Last year, I purchased a carbon fibre drone frame Mark4 for a 7-inch drone. It turned out to be of good quality, so I recently purchased another three frames from different vendors. In the end, I was quite surprised with what I got. Below, some retrospective of these purchases.

First frame

It is virtually the same frame I purchased last year. The arms are identical, screws and other parts are of the same quality and feel the same.

In this case, the frame turned out to be exactly the same.

Second frame

When comparing it to the first one, there are a couple of differences. The screws used are slightly different.

The other noticeable difference is related to the pieces that hold the arms together. When you look closely, you can see that these are exactly the same parts. In the first frame, the pieces were different. This most likely was dictated by some modeling changes aimed at cost reduction. There are two pieces which are the same, instead of two slightly different pieces.

The difference related to the screw placement can be clearly visible when comparing the top views.

Next difference cannot be seen in the above photo. However, it is still related to the holding pieces. There are some “insert” screws. In the previous frame, they were mounted directly. With this version of the frame, they are given as separate pieces for self assembly.

Third frame

This frame has the biggest changes. It still offers identical parts for holding arms as the second frame does. The material used for the carbon fibre is much smoother and seems to be polished.

There are other two differences, but not necessarily better ones. One is related to the screws and spacers. The screws seem to be made of brass. It is not the best material for these parts because it is softer compared to “normal” steel screws. To be honest, I am not 100% sure that they are brass, but they are definitely not steel.

The spacers are also made of a different material. One might have a feeling that these are made of plastic and only painted with silver paint. They are much lighter compared to others. The spacers in the previous frames were made of aluminum or maybe steel.

With this frame, there is definitely a drop in quality. The material used for the frame is still good, but the screws and spacers are not as good as they were in previous frames.

Lastly, there is one other change that is hard to notice. It is related to the self-adhesive pad attached at the top. It is around three times thinner than compared to the previous frames.

Summary

All in all, these frames are quite good. Later tests will show how well the last frame will perform. I think it will be fine, but I am not sure how long the screws and spacers will last. The first two frames are definitely of a better quality, but the third one is still acceptable.

This brings me to the conclusion. Once I have heard that when you buy in bulk, e.g., flash drives, you can get whatever price you want, the obvious would be to get the lowest price possible. Then, where is the catch? There is a follow-up question: what share of the pieces you are purchasing you want to work. Based on your expectations, the higher the rate of devices that work, the higher the price. This somehow applies to these frames, because I bought them one by one while getting lower prices with each purchase, but also lower quality.