Modifying the Velleman K8200 3D printer

My first 3D printer was a Velleman K8200 (DIY kit).
I already have this 3D printer for 2 year now, and in the beginning, I was not happy with the results. One of the first things I did, was improving the print-quality.
Because from time to time, people ask about my modifications, I decided to write a small article about it.

The modification consists of 3 individual changes …

1. modifying the Z-axis
The Z-axis is simply an M8 rod. These rods are “famous” for beeing a little bended and the “poor” quality. I replaced the Z-rod by a trapezium spindle, an M8x1.5D
(after this modification, you need to change your Z-steps in your firmware, you can do the math your own – the pre-programmed Z-steps are for 1.25 mm movement (regular M8 is 1.25 mm for one turn) the new Z-rod makes up for 1.5mm for one turn. (TR8x1.5)

Furthermore, I used a flex coupler, to connect the Z-rod to the stepper motor. (8mm/5mm) this skips out any errors with the Z-motor not perfectly aligned. (which is virtually impossible on this machine)

Because of changing the Z-rod, you also need to use another nut to move the axis up/down. For this, you also need to replace the plastic part that holds the nut. There is a perfect STL for this piece available on Thingiverse:

Another modification on the Z-axis, is the mount for the Z-axis stepper motor. The little piece for mounting this motor that comes with the printer itself, is not strong enough, it flexes and bends. Also for this, there is an excellent STL file available on Thingiverse:

2. replacing the extruder and hotend
The extruder and hotend could also use some love and care 🙂
I simply ripped them of the printer, and replaced them completely.
First, the hotend, I bought a J-head all metal hotend on Ebay. (for less then 10 euro, including shipment !)
Next, I was so happy with my extruder on my ecksbot, that I decided to modify it slightly,
so it could be used on the K8200.
This modifications consists of 2 parts:

– The actual extruder:  download it here
You need 3 608ZZ ball bearings, an M8 screw with groove to feed the filament, some M8 washers and M8 nuts, a long M4 screw, a few washers, a wingnut and a spring. (for the pressure of the guidance bearing against the M8 screw)

– the extruder holder: download it here
You can use the existing screws, nuts and washers that you used to mount the old extruder. you also need 2 M3 screws/nuts/washers to bolt the extruder to this holder.

3. make the filament-role “move” more smooth

aah, the spool holder, just an M6 piece of rod, where you slice the filament spool on.
Some spools don’t unwind that easy with this M6 rod, and if you want to use bigger spools, your completely out of the game with this method.
So, a nice spool holder with real ball bearings is an ideal solution.

Replace your M6 rod with and M8 rod (if you did the first modification, you now have a spare piece of M8 rod laying around 🙂
Furthermore you need 4x 608ZZ ball bearing, a few M8 washers and M8 nuts …

You can download the STL files for printing this filament holder here

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