New part: The propeller (machining)

posted in: Machining Projects | 0

As I said in the previous post, here comes the machining!
The first step is to ensure the stock to the table, or in my case, the martyr’s, but what it’s this? it is simply a timber that is used for working on it, mark it, and when no longer useful, use another. That if you have to be well anchored so that the stock aligns with the axis of the mill.

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Well, as in all machining, I must to define the origin, and I have chosen to 60mm in the X axis and 30 in the lower left corner of the stock, so that there aren’t milling movements out of this volume. In previous posts I explained this concept, so I will not repeat here.

So get to work, having done zero, the first mill starts, and eat wood!

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First problem: It smells like burnt wood … here I think I have not chosen the correct tool. I used a roughing Ø10mm 4 teeth and serrated edge. It seems that both friction burns wood, plus I think I have set the speed too high. Well, little by little, it was the first time I was machining this wood.

It shows in the next roughing that this problem does not occur, and cuts much better with a strawberry two lips Ø8mm

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Here ends the first phase of roughing, tool change, bur Ø4.5mm spheric tool
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Phase is over, now we have to turn it around. If I calculated everything right, it should be a good propeller. So dismount the martyr, the piece, and turned back to put everything in place.
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Return to start roughing stage of phase 2
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And of course the finish phase

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And with all this, the propeller is finished. Here is the result:
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Conclusions machining :
At this point , I appreciated that I made some mistakes, both application and concept :
First, it is quite noticeable that one blade is finer than the other, which clearly means that the tumbling process something went wrong, and it is probably that although the piece was well positioned with a pin, the martyr just four screws is screwed to the table, so you can make some errors.
Second, in the last roughing pass, in Phase 2, as the central part was machined, the blade bended due to the lack of material. Which makes the final geometry modified.

Solution would be:
Place pins to the martyr and the table to ensure the correct position of this at all times.
Design the piece with nerves in order to have to clamp the workpiece to the billet , and then can be removed with a small saw and some sandpaper.

I’m already working on the model to solve these setbacks , so soon will hang a new attempt!

Still propeller has been quite neat, after a simply sanding. If it is not spinning , it seems well finished!

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