3020 CNC 3D Printer Conversion Part 3: First Prints

 This weekend I finally got my 3020 CNC Router converted to a 3D printer setup. It was actually much easier than I expected! As I previously stated in my post on the MIB heater controller, I am using a conversion kit purchased from MIB instruments.

The kit did not include a mount for the spool of filament, so I grabbed some spare 8020 aluminum extrusion and fabbed one up. Also, the mount they provided to attach the extruder to the Z-axis carriage was not a direct fit because it was designed for a MIB 3020 machine, not the generic one I have. I don't like the way it mounts, especially that holds the extruder with only one bolt. This will have to be improved later. I also need to run the wires for the heater and thermocouple through the cable track. One important addition was a connector on the cable that was previously used to run the spindle. With this connector I can easily swap out the extruder head for the spindle again without running a separate cable. Then I just switch with port I'm attached to on the controller box (A-axis or Spindle).

The heated glass bed they sell is a standard 200mm x 200mm size. Again, the holes did not match up to my generic 3020 bed, so I had to re-drill them.

First and second print results of a 35 tooth gear wheel for a Harbor Freight 7x10 lathe. The original gear from HF is on the left in the first picture. The second picture shows the tops and the third picture shows the bottoms. The difference between the two prints was adjustments in the feed rate of filament and the temperature of the extruder nozzle.

I guess I need a post on my software setup as there is a lot missing as far as explanation for that aspect of this project. I am using LinuxCNC and Slic3r currently.

3020 CNC 3D Printer Conversion Part 1: Heater Controller

For the 3020, 3040, and 6040 series CNC Routers, there is a stand alone heater controller sold by MIB Instruments (based in China). This controller takes care of most of the necessary heating and monitoring needed to convert a CNC router to a 3D printer. The biggest problem I have encountered was that the unit was designed only for those who have an extra axis not currently used by their system. (i.e. A-axis) If you purchased from a cheaper reseller of the 3D routers you most likely do not have a compatible controller, at least without a little modification. These modifications will be discussed in another post. For now we will just discuss the heater controller made by MIB Instruments called the M3D-H2.

Here is a link to their website. They also have an eBay store where they sell all of their equipment.
http://www.mib-tech.com/
3D Printer page:
http://www.mib-tech.com/3d_printer.html

The "kit" is sold/advertised as a complete kit to convert your MIB Instruments 3020 CNC router to a 3D printer. It does not include everything you need, and the 2 components you do need to make a complete kit, are only sold separately on their eBay store.

Heater Controller & Heater Bed: (I paid $282.34, shipping included)
http://www.ebay.com/itm/321111260236

Filament Feed Stepper, Heater, & Thermocouple: (I paid $79)
http://www.ebay.com/itm/330943103747

I also purchase 2 1KG spools of filament. One PLA and one ABS so I can experiment with the different materials.

 

A dot-matrix LCD display is "glued" to the PCB. While this makes for a clean, single board installation, it's not so easy to replace if the back light goes out it you want to make any changes to the design.

 

I first impression was one of disgrace when I saw the hack-sawed heatsink that must've been pulled from a scrap bin. For the two most critical components on the board, the FET's that power the heaters, you would think they could put a little more effort into cooling.

The board is expandable. You could add two more thermocouples as well as 2 more heaters. I may throw together a schematic in the future to help explain this.

The microprocessor that controls everything is a PIC 16F866.

The thermocouple chip is a MAX6675 (U5).

A LM2575T (D3) switching regulator is used for ?

A IRF4905 (D8) ??? is used for?

A ND B1205S-1W DC-DC converter is used to isolate the control circuitry from the power circuitry.

 

The heater controller uses a 250W 24V switching power supply to power everything. Nothing special here.

I may revise this in the future, it's sort of a draft, but I want to get it posted and out there so you all can read it.

Upgrading 3020 CNC Router Cables & Connectors - Part 2

The track for the Z-axis was just a tad wider than the existing track, so I was able to use the same mounting brackets and tray. I am using the same cable and track as I did for the lower chain in the previous post. The only difference is this chain is a little narrower (since it only has to pass two cables). 0.41" x 0.79" instead of  0.41" x 1.18". I also only purchased 2 feet.
http://www.mcmaster.com/#55835k34/=q4lpi9 
See Part 1 of the cable upgrade for more links on the cables & chains.

All of the bends were tight with the cable, but don't strain the steppers, or impede movement.

There is a slight problem with the power cable for the spindle motor. Since it moves up and down, there needs to be a certain amount of slack in the wires. I had to add (after this photo was taken) about 3-4" of wire to give it the necessary range of movement. Technically there should also be some kind of cable chain to serve the motor, but on a CNC this small, it's hard to find anywhere to mount it that doesn't interfere.

All axes hooked up the the control box with the next connectors and shielded cables.

Limit switches are probably going to be my next project.

Upgrading 3020 CNC Router Cables & Connectors - Part 1

Why?
- EMF/EMI
The spindle is controlled using PWM and a high voltage. This can induce currents in the other wires locates close by.
- Low Quality Wire
CNCs see thousands...millions of repetitive motions. The wires will break at some point no matter how good. It's well known with these units that they ship with low grade wire that can have breaks after only a few hours of machine operation. I'm going to upgrade to wire/cable that is specifically designed for use in a CNC machine.

Cable Selection:
McMasterCarr - http://www.mcmaster.com/#catalog/119/802/=m38xy7
Manufacturer - http://www.igus.eu/iPro/iPro_01_0013_0021_GBen.htm?c=DE&l=en
Description:

• The bodybuilder of the wire world, this cable never gets tired of flexing. It has stranded copper conductors and is often used in cable chain and track for robotics, CNC machines, and material handling equipment. It has one green/yellow ground wire, unless noted. CE approved. Maximum continuous length is 100 ft. Note: The total number of conductors includes the ground wire.
• Shielded cable eliminates electromagnetic interference (EMI).
• 300-VAC Cable
• Has black insulated conductors with white sequential numbers.
• Shielded cable has tinned copper braided shielding.
• Standard—Good for general use; cable withstands periodic exposure to most oils and fluids. It has PVC-insulated conductors surrounded by a PVC jacket. Temperature range is 23° to 158° F. Passes FT1 vertical flame test. UL recognized and CSA certified.
• Oil Resistant—Handles continuous exposure to oil and fluid. It has TPE-insulated conductors surrounded by a polyurethane jacket. Temperature range is -31° to +176° F. Passes FT1 vertical flame test. UL and C-UL recognized.
• Heavy Duty—Made to last over 17 million high-speed cycles. It's oil, abrasion, and chemical resistant and has TPE-E (thermoplastic elastomer) insulated conductors surrounded by a polyurethane jacket. Temperature range is -40° to +194° F.

Required Cable Lengths: (approximate)
X-Axis -
Y-Axis - 26" or 65mm
Z-Axis -
Spindle Motor -

Total Length Required:

Cable Track:
McMasterCarr - http://www.mcmaster.com/#catalog/119/1531/=phqkmp
Manufacturer - http://www.igus.eu/iPro/iPro_01_0002_0002_GBen.htm?ArtNr=06.30.028.0&c=DE&l=en&aeartNr=060.30.12PZ
Description

• When space is tight, you need low-profile carriers. Snap-together links make length adjustment quick and easy. Join lengths by hand; use a screwdriver for dis-assembly. All are black glass-filled nylon. Operating temperature is -40° to 266° F. Compatible with this style of Igus carriers.
• Feed-through carriers require the cable and hose to be threaded through the entire length.
• Mounting brackets are made of black glass-filled nylon and have a built-in plate for strain relief. Fasteners for mounting the brackets to the surface are not included.

The lower, main track, requires capacity for 3x cables (X-axis, Z-axis, & spindle) while the upper track requires capacity for 2x cables (Z-axis & spindle). Depending on your spindle's current draw, you may find it necessary to double up on the wires you use (2x 18AWG for positive and 2x 18AWG for negative).

Length Lower Track:
Length Upper Track:

Connectors:

These obviously match the new panel I made in a previous post. They are decent quality and are definitely over kill for this setup. Best of all, they are metal, so I can ground them. I connected the shield of the wire to the connector itself so the entire cable's shield is grounded. I have not yet found optimal connectors for the stepper motor end of the cables.

Installation:

2" Wide x 1/8" Thick piece of flat stock cut to length. Drilled and tapped for M3 screws.

You could use a piece of angle bracket from a local hardware store. I used a piece of scrap aluminum from a power supply frame that I cut to size. I drilled and tapped the side arm of the CNC.

The tightest configurations looks to strain the cables.

So I gave it some more length even though it will not exactly be compact. Now the cables are nice and flat. Also there is less strain on the chain.

Final complete assembly of the primary cable chain. X, Z, & Spindle cables are run through it.

I will do another post (Part #2) on installing the secondary cable chain for the Z and Spindle cables.

YOOCNC T62-3AX CNC Controller for 3020T

Many people may want to add additional inputs and outputs to their 3020CNC, but not know how. In this post I will attempt to show others how one could possibly do this with their existing hardware. This eliminates costly (not that costly these days) replacement of the controller board (depending on what you want to do it may be worth upgrading your controller).

The YOOCNC T62-3AX is the controller board on my 3020T CNC. It has only XYZ axes (no A axis like other YOOCNC boards). There are no inputs being used from the factory other than the E-Stop. However, from my analysis of the PCB board we can add at 5 inputs and a single output channel to the existing board without much modification.

The board uses the EL 817 photo coupler as well as 74HC140 Hex Inverting Schmitt Triggers (for the outputs).

PCB Schematic/Routing:

 I tried to make this schematic/PCB design as close as possible to the original. It was drawn in FreePCB, and open source project. It's a great option to quick making quick circuits. Make sure to check it out as it functions very similar to PCB123. I might add more later to show additional options.

On the left you see the 5 photo-couplers that are unused with the exception of U25 which runs the E-Stop. Then on the right side you see U14, U24, & U10 which are an unused output. U4 is a photo-coupler which actually is not soldered to the board, so I would have to order one chip to make that functional. U14 & U10 are hex-inverting schmitt triggers that were mentioned above.

Some pictures of the board itself:

So that's on for now folks! I will follow up this post with the modifications of the circuit board to add my limit switches and possible spindle on/off control.