CTC Bizer Dual Nozzle

CTC 3D PRINTER "BIZER" WITH DOUBLE NOZZLE

Model	Bizer
Sometimes Called	CTC Bizer CTC Creator Dual CTC FlashForge Dual CTC Replicator 2
Lineage	Clone of FlashForge, which is a clone of MakerBot
Company	Zhuhai CTC Electronic Co., Ltd
Website	http://www.ctcprinter.com/
Official Manual	http://www.ctcprinter.com/u_file/images/16_06_29/33bca69ddb.pdf
Printable Upgrades	http://www.thingiverse.com/gaehl/collections/ctc-upgrades
SD Card Contents	CTC_SDCard_Files.7z 423M (as of August 2016)
Case Material	Wood
Input Voltage	AC 110V-230V
Output Voltage	DC 24V
Ports	USB2.0 type B, SD Card
Touch Screen	No
Printer Dimesion	320 x 467 x 381mm
Buidling Size	225 x 145 x 155mm
Packing size	565 x 430 x 535mm
Layer Accuracy	0.1mm-0.5mm
Positioning Accuracy	XY axis 0.011mm
SD Card Filesystem	FAT16, FAT32
Input File Types	gcode (USB), x3g (SD card)
Extruder Model	MK8 dual nozzle
Extruder Type	Direct drive
Extruder Barrel Liner	PTFE (teflon), Length: 33.5mm, InnerDiam: 2mm, OuterDiam: 3mm
Extrusion Nozzle Flow	About 24 cc/hour
Nozzle Diameter	0.4mm
Recommended Nozzle Moving Speed	35-40 mm/s
Print Material	ABS or PLA with 1.75mm diameter filament
Drawing Software	Rhino3D, Proe, 3dMAX, CAD, UG, Soliwork, SketchUp (with STL plugin)
Slicer Software	ReplicatorG, west to CTC Chinese Version, Makerware Desktop
Board/Chipset	Makerbot MightyBoard (Chinese Knockoff) (MEGA 1280)
Firmware	CTC Creator 1.0 (can be upgraded to Sailfish)
Stepper Motors	RB Step Motor 17HDC1031-20B
Stepper Motor Dimensions	body: 42 x 42 x 33.8mm, rim: diameter 21.95mm x depth 1.7mm, shaft: diameter 5mm x length 18.2mm x face depth: 0.4mm
Stepper Motor Drivers	+5V in
Fans	40 x 40 x 10mm; 2-pin DC 24V 1.44W
My Slicer Settings	MakerWare v3.9.2.1357 Download (as of 6/21/2018)

The biggest problem with this printer is the lack of documentation and part numbers! I am going to try to document as much as possible here.

Product Review

My Experience

In the least words possible, I would describe the CTC Bizer as frustrating at times, yet an excellent learning experience and a great printer in the end. When I started shopping for a 3D printer, I was debating whether I wanted to build my own and learn a ton about 3D printers, or buy a pre-assembled printer and get to printing things immediately. I discovered that the CTC is a great compromise between the two extremes. It comes pre-assembled and allows you to start printing after a few hours of tinkering, but it also has faults that force you to upgrade it and learn more about the inner workings of a 3D printer.

Pros

Heated bed
Decent print quality
Prints ABS or PLA
Dual nozzle
Highly customizable
Cheap

Cons

Stepper motors don't last long
Doesn't come with tube or filament guide
Spool holder is terrible
Static electricity causes failures
only takes .x3g format files from SD card
Print bed is not sturdy
Y-axis has some wobble

Upgrades

New Stepper Motors

Here is the data for the replacement stepper motors I got for the extruder. An important thing to note is that they are longer in the back, and so they were getting caught on the bolts on the backplate of the print bed. I replaced the bolts with washers and countersunk bolts that do not protrude as much. Also, the new motors are about 50% heavier, so it's like adding a third motor. I was getting backlash, resulting in sloppy prints. I could possibly compensate for it in software, but it will probably also cause more wear and tear over time, so I removed one of the motors and replaced it with a plastic frame. I never used the second extruder anyway.

Motor Specs
Model	Minebea Motor Manufacturing Corp. P/N 127K 40287 17PM-K402-P4V No. T9Y06-02
Current	Up to 1.4A
Voltage	Up to DC 36V
Step Angle	1.8 deg/step
Holding Torque	5.5Kg.cm (76 oz-in)
Connector	6 wire uni-polar or 4 wire bi-polar
Pinout	PIN1=B-, PIN2=COMMON, PIN3=B, PIN4=A, PIN5=COMMON, PIN6=A-
Dimensions	42 x 42 x 44.6mm, rim: depth 1.9mm x diameter 21.95mm, shaft: length 20mm x diameter 5mm, shaft has no face
Mass	322.3g
Comes With	GT2 2mm pulley (teeth count 25), Connection wires, Anti-vibration mounting bracket

So far, I've only needed to replace the motors on the extruder. The X, Y, and Z axes are still going strong. It takes a surprising amount of force to push the filament through the hot end.

Original Motor:

New Motor:

Extruder Mod:

Problems

Extruder Motor Clicking

Almost everyone who buys a CTC experiences extruder clicking. This happens when the stepper motors are missing steps. There are many reasons this would happen, but with the CTC the answer is simple:

THE STOCK STEPPER MOTORS ARE JUNK!

Like most of the parts in the CTC, the stepper motors are generic, undocumented, Chinese made rip-offs. They don't have the torque to do the job and they wear out very quickly, rendering them completely useless. Most people who angrily return the CTC do so because of this problem. I, personally, got about 20 small/medium sized prints (about 0.5 kg of filament) before the motor was wrecked. I never used the second extruder, so I swapped the motors and got another 20 prints out of it.

I initially found that I needed to print at excessive temperatures to extrude consistently: as high as 240C for ABS. This reduced the quality of my prints. I bought new motors (see New Stepper Motors) that were larger and heavier than the old ones. I found that they were too heavy to have two of them installed. This wasn't a problem for me because I never used dual extrusion anyway. I removed one of the motors and replaced it with a custom cowling and a fan to keep the other motor cool.

The new motor tends to get hot and the stepper drivers on the CTC do not have any way of adjusting current. Another crappy thing about the CTC is the the pinout for the stepper drivers are backwards, so you can't just buy different drivers and install them straight into the board. You would have to install them upside-down, but there is no room for the heatsink because there are some capacitors on the main board that are in the way. So you could install them with some kind of riser, but then the drivers would be sticking out of the bottom of the printer. You would either need to cut out a bit of the bottom panel, or just not use the bottom panel. Then there's the matter of cooling. You would have to mount the fan in a very awkward position to cool the drivers. It's just a mess; I opted to keep the original drivers and add a cooling fan to the extruder motor. It has been working fine for over a year.

Factors that contribute to wearing out the motors
Problem	Solution
Filament tension; requires too much torque to pull the filament through	Find a way to mount the filament spools above the printer to lower the filament tension. Use a spool holder with bearings.
Temperature too low	Raise the temperature until clicking is less frequent (don't go above 240C)
Nozzle clogged	Remove the nozzle and barrel, remove PTFE liner, soak nozzle/barrel in acetone for 5 minutes (closed container that won't dissolve in acetone), clean with q-tips, clear nozzle opening with small wire or guitar string.
PTFE liner is warped/split	Replace with new liner (L 33.5mm, ID 2mm, OD 3mm)
Printing too close to bed	Adjust the gap between the bed and the nozzle.
Over-extrusion: flow rate is too high	Reduce the extrusion rate in your slicer settings.
Printing speed too high	Reduce the printing speed in your slicer settings.
Filament diameter is not set properly in software	Don't believe the label; measure the filament with good calipers, measure it different places and directions, enter the averages of the diameters.

Filament Tension

You need to make sure that the filament is able to move freely enough so that the extruder can pull it through without slipping. If it's too difficult for the extruder to pull the filament, you can try putting the spool on a holder above the printer. When you pull filament from below the spool, it's much easier on the extruder and the spool tends to turn more consistently. If pulled from above, the spool will sometimes suddenly rotate because of uneven weight distribution. This causes the filament to become loose, slip off the spool, or get tangled.

For my CTC I ended up using this spool holder from Thingiverse (link).

You can put the spool on bearings, but I have not needed to do this. It's better for the spool to rotate on a steady axis instead if just hanging on a bar. Be sure the bearings still have some resistance. If the spool turns too freely, the extruder might make the spool unwind when it tugs on the filament.

Extruder Slipping/Grinding

Extruder slipping is when the drive gear starts eating into the filament and can no longer pull it through. This can be caused by several things:

Clogged nozzle

Solution: clean the nozzle and/or replace the PTFE liner.

Nozzle heat too low

Solution: Make sure your heat setting is high enough to melt the filament quickly.

Nozzle heat too high

Solution: Lower your heat. If nozzle heat is excessive, the filament can become molten too far up into the cool end of the extruder and the drive gear will eat into the soft plastic.

Inadequate extruder cooling

Solution: Get a better fan. Make sure there is good contact between the extruder block and the heat sink. If cooling is inadequate, the filament will become molten too far up into the cool end of the extruder.

Too much pulling force required to pull filament

Solution: Set up a better spool holder or increase nozzle heat. This can also be caused by a jammed spool or other situations that make it difficult to pull the filament.

Spool jam

Solution: Find a new spool holder. I found the spool holders on the back of the CTC were terrible. Things worked out much better when I hung the spool above the printer.

Drive gear teeth are dirty

Solution: Clean the drive gear. If the teeth are filled with bits of plastic, they won't be able to bite deeply into the filament. So if your filament slips, don't just re-feed the filament and try printing. There is a high chance that it will slip again unless you clean the drive gear.

Deviated filament

Solution: Clean any bits of plastic from the extruder and make sure the drive gear has minimal clearance to the extruder assembly. Deviated filament is when the filament is fed through the drive gear but it starts to curve and get jammed into a place that it's not supposed to go. In the CTC, it tends to jam in between the assembly and the extruder block.

Flow Rate

I found that I needed to reduce the print rate to avoid extruder slipping. For higher quality prints, I print at a much slower rate on the first layer, the outer shells, and the base of the raft.

Bed Adhesion

The best solution for bed adhesion I've found for printing ABS is this:

Heat the bed to 110° C
Use a borosilicate glass plate
Clean the glass with acetone and a paper towel
Cut a sheet of kapton tape that will cover the glass. I actually cut a piece that does not go all the way to the edge on the left and right, but hangs over the edge on the front and back.
Spray the glass with a window film application solution (or equivalent soap solution)
Apply kapton tape to glass
Use a rubber roller to eliminate bubbles and remove as much soap solution as possible from under the tape
Trim edges of tape with X-Acto knife so that about 1 cm of tape remains hanging over the edge
To accelerate drying, place the glass plate on the heated bed
Continue to use rubber roller to squeeze out bubbles as the heat causes gas bubbles to form
While heating, spray the top of the plate with soap solution and use a window film applicator/squeegee
When bubbles stop forming and all liquid around the edges of the tape is dry, take the plate off heat and let cool
Fold the edges of the tape under the glass plate. Take care to not allow any wrinkles or air bubbles
Sand the top of the kapton tape with fine-grit sandpaper until "cloudy"
Dissolve scrap ABS plastic in acetone to make a thick slurry about the consistency of maple syrup (white ABS is best)
Dab a paper towel in the slurry and apply it to the plate (while the plate is cool). Ensure an even distribution.
Once the slurry is applied, you may heat the plate, level the bed, and start printing

It is also important to avoid warping of the print to maintain adhesion to the bed.

Bed Warping

Before heating, the bed is slightly concave. After heating, it will expand and become flatter. It may still have a small curve to it. You can try taking the bed off and bending it a bit to straighten it out, but be careful not to damage the heater PCB on the bottom.

I ended up buying some pieces of borosilicate glass (Pyrex) as print surfaces. The dimensions of the glass are 23cm x 15cm (3mm thick). Be sure to adjust you Z-axis height to compensate for the extra bed thickness. Use clamps to hold the glass plate on, but don't clamp it with too much pressure or the glass will bend. Also, make sure the extruder nozzle won't slam into the clamp at any point.

Heated Bed Caught Fire

Yes, I had a fire. It was caused by the connector to the bed heater. To reduce the chance of this happening again I replaced the power and ground wires with thicker wires and I used a different connector for power and ground. I properly soldered the wires to the connector. I also put a fuse on the power that goes to the bed.

Nozzle Clogging

It's very normal for the nozzle to get clogged after a certain amount of usage. It's just part of normal maintenance.

Some signs that you need to clean the nozzle:

Filament is coming out oblong, flat, or with a groove in it
Filament is coming out with specks or bubbles
Filament is curling as it comes out
Nozzle stops extruding
Print has small voids or blobs (may just need to clean the outside of the nozzle)

Here is my nozzle cleaning method:
For short term nozzle cleaning, I use steel guitar strings. I bought a 3 pack of Fender electric guitar strings, and that one pack will pretty much last a lifetime of nozzle cleaning. I've been using the A-string. The inner wire has a 0.4mm diameter, and it fits snugly into a 0.4mm nozzle. The outer wrap wire has a 0.25mm diameter, and when you unwind it it has a wavy pattern to it. I sometimes use this because it's a little better for pulling material out instead of pushing it in.

Sometimes, I use a small soldering sponge (dry) to clean the outside of the nozzle.

After a while, shoving wire in the nozzle just won't cut it. You will need to replace the PTFE liner and clean the nozzle and barrel very thoroughly. This is pretty straight forward. Here's a little advice:

Remove the nozzle and barrel, remove the PTFE liner, and soak the nozzle and barrel in acetone
Cut the PTFE liner very carefully: use a 2mm/3mm inner/outer diameter tube and use calipers to cut it to exactly 33.5mm
After soaking in acetone, clean the nozzle with q-tips with the cotton removed
Use a guitar string or other small scraping device to scrape the inside
Ensure it is clean by inspecting the inside visually, otherwise it's hard to tell if you got everything
Hold the nozzle up to a light and look through the hole; it should be a perfect, circular pinhole

Wobbly Y-Axis

Some CTC owners have experienced wobbling on the Y-axis, which will cause "ringing" or waves in the print on the Y-axis and perhaps lower dimensional accuracy. I have yet to experience this problem, but I plan to mitigate this to see if I can improve the minor ringing that I experience.

The Y-axis pulleys are on the horizontal bar above the print bed behind the vertical rails. Many people have seen this bar become wobbly and start to flex as it prints. The solution is to install two support brackets with bearings. There are several designs available on Thingiverse:

Since I have not installed mine yet, I cannot comment on the effectiveness, but I will update this section when I do.

Drive Belts Wearing Out

If you are noticing an excessive amount of rubber powder coming from the drive belts, you may need to realign the pullies so that the belt is not rubbing on the inner edges.

Wire Fatigue (Motor Problems)

Sometimes the wires that go to the X-axis motor get fatigued from repeated bending. I have not personally experienced this problem, but it is a common problem with the CTC. People usually solve this by using a cable chain (link).

Unenclosed Chamber (Temperature Problems)

If you print in ABS, you know that it has a higher coefficient of expansion than PLA. This means that as ABS cools down it shrinks. While printing in ABS it is important to control the temperature of the print because if different parts of it cool down at different rates it will crack, warp, and even lift off the bed.

One of the best ways to control temperature is to create an enclosure for the printer. This keeps the heat inside and keeps the print at a consistent temperature.

For a long time, I used a bed sheet. I would hang it from my wall and draped it over the printer while it was printing. Recently, I got some clear acrylic and cut them into pieces to use as covers for the two sides and the front, and I constructed a large box to put over the top. I didn't want to make the printer inaccessible from the sides, so I put all side panels on hinges and used magnets to make them latch.

The CTC also has several holes. The chamber doesn't need to be air tight, but the less airflow the less cooling. There are many printed parts you download for free in Thingiverse:

Corrupt Print Files

If you start getting corrupt files on your SD card, try these:

Reset your slicer settings to the default
Reinstall your slicer software
Reformat your SD card
Test your SD card for bad blocks
Before you remove your SD card from your computer, right-click the drive and select "Eject", or on Linux run the sync command
If all else fails, the printer itself may be having problems with static electricity (Read more).

Print Stops or Carriage Crashes

I had an issue where prints were stopping mid-print and occasionally an axis would "run away" meaning it would try to move the carriage in one direction without stopping. I troubleshot everything (slicing software, SD card, configurations, limit switches) but I discovered that the problem was caused by a build up of static electricity. This started happening in the winter when the air was very dry, thus static electricity would build up on the electronics. At some point during the print this would cause a read error on the SD card (presumably when an electrical discharge occurs). The results were inconsistent (same file would fail in different places). The electronics in the CTC are not well grounded. I also read that RF generated by the wires that go to the stepper motors can cause interference.

Here are my solutions:

Provide proper grounding for electronics:
There are several grounding attachment points on the main controller board, but none of them were being used. Out of the box the controller board is completely ungrounded. I soldered a wire to one of these ground points and routed it to ground on the mains AC input plug.

Provide RF shielding for electronics:
I covered every ribbon cable with aluminum ducting tape, then covered the aluminum with kapton tape. I then covered the front panel and SD card reader PCBs with three layers: kapton tape, aluminum tape, and more kapton. I added wires so that all of the aluminum shielding can be connected to ground.

Re-route the stepper motor wires further from the SD card reader:
The stepper motor wires on the right side of the machine were too close to the SD card reader. I re-routed the wires so that they go through the print chamber. It's ugly, but it works.

Conclusion:
It was over-kill, but it is now a year later and I have yet to have a single problem with static.

Hollow Walls

There are times when I am tempted to add additional shells to my print. Sometimes when you are printing a thin wall with too many shells, there won't be enough inner volume to print an infill, so you end up with a hollow wall. he solution is to use fewer shells. Most models you download (from Thingiverse or other sources) will be designed for 2 shells.

Back Current from Moving Motors

If you move the extruder carriage by hand, move it slowly. If you move it too quickly the motors will generate an electrical current that flows back into the electronics. Even when the printer is off, you may see the LCD screen light up simply by moving the carriage. This has a chance of damaging the electronics, so be careful.

Build Plate Chassis is Weak

On the CTC, I eventually found that the plastic build plate chassis (the carriage that the build plate is attached to) was weakening and starting to get bent. On side was drooping more than the other. If you have the means to cut some metal plates as reinforcement, that would be ideal. I ended up buying metal reinforcement brackets designed specifically for the CTC. Sorry I don't have a link, but I can't find them anymore.

Other Resources

Stepper Motor Driving

https://beardedmaker.com/wiki/images/pdf/Stepper_ST.pdf

3D Printing