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where to start

Posted: Sat Aug 04, 2012 2:52 am
by bobt
I want to make my ShapeOko machine a flat surface on some aluminum parts that I have. I also am learning sketch-up. I have a working ShapeOko that ran the hello world fine after adding a shaft to the x axis and an additional drive pulley on the other side. What I really want to do is machine about .010 off the top to create a flat surface. What do I start with and then what is next.

Bob Teeter

Re: where to start

Posted: Sat Aug 04, 2012 3:13 am
by edwardrford
I don't have any experience facing a piece of aluminium that large, so keep that in mind when you read my suggestion.

If it were me, I would put a piece of MDF on top of the aluminum, then face the mdf. My thinking is the MDF will be significantly more forgiving than the aluminium. So when you plunge too deep, your bit will be hitting the MDF instead of the comparatively rock hard aluminium.

The MDF is also going to be significantly easier to face. If you're using a dremel, I would suggest picking up the closest thing you can to a 'fly cutter', like their 115.

Here's a nice video showing the difference between using an 1/8" endmill to do fly cutting vs the 5/16" cutter. The good stuff starts at about 16sec.

Re: where to start

Posted: Sat Aug 04, 2012 1:47 pm
by edwardrford
I just noticed what forum this was in Bobt. Now I'm wondering if you were asking more about *how* to actually do the facing?

I would do something like this:

-Set your machine to 0,0,0
-Drop your z axis by 1/16" (F200 Z-1.5875)
-Run the X axis pass (F800 X175)
-Step 'up' half the diameter of the bit (for a 50% overlap) (Y 3.96875)
-Run the X axis back home (X0)
- Step 'up' half the diameter of the bit (Y 7.9375)
- Run the X axis pass (x175)
- Continue incrementing the Y axis after each pass by 3.96875 until you have finished the whole piece of MDF.

Sorry if that's not what you're asking. I debated whether or not to even answer as I didn't want to insult your intelligence if you already knew this. If so, I apologize. Maybe this will come in handy for someone else.


Re: where to start

Posted: Sat Aug 04, 2012 6:39 pm
by bobt
Nope - Edward - both those answers were right up the alley for what I wanted. I also was wondering what was the best method using software would be? I am building a Gingery Horizontal Mill and have the aluminum castings for it and wanted to learn how to use my cnc environment for the machining of the parts as motivation to get really good at cnc because as soon as I get the milling machine working correctly I will cnc it. I am also building a 4 foot by 4 foot cnc machine for wood and metal machining. So to the answer of answer 1 - I will be machining aluminum parts for the mill and need to know the best way to do that. Initially I have to flatten surfaces for mounting of bed ways. And to the second answer - I am also wanting to learn how to do these operations with a cnc machine. By the way when Bart finishes his plasma cutter design I will be building that also.... :D :idea:

Bob Teeter

edited: bad spelling from posting on my tablet. Stupid machine......