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Author Topic: CNC machines  (Read 943 times)

bedlamite

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CNC machines
« on: September 03, 2013, 07:55:16 PM »
I know there's been some discussion about RepRap, but has anyone got a CNC mill up and running?

I just ordered motors, motor controllers, and a breakout board.

For Software, I've got LinuxCNC up an running on an older Sempron, and I've also got an older copy of AutoCAD I've been using for a few years. I'm looking at a few programs for toolpath generation: Freemill, PyCAM, and FreeCAD. Has anyone used any of these?
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Boomhauer

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Re: CNC machines
« Reply #1 on: September 03, 2013, 08:02:37 PM »
Get on Practical Machinist forum.

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DustinD

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Re: CNC machines
« Reply #2 on: September 04, 2013, 08:54:31 PM »
That and www.cnczone.com are awesome resources.
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Nick1911

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Re: CNC machines
« Reply #3 on: September 05, 2013, 10:53:18 AM »
I've thought about installing CNC on my mill, but never actually pulled the trigger.

What kind of mill are you using?

I'm curious how it turns out - please keep us updated with how the project goes.
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AZRedhawk44

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Re: CNC machines
« Reply #4 on: September 05, 2013, 10:56:13 AM »
Don't you need some sort of crazy-heavy platform for CNC milling?  Otherwise the vibrations knock your workpiece or even the whole platform around?
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Nick1911

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Re: CNC machines
« Reply #5 on: September 05, 2013, 11:08:08 AM »
Quote from: AZRedhawk44 on September 05, 2013, 10:56:13 AM
Don't you need some sort of crazy-heavy platform for CNC milling?  Otherwise the vibrations knock your workpiece or even the whole platform around?

Generally you start with a manual mill, and add servos, limit switches, etc to that.
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bedlamite

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Re: CNC machines
« Reply #6 on: September 05, 2013, 03:56:00 PM »
Mostly this is an exercise to learn how to do this. I'm building the frame from boxed 3/4" Sandeply, and it's moving on ABEC7 608RS bearings with 4140 precision ground square rails, and I'll be using a trim router. It'll have a fixed gantry and the x axis on a movable bed, y and z axis are similar to this.

It boils down to speed and precision cost money, and my goal is to keep the entire project under $500. Not ready for a Bridgeport, yet  ...
It should be able to cut wood, plastic, and soft metals, steel isn't going to happen. Part of me wants to make an AR15 lower out of walnut, just to bring to the arfcom roasted nuts shoot at some point.

Just got the tracking number for the motors and boards, UPS says they should be here Tuesday.
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charby

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Re: CNC machines
« Reply #7 on: September 05, 2013, 04:08:24 PM »
Quote from: bedlamite on September 05, 2013, 03:56:00 PM
Part of me wants to make an AR15 lower out of walnut, just to bring to the arfcom roasted nuts shoot at some point.


A company not far from where I live is already doing that.
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Nick1911

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Re: CNC machines
« Reply #8 on: September 06, 2013, 02:37:12 AM »
In machining, rigidity is everything.  When the cutter hits the work-piece very high cutting forces occur - if the frame isn't strong enough it will deflect resulting in loss of dimensional accuracy. 

This isn't to discourage you from the project.  Lessons learned can easily be applied to $1000 benchtop mills that can cut metal.  But... don't expect too much of it.  Proper mills weigh as much as they do because that much cast iron truly is necessary if one intends to hold tolerances expected of machined parts.

Good luck and have fun playing with G codes!
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