There are quite a few videos on YouTube of DIY homemade pellet mill projects. Some of these DIY pellet mills are a lot more successful than others. The video below is quite a popular example and not a bad attempt at a wood pellet mill. While I respect those that put the time and effort into a DIY project to make a pellet mill the limitations of these machines is not clear to many people. The reasons being, most people don’t have the experience of how to make wood pellets. With this post below I’m not attempting to discourage anyone from attempting a homemade pellet mill if you are willing. I just want you to approach a DIY pellet mill project with realistic expectations. You need to be realistic on what a DIY pellet machine can achieve and the grade of wood pellets you will produce.
DIY Flat Die Pellet Mill Design
The first thing to note from this video is the basic vertical flow flat die pellet mill design. Material is fed through the hopper on top and the wood pellets come out from under the die. Not the most efficient pellet mill design, however, it’s very popular in China due to its simplicity. In fact, many homemade pellet mills actually use a die and rollers made in China. What is actually homemade is the chassis of the pellet mill, the gearing etc. The most efficient pellet press design is a ring die pellet mill. However, that would be much more technically demanding DIY project.
Pellet Press Power Input from a Tractor PTO
The video states that an 80HP (60kw) motor is used, as you can see to the right there is a PTO shaft so this pellet mill is running from a tractor. A lot of people are interested in PTO pellet mills, however, it’s not something I personally encourage. For one, its dangerous, many people die every year from getting caught up in PTO shafts. With a pellet mill, you are standing very close to that PTO shaft.
Even with a cover on the PTO shaft, it’s still not very safe being stood next to it. Secondly, an 80HP diesel engine is being used to power a very small pellet mill. It’s stated in the video description that this DIY pellet mill is producing 130 kg/h. I don’t believe that’s realistic, its probably around 40-50kg/h. Therefore, those wood pellets will have a very high cost per tonne.
DIY Pellet Mill Productivity
With regards to the productivity per hour of this DIY pellet mill, let’s be generous and presume it can produce 130 kg/h of wood pellets. You are having to load the material in above the pellet mill via a bucket, metering it in bit by bit. That’s a lot of hard work. Also, you cannot really be doing anything else such as bagging up the wood pellets.
With this particular DIY pellet mill, the operator also seems to be experiencing a bridging issue where the pellets are coming out of the machine. This is likely due to the high fines percentage. Fines are particles of material that were not compressed into wood pellets, they are then separated from the finished pellets and returned into the process.
DIY Pellet Mill Issues
This particular DIY pellet mill is producing quite a lot of fines. This is either down to one or two issues. The material could be too dry. If this is the case with a DIY pellet mill such as this you have no means to precisely control moisture content to address the issue. Secondly, it could be an issue with the compression ratio on the die holes, or the die is worn and needs replacement.
When we get to see the finished wood pellets at the end of the video you can see that there are very few good quality wood pellets. There is a poor consistency with some very short pellets that look to have a poor density. With a small pellet mill such as this, it would probably benefit from the use of a suitable pellet binder.
Conclusions on DIY Pellet Mills
While this DIY homemade pellet mill is a respectable attempt you should not look at a machine such as this and think that producing wood pellets at home is a viable option. When you work out the cost per tonne of wood pellets covering your time and equipment costs it just doesn’t add up.