Another Instructable dedicated to the upgrades on my Velleman K8200 3D printer! Although my base model is a K8200 these upgrades can very easily be adapted to most RepRap printers. The first upgrade I published was adding a heat enclosure with some other great features. You will notice the enclosure in the pictures of this Instructable so if interested here is a link to that Instructable: https://www.instructables.com/id/DIY-3D-Printer-En...

So far positive feedback has been amazing so I'm back at it with another great upgrade, this time focusing on the print components by upgrading both the Extruder and Hot End.

This upgrade will feature a Bowden Extruder and a E3D V6 Hot End, and will include an in depth tutorial on assembling, printing brackets, installing and wiring. As usual, this is not meant to be a step by step guild to be followed to the tee, rather an overview of my experience, as well as tips, tricks and design ideas I came across in the process of these upgrades. Im all about collaborating to create an even better final product, so if you have and input, be it positive or critical, don't hesitate to chime in!

Here is a link to the original Velleman K8200 Kit: https://www.vellemanstore.com/en/velleman-k8200-3d-printer-kit

On to the build!

Step 1: Overview of Original K8200 Parts

Lets me start by giving a background as to why I felt the need to implement extruder/hot end upgrades. My K8200 worked well for me as a close to stock machine for some time, it wasn't until I began to used the printer far more often for rapid prototyping that noticed issues that might improve efficiency if corrected. Here are some issues I encountered along with some proposed solutions:

- Excessive filament jam

One of the biggest issues was the amount of time I spent on maintenance of the K8200 extruder/hot end. The path of filament from extruder to nozzle was somewhat dynamic which lead to frequent jams. This hot end/extruder combo especially had trouble retracting filament and getting it removed completely without a jam.

Possible fix: An extruder/Hot end combo that has a ver direct path from start to finish. In addition having components lined internally with PTFE tubing would allow the filament to extrude and retract much more smoothly.

- Inefficient filament jam correction

With the K8200's enclosed extruder/hot end combo unjamming the printed head was a task the included disassembling quite a bit of the print head/extruder.

Possible fix: Explore options of a move open and accessible extruder and hot end combo.

- Exposed filament from filament spool

Another problem was that with the K8200's original design the filament leaving the spool is exposed to moisture and dust when idling. This resulted in breaks in the filament during non use that would result in more maintenance.

Possible fix: An extruder with an input for PTFE tubing to protect filament from spool to extruder.

- 3mm filament became brittle and caused breaks during no use

Along with the filament becoming brittle from being exposed, I figured the 3mm filament might be more susceptible to breaks that the 1.75mm filament.

Possible fix: An extruder/hot end combo that allows 1.75mm filament to be used.

- Slow hot end temp gains

Lastly my original hot end seemed like the heat process could have been more efficient. I believe the problem came from lack of current through the high gauge wires of the original K8200 ribbon cables.

Possible fix: A hot end with high quality heat source along with revision to the original wiring.

Step 2: Upgrade Parts List

After coming up with a list of design aspects that needed revision, I spent some time exploring options for hot ends and extruders online. After seeing what was out there I settled on these parts:

E3D V6 Hot End by 3D Cam

- I went with this hot end for a few reasons:

This hot end allows a PTFE tube to insert almost all the way from top to nozzle which results in smooth, low friction extrusion and retraction.
Included fan to disperse excess heat
Heavy gauge wiring included with hot end
Widely available nozzles in a variety of sizes (it came with 0.4 but I purchased 0.2-0.6 on amazon)
Overall price is extremely affordable

E3D V6 by 3D Cam on Amazon $19.99

Bowden Extruder

- There was also a verity of reasons I chose the Bowden Extruder

Open design in attempt to easily fix jams
Ability to visualize filament slippage in the gear
Easy adjustability
Compatibility with PTFE tubing
Compatibility with original NEMA 17 Stepper Motor
Again overall price is extremely affordable

Bowden Extruder on Amazon $25.97

Step 3: Printed Bracket Design

The design process was built around an attempt to make the the Bowden Extruder and E3D V6 work together as synergistically as possible, as well as be easily removable and or displaced for other CNC attachments that might be included in the future. Other attributes of high importance included rigidity and consistent mountability, to avoid having to make print bed and leveling screw adjustments on a constant basis. I have seen plenty of examples of Bowden Extruders being used where the extruder is relatively far from the hot end, it seemed to me that the most efficient design would be to use the extruder to draw filament from the spool and directly send it into the hot end, rather than push the filament through a long tube of TPFE. That being the case my bracket has mounting holes for the bowden extruder as well as a mount for the neck of the E3D V6 Hot End.

- Overview of design -

The design includes:

Mounting holes for Bowden Extruder on top portion of bracket
Mounting spot for neck of E3D V6 hot end with gradual thickness increase for tight fit
Dual fan mount holes on either side for what ever works best ergonomically for your setup
Multiple extra supports to increase rigidity, thus consistency in prints
Mounting holes to connect to original square nuts from K8200 with the original bolts
Designed to fit perfectly with the extruded aluminum cross beam of the K8200

This design can easily be adapted for other RepRap printers. I can include the original file made with 123D Design so modifications can be made.

Click here: Thingiverse Download

Step 4: Assembling the Bowden Extruder

The Bowden extruder doesn't come with any instructions when purchased on amazon, however the seller has provided a small series of pictures that reprints the assembly on the amazon page. Because these instructions were difficult to find and even difficult to understand i will provide a quick rundown or the Bowden Extruder assembly.

- BEFORE THE BUILD -

Make sure you receive all the necessary pieces. I had to add a nut to what came in the shipment for the adjustment spring.

The amazon Bowden Extruder that I have link to does not include the necessary NEMA 17 stepper motor but the original K8200 extruder stepper does fit and work perfectly fine. You need to either remove it from the original extruder or purchase a new one separately.

- THE BUILD -

*IMPORTANT SIDE NOTE TO SAVE YOU TIME* This step is the assembly of the Bowden Extruder as a tool for all who purchase it, regardless of the possibility some might be following pretty closely to the other steps and using the printed bracket. If you are using the printed bracket you will need to mount the black metal bracket to the printed bracket before assembling the extruder. The stepper motor gets in the way of the mounting bolts if assembled prior. Back to your regularly scheduled extruder assembly.
First attach the Extruder Driver Feeder Gear to the NEMA 17 motor shaft, leaving about 2-3mm of shaft sticking out passed the gear.
Add the second black metal piece to the bracket as shown in the pictures included and use the small bolts included to secure the motor to the bracket pieces in 3 of the 4 holes. The upper right hole will be used to hold the adjustable spring loaded portion.
Attach the wheel to the red aluminum without over tightening it to prevent to much friction for the wheel.
Using another bolt with a washer attach the red aluminum tension adjuster to the main frame so the wheel is contacting the feeder gear.
Insert both larger bolts into the two holes that will become the tension adjustment.
Add the nut to the bottom bolt and add the spring between the two.
Lastly attach the two PTFE sockets to the top and bottom of the Bowden Extruder.

Step 5: Connecting the Extruder to the Printed Bracket

Like stated in the previous step the Bowden Extruder needs to be secured to the printed bracket before the motor and other components are attached. The NEMA 17 Stepper motor covers the area were the Bowden attaches to the printed bracket. Bolt the metal Bowden bracket to the printed bracket and fasten with nuts. You will notice the metal bracket will sit slightly off center of the printed bracket, this is because when assembled the PTFE fittings ar not centered on the extruder, to line up well with the E3D V6 Hot End the extruder is slightly off center.

Step 6: Connecting E3D V6 Hot End to the Printed Bracket

Next step is to attach the E3D V6 Hot End to the printed bracket, which now includes the Bowden Extruder. Again, a very simple and self explanatory step. The printer mount includes a ramp in the area to attach the neck of the hot end.

Before sliding the hot end into place on the bracket, a length of PTFE tubing needs to be cut to connect the extruder to the hot end. Be sure to account for the depth that the tubing slides into the hot end, which is close to 3/4 of the length of the entire hot end. The fittings on the hot end and extruder allow the tubing to slide in but not out so slide the tube in part way and insert the hot end into position on the printed bracket. Refer to the pictures for further clarification.

Step 7: Mounting to the Printer and Wiring

This step is also very simple, the intension of the design of the mount was to allow removing the hot end/extruder to be easy and quick. Originally I created a mount that held only the hot end and the extruder was mounted separately to the aluminum extrusion. This would make moving these components far more difficult because as I said before the majority of the extruder needs to be taken apart to get to the mounting bolts.

The printed bracket is mounted to the z axis spanning extruded aluminum with the original hardware that the K8200's printhead was mount with. I included the large washers in between the bracket and beam to once again increase the rigidity.

After mounting basically all we are left with is the wiring of the new components. The original wiring did the trick well enough for the original parts, but I figured, instead of just wiring the upgrades into the original ribbon cables I would rewire the printer. Main benefits of this would be to use heavier gauge wire to allow more current to flow so temperature gains while prepping would be much quicker. Also going along with the design of having the print head easily removable I wanted to wire in connectors in close proximity to the printing hardware. As you can see in the pictures the extruder stepper motor and thermosistor still use the original ribbon cables, but the heat element is wired directly to the RAMPS board with the thermal protected wire that comes with the E3D V6.

The heat dispersion fan that is on the E3D V6 need to constantly be on when the hot end is on. My first idea was to splice into the heat element power, in an attempt to have the fan on anytime the heat is on. This will not work because once the extruder reaches its desired temperature the power that is supplied to it drops dramatically and won't power the fan, therefor the fan would only be in operation as the hot end is heating up. I decided to wire the fan directly to the power supply, which in my enclosure, is wired to a master ON/OFF switch. The fan runs as long as the printer is powered which works fine for me.

Step 8: Finishing Touches and Review

Last small addition is to add the main cooling fan back to the printer. I decided to upgrade the original 40mm fan on the K8200 to a 60mm fan. The air flow is far greater and it is much quite than the original. The fan mounts to either side of the printed bracket with the same metal bracket that was mounted to the K8200 frame.

Obviously there are software changes that need to be made to accommodate the new hardware. I use the recommended software for the K8200 which is Repetier Host. The main change that needs to be made is to slow down the extruder stepper motor, in the original layout the extruder had a large gear to gear down the speed of extrusion. Now the rotational speed of the stepper is directly proportional to the extrusion speed. This can be slowed by lowering the "Extrusion Multiplier" in slic3r. I lowered mine as low as 0.20. Also the retraction length and speed need to be lowered considerably to compensate for the lack of gear reduction. Other settings like filament diameter and nozzle diameter also need to be adjusted accordingly.

And thats it!!

That about wraps up this upgrade process. Here I will review the results and value of the upgrades:

Noticeable changes since implementing upgrades

- Faster quality print speed

- More precise print quality

- Quicker print prep time

- Not a single jam since the upgrade

- Ease of filament change (no more retraction problems)

- Ease of nozzle changes to increase precision or print speed

- Overall less failed prints

Other Pros of Upgrade

- Very low cost parts

- All hardware is reused from original K8200

- I've noticed that there seems to be a wider variety of 1.75mm filament, so this upgrade introduces new filament options.

I truly hope this Instructable provides guidance or inspiration for future makers. Further upgrades are in planning at the moment. Next up will be adding a rotary attachment to be able to engrave PCB's. Also if interested in the enclosure that can be seen in the pictures, check out my previous Instructable here:

https://www.instructables.com/id/DIY-3D-Printer-Enc...

Thanks Again and until next time,

Never Stop Creating!