120mm Micron Build Log

[Le0n]

References

• GitHub - PrintersForAnts/Micron
• Kit - DFH Powder-coated White Micron
• Filament 1 - Fusion Filament’s Electrolytic Deuterium
• Filament 2 - Fusion Filament’s Mushroom Cloud Grey
• Octopus - Pinout, v2.4 Wiring Guide, 3DWork Guide

Upgrades & Add-ons

• Aluminum Bed - PrecisePrinterParts v0 Bed
• Stainless Steel Fasteners - West3D BDF Fasteners Kit for Mcron
• Titanium Backers - DFH
• Titanium Nut Bars - DFH
• Blue Manganese Flex Plate - DFH

 

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More accent parts.

 

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Lots of nuts. And main color prints.

 

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Organizing the Fasteners and Assembling the Rails

The DFH Micron kit comes with all the required fasteners, but in a mix of black oxide and stainless steel, and a mix of resealable zip pouches and tear pouches. With the colors I chose (Fusion Filaments’ Electrolytic Deuterium and Mushroom Cloud Grey), I wanted the lighter color of stainless steel so I bought a set of West3D’s “Best Damn Fasteners” for the Micron. They really are great!

Organize the screws. Left column contains West3D’s “Best Damn Fasteners”, sorted from smallest to largest. Middle column contains the stock fasteners from DFH’s kit. Right columns hold nuts, shims/washers, heatset inserts, etc.

Flush the rails and carriages with some isopropyl alcohol and use the itty bitty allen key to push a bit of paper towel through the rails’ grooves. Spray a bit of white lithium grease into the carriages’ ball bearings until they are all coated, but not sopping wet. Add a bit of white lithium grease to the rails’ grooves, and spread and coat the rail to prevent rust. Re-assemble the carriages and rails, move the carriages back and forth along the entire lengths to ensure good spread of the white lithium.

 

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Z Rail Assemblies

Align the MGN7 linear rails so that the holes line up to the nut bar. Add two M2x6 SHCS to the ends and lightly screw them in.

Attach the printed jigs to both ends of the linear rail and ensure they are flat against a surface. This will center the rail and set it ~36mm from the end of the aluminum extrusion.

Add the remaining screws. I like to start on the ends and work my way to the center, skipping every other one. In this case, the two in the very center both end up filled.

Slide in M3 nuts from both ends of the aluminum extrusion and secure the printed end stops with M3x8 BHCS.

 

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Assembling the Frame

Standard blind-joint assembly. Remember that the vertical members with the linear rails touch the table, and the rails are on the lower half.

Make sure to pre-insert any necessary M3 nuts as you go. It’s not possible to add them later without some disassembly. In my case, because (1) I’m using a v0.1 aluminum bed with 3-hole mounting and (2) using the leftover 10x11 cable chain from my Trident build, the amount of nuts will not match the manual. This is a good time to add nuts for future mods as well.

Now that the basic frame is assembled, this is a good time to check for squareness. For each face, measure the two diagonals to see if they are within 1mm of each other. For the bottom, check to make sure it’s not rocking.

The PrecisePrinterParts v0.1 bed that I am using has 3-point mounting, while the latest iteration of the Micron design has 4-point mounting like the v2.4. It’s possible to re-drill (there are even drill guides in the STL folder), but I only have hand tools and would prefer not to mangle it. Instead, I’m prepping these bed extrusions like the earlier Micron design, horizontally with a front printed piece to line up with the front mounting hole. A nice benefit is this horizontal mounting makes it compatible with Zruncho’s ZeroFilters.

 

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Z Joints

Insert the Igus KGLM-3 spherical bearings into the printed parts and secure each one with 4 M2x6 SHCS. These bearings can rotate in 3 dimensions and allow the gantry to adjust.

 

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Deck

These photos are showing the original design from the Micron STLs folder, but I ended up tweaking the design to center the hole within the ZeroFilters and reducing the corner cutouts for the belts to eliminate gaps.

As an aside, this is the perfect use-case for titanium white, which is infamous for horribly uneven sidewalls.

 

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Z Drive

I created a little 3.5mm spacer to set the proper distance between the two pulleys on the shaft. Holding the bottom bearing with the M5 shims is fiddly. You will keep dropping them and picking them off the floor until these assemblies go into the printed housings. The printed wheels are very easy to mount at an angle, which will introduce drift to the belt loop. Try to keep things square, and secure the grub screws in an X pattern to keep things even.

Testing the pulley assembly in the housing without the belt is a good way to see how planar the wheel’s rotation is.

Stepper motors' wires face in towards the Micron’s center.

 

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Z Drives (continued)

When mounting the motors to the frame, it’s important that the motor pulleys are parallel to the corner Z drive shafts. This will keep the belts centers on the pulleys. If they are canted, the belt will drift and rub against the pulley sides.

 

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Z Idlers

According to the manual, M3x16 BHCS are used to secure the two printed parts together, but neither the DFH kit nor the West3D fasteners kit came with any. Additionally, even M3x12 BHCS poked out a bit far through the nuts. I opted to use M3x10 BHCS and they look perfect.

The screws holding the bearings enters the printed part opposite the side with the frame notch.

Adorable.

 

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Z Endstop

There are supposed to be four M3 shims to extend the barrel. In my case, the screw is already short, so they are not necessary. I will use a bit of low strength thread locker later to set the proper height.

Update: I am sourcing a taller M4x5x20 chicago screw. The ZeroFilter mounting brace presses against the Fabreeko edge-to-edge heater bed and prevents the mounting screws from actually mounting. To solve this, I’m using some M4 nuts on top of the knurled nuts to give some more clearance and longer mounting screws, but the M4x5x12 chicago screw is too wobbly when extended to that height.

 

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Bed

This is a bed from PrecisePrinterParts. A few of the nicer features are the thermistor slot, indexing hole for flex plate alignment, and flatness within 0.02mm.

The newest Micron design actually uses 4-point bed mounting like the v2.4, but my bed has 3-point mounting. To get around this, I am using the bed mounting system from an older Micron design where the aluminum extrusions are horizontal and accommodate v0.1 beds. Plus, it works with ZeroFilters. Alternatively, you could use the included printable drill guides to make it 4-point mounting, without ZeroFilters.

To keep the thermistor from sliding back out, I added a dab of super glue. The datasheet says it should be able to withstand up to 275°F, so it should hold for awhile.

Installing the Graviflex magnetic sheet just like how Nero does it. Peel back a small section to align to one edge. Tack the adhesive down with even pressure from the center towards the sides. Peel back a bit more and tack it down. Repeat until covered and trim the excess.

 

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ZeroFilter

Here is where I ran into a couple of issues. The original deck’s center hole was not centered to the ZeroFilter, and moving the horizontal extrusions to make room for the parts pushes out the front mount for the bed a bit too far. I adjusted and reprinted both the deck panel and the front mount, and I added another brace to the front of the ZeroFilters to keep it all square and tight.

 

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Y Axis

There is a printed jig for setting the distance of the linear rails from the ends, but I found that with it’s curved inner corners, it was not accurate enough for me. I had to go back with calipers to nail the centering. The other jig from the Z rails is also useful here.

 

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X Axis

No fancy nut bars for the X axis. Just floating M3 nuts. Since there are a total of 8 holes for mounting, I did pairs with a blank in between.

Install the titanium backers on the X axis.

 

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A/B Idlers

If you look at the shims closely, you can see that they are punched out of a sheet and one side is smoother and the edges don’t catch. This is the side I prefer to place against the bearings. The rougher side will face plastic.

Its easy to get the parts confused. You’ll know you did it right if the SHCS heads on the tensioners (the accent parts) are on top.

 

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A/B Drives

After soldering the wires and directing them into the wire channel, they naturally form 90° bends. I’ll need to add heatshrink to reinforce the connection and zip tie this up somewhere for strain relief.

Maintaining the stacks while assembly the top and bottom together is pretty tricky.

Adjust the A pulley so that the teeth are centered against the top bearing stack, then loctite and tighten the grub screws.

Adjust the B pulley so that the teeth are centered against the bottom bearing stack, then loctite and tighten the grub screws.

 

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X/Y Joint Assemblies

It’s easier to get the parts to mate up if you give the screws some slack.

 

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Y Endstop

Inset the endstop 8mm from the end of the aluminum extrusion.