Building a stainless steel apple crusher

October 19, 2013 in DIY, Fabrication, Homesteading by Claude

We have three big old apple trees in our yard. The first autumn after we moved here, these trees produced heaps of delicious apples, and we had no way to use them other than eat them or give them away. There’s only so many apples you can eat without consequence and almost all neighbours have their own apple trees, so there’s little demand for apples when they are in abundance. We ended up putting literally wheelbarrow loads of apples onto the compost. That seemed wasteful.

The next year, we bought a cider press so that we could put some of the abundance to good use. But for some reason, that year, the apple trees yielded very poorly and it wasn’t worth bothering trying to make cider. The fruit press still came in handy to make lingonberry juice.

crushing apples

Crushing some apples!

Fast-forward another year, and the apple trees were again growing huge amounts of fruit. This time we were going to make some proper juice! Well, a cider press is all good and well, but it will not press much juice out of whole apples. In order to get any juice, it is necessary to crush the apples first. The finer the pulp, the more juice you’ll get out of them. One way to get a fine pulp is to use a garbage disposal to grind the apples. However, grinding them too fine is not so great, because that will likely grind the seeds too, which can give a bitter side-taste to the juice. The best way to crush the apples for pressing juice is to use a crusher designed for the job. There are various homestead scale crushers commercially available, but they all come with quite a hefty price tag attached. We purchased the fruit press because I calculated that it was not worth making myself, but the crushers all seem too pricey for a relatively simple device.

After a bit of research on the mighty Internet, I found out that it really doesn’t take much to crush apples. Several people have built apple grinders based on a wooden cylinder with a bunch of screws in them. Seems simple enough, but getting a suitable piece of wood isn’t and I don’t have a lathe to make a wooden cylinder. I’d also prefer the apple crusher to be made of metal. It’s cleaner that way and I have better tools to do metalwork rather than woodwork. I found one version of the screws in a cylinder design made of metal, but then I came across a bad-ass all-metal design based on edgy U-shaped steel bars fixed to a steel drum. The U-bars have “teeth” ground into them to bite the apples better. Very nice! There was the inspiration for my own design.

So, off to the junk yard / metal dealer, and here’s what I found: a 60 cm long stainless steel pipe, some rectangular stainless steel tubing and a stainless almost-U-shaped piece of sheet metal. The steel pipe was new stock, the rest recycled. I have no idea where the bent sheet metal came from, but I figured it would make a good case for the grinder. One side was bent at a 90° angle but the other side was at a slightly larger angle…?!?  The sheet metal was 4 mm thick, so not easy to bend into shape without a press or a high heat, neither of which I had available. Well, never mind, it would be good enough for a box…

stainless steel raw materials

These three pieces of stainless steel are the raw materials for the business end of the apple grinder

First, I cut the pipe to fit the width of what was going to be the box. Then I cut the rectangular pipe lengthwise in half, to create two identical U-shaped bars. They will be the teeth of the grinder. After cutting them to size a few mm shorter than the section of pipe thy would be welded onto, I marked out points on the edge of the pipe to give an even spacing between the sections. I found that seven sections would leave the most suitable spacing. I defined “suitable” as “whatever looks right”. That tends to work ;-)

marking out a line on the steel pipe

This is how I used two of the three bits of raw material to mark out a cutting line on the third one. I cut all my steel with a 9-inch grinder, so I need accuate markings if I want any hope of a straight cut through a three-dimensional piece of material.

I welded the edges of the U-bars with their centre-points at the markings on the pipe. I then set about welding along the long edge of the U-bars but I realised that would cost me a lot of welding rods and probably warp the cylinder from the heat, so I only welded a couple of centimetres at each end on either side of the U-bars. That’s no doubt strong enough, but I would have preferred a full weld bead along the edge so as to make it easier to clean. But, I figured it’s stainless steel, not wood, so it will probably be easy enough to clean. In the design that served as the inspiration, the U-bars were screwed onto the pipe, not welded, so that also left a narrow long edge.

The business end of the apple crusher

This is the business end of the apple crusher before cutting the teeth.

welding the box of the apple grinder

The box of the crusher half welded together.

Next, I used a 5 mm thick grinding disk on an angle grinder to grind teeth into the U-bars. Then I used the crusher pipe to estimate the suitable width and depth of its housing. I cut the bent sheet metal into two pieces of equal length, and cut the “walls” off one of them so as to give a proper sized counterpart to the housing box. A few weld beads later, the housing box was almost ready. Now I still needed to drill holes into the housing and figure out a way to get an axle fixed to the inside of the pipe, dead centre. Rather than cutting out discs and weld them to the pipe, limitations of available materials combined with the thought of how to clean out the inside of the pipe, should any apple pulp get in, lead to the solution of a semi-open fixture for the axle. I cut two rectangular pieces of the left-over sheet metal and ground them round at the ends so that they fit snugly inside the pipe, like a massive sprocket. Some precise measurements later, I marked the centre-points for drilling out the hole for the axle in the box and the rounded sprocket rectangles. I used a 20 mm wheelbarrow axle for the job, so I drilled the holes in the box to 22 mm and the ones in the sprocket rectangles to 20,5 mm to fit snugly. I then welded the sprockets in place, inset 50 mm from the edge of the pipe and I ran a small bead on one side of the edge of the holes in the sprockets, which I then filed to a flat edge. I also ground a flat side onto the axle. That way, crusher cylinder turns with the axle and does not run freely.

Finished parts of apple crusher

These are all the parts needed to assemble the apple crusher, finished and ready to assemble.

In order to mount the axle, I purchased two pillow block ball bearings, which I mounted onto two small plates welded onto the outside of the box. These would also serve as the attachment for the handles. All that was now left was the power mechanism. I had initially intended to hook the apple grinder up to an electric motor via a belt, but I didn’t have the time for that this summer, so I just quickly welded together a handle out of a short piece of pipe which holds onto the axle with a simple screw that sits in a threaded hole. Does the job.

Homemade apple crusher fully assembled

Finally, the home-made apple crusher fully assembled.

Well then, finally, does this thing crush apples? Fortunately: yes! It produces chunks about twice the size of sugar cubes. We made quite a good amount of juice with it this year. After pressing, the cake of pulp is pretty dry, in any case, so I think the yield of juice is quite good.

Next year, I’ll definitely fit a motor to the apple crusher. That’ll make the whole job much easier and quicker. Although the crusher does a good job of crushing and grinding the apples, they do need pushing a bit for it to bite them, especially once the teeth get a bit clogged up with chunks of apple. A motorised crusher would leave more free hands to handle the apples and a higher speed would probably reduce the clogging of the teeth too. But that’s for version 2.0 …