I noticed when researching the printer that there was a newer replacement extruder available and that the mk8 extruder that the printer came fitted with had an inherent problem where the plastic breaks and pinch wheel comes away. Fortunately we purchased the printer from the main supplier and they where offering the upgrade for free to their customers so I dropped them an email which was followed up by a call from Dan Safar from PrintME 3D. Good chat with him and he sent on the upgraded mk9 extruder. Thanks very much PrintME 3D and your support from your techs there 🙂

Here is what I found on opening up my mk8 extruders

I actually have no idea how they were supposed to work as there is no way to adjust for tension or varying thickness of filament. Its no wonder they are broken as the shaft for the bearing has to give to allow for this.

Considering that this is a brand new machine its pretty poor that both extruders are broken and I have done virtually no printing yet. So if you are considering purchasing a D4 then make sure it already has mk9’s or comes with them to fit.

The mk8’s are the same both sides so I guess you could buy a bit of time by switching them over from side to side.

Next problem to deal with is the head alignment, or rather to use the correct term if you want to find info on it, nozzle alignment. This is to get the two heads to print in the same place.

In RepG under onboard preferences you can find x and y head alignment and you can put the distance between the nozzles into the x parameter dialog box. I measured the distance with the calipers which turns out to be about 33.05mm. After that run the RepG nozzle calibration and pick the line which is aligned best then enter this in the nozzle calibration entry on the printer. Incidentally the printer will always show 7 when you recheck this but if you go back to the onboard preferences dialog you will see it has changed there.

During this process I found that the left feed was becoming worse and worse until it wasn’t really feeding at all.