New part: The propeller (programation)

posted in: Machining Projects | 0
I had thought long start making examples of things more practical. So it occurred to me to think about the world of model aircraft, and a piece that may break frequently and need to replace it, is the propeller. And if I make a model of one? Said and done. I found a page in a 3d models free 3d engineering, and started to work it.

Prior to program anything, you have to think how is going to be machined. First you have to see that this piece needed a change of phase, ie, we must mechanize both sides, which means release from their moorings, and turn. This poses some problems to solve, mainly how to get the position and keeping the origins. Secondly, we see that the blades are very thin at the ends, and in the finish path, wood will vibrate. These are the first problems to be solved.
First, I will slightly modify the geometry and adding references reinforcements, once machined are easy to remove manually. could be something like this:


These little pieces of wood, I would serve for two uses. On the one hand, serves for the blade does not vibrate, and theoretically can mechanize smoothly. Also, helps me through a small hole, screw the billet to the table at both ends, and this is a point very important.
On the other hand, I will machined this part with some accuracy to use it as a reference for subsequent turning of the workpiece. At least all this in theory.
Let’s see what else to do:

In the part program, as always, I must insert the dimensions of the stock, it’ll start with a general roughing, to leave a rectangular geometry, the dimensions of the stock that I put on the ends.


So we have a symmetric geometry billet to which we can turn it around with confidence, provided that this well tied.

Below one second roughing, now whether to begin taking the geometry of the part. This I will do with a Ø8mm tool two lips, low-end to avoid burning the wood. I will give an increase of 1mm material, for the finish path. I still don’t know what would be the correct feed rate for the material (good quality wood, but do not know the type) So I will risk 700 mm / min.

Before proceeding with the finishing pass, be advisable to make a path to define the profile of the propeller. This not we let the finishing operation with a spherical cutter have to define a line as necessary:
Okay, now I’m ready to make the first finish milling with a spherical tip Ø 4, 5mm. If I need to keep one thing in mind, is that this operation should NOT have to touch horizontal surfaces we have achieved with the first machined. If these surfaces are changed, I will not have good references in order to turn the piece and may not match the origins, which cause the piece not serve. There are options in the menu of the finishing operation that allow you to avoid certain areas, so with this and some imagination, this path is achieved:

Perfect! We have the first phase. Now it flip …. ops, problem. I don’t know if there is any tool to define a workpiece change, change of mooring or just turn around changing the machine axes. I’ve tried almost all the icons, but I have not found anything. So I’ll have to use my imagination:
After much reflection, what I’ve thought is use two different bodys on CATIA, one for each phase. Since this is part of the same but in different positions, the stock must be exactly the same. So I will place a copy of the piece but symmetrical position, so I can keep adding operations as if it had been around:


Phase 1


Phase 2
Problem solved! Now, no fuss origins of changes or anything I can stick with the program. The bad: I can not simulate the actual machining phase, for the purposes of the simulation, I have not been turned the piece, but trust that we have done things right.

And voila, we have done the program for machining a workpiece on both sides. Just put it into the machine and go!

Here I leave the simulation program. The next entry will be the real machining. We will see how it looks!