3D printer build log

[jenschr]

Hi all,
I’ve played around with the idea of building a new 3D printer based on Makeblock for a while and now I’m finally started! I’ll use this post as a build-log for the project.

The plan

The idea is to build a printer based on the ideas in Lulzbot’s TAZ printer. The TAZ is basically the same as a Reprap Mendel 90, but it has a vertical X-axis for the print head carriage. My plan is to use a horizontal carriage (like on Mendel 90), but since I`m building it with Makeblock, it will be fairly easy to switch this later.

I’ll use only Makeblock parts if possible and anything that is suitable using just standard parts. This means that I’ll try to build all linear parts with the linear blocks rather than the typical LMU8 used in other printers.

I already have an Ultimaker & a Printrbot, so I’m not just building any old printer. The build volume should be huge (almost 30x30x30cm) and the hotend will be from E3D in the UK. The E3D hotend can reach the 260C required to print Nylon without melting. I can’t do that with the other two printers.

I got great help from the Makeblock crew getting hold of parts and the first thing I did was to build the main frame. It`s really quite solid! Here’s me standing on top of it in the Bitraf hackerspace lab.

After going through the parts and testing some ideas, I solved how to fasten the Z-axis (up/down) steppers and linear rails this first evening.

Here’s the frame before I attached the linear rails.

[jenschr]

Day 2

Today it was time to start on the Y-axis. I want it to be detachable for transport (like on the TAZ) and fairly wide so I can easily fit the build surface onto it. The first annoyance was that the two 24x24 beams will not fit perfectly hole-wise. Bummer. I`ll have to use the main holes on one side and then the center-slot on the other side. Both will work, but I had hoped for it all to align.

I didn’t have any beams that were wide enough, but I’ve joined some 8x24 beams in a way that looks good. Two nylon spacers at the end of the linear rails make these fit as well. Looks good!

In this picture you can also see the Z-axis steppers that I fitted the day before. Now it’s gliding, so next up it’s time to add the stepper that moves it. The first three designs I did for this, had a major flaw - they used the 18T pulley. No matter how I tried to force the belt stay onto the pulley, it still slipped

Now if I only had a slightly bigger pulley, this would not happen. The ideal would be a 32T pulley or something like that, but that’s not part of the Makeblock system (yet). The next size is the 62T pulley, but this one is missing pulley slice’s so I’ll have to use the 90T version then. Oh! I also have some of those new Nylon pulleys with bearings! Let’s see…

Yeah. This will work. Next problem - building a platform that clears these rods and pulleys. I soon realised that I didn’t have the most suitable beams at hand. I tried lots of variants, but this is the solution I settled on:

This will do for now, but I’ll need to change this a bit. Hopefully I’ll get some extra parts from Makeblock.no (my local reseller) tomorrow, but in the mean time I’ll work on the Z-axis. In the back, you can see the 30x30 cm wooden board that will hold the heater.

[Johnny]

Super cool! The frame is amazing! I have sent the log to our Chinese fans. All of them are very interested in your work. The huge printing space is very attractive.

As for the 18T pulley, the slipping seems an old problem…0.0 Can you try to install the stepper motor on the one side of the Z-axis and bulild a structure like the picture below? It would drive the platform on both side. And since it have more pulleys, It might solve the problem of slipping.

And I have got the LCD for Megatronics, You can check whether you need more parts. I will send to you together. Or It would be nice if you can get the parts from Makeblock.no – much more convenient.

Thanks! Waiting for the update:)

[geminicxw]

Super cool! The frame is amazing! I have sent the log to our Chinese fans. All of them are very interested in your work. The huge printing space is very attractive.

Amazing, it look very cool and attractive, I will share it with our friends. Waiting for the finished goods.

[jenschr]

Day 3

Today was a day for rethinking. I was unhappy with how complex and large the Y-axis (forward/backward platform movement) turned out. I basically kept trying out ideas all day and I actually didn’t get very far either. I gave up on solving the platform and started working on the Z-axis (up/down) instead.

During the first half of the day, I actually had to go pick up more screws and nuts. That’s a first! While out shopping, I picked up a meter long threaded rod from my local hardware supplier. This is basically a really long screw that you can cut to any length. I also found some 35mm long nuts that fit the 8mm rod. These are made for joining two lengths of threaded rod, but they’re basically just a long nut. I’ll hold this still so that when the screw is turned, it will move up/down along the threaded rod.

I used some plastic tubing and normal plastic strips to fasten the threaded rod to the stepper motor:

This is a fairly typical Reprap way of doing this. It’s flexible and cheap. I had ordered some “proper” 5-8mm CNC couplers, but they have not yet arrived. Maybe I won’t even switch to these when they arrive as the tubing seems really solid.

[jenschr]

Day 4

Today I simplified the Y-carriage quite a bit and with the help of some new 2424x320 beams, I got the platform just how I wanted it.

The hardest part was to make the stepper motor fit in the much narrower space. By lifting the whole Y-axis up 16mm and turning the stepper sideways, I found a very nice solution. I also changed to the 62T pulleys since I didn’t have room for the 90T one I used before. Since there’s no “slice” for this, I just modeled & printed some on my Ultimaker.

This setup for the Y-axis will allow me to add leveling screws at the bottom of the bed. Next was the X-axis. With this in place, I can start connecting the electronics tomorrow! After some testing the day before, I knew that I had to do some 3D modelling for this.

This is the first version and I’ll surely change it as I go along. I’ll publish the 3D model for this when it’s final, but it’s a very simple thing. It’s two pieces that wrap the 35mm nut. They go on top of each other and screw into the linear motion slider.

I had to cut off about 20mm from the 496mm rods to make them short enough so they can be moved up and down without hitting the outer frame. I’m currently printing a plate that will be 11x11 holes and that has a big hole for the extruder in the middle. That’ll go onto the 4 sliding blocks on the X-axis and I’m ready for testing electronics tomorrow!

[Perome]

That’s cool, go forward!

[jenschr]

Day 5

Today I got the electronics working and I now have an extruder setup that works. The electronics I’m using is called Megatronics 2.0. It is basically the same as the typical Ramps 1.4 cards you can buy very cheap, but Megatronics integrates everything on one single board (arduino, stepper drivers, power in/out, temperature control + more). In addition, it also supports up to 3 extruders.

The Extruder is now basically complete. I had to decide on using either an existing design or making a new one. I don’t want to spend too much time on reinventing the wheel, so I’ll use a normal Wade’s extruder that I’ll change to fit with the 8mm hole pattern of Makeblock.

Once I had decided on an extruder type, I had to get the other hardware required. I had the 608 bearings already, some screws and nuts, but I needed a hobbed bolt to pull the plastic through the extruder. Since I organise 3DP meetups at my local Hackerspace, I called up a friend that made me a custom 8mm bolt. He also helped me solve another problem - some new steppers!

It turns out that the Makeblock steppers are too weak. I can easily hold them back with two fingers, so that won’t work if you’re moving a heavy platform around. The extruder also needs a powerful stepper to work well. I’m now trying with some new 78N ones, vs the 40N ones I had. Here’s how the finished extruder looks with the new steppers:

Here it is from another angle:

The firmware that comes with the Megatronics board just beeps the buzzer & turns the steppers randomly. You also cannot connect to it with Pronterface or other software, so it must be replaced with your own version of the Marlin reprap software. Whenever you are bulding a non-standard printer as I am, you will have to create a custom firmware and then upload it using the Arduino IDE.

I’ve adjusted many of the settings in the Marlin software to fit exactly this printer. One of these settings are the dimensions. It looks like I’ll be able to get 32 x 32 x 35 cm (w/h/d) of build volume. Not shabby! These settings have to go into the machine’s firmware so it knows when to stop moving.

Josef Pruza has made a series of small web-based calculators that are really handy. To calculate the required Steps per millimeter value for the Z-axis, I just scrolled to “leadscrew driven systems”. To calculate this for the Y-axis, I used the belt-calculator. Very convenient, so thanks Josef! When I had all settings correct, it was time to upload the firmware.

I added an endstop on the Z-axis and tested that it all worked as it should. Apart from needing new steppers, the testing turned out well. The new stepper motors all have 5mm shafts, so I’ll need to solve that in some way… Now it’s time for the weekend and some other building projects outdoors!

[Johnny]

@jenschr, I post the log to reddit/r/3Dprinting. The people are very interested in your work. And they also have some questions to you.

3D printer build log(Day 5, keep update) • r/arduino

Looks good, man! What are you planning on using to adjust the belt tension? Are you going to do a heated print bed?

[jenschr]

Cool. I’ve replied, but it looks like it was posted to /r/arduino?

[Johnny]

Yeah, I have posted it to both channels.

[jenschr]

Day 6

I didn’t get much done on the printer over the weekend, but I re-printed the Wades extruder with proper 8mm holes that match up with the Makeblock system so that it mounted nicely on the 11 x 11 plate that the extruder rests on.

This day of the build was primarily about solving problems. The Lulzbot TAZ has the power supply & electronics bolted to the side of the printer. This is quite nice, but I had an even better idea - what if I could make it all fit beneath the build platform? I moved the Y-stepper outside the center to make room for the power supply. Looks possible?

My goal was to achieve 30x30x30 cm build area (27000 cm2) and I’m actually getting more than that along the Y & Z axis. By sacrificing two centimeters along Z, I could make it all fit beneath! I printed a couple mounting plates, but these are probably made much easier using a laser cutter as one solid piece. Here’s how it looked in the end:

I’ve also changed all the steppers to stronger motors. The new ones have a holding torque of 52N vs the original 40N. The improvement was noticable, but not too impressive. I pondered why and figured that maybe the typical A4988 stepper drivers didn’t deliver enough power? To check this, I ordered six of Polulu’s DRV8825 Stepper Motor Driver that can be used interchangeably on the Megatronics board.

The A4988’s are rated to deliver up to 2A when kept cool, but it did not seem like they delivered as promised. I’ve read reports about clone-chips not delivering the full amps. While I have not measured this, it seems likely as they didn’t even get hot. Using A4988 stepper drivers, the stepper that moved the Z-axis could be held back with barely no force.

The DRV8825’s really changed this. They do get rather hot (95-110C) and the IC’s on these are guaranteed original, but I have to hold really hard to make them skip steps. Another advantage is that the DRV8825 can do 1/32 microstepping, so they can position the motors even more precisely. They also have another major advantage - they are significantly more silent and that’s a very nice bonus if you do overnight prints. A drawback is that they do require cooling, so I’ll have to solve that in a permanent way.

I also received the metal-couplers (Z-axis) so when I swapped the steppers, I added them as well.

[jenschr]

Day 7

I sort of want to forget this day completely as I killed the Electronics today

I had positioned all the electronics nicely at the bottom of the printer, connected the hotend electronics, swapped the Y-axis stepper, shortened several cables to make it all look good… and then the Megatronics board just died. The FTDI-chip got really hot in just seconds - more than 100C! The same happened with either USB or 12V direct power connected, so I assume the FTDI chip broke down for some reason.

I looked over all the connections, stepper driver orientation, measured power sources… It all looked correct, but the board refused to register as a COM port on the PC. Not much to do other than getting a new one. I still don’t know what broke it.

The rest of the day I spent sourcing a replacement from a friend that had a Ramps 1.4 extra. Tonight I have it all connected again, so hopefully I’ll get the X-axis up and running tomorrow!

Here’s a (crappy) vid that shows the homing of the Y / Z axis:

[Johnny]

and then the Megatronics board just died.

OMG, I’m sorry for the accident. It’s very strange about the FTDI chip was burnt.

I have posted this to reddit(3Dprinting/Arduino/Robotics) and facebook. Maybe there are some people could help you get the reason.

[Johnny]

There is someone ask question on reddit:)

I read your blog about changing stepper drivers and motors. Are you sure you had the pots turned high enough? I have similar spec’d motors to the original ones and they can get hot and hold extremely well. I have the black edition with heat sinks and active cooling though.

3D printer build log (Day6 and day 7, keep update) • r/3Dprinting

[jenschr]

Day 8

Short day due to meetings, but I got the X-axis up and running. This is the axis that pulls the least weight, so I’m trying to use the original 40N stepper here, along with a 18T pulley. Curious to see how that goes once the printer gets up to speed…

Soldering headers / extending cables also takes quite some time, but it’s getting there. Here’s a short vid showing XYZ homing.

I also received a new set of the Megatronics electronics from Sainsmart. Sainsmart produces loads of hobby electronics at really low prices, but the quality can be varying. This one looked really dodgy and had soldering bridges on the FTDI chip, so I’m unsure how long that’ll last. I removed the bridges and then tested it. The board programs as it should, so I guess I’ll use and see how it goes.

[jenschr]

Day 9 - first extrusion!

Today was spent mostly on making cables. The two printers I’ve built before have both been nice, premade kits. You don’t think much about it when putting together a kit, but extending and making cables is a big part of the job. In a kit it’s all easy, but when you make it all from scratch, you have to first measure and cut all cables to the right length. If they are too short (like those on the steppers) you’ll have to extend them. Then you must solder and crimp each extension to protect against short curcuits. Along the way, you must not mix up what cables so it all looks like a rather colorful mess.

Here I’m using a clear shrinkwrap when extending cables in stead of the typical black one. I prefer this since it’s easy to inspect a joint later. I could of course just wrap some tape around this “cable spaghetti”, but it looks so much better if you pull a braided sleeve over them. These plastic “socks” will expand to let you pull cables through, but once you let go of them, they tighten up to make your cables look nicely organized.

Note how it looks like spaghetti going in and a nicely organized blue mesh going out as I feed the cables through the sleeve. Before doing this, I put a little bit of crimp on the tip of all cables so that they would not get stuck in the mesh of the sleeve as I pushed the wires through.

When all cables are the correct length, You’ll need to add some kind of receptacles. The most common one on Ramps-electronics are plain old Dupont headers. I’ve soldered and crimped maybe 50 of these thus far. It’s a tedious job, but it makes it so much easier to connect and reconnect and the result looks much better.

With cables made for the extruder’s heater, temperature, fan & stepper (10 alltogether), it was finally time to test it all. Here’s the first plastic extrusion!

As you can see, I need to adjust the power to the extruder-stepper, but a little helping hand got the plastic through. It’s a quick fix, but that can wait until I’m back on Megatronics instead of Ramps 1.4. I’ll try to fasten the bed next so that I can start printing actual models!

Note: it’ll actually be a few days until the next update as I’m tied up at the #ndcoslo conference for a few days.

[Johnny]

I like the sleeve! The cables are nicely organized by this.

It seems that the extruder was working very well in the video. Waiting for the first actual model!

[jenschr]

Day 10 - Printing!!!

To be able to print, I had to finish the build surface. I changed the moving platform so it’s not using the 2424 beams, but rather normal 0824 beams. This gave me 1,6 cm extra build height, but also reduced the weight of the platform a little. This is how my final platform base looks:

It’s completely stiff and square. Once I had the design of the platform locked down, I could start fastening the MDF board that I have precut to 30x30cm to the aluminium frame. I drilled holes and countersunk the screws.

I have some spacers, nuts & a spring that allows me to adjust the distance of the MDF from the platform.

You flip this around and take the screws through the platform base and then secure them with a wing-nut. Once the platform is in place, you cover the MDF with blue painters tape and you’re ready to go.

I’ll need to cut off some centimeters of the screws that hold the platform, but other than that it’s pretty much done. After a little more testing that revealed that I had inverted a couple of the axis, I was ready for the first print.

The audio isn’t too good on the video, but the first print failed when I connected a fan (1). Not sure why this disturbed the USB comms enough to cancel the print, but the second printed as it should have (2). This morning I did one at slower speeds and that looks even better (3) but it’s far from the quality I’m after.

As you can see, there’s quite a bit of “ringing” from the belts, even on the last print. I’ll tighten them, keep tweaking the settings and post progress here later.

[jenschr]

I’m just back from summer holidays with the family and have had some more evenings to tweak the output. The main build is finished, but I’ll keep updating this thread as I go along.

I’m now at a point where I feel the quality is “good enough”. It’s not perfect, but it’s a really good start. It’s not that apparent in the latest prints, but there is still some vibration in the printer that affects the prints. I’m not 100% sure of what it is, but I am sure that I will solve it over the summer. As can be seen from the image below, I’ve done lots of printing and this is only the ones I kept to show progress. Altogether I’ve probably printed this robot more than 30 times.

Here’s a list of what I’ve done to tweak the quality:

• All belts have been tightened. This required some minor changes in the design.
• I’ve experimented with cooling the print. This had surprisingly little effect, but I realised that the E3 hotend reports temperatures quite differently than my Ultimaker. The E3 hotend/thermistor combination requires at least 15C lower temp than the Ultimaker does for the same plastic.
• I’ve spent a lot of time adjusting the power from the stepper drivers. The stepper drivers as well as the motor itself will run hot if you apply too much power. When this happens, the print fails. If you don’t supply enough power, the print will slip I had to make a lid over the electronics that has a solid 50mm fan that cools the stepper drivers.

This is how it looks when the X-axis slips at the end of a print.

As you can see, it’s quite easy to identify what has happened, but it’s really annoying when this happens. The stepper should be adjusted so that it does not overheat, but still supplies enough torque so that the motor does not slip. Finding the balance can be a little tricky.

Right now I’m working on shrinking the carriage from 11x11 to 8x11 holes in platform size. The current Wades-based extruder is simply too big. I’m now making a small, compact extruder based on this design that uses a MK8 drive gear instead of a hobbed bolt. If this design works as well as planned, I’ll be able to add a second extruder similar to how it’s done on this Bokubot.