@@ -55,18 +55,41 @@ W/R/T Layout, there are a number of permutations of how to go about adding axis
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@@ -55,18 +55,41 @@ W/R/T Layout, there are a number of permutations of how to go about adding axis
I tend to 'work out' from the Z-axis, towards the edges - this way I can keep track of where I need extra offsets (length of travel != length of gantry). Here's the layout with the Z-and-X axis group moved around to the extents.
I tend to 'work out' from the Z-axis, towards the edges - this way I can keep track of where I need extra offsets (length of travel != length of gantry). Here's the layout with the Z-and-X axis group moved around to the extents.
This is all just loosely blocked out, in this stage I am really trying to get good numbers for the lengths of all of the axis, etc. Now I'll get into the actual Axis detailing.
This is all just loosely blocked out, in this stage I am really trying to get good numbers for the lengths of all of the axis, etc. Now I'll get into the actual Axis detailing.
## Parametric Axis
## Parametric Axis
- Go Here https://github.com/fellesverkstedet/fabricatable-machines
- Racking (two senses)
Jens Dyvik is on some [wonderful machine building sprials (link!)](https://github.com/fellesverkstedet/fabricatable-machines) and we're going to put them to work this week. In particular, the [chamferrail system](https://github.com/fellesverkstedet/fabricatable-machines/tree/master/chamferrail). Take a look at his documentation to get an overview of the machines!
- Pinioning
I'm using his Chamferrail Generator in Rhino and Grasshopper - included in this repo under /cad/axis-generator/ . Now that I have my axis lengths laid out, I'll generate the axis, and go through the process of milling them. I'll do this first on the X Axis and circle back to make any adjustments to the system I see fit!
Use Grasshopper to adjust the parameters - you'll find them all on the left. Things I adjusted were:
- Make sure 'Output Geometry Type' is set to 3D
- 'Make Hole Pattern at Edges' is Yes (I turned this off for the Z axis, where I'll be drilling different holes for mounting end effectors)
- Milling Bit Diameter: 3.175 (1/8")
- Motor Shaft Diameter: 6.35 (for our 1/4" shaft motors)
- Axis Length: 550mm (X Axis, 850mm Y Axis, 260mm Z Axis)
- Axis Width: 80mm
- Material Thickness: 12.5mm (this is important! Measure your stock!)
- Chamfer Distance: 5mm
- Rack Tooth Height: 6.5mm
- Hole Grid Distance: 48mm
- Hole Diameter: 5.25mm (this means we can use M5 Screws to secure the rails)
- Screw Pocket Diameter: 11mm (an M5 washer is 10mm in diameter)
- Edge Screw Pocket Depth: 6.5mm (an M5 Socket Head Cap Screw<sup>9</sup> is 5mm, a washer is 1.1mm thick)
Now I use the 'bake' command to pull the geometry out of grasshopper and into Rhino.
## Axis Blocks
## Axis Blocks
- Connect ur axis
- Connect ur axis
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@@ -74,6 +97,7 @@ This is all just loosely blocked out, in this stage I am really trying to get go
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@@ -74,6 +97,7 @@ This is all just loosely blocked out, in this stage I am really trying to get go
- It's almost as if I knew about this system while I was doing layout! *~!NONLINEARITYALERT!~*
- It's almost as if I knew about this system while I was doing layout! *~!NONLINEARITYALERT!~*
## Doing the Milling
## Doing the Milling
- Layout and Material Planning in Rhino
- First we go to fusion
- First we go to fusion
- Then we do the milling
- Then we do the milling
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@@ -104,6 +128,7 @@ This is all just loosely blocked out, in this stage I am really trying to get go
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@@ -104,6 +128,7 @@ This is all just loosely blocked out, in this stage I am really trying to get go
6. ~ 305x610mm
6. ~ 305x610mm
7. ~ 127mm
7. ~ 127mm
8. So I want an H-style layout, because I want to keep the machine small relative it's total work area. One of the biggest drawbacks with an H-machine is that the two sides of the Y-axis are not always set up parallel. The result is what's called 'racking' - i.e. imagine opening a screen door, and the top or bottom exhibits more friction - the 'jam' that this causes happens in CNC Machines as well. A drawing. By cutting both Y-axis rails out of the same 'frame', Jakob gets around this issue - the parallelness of the two rails is a mirror of the parallelness of the machine which cut them. It makes it a bit bulletproof to novice assemblers. He has also done a really good job of keeping the X-axis loads really close to the Y-axis rails (so, a small structural loop).
8. So I want an H-style layout, because I want to keep the machine small relative it's total work area. One of the biggest drawbacks with an H-machine is that the two sides of the Y-axis are not always set up parallel. The result is what's called 'racking' - i.e. imagine opening a screen door, and the top or bottom exhibits more friction - the 'jam' that this causes happens in CNC Machines as well. A drawing. By cutting both Y-axis rails out of the same 'frame', Jakob gets around this issue - the parallelness of the two rails is a mirror of the parallelness of the machine which cut them. It makes it a bit bulletproof to novice assemblers. He has also done a really good job of keeping the X-axis loads really close to the Y-axis rails (so, a small structural loop).
9. That's a SHCS
to be linked - dan gelbart
to be linked - dan gelbart
talk about resolution vs. accuracy - repeatability vs absolute accuracty - global vs. local resolutions
talk about resolution vs. accuracy - repeatability vs absolute accuracty - global vs. local resolutions
