Saturday, October 17, 2015

Still Cutting Pieces

I've been working on my G0704 CNC Conversion project as time allows on weekends.  Today, I wrapped up the last of the lathe work - I think.  Four more threaded spacers, 1.5" and 10-32 threaded both ends, and then a couple of shaft collars.  Along the way, I got quite a bit more efficient at making these.  The first ones took a long time.  The last four took a few minutes each. 
I should probably powder coat those, or some other sort of finish, but not right now. 

The next phase is to make the motor brackets.  I plan to make those on my CNC Sherline, which requires I create instructions to make the part; numerically described tool paths called G-Code.   This is a standardized language (RS-274), although not every system has to recognize all of the possible codes.  G-Code can often be generated by hand with a dimensioned drawing, but complex shapes (for example, carving wax for jewelry casting) require another software package to take a 3D model and convert it to tool paths.  This is called a Computer Aided Manufacturing, or CAM, program.  If a CAM program is required, the first step is to draw them in 3D Design Software. 

It has been a while since I've looked to see what software is out there, but the program I use is Rhinooceros, usually called Rhino3D.  If you're not familiar with this world, it's got quite a learning curve.  Rhino is considered a modelling program rather than a true Computer Aided Design (CAD) program.  The differences are kinda subtle, but while Rhino can give you dimensions of anything you draw, and allow you to do things like rotate something to make sure it clears some other part of your design, it takes a bit more manual effort than a true CAD program.  While Rhino probably comes across as pricey, it's around what a mid/high end production pistol costs (my current "object du lust"), the true CAD programs cost quite a bit more, like 30-40 times that.    

The advantage of using CNC for this is that it will make doing anything other than drilling or boring holes easier.  I'm not doing this because I intend to make lots of these, just to make my work at the milling machine easier.  The work shifts from cutting metal to moving traces on this screen or deriving XYZ coordinates for where cuts have to happen, or where holes have to be drilled. 


  1. Very nice work. My mind skipped ahead to the motor mounts, and I wondered if the CNC mill could put an engine turned finish on the mounts, if enough flat area exists. You just do not see much engine turned finish anymore.

    Anodizing the supports would be way over the top, but maybe a faux anodize using dyes would be colorful.

  2. John - good idea. With the CNC, it's step and repeat. The way to get a the circles in the metal surface is to twirl a pencil's eraser, or a piece of Scotch Bright pad.

    I have some powder paint that I use for fishing jigs, and cure it in a toaster oven. Hoss (the plans I'm following) painted his red, rather than a Grizzly green. I was thinking it shouldn't look like it's Griz factory, but not sure what. I could engine turn them and then just shoot some clear varnish over them.


  3. IMO- deburr, wipe it off, and call it good. Aluminum is not going to rust. I look at this sort of thing from the viewpoint of making a tool, to make money- make it as good as it needs to be, to do the job. It is just a habit, I guess.

  4. If it is steel, I would just acid etch with muriatic acid and drop in a pan of hot rust converter. This will parkerize it.

    Personally I find that spacers made from acrylic work very well. If comes with tight tolerances already and can be lasered to shape at a sign shop.

    Make the tolerances for the holes a little large as sign shops usually dont care much about maintaining accuracy on their machines.


  5. I had not heard about the abrasive pad wrinkle. I will try to keep it in the memory bank for a future project.

  6. I converted one of my chinese knee-mills and a lathe over to CNC. It's well worth it. I use an older version of Rhino I bought years ago, you might look into Visual Mill for the gcode side of it. I design in Rhino and then directly import the .3dm files into VM for cad/cam conversion, then I use a couple different tools to simulate the gcode run and check for faults. If there are any faults I just hand edit them.