DIY CNC Router: Difference between revisions
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=== Drivers ===
=== Drivers ===
Revision as of 22:51, 6 October 2009
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.
Phase 1 - "Get something working"
We have general sketches, but need to nail down some details, and prototype the CNC.
- How will the motors and drive assembly be linked to the T-Slot frame? Custom parts may have to be made.
- Something like this: http://www.garagefab.cc/user/albanetcsr/photos/size-23-stepper-mount
- It would be optimal if we can design for any custom parts to be constructed of metal plate, because it makes it more feasible that they could be fabricated on a similar CNC machine.
- 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..
- plastic, self lubricating skid plates.
- 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.
|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
- 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
- skate bearings
- captive nuts
- driver boards
- endstop sensors
- atx power supply??
- We need at least 3 stepper motors.
- Target motor: NEMA 23 stepper.
- Standardized dimensions: http://www.rhonmac-cnc.co.uk/Nema_23_drawing.gif
- NEMA 17 motors from Sparkfun?
- RepRap Gen3
- Will drive all the motors
- Arduino compatible
- Adafruit Motor-shield
- Board can only control 2 stepper motors at once.
- Home Grown
Something Arduino-based seems like it would be a good idea
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?
- Ink pen
- Rotary cutter (Dremel or router motor)
- RepRap extruder
- Laser cutter
- Vinyl / paper cutter
- Paint air gun
- Maybe we can use the RepRap electronics or at least the stepper motor driver boards ( http://www.reprap.org/bin/view/Main/Generation3Electronics ) DaveMenninger 15:24, 3 September 2009 (UTC)
- Agreed. Unless there is another open source, currently supported and sold controller - that we already have a bit of familiarity with - using the motherboard and stepper controllers from the RepRap / Makerbot would make the most sense to me. The firmware will need customization, but I think there will be zero physical electronics redesign required. I'd suggest the full Makerbot Gen3 electronics kit ( http://store.makerbot.com/electronics/assembled-electronics/generation-3-electronics-mostly-assembled.html ) since we need everything but the extruder controller, but that could be used to build a second extruder for Dave's Makerbot. --Cjdavis 19:26, 7 September 2009 (UTC)
- 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.