Difference between revisions of "DIY CNC Router"

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(Misc)
(Electronics: Added Drivers sub-section and cleaned up a little)
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* Target motor: NEMA 23 stepper.
 
* Target motor: NEMA 23 stepper.
 
** Standardized dimensions: http://www.rhonmac-cnc.co.uk/Nema_23_drawing.gif
 
** Standardized dimensions: http://www.rhonmac-cnc.co.uk/Nema_23_drawing.gif
** Can be driven by RepRap Gen3
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 +
* NEMA 17 motors from Sparkfun?
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** http://www.sparkfun.com/commerce/product_info.php?products_id=9238
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 +
=== Drivers ===
 +
 
 +
Possible Solutions:
 +
* RepRap Gen3
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** Will drive all the motors
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** Arduino compatible
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* [http://www.adafruit.com/index.php?main_page=product_info&products_id=81 Adafruit Motor-shield]
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** Board can only control 2 stepper motors at once.
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* Home Grown
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** Lil' bit more research required
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*** http://www.cs.uiowa.edu/~jones/step/types.html
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*** http://ww1.microchip.com/downloads/en/DeviceDoc/21425b.pdf
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*** http://www.st.com/stonline/products/literature/ds/1373/l6201.pdf
  
 
==== Controller ====
 
==== Controller ====
  
* something arduino-based seems like it would be a good idea
+
Something Arduino-based seems like it would be a good idea
* I am not an electronics expert, but the [http://www.adafruit.com/index.php?main_page=product_info&products_id=81 Adafruit Motor-shield] makes stepper motor really easy to program. However, the board can only control 2x stepper motors at once.  If we maybe look into how the board works, we could probably work something up ourselves.
 
  
 
=== Software ===
 
=== Software ===

Revision as of 22:49, 6 October 2009

Overview

Make something similar to MakerBot but leaning more toward the 2D / routing / cutting aspect. Something that could concievably be distributed as a "kit" with open-source design, off-the-shelf or lasercuttable/makerbottable parts.

Project Members

Project Plan

Phase 1 - "Get something working"

Status

We have general sketches, but need to nail down some details, and prototype the CNC.

Outstanding issues

  • How will the motors and drive assembly be linked to the T-Slot frame? Custom parts may have to be made.
  • How will we achieve low-friction movement between axes constructed of T-Slot? Plastic skid plates, wheels, etc?
    • plastic, self lubricating skid plates.
      • less likely to be clogged by cutting debris
      • they are available as COTS (commercial off the shelf) parts
      • alternately you can procure blocks of the plastic and machine / carve your own
      • there are many low-tech alternatives that could be used. For example, I bet you could cut something out of wood with a hand saw and saturate it with motor oil -- good enough that you could then use the CNC to machine your own plastic plates out of melted down milk bottles or something..
  • What electronics should we use in prototyping? Should we purchase a set of RepRap electronics, or start with something simpler?
    • If there is something more simple than the RepRap controller available, we should look into it, but I am not aware of anything. The RepRap people already went through this exercise, with the exact same requirements - low cost, simplicity, etc.
  • What software package will drive the prototype?
  • What should be toolhead #1? Spring-loaded Sharpie marker?
    • Yes. A hexagon should be our first test drawing.

Parts List

Part Source Status Description
Frame COTS (Lubic) We have cjdavis' Lubic kit. Frame construction can begin. Hopefully we have enough pieces. T-Slot. Various lengths. Lubic is ~16mm square extruded t-slot aluminum.
Motors COTS (Mendelson's) Dave bought a set of 3 NEMA23 motors at Mendelson's. They are untested. Target motor: NEMA23 stepper dimensions
RepRap Gen3 Electronics COTS (MakerBot.com) Needs to be purchased. $175 http://store.makerbot.com/generation-3-electronics-mostly-assembled.html http://www.reprap.org/bin/view/Main/PartsSupplies
Threaded rods COTS (hardware store) Needs to be purchased. mcmaster: 98861A080 / 330mm Metric Thread Size: M8 (How many? What lengths?)
Skate Bearings COTS (skate shop or http://www.thebigbearingstore.com/ ) Needs to be purchased. At least 6, maybe 12. ( http://www.thingiverse.com/part:416 http://www.thingiverse.com/part:415 http://www.thingiverse.com/part:459 )
Nuts, bolts, washers COTS (hardware store) Needs to be purchased. Sizes: fitted to the threaded rods (M8), fitted to Lubic frame, fitted to NEMA23, fitted to electronics.
Belts, Gears COTS (??) Needs to be purchased. Lengths? Teeth?
Plastic skid plates COTS (??) Needs to be purchased. Number? Sizes?
Sharpie Toolhead Custom built. Not yet designed. Spring loaded Sharpie Marker. Detachable from frame.
ATX Power Supply COTS Several on hand already at Hive13.
Motor Mount Plate Custom built Not yet designed.
Bearing Mount Plate / "Pillow Block" Custom built. Not yet designed. Something like this: http://www.thebigbearingstore.com/pillowblockbearing.html
Captive Nut Mount Plate Custom built. Not yet designed. Something like this: http://www.garagefab.cc/user/albanetcsr/photos/captive-nut-angle
Electronics Mounting Plates Custom built. Not yet designed.
Endstop flags Custom built. Not yet designed.

Phase 2 - Redesign for simplicity, replicability

  • Reduce number of unique parts.
  • Reduce number of custom made parts.
  • Integrate open-source electronics, software packages (RepRap).
  • Refine toolhead interchangeability.
  • Document and publish design, instructions online.

Phase 3 - ...

  • Produce a product that can be purchased either as a kit you can put together over a weekend, or as a fully pre-assembled machine. A shameless copycatting of the Makerbot Cupcake idea is what we are after here.

Design of a CNC

Frame

I think it would be smart to try to design a frame that can be created using the CNC itself, so that it is self-replicating. DaveMenninger 15:32, 3 September 2009 (UTC)
Just like the RepRap, I think this should be a primary design goal, but I'll consider the first one a success if it can carve balsa wood :) --Cjdavis 21:27, 7 September 2009 (UTC)
What size cutting area are we looking to have? TP
I think I would shoot for 8.5x11 as a minimum. Hopefully more like 10x14 or 11x17 would be doable. The bigger, the better, IMO. DaveMenninger 18:35, 6 September 2009 (UTC)
We should base the design on t-slot aluminum extrusions.
  • There are a number of suppliers of them, many of which are compatible with each other.
  • If we handle the design correctly, simple steel box tubing could easily be used in place of the extrusions, which is available pretty cheaply anywhere in the world.
  • There are even linear motion parts for use with them that could remove a lot of design effort to start with - see ( http://8020.net/Application-106.htm ) from this page ( http://8020.net/Solution-8.asp ). However, I think this is probably too specialized a part to use in a long term design. We should at least have an alternative for people using box tubing for example.

Parts that need to connect to the frame somehow

Electronics

Motors

  • We need at least 3 stepper motors.
    • X-Axis
    • Y-Axis
    • Z-Axis

Drivers

Possible Solutions:

Controller

Something Arduino-based seems like it would be a good idea

Software

Toolheads

Should be swapable as quickly as possible. The Makerbot is pretty cool in that you can just disconnect a single cable and pull the entire extruder platform out (is that possible, or do you have to unscrew the extruder head first?) Wait, is that true? Can we just mount a tool holder where the extruder goes in the Makerbot?

Possible toolheads:

  • Ink pen
  • Rotary cutter (Dremel or router motor)
  • RepRap extruder
  • Laser cutter
  • Vinyl / paper cutter
  • Paint air gun

Parts

  • Step Motors:
    • The controller interface for the RepRap stepper driver board ( http://www.reprap.org/bin/view/Main/Stepper_Motor_Driver_2_3 ) has the signals Min, Max, Dir, Enable, and Step - with Min/Max just routed straight through to the opto boards. So it sounds like we could probably wire [the funky] motors straight to the motherboard, OR get the RepRap stepper drivers with more standard steppers - with little to no redesign needed. --Cjdavis 19:26, 7 September 2009 (UTC)
    • These motors might be appropriate for this project, esp given the target cutting area: http://www.automationdirect.com/adc/Shopping/Catalog/Motion_Control/Stepper_Systems/Motors_-z-_Cables/STP-MTR-17048 ($19 each, minus shipping). Depending on the tool, the Z-axis motor might need to be a little beefier than this. Nice bonus - they come cabled with reasonable connectors. Being basic 4-wire steppers, they should work with any driver system chosen. TP
    • I would suggest a trip up to Mendelsons, they literally have 2 Aisles of just assorted stepper motors. They are very assorted, and finding 3 matching ones could be a challenge, but it would save us shipping and we might find a good deal. Paul
  • Frame: I have an Aerocool Lubic 4480 computer case kit, which was basically a set of slightly smaller t-slot aluminum extrusions. I think they are 5/8" square if I remember correctly, and there are 12 of the longest pieces, which are ~18" long. There should be plenty of pieces for a full design. We can at least mockup the design with them, but they should be just fine for a fully functional CNC. The design should be directly transferable to use with any standard t-slot extrusion available.

Brainstorming Links

Best Links

Misc