The project has moved forward a little over the last week.
I have finished up a few more parts for the group.
The first is what I call the retainer plate. Its function is to hold the group lever in alignment with the axis of the machine and to provide a stopper for the lever in the resting position. Originally, it is a casting with some secondary machining, but the material seems to vary - the two examples that I have may be either nickel or brass. Given that the function of this part is purely mechanical, the only reason I can see not to substitute aluminum is the possible differing coefficients of thermal expansion. For now, at least to check my design, I will be using aluminum and, rather than paying for another mold just yet, I am machining the part from solid stock.
My other preoccupation this week has been test driving some new cam software. So, with the twofold intention of protecting my mill and not scrapping a nice chunk of aluminum, I ran the program first on some high density foam. No worry about destroying expensive tooling if there is a collision with this stuff!
The problem with making parts like this is material removal. The final part is less than a quarter of the volume of the stock which means rather a lot of chips are going to have to be made in this process. Although it a little unorthodox, I am using an indexable carbide face mill as a clearing tool. At 1600rpm, the spindle on my machine just doesn't go anywhere near fast enough to make small diameter tools efficient. Here, the first rouging operation is mostly complete and the form of the part has started to emerge from the stock.
...moving onto a 1/2" corncob roughing end mill to remove the internal pocket and cut the external profile.
...and finishing up with a 1/4" ballnose to put the fine detail on the raised shoulder that serves as the lever rest.
The finished part in foam. I caught a number of mistakes with this test, among which was an offset problem with the cam program (note the four threaded holes are not centered correctly) and, more importantly, a few small errors in the part design. Prototypes are important!
I have finished up a few more parts for the group.
The first is what I call the retainer plate. Its function is to hold the group lever in alignment with the axis of the machine and to provide a stopper for the lever in the resting position. Originally, it is a casting with some secondary machining, but the material seems to vary - the two examples that I have may be either nickel or brass. Given that the function of this part is purely mechanical, the only reason I can see not to substitute aluminum is the possible differing coefficients of thermal expansion. For now, at least to check my design, I will be using aluminum and, rather than paying for another mold just yet, I am machining the part from solid stock.
My other preoccupation this week has been test driving some new cam software. So, with the twofold intention of protecting my mill and not scrapping a nice chunk of aluminum, I ran the program first on some high density foam. No worry about destroying expensive tooling if there is a collision with this stuff!
The problem with making parts like this is material removal. The final part is less than a quarter of the volume of the stock which means rather a lot of chips are going to have to be made in this process. Although it a little unorthodox, I am using an indexable carbide face mill as a clearing tool. At 1600rpm, the spindle on my machine just doesn't go anywhere near fast enough to make small diameter tools efficient. Here, the first rouging operation is mostly complete and the form of the part has started to emerge from the stock.
...moving onto a 1/2" corncob roughing end mill to remove the internal pocket and cut the external profile.
...and finishing up with a 1/4" ballnose to put the fine detail on the raised shoulder that serves as the lever rest.
The finished part in foam. I caught a number of mistakes with this test, among which was an offset problem with the cam program (note the four threaded holes are not centered correctly) and, more importantly, a few small errors in the part design. Prototypes are important!
No comments:
Post a Comment