MakerFarm 8" i3v Prusa build by Printbus

[gmay3]

printbus, good to see that you're taking you time and enjoying the build! I had a great time building mine, but it seems like you're having an ever greater time! haha

I'm intrigued by your led strip lighting on the bottom of your x carriage. I have the same strip lighting on hand and I'm very interested in seeing how yours turns out when the lights are on during a print!

[old man emu]

I'm intrigued by your led strip lighting on the bottom of your x carriage. I have the same strip lighting on hand and I'm very interested in seeing how yours turns out when the lights are on during a print!

I've fitted the same sort of thing to my printer. I'll post some pix tomorrow.

OME

[gmay3]

Awesome! Thanks OME!

[printbus]

WIRE ROUTING (PART TWO)

Z endstop switch wiring
Wires for the Z endstop switch were just dropped through the aluminum rail where they are bundled with the Z motor wires.



X Motor wiring
I fed the X motor wires to the other side of the printer through the top side channel in the lower X axis rail. A cut-to-fit slot cover keeps the wires in place. Sleeving extends from the motor to a few inches inside the rail.



X endstop switch wiring
Other than adjustment access, there's nothing magic about the X endstop switch being on the top side of the X axis. For the cleanest wire routing, I moved it to the bottom and fed the wires to the end of the rail using the lower side channel. The X endstop wires and the X motor wires combine into a single bundle that loops around to the back of the printer. Note that moving the endstop switch required the switch to move to the other side of the endstop block.

FOLLOWUP COMMENT: After increasing the length of the notch in the endstop bracket, moving the X endstop switch underneath also allowed the switch to located a bit more to the right than would have been possible up on top. This was helpful in working to achieve the full 200mm printable area in the X direction.



Extruder wiring
I used 3/8-inch sleeving over all the wires that are attached to the X carriage since 1/4-inch would have been a tight fit. The bundle is attached to the extruder motor using what I think is a spring contact from an old lamp assembly tore out of equipment eons ago. I could have used a cable clamp here, but would have to find an M3 x 45mm bolt to replace the 40mm one from the motor. The bundle of wires passes over the top of the printer. Immediately on the back side, the bundle passes through a Molex connector. The connector allows the extruder and cable harness to be removed from the printer. The current rating on the contacts should be more than adequate. (I'm in the process of reapplying the kapton tape and zip tie around the heater and thermistor wires - that's why they're not in the picture)

FOLLOWUP COMMENT: I didn't put the cable connector(s) at the extruder end since that would have added more weight to the extruder. More weight would mean more motor work is required to move the carriage around.



RAMPS Side View
Sufficient service loops were ensured for the X axis, Y bed, and extruder cables. Cable clamps used to ensure wire movements don't reach connector contacts, switch terminals, screw lugs, etc.

For misc low current 12v needs, I wanted something that was expandable to more loads and provided a means to easily disconnect loads when I wanted to do so. The 6x2 socket header is what I came up with using the parts I had on hand. In response to a later question, more info on this is here.

[printbus]

WRAPUP COMMENTS ON THE INITIAL BUILD

After completing about a dozen items and calibration prints, I'm pretty content with my decision to build the i3v. It appears to be very capable, yet obtained at the lower end of the price range for 3D printers without having to gamble on a crowdfunding effort. Yeah, I spent a lot of time building it, but I knew I would going in. Others have shown you can get an i3v functional without as much extra effort. For the long haul, I know I've got good support available at MakerFarm, and the parts are mostly generic and available elsewhere.

I found it extremely helpful for MakerFarm to have provided configuration files for Slic3r and for the electronics to arrive preconfigured with firmware for the i3v. This allowed me to get the printer up and running without having to fret over configuration and firmware download details that I wouldn't have understood at the time. I can now work through them as I learn more about printing and the i3v printer.

KEY BUILD POINTS
Expect to use the MarkerFarm build guide and build videos only as a guide. Don't assume they tell you everything. Think about what you're doing, and be ready to fill in the missing details yourself. Post questions on the board here or contact Colin. I only asked him two questions, and got responses quickly.

Watch for hardware fit conflicts. Some things won't fit if adjacent nuts aren't rotated right. I had some X carriage screw heads rubbing on the X axis extrusions, and had issues with the length of the bolts on several of the X carriage and X idler wheels. Several holes required elongating. This may be more personal opinion than fact, but work to eliminate any mechanical slop in the hot end tip when you have the extruder done. It seems to me that you can't expect good prints if the hot end tip isn't fairly rigid.

DESIGN CONCERNS
Here are my concerns with the i3v design, regardless of whether they're systemic to the Prusa i3 or specific to the MakerFarm i3v. While I call them concerns, remember I'm still happy with the i3v. Resolving these issues would make the thing pretty perfect as far as I'm concerned.

• Adjusting bed clearance with the Z endstop switch and a fixed spacer between the heatbed and Y bed at the home corner. What a pain. Leaving the endstop position alone and adjusting the heatbed height at all four corners is perhaps the best mod I did to the i3v.

FOLLOWUP COMMENT: Clough42 has been posting great things for the i3v on Thingiverse, including parts for a screw-based Z-stop adjustment.

• Lost capacity in the X axis. The X motor mounting plate limits how far the X carriage can move to the left. I had to get creative to find ways to allow the extruder to move farther to the right in order to achieve the specified 200mm range in the X axis. Why couldn't the X axis aluminum rails be a bit longer and the frame stretched a few mm to resolve this?
• Rinky dink approach to the Y idler that requires tinkering if you don't want the belt rubbing on the wood brackets. Issues here are exaggerated by misalignment between the Y bed belt mount and the Y idler. Why don't they line up better? The X idler design is similar, but at least there it's easier to adjust the angle of the bolt holding the pulley bearings as a belt adjustment.

FOLLOWUP COMMENT: A custom belt guide wheel has recently been added to Thingiverse, with an improved one at http://www.thingiverse.com/thing:790138. This would resolve the Y idler concern, and could also be used on the X idler.

• There are worrisome places I can see the wood plates flex. Pressing back on the Y idler front just a bit causes the Y belt to sag. If I manipulate the Z motor cases by hand, I can see the frame sidewalls flex. Maybe neither is significant, but reinforcements could have been readily added to prevent both. I'll also be watching for warping in the Y bed since it's always under stress from the heat bed springs.

[AbuMaia]

For misc low current 12v needs, I wanted something that was expandable to more loads and provided a means to easily disconnect loads when I wanted to do so. The 6x2 socket header is what I came up with using the parts I had on hand.
Attachment 1572

Could you post more details about this?

[printbus]

Could you post more details about this?

Here's an additional picture that didn't make the picture limit for the original post. A pair of heavier gauge wires from the power supply is fanned out to individual pins in a 5x2 configuration socket header - like you would use to plug onto rows of pins on a circuit board. Wire-wrap length header posts are broken into two pins each and used to provide connection between the 5x2 header and individual socket headers for each fan, etc. Wire wrap length posts are used since they are long on both sides of the plastic block holding the pins. A bit of CA glue can be used to attach the header post part to the connector going off to wherever. This isn't the most elegant, but I wanted something that was quick and easy to change connections at and had to be made from parts I had on hand. I didn't want to wait another week for parts to arrive before I could power up.



I'm always short on the socket contacts for these connectors. On a couple of things I've since added, I drilled out the holes in the 2-pin shrouds a bit so wires could pass through them, carefully soldered the wires directly to the short side of standard circuit board length header posts and then slipped the shroud down to cover the solder connections. A dab of glue keeps the shroud in place.

[AbuMaia]

Thanks. I think I may emulate that setup, with two header sockets, though. I currently have two switches on my printer, one for fans and one for lights, and this header socket idea will make connecting fans and lights easier, as well as leaving an open, easily-accessible place to add more if needed, as you said.

[printbus]

Thanks. I think I may emulate that setup, with two header sockets, though. I currently have two switches on my printer, one for fans and one for lights, and this header socket idea will make connecting fans and lights easier, as well as leaving an open, easily-accessible place to add more if needed, as you said.

Sounds like a plan. Another thing I liked about the header approach is that any extra, unused connections were well protected. No exposed screws on a terminal board, etc.

[printbus]

DISABLING POWER FROM USB
I've been one of those annoyed with how RAMPS stays powered up when the printer power supply is turned off but the USB cable is plugged into a host computer. A review of the MEGA2560 card indicated there's no jumper or other built-in means to change this. The board is designed so that if there is power on the USB connector, it will be used.

There's still a pretty easy fix for this - use a narrow strip of kapton tape to cover the 5V contact in the USB Type B connector that plugs into the RAMPS board.



Some USB interface designs require the 5V from the USB for at least the initial connection. The testing with the Arduino-type Mega2560 board in my i3v went OK without 5V being applied to the USB at all.

If you perform the mod, it might be a good idea to tag the cable as being modified in case the cable is reused for some other application later.

DISCLAIMER: The Arduino reference design for the Mega2560 board connects USB 5V to the UVCC pin on the ATMEGA16U2 USB interface chip. That pin no longer gets 5V with this mod, and the ATMEGA16U2 datasheet doesn't provide enough detail to understand what, if any, ramifications this may have. Also note that in a later post, a user observed erratic operation of his Auto Bed Leveling (ABL) servo with 5V removed from the USB cable, likely because the 12V-to-5V voltage regulator on the Mega2560 can't handle the extra 5V load from the servo. Implement this mod at your own risk.