Finally... 4th axis

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ThatDamnGuy
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Re: Finally... 4th axis

Post by ThatDamnGuy » Mon Mar 10, 2014 1:27 pm

PsyKo wrote:ThatDamnGuy,

That is possible but now right now. Maybe in 2 weeks from now.
My Shapeoko is not at my place because I don't have enough space.

The setup is quite hasardous for now :) I also have to give my shapeoko a higher Z so the axis can actually pass below the endmill. Right now the spindle is almost at the top of the Z axis rail and the 4th axis shaft is along the Y axis.
Awesome, I look forward to seeing this completed. I am about to start a new build of a 1000mm x 1800mm setup and would love to add a 4th axis sometime this summer.

PsyKo
Posts: 430
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Re: Finally... 4th axis

Post by PsyKo » Mon Mar 24, 2014 10:26 pm

Hello folks,

As requested, some more pictures of the setup :
IMG_1122.jpg
The Chuck attachement being milled
IMG_1122.jpg (221.13 KiB) Viewed 4216 times
IMG_1118.jpg
The chuck attached to the delrin mount
IMG_1118.jpg (110.71 KiB) Viewed 4216 times
IMG_1123.jpg
IMG_1123.jpg (176.83 KiB) Viewed 4216 times
Shapeoko #736
Kress 800, Z Axis upgrade, dual Y, 600mm X&Y rails, metal spacers and V Wheels, home switches, 4th axis
Goko - Free CNC Control Software - http://www.shapeoko.com/forum/viewtopic ... 380#p44380

PsyKo
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Re: Finally... 4th axis

Post by PsyKo » Mon Mar 24, 2014 10:30 pm

More pics.

On this picture the 4th axis is almost finished. Cleaner base plate, almost completely closed, etc...
IMG_1141.jpg
A Skull being milled
IMG_1141.jpg (242.49 KiB) Viewed 4215 times
IMG_1144.jpg
IMG_1144.jpg (206.7 KiB) Viewed 4215 times
IMG_1146.jpg
The result
IMG_1146.jpg (93.11 KiB) Viewed 4215 times
I'm still having issue with precision. I have to design a belt tensioner so the chuck can't move (right now, it can rotate a little bit due to the belt). I also have to find a way to home it, and get used to aligning the bit with the center of the piece.

I will replace the Derlin chuck mount soon, because it's not rigid enough. The good side is that when beginning in 4 axis milling, it won't break anything in case of wrong moves. It will bend a little, just enough to hit the stop button :)
Shapeoko #736
Kress 800, Z Axis upgrade, dual Y, 600mm X&Y rails, metal spacers and V Wheels, home switches, 4th axis
Goko - Free CNC Control Software - http://www.shapeoko.com/forum/viewtopic ... 380#p44380

danimal
Posts: 332
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Re: Finally... 4th axis

Post by danimal » Sat Mar 29, 2014 6:43 pm

I want to build one of these so bad. I even have most of the parts, I just need to get on it. Just for clarification, your method is to develop the model in CAD, then create 4 separate CAM files for 90 degree rotations of the object and manually rotate the 90 degree shift between running each of the gcode files? As soon as I finish my last five upgrades, I will start this. :lol:

I would really appreciate any advice or heads up on any of the problems that you are encountering.
Shapeoko # 1458

RT0701C Spindle || dual y motor || x axis nema23 with custom carriage 1000mm length || z axis nema23 linear rail upgrade with 1/2-10 ACME

Will Winder
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Re: Finally... 4th axis

Post by Will Winder » Sat Mar 29, 2014 7:03 pm

It shouldn't be too hard to slice a 3D model into something which could be processed by a 3-Axis CAM program. I have an algorithm in my head, but I don't know enough about manipulating STL files to do anything with it.

The basic idea is to center your model along the rotation axis and take a 2D cross section of the model, split it along the rotation axis and take one half. Save the first half cross section for reassembly later. Now rotate the model slightly (say 1 degree) and repeat the process to get the second half cross section. Repeat for 360 degrees. Finally give the half cross sections a little depth and stack them next to each other.

Now you can create the gcode with standard 3-Axis software. The trick now is that you need to hook the 4th axis up as though it were the X, Y or Z axis, whatever you used as the rotation axis while preprocessing the model.
ShapeOko #367: Dual-Y drive, Belt on outside, 1000mm Y-Axis, DW660 Spindle, Nema-23 X/Y motors.

Primary developer on Universal Gcode Sender.

danimal
Posts: 332
Joined: Wed Mar 13, 2013 5:53 pm
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Re: Finally... 4th axis

Post by danimal » Sun Mar 30, 2014 4:59 pm

I use a G540 now for my controller so my plan was to take the 3D model and designate a rotational axis. Then create 4 separate gcode files for each 90 degree rotation. At the end of each file I plan on adding the A axis rotation then combining all of the files together. That should produce some decent results. I see what you are saying about the 1 degree rotations, but that seems a little out of reach for my programming abilities as of now.
Shapeoko # 1458

RT0701C Spindle || dual y motor || x axis nema23 with custom carriage 1000mm length || z axis nema23 linear rail upgrade with 1/2-10 ACME

PsyKo
Posts: 430
Joined: Thu Aug 30, 2012 8:42 pm
Location: France

Re: Finally... 4th axis

Post by PsyKo » Mon Mar 31, 2014 10:31 am

danimal wrote:Just for clarification, your method is to develop the model in CAD, then create 4 separate CAM files for 90 degree rotations of the object and manually rotate the 90 degree shift between running each of the gcode files?
Basically yes except that I do not rotate by hand. The toolpath for each 4 sides are merged in a single file (using CamBam) and GCode is manually inserted between the toolpath of each side to make sure it happens at the correct A position/angle.
Once started, the CNC will machine all the four side alone.

It also depend on you model. For instance I tried to mill a screw (just for the test). I simply wrote a G1 F1200 Y10 A1080 (to have a spiral making 3 turns around my cylinder)...
Will Winder wrote:The basic idea is to center your model along the rotation axis and take a 2D cross section of the model, split it along the rotation axis and take one half. Save the first half cross section for reassembly later. Now rotate the model slightly (say 1 degree) and repeat the process to get the second half cross section. Repeat for 360 degrees. Finally give the half cross sections a little depth and stack them next to each other.
That's the idea, but I'm using Cambam and doing it by hand is not very handy :) Maybe a script might help.
I tested a small script of mine that unwrapped the 3D model by calculating the position of each vertex in a cylindrical space, and using these coordinates in a orthonormal space. It looks ok but few problems occur :
- I need to slice the model so it can be properly "unfolded",
- The width of the tool is not constant in cylindrical space, so standard 3D toolpath won't give good results...

I think the CamBam team is working on 4th axis support, but I'm not sure...


Danimal, for the issues I encoutered :
- No CAM software for 4 axis machining,
- Difficulties to center my machine on the center of the 4th axis and align it to the XYZ axis,
- Not enough space below the X axis and the Spindle holder plate,
- No Home switch for the rotary axis. So you'd better not lose its position,
- Spindle holding bracket coming to close to the jaws of the chuck,

So a few stuff to think about :)

I recommend watching https://www.youtube.com/watch?v=RCrjBRDKLz4
Shapeoko #736
Kress 800, Z Axis upgrade, dual Y, 600mm X&Y rails, metal spacers and V Wheels, home switches, 4th axis
Goko - Free CNC Control Software - http://www.shapeoko.com/forum/viewtopic ... 380#p44380

mmorlan62
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Re: Finally... 4th axis

Post by mmorlan62 » Wed Mar 04, 2015 6:19 pm

Very nice custom axis. Any reason you chose this course rather than some Chinese offering on eBay?

I invested in a hobby license of DeskProto because of its access to 4th and 5th axis at a price far below any other solution. Note that its calculation of tool paths is fine for non-precision, organic shapes. If I need to design a precise tool path, I'll calculate that elsewhere. Deskproto can import some 2d/3d line elements and can be used to generate the tooling code.

Michael
Shapeoko 2 + Bosch Colt mount . PreciseBits ER20 1/8" & 1/4" collets . stock electronics in a custom control box.

PsyKo
Posts: 430
Joined: Thu Aug 30, 2012 8:42 pm
Location: France

Re: Finally... 4th axis

Post by PsyKo » Mon Apr 06, 2015 9:19 am

mmorlan62 wrote:Very nice custom axis. Any reason you chose this course rather than some Chinese offering on eBay?
Because I like building things :)
mmorlan62 wrote: If I need to design a precise tool path, I'll calculate that elsewhere
Did you already need on precise toolpath ?


Here is the result with Deskproto 6
http://www.shapeoko.com/forum/viewtopic.php?f=30&t=5349
Shapeoko #736
Kress 800, Z Axis upgrade, dual Y, 600mm X&Y rails, metal spacers and V Wheels, home switches, 4th axis
Goko - Free CNC Control Software - http://www.shapeoko.com/forum/viewtopic ... 380#p44380

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