build:

- the engine needs to be powerful enough - so higher displacement is better

- the typical engine rpm shaft output i in the range of 6-8k rpm. So I will need to make a gearing system that will spin the cutting blades faster than the engine shaft, otherwise blending performance will be compromised

- I need to make a metal chassis that will hold everything together

- i need to find a big bowl

- i need to find good cutting blades

- I need to find gears for the transmission

There are many ways you can make this machine, I have used an angle grinder, a drill, lathe, stick welder, CNC router, 3D printer and a woodworking router.

But would say that the lathe, CNC router and 3D printer and woodworking router are not strictly necessary, since you can make the required parts with simpler tools, it will only take a bit more time.

As you could see in the video in the beginning, I got an old grass trimmer engine for free.

It ran badly, and it was not possible to tune it properly. I suspected that the carburettor could be the problem as the engine smoked a lot and did not reach high rpm. This indicated fuel mixture that was too rich.

I ordered cheap Chinese clone of the original carb for 14$ from Aliexpress and bolted it on. And the engine now runs as new!

The engine was 40cc which is powerful enough. 50cc would be better, but I used what I got.

The bowl was a critical part.

I didn't want to use typical blender bowl, as it doesn't look cool enough for a build like this.

The bowl needs to be tall and not too wide, so the ingredients don't run away as easily.So I searched the internet for the appropriate bowl for ages.

I didn't want to use glass one, since the gasoline engine produces a lot of vibration and I didn't want the bow to break if I drop it. And drilling into glass for mounting the blades is difficult.

So I decided to go with stainless steel.

I got an used kitchen robot - dough mixer bowl for 20$. The bowl is tall enough, it has 4.5liter/1.2gal capacity and is perfect for the project.

Dough mixer bowls do not have lids, so I needed to make one.

I wanted a transparent lid, so I could see what is going on inside the bowl.

I used 1cm thick acrylic sheet (plexiglass) and with a handheld router I carved the outer shape and the notch for the bowl. From a friend I borrowed a simple jig for making round cut-outs with a router

I used self-adhering foam tape to make a simple seal inside the notch so the insides stay (mostly) inside the bowl.

I searched the Aliexpress for good and affordable blades and I found these:

https://www.aliexpress.com/item/33052081909.html

and the coupler:

https://www.aliexpress.com/item/32868069523.html

I like them because they are:

- big and they have cutting teeth on the blades (good for ice)

- made from metal and are quite robust

- nice an big bearing
- it also has a metal coupler which will be able to transfer high power without problems.

I needed to cut a hole in a bottom of the bowl in order to fit the cuter blades.

The bowl had a double bottom, and I needed to cut out the lower bottom out for the blades to fit.

First I tried it with a holesaw, but it was unable to cut stainless steel.

So I cut a few dozen holes around the perimeter and use a dremel to cut it out. After some grinding it came out good enough.

I needed to find gears that will multiply the engine rpm to around 20 - 25k rpm on the blades.

And I needed a 90 degree transmission, since the engine shaft is horizontal.

I came to an idea of using replacement hears for an angle grinder.

I found these:

https://www.aliexpress.com/item/32857720778.html

I like them because:

- are made from hard metal which doesn't wear out quickly

- are to be mounted to the 15mm and 8mm shafts which are easy to find

- i get 90 degree angle

- helical gears are quieter

- are cheap (6$)

EDIT:
When I tested the machine, I measured 41k rpm on the blades which is way too much :) I underestimated the speed this little engine is running at :) If I would do it again, I would use an engine which works with less rpm, or I would reduce the gear ration to 1:2 approximately.
With having so many RPMs on the blades, the engine is a little bit underpowered for running them when mixing thick mixtures.

And I ordered some cheap shafts and bearings from Aliexpress for making my transmission system:

https://www.aliexpress.com/item/4000679847644.html

https://www.aliexpress.com/item/4000176610214.html

https://www.aliexpress.com/item/4000678202056.html

https://www.aliexpress.com/item/4000679869566.html

I needed to cut the notches in the shaft. In these notches, the pins that will hold the gears are inserted.

Horizontal shaft attaches to the engine clutch. I used the old grass trimmer flexible shaft as a flexible coupler for the horizontal shaft.

You need the flexible coupler else the slightest misalignment of the shafts will cause catastrophic breakdown.

This shaft holds the big gear which is secured with a pin I also needed to make from a sheet of stainless steel.

The vertical shaft holds the bowl coupler element and it is driven by a small gear. I cut a small notch on top of the small gear which slides across the pin inserted in the shaft hole. This ensures the power delivery to the shaft.

The gear is fixed with a pin and a retaining ring (circlip) which prevents it from sliding on the shaft.

The transmission is now complete.

I needed to print a custom bowl holding bracket, so the bowl can be locked in place so it does not fly away when mixing.

If anyone wants the 3D model:

https://www.thingiverse.com/thing:4598619

Used some nice orange color which matches my youtube channel logo :)

For the tank I used a random plastic flask. I made a custom brass fuel inlet on a lathe for connecting the fuel line, since I was not willing to wait for few weeks for an inlet from ebay :)

I had a problem - the exhaust of the engine was pointed directly to the mxing bowl. This meant the stuff I will mix will be splashed with the unburned oil and smelly gasses from the engine.

I used a piece of pre-bent steel tube for deflecting the exhaust gasses away from the mixing bowl. I welded a nut on it and it was screwed in the frame.

It works quite well!

I added a kill switch, which is used to shut down the engine. The engine has only one wire sticking out of it and if you connect this wire to the engine frame the ignition spark is disabled and engine shuts down.

I installed a simple ball on the throttle cable to manually add the throttle input. Nothing fancy.

Initially I wanted to make a throttle lever (as seen on boats) but It was too much work and it would prevent me from being to rev it up unnecessarily :D

I also made a simple wooden swing arm which holds the lid pressed down with a help of a spring. Otherwise the contents of the bowl would leave the bowl with great speed :)

Here is the finished beast!

Don't forget to watch the PART 2 video where I made some blending of different stuff!

I hope you enjoyed my Instructable! Please vote for it in the make a tool contest!

Thank you!

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