Saturday, January 30, 2010

And so it begins...

I originally wanted to build a nice desktop 3 axis CNC machine for milling circuit boards but after following the RepRap project and seeing a MakerBot in action I knew I just had to build a 3D printer. The trick was to build it with enough rigidity for accurate CNC machining in order to get the best of both worlds. I also wanted to use as many off the shelf parts as possible to reduce the amount of custom machining/fabrication.

The build area measures 150mm x 150mm x 75mm but since it is a modular design I will be able to increase the travel of any one axis without completely rebuilding the machine.

I quickly made a list of requirements:

3D printing
accurate CNC machining
swappable toolheads
modular construction
heated build platform
small footprint
low cost

When I'm finished building it I'll post an entire build tutorial on Instructables.


So here's the parts I've gathered so far-


 
These two 80/20 Aluminum extrusions will form the main chassis components- they're quite heavy.


















 
 

The electronics (stepper driver boards, motherboard, end stops, extruder controller) all come together as a package from the nice folks at Makerbot, as does the power supply. Eager helper not included....

















 
For motors I'm using some surplus NEMA23 stepper motors. These will drive the linear slides using timing belts and pulleys.

 
The linear slides are manufactured by Igus- they're very high quality and can handle high loads.
 
 


The machining spindle will consist of a Foredom handpiece driven by a DC motor. Motor control is provided by an old R/C speed control that will get a PWM input from an Arduino microcontroller. Electrical power comes from a salvaged PC power supply. Eventually I'll make a better quality spindle using an ER11 collet system and a more powerful brushless DC motor.

The extruder toolhead will be built using some parts from Makerbot combined with my own design nozzle assembly.

 

Control for the heated build platform will be done using a PID controller w/thermocouple. The build platform will also double as a surface mount soldering hotplate.

I still need to get the drive belts, some bearings for the belt tensioners and the aluminum for the build platform.

Stay tuned.... 


15 comments:

  1. Those are very nice linear slides. Did you find them surplus?

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  2. Those are very nice linear slide assembalies. How big are they?
    Did you find them surplus

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  3. I ordered the slides directly from Igus- I'll have part numbers posted soon. The slides have 150mm travel in the X and Y axis and 75mm for the Z axis.

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  4. One of the things that caught my interest in you inscrutable post, was the use of laminated plywood for the column. It got me wondering about stiffening a wooden CNC frame with laminates. Although different in scope from your projects, I thought that this builder did some interesting work with laminates as well as building a beautiful machine:

    http://lumberjocks.com/SPalm/blog/2271

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  5. A thought about your project:
    Having made the investment high quality slides, you might at some time want to consider closed loop servos over stepping motors. I love the CNCcookbook site. Its an increasable compilation and ideas and work. I don’t know where Robert Warfield finds the time to keep it so complete and actually build things and have a career too. He has an excellent article comparing servo and steppers here: http://www.cnccookbook.com/MTCNCStepperServoBacklash.htm

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  6. David,

    The first milling machine I made was a great learning experience- having said that I don't think the original plywood column I made was anywhere near stiff enough. I definitely like the laminate approach made on that website and I think it would be an improvement. Since the MultiBot is using aluminum extrusion for the chassis it should be much stiffer.

    I've had a very long long discussion with a machinist buddy of mine about closed loop servo motors and their benefits. The big problem is expense! I'll be curious to see how everything works out with the Makerbot electronics- time will tell....

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  7. Servos do look like a big part of the slippery slope in DIY CNC. Surplus steppers and the reprap board should be very good.


    I think you are very well served in building a rigid frame.

    I am curious if your rigidness issues with the plywood column were the column itself or its attachment to the base? I doodled a version of the column using large corner blocks to provide additional support. I also pondered a three layer composite base/ or torsion box where the column would be connect to the lowest layer and use upper layers as support...

    The way the world looks today I am likely 12 months away from building my first machine. So in the meantime, all I can do is sit back and ask a lot of questions to guys like you, doing interesting work.

    Thanks.

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  8. David,

    If I were to build another vertical column type mill I'd make a torsion box from MDF and then fill it with lead shot or concrete. That would go a long way toward eliminating vibration.

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  9. What happen to the Build?

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  10. Still working on it- there's going to be some good stuff pretty soon!

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  11. You do great craftsmanship.

    Very much interested in your spindle and motor. I am making a machine out of 8020 to cut foam sheets for RC planes and would like to put a spindle on that is quite as possible.
    Would be great if you posted more info on it.
    Thanks for the blog, got some good ideas from it.

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  12. Looks like this build died!

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  13. It hasn't died- it's just been in hibernation while I was buried with other work. Three kids and an insane work schedule will do that...

    My plan all along has been to finish it by the end of the year- it's going to be cutting it very close!

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  14. What sizes are the extrusions you are using?
    and When do you expect to complete this project?

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  15. I used 10S 1030 and 10S 2040 80/20 extrusions. Hopefully I'll have it done soon- I'm working on the extruder right now.

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