Project: FFF 3D Printer “Eta” Part 9

Hello, SUNDAY!

Whew, it’s been an unfortunately long time since my last post, I’ve had to move my base of operations and un-discombobulate everything, and much is still a mess. However, this move comes with it’s benefits, as now I have a dedicated areas for my computing, electronics, metal, resin, wood, plastic, and 3D printing work. This compartmentalization allows me to quickly finish tasks in any field, so I should be clipping along speedily henceforth.

On the topic at hand, Printer ETA is finally fully online and mechanically sound (for the most part)! I had to disassemble Eta to move it, so I used this opportunity to upgrade the X & Y axes with shiny new bearings and carriages, which now means I have more accurate and precise prints.

Here are the upgrades I’ve installed,


Printer feed is a sensitive area, and feeding dirty or dusty filament is asking for a jam. To fix this, I hacked together a rudimentary but very effective filament cleaner (could be used to oil it too :] )


New Y axis carriages, printed in ABS by my dear friend Balaji, equipped with 3 LM8UU each to counter the HBOT mechanism’s XY torque.


A new belt clamp, to allow me to remove/adjust the hotend without loosening the belt.


As much as I like to wave around my successes, I’m open with my failures, so that others may gain from it at the very least. Here, I miscalculated the offset between the two belts, leading to a bend in one side. Luckily, this did not affect print quality.

Moving forth, I’ve setup my printer on the bay window in my room. Even though my printer’s bearings and steppers are extremely quiet, I can detect it’s movements by placing my ear to the walls even a floor away due to it’s discreet vibrations transmitted through the building. Truly a highly advanced monitoring system.

Now that we’re done with the nerd stuff, we move onto seeing what I’ve been printing!

I’ve been calibrating and printing, and Eta’s functional enough at this point for me to simply select the print job and leave. That said, keep your eyes and ears on your printers, they apparently  suffer from separation anxiety and are prone to spontaneous self injury.

I’ve also  started using very watered down PVA white glue to coat the print surface, and I’m extremely happy with it. With plain heated glass, I had to amp up the temperature to get anything to stick, and even then, lines getting peeled off were far too common on even small prints. However, first coat of PVA I slathered on instantly fixed all of that, and parts detach perfectly afterwards. If I need to reapply the coating, I simply take the glass out, pour water over it, and scrub it after a few minutes, then reapply the coating with a sponge.

I’m looking forward to working on many projects using Eta, so keep your sensors scanning the horizon for more to come!

That’s it for now, but stay tuned, there may be additional posts flying in very soon!

Singing off,



Project: FFF 3D Printer “Eta” Test print Timelapse

Hello, Sunday!

We meet once more, this time to spectate the video of mine 3D printer, Eta, printing a tiny calibration cube.

It still has room for improvement, but what do you think?

Project: FFF 3D Printer “Eta” Part 8

Hello, Sunday!

So Eta was on hold for a while as I was awaiting a few parts, and where I left off last I was having hotend problems. It was a Chinese clone of the E3D v5 and it was jamming harder than an amateur jazz band, and I had to blowtorch solidified PLA out of it several times.

However, my grandfather, Jairam Thatha came to my rescue and brought me a E3D lite6 from America. The lite6 installed easily and worked like a charm, easily extruding PLA once calibrated. However, as you all should know, problems present themselves like hydras, lop off a head and two more shall sprout. In this case, it was Z axis wobbliness!

Project Eta (123).jpg

I used LM8UUs fixed into the Z axis bed platform with a little hotglue, so there was a minuscule amount of play in the fitting, but this meant that the platform could pitch back and forth about ~5mm. When the threaded studding rods lifted or lowered the platform, it would cause a slight variance in the height of the bed. Not by much, but I’m trying to lay down plastic lines 0.4mm thick, so a minute wobble is all you need for it to not work.

Hence, Once more, we venture into the fray! IE,  SJP road.

Having returned from SP road with flanged bearings, I set about installing them into place in Eta. They didn’t have many flanged bearings in stock, so I just about managed to get two LMK8UUs and two LMF8UUs, which works out fine for me.


I also had a small issue where the bowden tube & hotend cables kept flopping over, so I devised a highly sophisticated mechanical construct to keep it upright.



The flanged bearings nearly completely eradicated the the wobble, and while I was installing them I also straightened out the Z threaded rods by placing them against a pane of glass and gently rapping them while turning them to find the high spots. #highlyadvancedproblemresolution

I’m certain no one found the the double the in the prior paragraph. 🙂

Next, I spent a lot of time just banging about Marlin’s parameters, and trying to bludgeon the bed leveling code to work. No matter what I try, the Z axis kept getting muddled. I made a Z probe using contacts glued to the bed’s glass, and the nozzle itself as the contact, which worked splendidly as long as the nozzle isn’t covered with plastic. However, the leveling code itself is still non-functional. Any suggestions welcome.

I started Eta at the start of this year, just after the clock struck 0000, I decided to go over to my computer and resume some reading I was doing on 3D printers, and then I decided to go along and design and build one. 5 months, on and off designing and reading about them, and then 6 months buying parts, waiting on deliveries, and prototyping.

Finally, HenriETA, my printer, IS COMPLETED! nearly, at least. I still need to add-on a few parts, like a print cooling fan, but for the moment, it’s functional and that makes me happy. I’d like to thank my parents, Jairam thatha, all Indian online electronic parts stores, and the entire opensource community on the internet. Wouldn’t have been possible without all you guys =)

Stay tuned for the next post, which will have a talk about Eta over a timelapse of it printing a test object 😀

Singing out,



Project: FFF 3D Printer “Eta” Part 7

Hello Sunday!

I’ve been a bit busy repelling the fusillade that is life, with varying success. Those of whom live in close proximity to me may have experienced paranormal sounds and or mumbled exclamations emanating from my lab-cave, but worry not, its just me trying to get my printer online.

A Series of Iterative Incidents of Murphy’s Law

Where I left off, It was 4 weeks ago (Five weeks now, time really does fly), and I had just finished the physical construction of my printer. Most of it, that is. I started by installing the endstops onto the smooth rods. I used microswitches for the Xmin, Ymin,Ymax, and Zmax endstops, and an opto endstop for the Zmin, to ensure accuracy. As my system is a Hbot, I decided to use both min and max endstops to help prevent any accidental crashes.


I attached them using zip ties and strips of latex cut from surgical gloves,  to prevent them from slipping on the smooth rods.

All the wire I used was twisted for convenience, neatness, and signal clarity. Next, I began configuring the software tool chain for controlling my printer. I used Marlin, an open source firmware for the RAMPS 1.4 control board, Pronterface for direct printer control from my computer, and Cura for slicing.

Attempting to configure a printer is akin to teaching a baby how to move, and then trying to catch it as it bolts off the dinner table headfirst. Eta did ram her print head into the boundaries several times until I got it to understand which axes were which and which endstops applied to what, but it turned out all right with no damage.

MOSFETS and overthinking solutions

I spent a better part of my time planning figuring out how to power the obnoxiously large heated bed that I decided to use, due to its high rated amp consumption. 30A is no joke, and my lack of electrical engineering skills could very well jeopardize my printer, and possibly my continued presence in my house.

After much research, a good deal of headbanging and SP road trips, I finally settled on using three IRLB8743 Mosfets to switch the current to my bed. The RPF ‘fet on my ramps board was simply unsuitable for the task, so I didn’t even try it out in fear of combustion. I soldered the fets to a PCB, wired them up in parallel using thick housing wiring, added a 10k resistor to keep gate at ground, and slapped the largest heatsinks the shop had to offer on fets.

It’s pretty self explanatory what’s going on here. To all of those facepalming about why I’ve mounted a PCB in a metal box, its so that it is less likely to catch fire. The PCB is mounted on a biscuit of wood, and everything is fixed down. With zipties and hot glue. Clearly brilliant engineering.


A rough diagram I drew when I was visualizing how the mosfet circuit would be made.

Finally, I bolted down all the connectors, checked every joint and connection thrice, and finally turned on the 12v 50A PSU and activated the heated bed!

But nothing happened. Or more accurately, nothing bad happened. I ran the heated bed for several tests, it heated up properly, no melting, no fumes, nothing. The mosfets were room temperature even after running the bed for 30 min. I somewhat suspect that the heated bed is drawing approx. 14-18a, judging by ohm’s law and the PSU’s fan’s duty cycle. On the flip side, the system I engineered could possibly take up to atleast 60a at 12v.

Better more than less, I suppose.

More software tweaking was done, I installed the LCD control screen into a large box, and hooked it up as well. The fourth box as enough space for more additions as well, like an E-Stop button or arduino.

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Here we encounter another incident of Murphy’s law, where my computer decides to crash. Permanently. After a quick series of diagnostic tests, I decided to abandon the 14 year old PC, and instead use an old laptop I had laying around, so that was quickly solved. I like to use Linux mint for my lab computers, due to its lightweight, features and speed.

Worse congestion than a cold in Monday traffic

I’m using a e3D v6 clone, featuring an all metal body. I hooked up the hotend, bowden tube, and the extruder body, and started running configuration tests. The hot end heated up, fan ran, and everything was peachy until I tried to extruding plastic. The filament went smoothly in, and then the extruder gear began grinding like a lion with anxiety. I unwound the filament, and then tried pushing it through manually, and it kept hitting something inside the hot end.

If that wasn’t bad enough, thermal creep started, and the plastic melted in the colder part of the hotend, which is bad because that can’t be cleared easily. With my plastic firmly frozen in the upper heatsink, I was forced to disassemble the hotend to clean the jam, and use a blowtorch to burn out the filament in the heater block and nozzle.

This proceeded to occur with mildly different scenarios three more times. Finally, after the pneumatic press-fit joint proceeded to join the rest of the hot end in failing miserably, I decided that I need to take a short haitus from building Eta, while I wait for the replacement parts to arrive.

I estimate that I’m about 90% done with Eta, as I just need to install the new hotend, calibrate, and slap on the final safety features. Until then, I’ll be working on other projects, Comic con is approaching!

Signing off,


MiniMake: Benchtop PSU

Hello Sunday!

So as I’m working on Project Eta right now, I need a source of power while I’m prototyping. Historically, I’ve been using 9v batteries and AA battery holders to provide power while prototyping, but obviously, that is less than perfect as a solution. So I had a couple old computer ATX power supplies laying around, and I decided to turn one of them into a benchtop power supply, as these handy little supplies provide 12v, 5v and 3.3v in neatly regulated cables. This project takes less than a weekend to finish,  and presumes you have basic skills with soldering connections and a grounded understanding of how electricity works.



  • Computer PSU, 2nd hand works well, ATX preferred.
  • LED/bulb for indicator
  • Switches
  • 2.1mm plugs, screw fit connectors, crocodile clips, etc.
  • Heat shrink tubing & solder


  • Multimeter
  • Drill
  • Sheet metal snips and tools
  • Soldering Iron
  • Wire Stripper

On Choosing ATX PSUs-

Most PSUs should work ATX works well because they usually have a bit more headroom for circulation, and they’re the most common and cheap. It’s advisable to use a second hand PSU for this project, as long as it works. Some old PSUs require a minimum load on the 5v line in order to properly regulate the 12v line. This can be fixed by adding a resistor onto the 5v line, but at low current applications it shouldn’t be an issue.

Benchtop PSU (2)

Here’s my PSU’s specs, and I doubt I’d be reaching anywhere near the limits


Start by unplugging your PSU and leave it alone for around 15min, just in case the capacitors have any remaining charge in them. Remember to exercise caution and possibly even common sense while working.

Unscrew the 4 screws on the top of the box, and remove the upper shell. The PSU has two U shaped shells, one upper and one lower, which forms the body. The lower one has the electronics, fan, power port, and cables attached. If you want to paint your PSU afterwards, peel off the labels now, and give the upper shell a thorough scuffing with sandpaper, 120 should do it.

Now plan your layout for what you plan add to the box. I’m using 3 sets of crocodile clips, a 2.1mm jack for arduinos or the like, a 2.1mm port, a potentiometer, an indicator bulb and a power switch. You may want to adjust this depending on your anticipated usage, maybe using header ports instead of barrel plugs, your choice.

Use a marker or scriber to mark your layout, then use a drill to make the holes. Keeping a scrap of wood under the sheet metal as you’re drilling will prevent it getting dented or damaged as you drill. After drilling,  I used a pair of snips to cut a square hole for the main switch, and clean up the edges of the circular holes.

Benchtop PSU (3).JPG

Upper shell of the PSU, drilled and ready to receive the components.

After drilling the holes, give your box a gentle scuff of sandpaper to prepare it for painting. For my texture, I decided to go with hazard stripes, a lightning bolt and the word HAZARD on the top shell, and leave the lower shell as plain metal. I painted the entire box black with gesso primer, then I used 1in masking tape to create a diagonal masking pattern on the box. Using a paper cutter,  I cut out the details out of the masking tape strip, and then painted the entire shell lemon yellow.

Benchtop PSU (4).JPG

After the paint dries, peel off the tape, and behold your work. You can screw in your accessories at this point, I went with an old fairy light bulb for a mildly retro look, a potentiometer and a 2.1mm port.


Standard Pin layout for the thick wire bundle from your PSU, older PSUs use version 1, mine was v2

Next, we start the fun part, wiring. Observe the tangle of wires on your PSU, you’ll notice one thick bundle of around 20ish wires, and several thinner bundles. Use a wire cutter to cut the plugs off the thinner bundles. All the wires should be colour coded, although the colours vary depending on the manufacturer, but typically the yellow wires should be 12v, red is 5v and black is common. Use a multimeter to check just in case. Leave the PS_on, -12vdc, 5vsb and PWR_OK wires connected to the big plug for now, and cut all the 12v, 5v, 3.3v, and ground cables from the plugs as long as you can, pull them into the case and group them.

Benchtop PSU (5)

12v yellow, 5v red, ground black, 3.3v orange

Next, carefully observe which wires are PWR_OK, -12vdc, and 5vsb, and cut them from the plug. You can either snip these cables as close to the board as you can, or tie them up inside the case. The PS_ON wire is useful because when it is connected to ground, the PSU turns on. This cable is what we will connect to the power switch on the case. The 5vsb provides 5v dc at approx. 400ma even when the PSU is plugged in but off, so it can be used if you want to control the outputs with a micro-controller.

Next, we start soldering. I connected a ground cable and the PS_ON cable to the red main switch, and  I connected one of the 3.3v cables to my bulb, so that when the PS_ON switch is flipped the light comes on to indicate the PSU is live. Two 12v lines went to a pair of crocodile clips and a 2.1mm barrel plug. I used the potentiometer as voltage divider to control the power to one set of croc clips. I like to twist the wires around each other to keep them together, with a little ring of heat shrink at each end to prevent them unraveling. Remember to insert heat shrink before soldering!

Benchtop PSU (6).JPG

Once you’ve soldered all the wires you’re going to use, curl up the additional wires, zip tie them and push them to the side of the case. Remember, airflow is important inside the case to prevent overheating, so ensure that you haven’t blocked off the fan or its airflow path. Do a final test with a multimeter to check that all switches, plugs and wires function properly. Pull the crocodile clip wires out through the hole in the PSU case, and close up the case. Check that the tabs on either side of the upper shell properly align with the ones on the lower shell, and that its facing the right direction, and tighten the screws.

Thats it! Your PSU should be fully functional now, plug it in and give it a trial run. As a last minute feature, I glued a small strip of PVC foamboard (sunboard) to the rear of the case, and made some impressions in it so that I could clip my crocodile clips to it. This prevented the clips from accidentally touching and shorting out.

I hope you enjoyed this short MiniMake weekend project tutorial log, and I hope it was of use to you. If you’ve got any queries, please do leave a comment and I’ll reply as soon as I can and do consider sharing and subscribing for more weekly content.

Until next time,

Signing off,


Project: FFF 3D Printer “Eta” Part 6

Hello Sunday!

This project is the largest I have ever undertaken, and its goal is multifold. Besides the obvious benefits of having a 3D printer, it has taught me a lot of valuable information as a designer. The most recent lesson it taught me was how errors in the initial stages can result in compounded errors later.

3D Printer HBOT v47.png

Top view of ETA’s CAD model, Note the two motor mounts in the lower sides.

While designing the rough CAD layout for Eta, I placed the XY steppers on both “legs” of the H formed by the X&Y rods, as it should be. However, I later rotated all smooth rod axes vertically to facilitate easier access to the printing surface from the front. At the time, I didn’t think there could be any conflict, but after around 5 months when I finally finished making, aligning, and bolting down all the axes, motors and mounts, I realized that this arrangement meant that the motors were countering each other’s movement.

You done goofed.

Since both motors were on the same side, one of them turning would have prevented the other one turning in the opposite direction. To correct this, I swapped the motor on left with the idler mount diagonally opposite, which fixed the issue. The problem with large or long duration projects such as this is that you tend to sometimes lose focus of your original goal, or change a system without realizing its effects on another system.

Design life lessons aside, I’ve extended and linked up the cables from the hot end, and now all that’s left is to hook up the mechanical endstops, setup the heat bed, make the fail safe systems, create the secondary control board and relay board, and I’m done!

With the hardware section, that is.

Next up, the software, and how I’m attempting to control a 3D printer with a 15 year old desktop jury rigged into working order with string to hold it together. I’m running linux mint on that PC, so at the very least it isn’t too slow.

Signing off,


Project: FFF 3D Printer “Eta” Part 5

Hello Sunday!

The last few weeks have been busy, both on the academic front as well as the project front. I’ve done quite a bit of progress on Eta, primarily involving the mechanical aspect of Eta.


I ended my previous build log staring at a large pile of plywood cutouts. After sorting out the pile, I started assembling the bits according to my design. It started with the extruder, which is based off a collection of  spring loaded direct drive extruders.

I also modified it by adding using a single hole to mount it onto a hinge, which was them bolted to some support plywood. This structure essentially allows the entire extruder to rotate along two axis as the bowden tube moves. In theory, this should keep the friction or constriction of the tube down, and prevent any dislodging of said tube. It isn’t fully balanced, but I’ll design a proper gimbal mount for it once I get the printer working.

Z Axis and Carriage

So Eta has a vertically mobile heatbed, and the extruder moves in the XY axises. 4 8mm support rods align the carriage, and 2 threaded rods on stepper motors hold it up. Originally, the plan was to have the stepper motors on the ground end of the axis, but space constraints made me place them on the upper side instead.

I drilled 15mm holes in the bed for the LM8UUs, and 13mm holes for the Z axis nuts. Since the nuts were hexagonal, I took the average distance between the tips & flats of the hexagons and drilled a hole in that diameter. I then broached the holes using the nuts themselves and a hammer, using two nuts in each hole to counter backlash.

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Y Axises, Carriages & Stepper mounts

This took the most amount of work, I’ve assembled, adjusted and fixed the stepper motor mounts and motors, the idler pulleys, X carriage, Y carriage, and the X and Y axis rods.

The stepper motor mounts are straightforward, an L shaped plate with the stepper mounted in the middle, supported by small ribs. A limited amount of adjustment can be made using shims under the bolts. The idler pulley mounts are identical, except that they have an additional support structure which goes over the pulley. All four were assembled, leveled and bolted down.

Project Eta (70)

Next I assembled the Y axis carriages. I’d made the upper parts of  solid wood using a drill press to ensure accuracy, and added a support to fit the pulleys to below.

Project Eta (69).JPG

V2 Y carriage

After testing however, I noticed several discrepancies between the Y carriage pulley placement and the X carriage. After extensive debugging, I discovered that the fault was the result of a miscalculation in my CAD design, and a machining error when I was making them. The errors meant that these Y blocks were a failure, and I’d have to make another pair. However, it takes an entire day at my college workshop to properly make these, and I am short on time, so I instead opted to modify the blocks.

I sliced apart the glue joints holding the plywood support frame onto the solid block, and measured the upper side of each block. I flipped both carriage blocks vertically, so their smooth sides pointed downwards. I drilled the holes at the correct distance, and cantilevered the pulleys on screws and washers. The threading in the wooden block is reinforced with superglue soaking into the wood.


Y carriage blocks V2.5

The new blocks hold up to preliminary examinations, so I hope they’ll work well until I get proper blocks printed.

X carriage, and support rods

The hot end mount block is relatively straightforward. It consists of two symmetrical parts clamping onto a hot end and riding on a pair of LM8UUs. The rods themselves are fixed into the Y carriages.


The X carriage has an opening on the right to allow the belt to pass, and clamps the belt on the left.

Originally, I had planned for the X axis rods to measure 40cm, but due to the prior mentioned error with the Y carriage blocks, I mistakenly thought that I had miscalculated the length, and had another pair of rods cut. It was only when I was adjusting the setup that I realized my error and swapped out for the older rods.

To align the After a lot of careful measuring, modifications to the Y axis support biscuits, and tender, loving adjustments with a sledgehammer, I got the XY axis fully setup.

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At this point, all 5 stepper motors are in ready, and all that’s left is to add on the belt, tubes, wiring and finer details. Stay tuned, as next week will feature testing out more electronics, and the possibility of having to use a decade old fire extinguisher in case the need for sudden fire drills arise!

Till then, Toodle pip, and thanks for following my development.

Signing off,