Monday, June 22, 2020

CTC DIY A8 printer - Part 2 - Setting it up


As indicated in Part 1, I assembled a CTC DIY A8 3D printer from a kit which I picked up on eBay for £80GBP. It has enabled me to explore the potential of 3D printing for my 16mm scale garden railway at reasonable cost and I am pleased with the results I've had so far. It isn't perfect - but considering the printer was substantially cheaper than many alternatives, I think it was well worth the outlay.

Part 1 covered putting the kit together, this part outlines how to get the printer up and running for the first time. As discussed in Part 1, the instructions lack some clarity in essential places so, if you are following in my footsteps, hopefully I can help you take your first steps.

There are several steps which need to be taken before the printer can be used for the first time - some of which do not seem to be covered in the instruction manual.

It is a good idea to preheat the bed and printhead before making adjustments, and it's essential before loading the filament. On the A8, it is quite a simple process.

Turn on the printer and after the LCD has displayed its welcome message the screen presents a summary of the printer's status.

Access the menu by pressing the centre button to the right of the LCD screen

Once the menu has been displayed,

..... use the lower button ......

..... to move the highlight (square) down to "Quick Settings" ....

...... and then press the right hand button to select this option.

This displays the Quick Settings menu.

Move the pointer (square) down to "Preheat PLA" and press the right button to select it.

This should then take you back to the main screen, only this time "Preheat PLA" is displayed at the bottom of the screen and you should see the temperature readings rising at the top of the screen .....

.... until the actual temperatures of the printhead and the printbed have reached their targets (190 and 55 degrees respectively).

NOTE: At any point you can move back to the previous menu by pressing the left button

Tighten the four spring-loaded screws holding the printbed to the baseplate until the printbed is about 1/4 of the way down each screw.

Slide the printhead carriage (on the X-axis) and the printbed (on the Y-axis) so the printhead is roughly in the centre of the printbed.

NOTE: If the printhead carriage and the printbed won't move, the stepper motors might have been actuated and so they need to be disabled - see Disabling the stepper motors below

Lower the X-axis by twisting the threaded rods on either side of the printed with your fingers/thumbs until the printhead just touches the printbed.

NOTE: If the Z-axis microswitch stops the left had X-axis plastic bracket from being lowered sufficiently, then slacken off the two screws holding the microswitch mounting plate and slide it downwards.

Measure the height of the left hand X-axis bracket above its stepper motor and make a note of the height.

Measure the same height for the right hand bracket and adjust it by twisting the threaded rod until it matches the height of the left hand bracket.

The printbed must be perfectly level to ensure the printhead remains the same distance above it when printing.

Move the printhead close to each corner of the printbed and adjust the spring-loaded corner screws until a piece of ordinary printer paper is just released from beneath it.

NOTE: You may need to go round the the bed doing the adjustments twice as the baseplate has a tendency to distort when the screws are tightened.

The next job is to adjust the Z-axis microswitch so detects when the printhead is at its home position above the printbed.

Loosen the two screws holding the Z-axis microswitch bracket so it can slide up and down.

Slide the bracket up until you can hear the microswitch click as it makes contact with the lower part of the plastic X-axis bracket.

NOTE: I find it easier to tighten the left hand screw first and then swing the bracket up and down slightly to find the exact point when the switch clicks, then tighten up the right hand screw.

NOTE2: It is possible to download and print out Z-axis adjusters from Thingiverse to make this process easier - eg

To move the printhead carriage and printbed manually, the stepper motors need to be disabled.

Access the main menu on the LCD display by pressing the middle button.

Move the pointer down to "Quick settings"

Press the Right button to select it

Move the pointer down to "Disable Stepper"

Select this with the Right button

If you haven't already done so, preheat the printhead for the type of filament you are using (see above)

The first job is to cut the end of the filament at an angle with a pair of scissors or snippers. Then make sure the last 10cm of the filament is perfectly straight. If it is not, it will curl up inside the extruder and miss the entrance to the printhead.

Next, release the tension on the extruder by depressing the lever section on top of the extruder with your thumb - it is a good idea to support the bottom of the extruder with your fingers so the carriage isn't put under too much pressure.

Feed the filament into the hole (beside your thumb). You might need to twist the filament if there is a slight bend in it so it locates the hole into the hot-end of the printhead. You will know when you have been successful because melted filament will appear out of the printhead.

Release the lever so the extruder wheel can grasp the filament.

To check the extruder is feeding the filament properly, access the main menu on the LCD panel by pressing the middle button.

Use the lower button to scroll down to "Extruder"

Select this option with the right button. From the next menu select "Extr. Position" with the right button

Use the UP button to feed the filament through the extruder (Yes, it's counter-intuitive but the Up button feeds the filament downwards and the Down button feeds it upwards).

You should see the filament oozing out of the nozzle when the up button is being pressed. If not, give the filament a bit of assistance by pushing it down into the extruder with your fingers. You might hear a clicking sound if the knurled wheel in the extruder is slipping on the filament.

If it doesn't work, you might need to disassemble the extruder and clean the knurled wheel - it can sometimes get clogged with plastic.

Finally, I feed my filament through the handles of a document clip attached to the top of the printer frame to help ensure it doesn't become snagged.

You can download and print-out various filament guides from Thingiverse if you fancy something a bit more sophisticated.

I have positioned my reel of filament as close to the height of the printer as is possible. At the moment this is on top of a couple of boxes on a shelf - eventually I will create something a bit more elegant!

Now you have finished setting up your printer, we come to the exciting part - printing out your first object.

First, you need to find an object to print out. I would suggest you start with something small scale. This helps you avoid disappointment if it doesn't work out, doesn't stretch the settings on your printer and overtax your setting-up arrangements and also won't keep you waiting too long until it's finished.

As my garden railway is 16mm scale and set in the 1930s, I opted for  something which might have been found on a platform during that era - a wicker pigeon basket.

Firstly, I went to the website and searched for 'Pigeon basket".

I then downloaded the files on to my computer and extracted them.

Once the files had been downloaded, I loaded them into the version of Cura which came on the CD included in the printer kit. When Cura loads, it might indicate that there is a more recent, more powerful version of Cura available but I discovered that the latest version won't run on the antiquated laptop I use in my workshop and so I have remained with this earlier version.

The model of the basket was far too large even for a 16mm scale railway and so .......

,,,,,, I selected the scaling tool (the middle icon in the bottom left of the screen). I worked out that the length of a basket in 16mm scale would be about 30mm .......

....... and so changed the Size Y dimension to 30

I next had to check that the settings were correct for my printer and the filament I was using.
NOTE: If you have the most recent version of Cura, you can select the settings for an Anet A8 printer.

It is important that you set the size of filament to 1.75 and the nozzle size to 0.4 (at the base of the basic settings)

You might need to experiment with the settings for the printhead temperature and printing speed to get the best out of the combination for your printer and the type of filament you are using but for now, try using the settings shown above.

NOTE: To help ensure the first layer sticks to the printbed, I would suggest using a Brim support.

Once you have done this, the software will tell you how long the print will take and how much filament it will use. Don't worry if your figures are slightly different to mine, I have been tweaking some of the settings in the background since I got the printer.

You now need to generate the slicing code used by the printer. From the file menu, select "Save GCode".

Save the file somewhere you will be able to relocate it and then save it or copy it on to a Micro SD card.

Once saved and ejected from the computer, the SD card needs to be inserted into the card slot on top of the motherboard on the printer.

Access the main menu on the LCD screen and select "SD Card" from it (with the right button)

Then select "Mount Card"

Next, select "Print file"

You may only have one file on the card initially, but if not scroll down until you find the gcode file you saved on it (in my case PigeonBasketAllClosed).

The display should now revert to the home screen, with "Printing" showing up at the base of it.

It might take a short while for the printer to start as the bed and printhead temperatures need to be adjusted to those required by the gcode for your object.

Once the printing has started, you will be able to watch in awe and wonder as it gradually takes shape on the printbed.

You can check the progress of the printing by seeing how much, in percentage terms, of the model has been printed so far.

If something goes wrong, you can abort the printing by either pressing the reset button in the middle of the motherboard or, less dramatically, by selecting "Stop Print" from the SD Card menu.

You can then send the printer carriage and the printbed back to their origins by selecting "Home All" from the Quick Settings menu. You might then want to disable the stepper motors if you want to re-level the printbed.

This may all sound daunting at first but you'll be astonished at how quickly all this becomes second nature to you.

Don't despair if, or rather when, things go wrong. With such a complex process, it's inevitable that something will go wrong at some point. I am rapidly collecting a box full of misprinted or part-printed parts. Rather than seeing them as failures I am trying to see them as learning experiences.

I suppose my most ambitious print so far has been two 3D printed diesel locomotives which I have coupled back to back as per Australian sugar cane railways. (See How I 3D printed a pair of diesel locos - pending)

I still have many ideas for the printer. All I need is time to implement them - but life keeps getting in the way!

There is plenty of information on the internet about how to get the best out of your printer. I've lost count of the number of forum posts I've read, web pages I've browsed through and YouTube videos I've watched on various aspects of the 3D printing.

I'm now on my third reel of filament and have made quite a few changes to the printer which came out of the box a few months ago. When I first floated the idea of investing in what must be the cheapest commercially available 3D printer with some fellow modellers on one of my forums, one responded, "Don't think of it as buying a printer, think of it as taking on a project". He wasn't far wrong.

Good luck and happy printing!

If you want to see what modifications I have made to my printer so far, see Part 3 - Modifying my budget 3D Printer - pending

Sunday, June 21, 2020

How I assembled my CTC DIY Anet A8 clone 3D printer

I recently purchased a CTC DIY A8 3D printer (often advertised as an Anet A8 or Prusa i3 clone) and struggled to make sense of the assembly instructions. I thought others in a similar position might find my experiences helpful, having now put the kit together and got it working satisfactorily.



I have long been fascinated by the concept of 3D printing but could never really justify the £500+ price tag, so when I saw a printer on eBay with a price tag of £69.99 I was tempted.

At first I was hesitant - surely at that price there must be a catch. I consulted a few members of the Garden Rails forum and the consensus seemed to be, why not give it a try as a sort of toe-dipping exercise. So I consulted the household authorities and was given the go ahead. A week had passed and the price had risen to £79.99 (and as you can see, two weeks later it has now risen to £92.39). I was reassured that it was coming from a UK supplier and so I wouldn't have to wait weeks or get stung for import duty if it had been sent direct from China. Three days later, a parcel arrived. It was a good job I had cleared it with the missus - its identity was emblazoned on the box for the world to see.

It was certainly well packed, but I was daunted by the sheer number of components - they weren't kidding when they described it as a DIY kit!

However, it was reassuring that they provided a couple of screwdrivers (and some Allen keys) ....

..... together with some assembly instructions in a Word file on a CD which was included with the kit.

As was suggested, I thoroughly read the instructions before tackling the kit. They seemed to have been translated from the original Chinese, maybe through Google Translate, so some of the phraseology was slightly obscure, but I felt the process was reasonably explicit and clear and so I set to work.

Immediately, I found that the instructions related to a different kit. The first three components described in the instructions were quite different to anything in the kit. So, I trawled the internet for something more suitable and discovered a video on YouTube depicting an employee of the CTC company constructing a printer which more closely resembled that in the kit.

However, the video was presented at double speed and omitted closeups at critical stages, so I was often baffled as to which components were being fitted, which way up they went and where exactly they were positioned. There were also a few differences between the components in the video and those supplied with the kit - as you will see below.

So, if you find yourself in a similar position, I hope this explanation as to how I assembled my printer will be useful. I made a few modifications during its construction and sometimes had to backtrack when I discovered I had made a mistake. Hopefully, I will help you avoid these errors.

How I assembled my printer 

The frame

The first stage was to identify the three main structural components.

Also needed were four M3 x 16 screws and four nuts.

The nuts were fitted into the two slots at the top of each side member. They are a very loose fit and so once inserted the pieces needed to be kept vertical to stop them from falling out (this becomes easier with practice).

The top piece of the printer was then slotted into tabs and screws tightened into the nuts using the screwdriver and fingers to hold the nuts in place. Note which way up the top piece faces.

Once both sides had been screwed into place.....

.... the front piece was identified .....

..... and similarly screwed into place with four M3 x 16 screws. Note: The two front pieces are symmetrical and so it didn't matter which way round they were fitted.

Next, the Y axis microswitch was identified (it has a Y tag on one of the leads), together with its mounting plate and two self tapping screws.

The switch was screwed to the mounting plate - note which way round it is fitted.

I then found one of the stepper motors with a cogged pulley, together with its mounting plate and bracket and four M3 x 8 screws with Allen socket heads.

NOTE: This was my first mistake. I hadn't noticed that the pulleys on the motors were different. The one on the left is the Y axis motor while the one on the right is the X axis motor. I didn't discover this difference until much later in the build.
Make sure you use the motor with the pulley mounted as shown on the LEFT!

 The motor was attached to the mounting plate as shown.

NOTE - The connector on the motor faces towards the larger part of the bracket - ie the base (something else I got wrong the first time!)

The rear of the printer chassis was then taken from the box ....

The motor support bracket was fitted into place first (M3 x 16 screws used throughout this stage).

...... followed by the motor bracket.

NOTE: The connector on the motor should be pointing towards the camera.

The mounting slot for the  microswitch was then identified ......

..... and the microswitch fixed in place.

The rear chassis member was then screwed to the uprights.

 The next stage was to construct the supports for the printer bed. The front chassis member for this was laid out .....

..... and the pulley and bracket assembly (mine was pre-assembled and in a packet).

The pulley bracket was attached to the front panel.

.... with M3 x 16 screws and nuts in the usual way.

Two rectangular retaining plates were then selected, together with eight M3 x 16 screws and nuts.

The plates were mounted on the ends of the front support  member

..... blanking off the holes for the spacer two rods. this is where the additional instructions supplied with my kit varied from those shown in the video. the video showed two long 8mm diameter threaded rods and six 8mm nuts and washers being attached to the large holes. if your kit includes four threaded rods then you need to refer to the manufacturer's video at this point.

Another two blanking plates .....

...... were attached to cover the 9mm holes .......

....... in the chassis back cross member.

following the appended instruction sheet, two smooth rods were then threaded into the holes in the middle chassis cross member and butted up to the retaining plates in the end members - as shown in the photo.

No instructions were provided as to how the front chassis member should be fixed in place - I can only assume that it was meant to be held there by the tension in the toothed belt running between the stepper motor pulley at the back and the pulley at the front. This seemed to me to be very unsatisfactory and so I decided to add my own timber strut linking the front chassis member to the middle chassis member.

A 229mm long piece of 34mm x 15mm pine wood was cut ....

..... to fit between the middle and front chassis members as shown. Initially, I screwed this adjacent to the pulley bracket ......

...... however, this proved to be inadequate to hold the side rods in place, and so later it was moved to be adjacent to the side rod and another 229mm long piece of timber was fixed beside the other side rod - as shown here. This greatly improved the rigidity and integrity of the structure.

Next, the two upper brackets for the Z-axis screws were located ......

..... and screwed to the top corners of the frame.

 The printbed

 The mounting plate for the printbed was tackled next.

 Four M3 x 16 screws and four nyloc nuts were extracted from their packs .....

 ..... and the four oval shaped belt retaining clamps fitted to the centre of the baseplate. These were left as a loose-fit at this stage.

 The four plastic runners were then bolted to the baseplate, mounted on their four wooden pedestals using M3 x 20 screws.

 The oval retaining plates ........

 ...... were then attached to the front and rear chassis members with M3 x 8 screws

 .... so they could be swung to cover the holes for the Y axis rods.

The polished rods were then slid into the holes in the chassis and through the plastic sliders on the base of the printbed baseplate.

The baseplate was slid back and forth a few times to make sure it was running smoothly on the rods. You might need to adjust the screws on the plastic sliders if you find any of them is binding on the rods.

The toothed-belt was then clamped under the baseplate ........

..... and threaded through the pulley on the Y axis motor ......

..... and through the pulley on the front of the printer .....

 ..... before being pulled tight, clamped under the other bracket and trimmed to length.

 NOTE: I found it was easier to slacken off the screws holding the pulley bracket on the front of the printer chassis before clamping the belt. I could then tension the belt by tightening the screws on the pulley bracket.

 Four M3 x 30 countersunk headed screws were then found, together with four wing-nuts and springs.

The printbed .......

...... was then attached to the mounting plate .....

....using the holes in each corner.

The Z axis microswitch

The z-axis microswitch .......

...... and its mounting plates were then located. The microswitch was screwed to the mounting plate ......

..... with a couple of short self tapping screws ......

..... and a couple of M3 x 12 screws were used (with washers which were not in the kit) .....

...... to mount the switch in the slots on the left-hand chassis plate.

If I had had more wing-nuts, I would have used them as this would make the adjustment of the microswitch at lot easier.

Z axis motors

The Z axis motors and their mounting brackets were located next ....

...... together with eight M3 x 4 screws and the Allen key needed to tighten them.

The motors were attached to the brackets .......

..... and the side-plates located.

The sideplates were attached to the brackets with M3 x 8 screws and nuts in the usual way.

The motors were then attached to the side members of the chassis ........

.... using more M3 x 8 screws and nuts.

The retaining plates for the vertical polished rods were then .......

...... screwed into place on the top brackets .......

.... and the rods slid down into place ........

...... threading the two X-axis plastic brackets on to them .......

..... before being held in place by sliding the retaining plates over.

The M8 threaded rods were then passed through the holes in the top bracket and screwed down into the threaded bushes in the plastic X-axis brackets.

The bottom of each threaded rod was then slotted into the ferrules on the motor shafts and held in place with the grub screws using the relevant Allen key to tighten them.

NOTE: At a later date, I flattened off the ends of the threaded rods with a file to help the grub screws hold the rods more steadily. I found rods tended to work loose otherwise.

The X-axis carriage and motor

The polished rods for the X-axis an the plastic sliders were then sorted out.

The rods were slid into the holes in the plastic X-axis brackets and the sliders put on to the rods.

The grub screws on brackets were then tightened with an Allen key .....

..... to hold the rods tightly in place.

The stepper motor for the X-axis (note the way the pulley is mounted) ......

.... was attached to the plastic brackets with four M3 x 20 screws.

 Then the printhead bracket was attached to the sliders on the X-axis rods using M3x20 screws ......

.... and nyloc nuts.

The X-axis microswitch ........

..... was screwed to the holes in the top of the left hand X-axis plastic bracket with self tapping screws.

The fan, cooling fins and safety grille ........

 ...... were loosely assembled with two M3 x 30 screws

The lower part of the extruder was carefully removed from its stepper motor (the spring can shoot off across the room!!) using an Allen key.

 And then it can be re-assembled using the two screws on the fan assembly to hold it back into place.

The broad-headed screw on the base of the printhead assembly was then unscrewed slightly .......

..... to allow the printhead to be slotted into the bracket on the X-axis sliders.

The broad headed screw was then tightened to hold the printhead in place.

Two M3 x 12 screws were screwed into the back of the X-axis slider bracket......

...... and a loop made at one end of the remaining piece of toothed belt, using a cable tie to fasten it together.

The loop was then passed over one of the screws on the back of the bracket ......

..... threaded around the toothed pulley on the X-axis motor ......

...... around the pulley on the other bracket .........

...... then tensioned and looped around the other screw on the back of the printhead bracket.

As with the other end of the belt, the loop was held in place with a cabe-tie.

NOTE: It is easier to thread the belt over the pulley if the X-axis motor is unscrewed, the belt looped into the space and the motor replaced.

The ducted printhead cooling fan .......

.... was fitted with its 3D printed nozzle .......

...... before being screwed to the front of the printhead carriage with two M3 x 10 screws.

As can be seen, the printer was now taking shape.

The LCD screen

 The LCD screen and its mounting plate, together with four M3 x 30 screws and 10mm plastic spacer sleeves were identified.

The screws were passed through the holes in the top chassis plate  and the spacers slid on.

 The LCD panel was then attached ......

...... and its backing plate slotted on.

The nuts were then tightened on the screws to hold the panel into place.

The Power Supply

The power supply was then extracted from its box, together with the relevant leads and mains socket.

Fortunately, the connectors are clearly labelled and so the leads from the socket were attached to the live (red), neutral(black) and earth(yellow) connectors on the left of the supply and the neutral and live output leads connected to the screws on the right - as shown below.

The plastic cover was then slotted over to help prevent electric shocks.

Three M3 x 8 screws and washers were found ......

 ..... but I was unable to find three holes in the right-hand side panel of the chassis in the right places for mounting the supply and so had to drill my own.

The power supply was then attached to the panel

 There was a square hole beneath the power supply which matched the size of the mains socket, but no holes for the screws.

 So, a couple of 3-5mm holes were drilled in the relevant places .......

.... and the socket attached with a couple of M3 x 8 screws and nuts.

 The Motherboard

The motherboard, together with four M3 x 20 screws, spacers and nuts were gathered together.

Fortunately, there were some holes in the right places in the left hand chassis upright and so the screws were threaded through and the spaces slotted on .....

..... and the motherboard screwed into place.

I decided to add some washers to avoid putting too much stress on the PCB.


Although this seemed initially daunting, it turned out to be a lot easier and more logical than I expected.

Firstly the two-pin microswitch leads were connected to the sockets on the right of the board. The plugs have lugs which correspond to slots on the sockets and so they can't be connected the worong way round.

The plug from the X-axis miroswitch went in first ........

..... followed by the Y-axis ........

..... and the Z.

Next came the thermistor for the heated printbed (BT) .......

..... followed by the thermistor for the extruder (ET).

Then came the four-pin connectors on the left of the board leading to the motors.

Firstly the lead for the motor on the printhead extruder (E motor).

..... which was then attached to the connector on the motor on the printhead carriage(again, it can only be inserted the right way round).

Then came the right hand Z motor ....

..... which was attached to the motor on the right hand side of the printer as it faces you.

The left-hand Z motor was connected next .....

Next, the Y-axis motor on the back of the printer was connected ......

..... to the board.

 And then the X axis motor which moves the printhead carriage to and fro .....

..... was connected.

The lead from the fan on the front of the printhead carriage ........

 .... was connected to the right hand socket beneath the X-Motor socket.

While the lead from the fan on the side of the printhead carriage ......

.... was connected to the left hand socket.

The two output leads from the power supply ..........

...... were connected to the power terminals on the bottom right hand corner of the board - making sure the polarity was correct.

The leads from the heated printbed ...........

....... were then connected to the BED terminals as shown.

And the leads from the hot end of the extruder ........

.... were connected to the remaining terminals.

The printer was now more or less ready for action (excuse the rather shaky shot, but it was getting quite late at night when this was taken!).

Before printing can take place, the printer needs to be set up. This is quite a long process but I have found from experience that it is important to make sure everything is properly done if you want decent prints. See Part 2 - Setting up the 3D printer (pending)

Given that I did not have the instructions, the assembly of the printer was fairly straightforward once I understood the function of the various components. It was difficult to decide on the orientation of some parts and had to back-track on several occasions however, dismantling was not difficult and so rectifying some of my mistakes was not to onerous. I suppose that having constructed the printer from its component parts has given me an awareness of the function of each and every part of the printer and I am already beginning to discover ways in which I can now enhance the quality of the prints which it produces by making improvements to the original design (see How I improved my 3D printer - pending)