Sunday, February 8, 2015

Minor updates to my printer (Mendel90 scratch build)


Quick post showing some minor printer updates I've made in recent times:
Moving to the newer Mendel90 x-ends, with their 4-screw bar clamps, has made a good difference to my printer. The older design, (second photo below) was unable to clamp the bar tightly enough and I was loosing belt tension over time. The clamp was also beginning to split along layer plane. The newer design doesn't have this issue as the layers are in compression because of the clamping direction.
Newer x-end installed above. Nophead relesed this design back in Oct 2013, and has been incorporating this design in the kits he sells since then, but if you have an older printer it's worth updating. Full detail on this and other design improvements he has made to the Mendel90 can be found here: 
This is the older x-end design, with it's weaker x-bar clamp arrangement.

I'm trying out an E3D V6 hotend at present, swapping it out for a J-Head which, by the way, I've never had an issue with. I just want try some printing in some materials that require higher extrusion temperatures, beyond that supported by the J-Head.

 To mount the E3D Hotend on Mendel90 without loosing any Z-heignt, I took inspiration from the hot-end clamping idea devised by Ralph Hilton which he shares here: http://www.thingiverse.com/thing:371252. I applied this hot-end clamping approach to Nophead's original extruder, importing the original STL into Sketchup and hacking away there until I got it as I wanted it. It's not pretty, but anyone is welcome to the Sketchup original if you think it's of use. (just give me a shout on the RepRap Forum under user name NumberSix).
Screenshot of extruder modified to clamp E3D V6 hotend in a way that does not result in loss of Z-height. The keen of eye may also observe I've moved the left extruder clamping hole. I want to be able to attach/detach the extruder to the x-carriage without having to remove the E3D fan assembly so have also made an x-carriage with an enlarged hole. See screenshot below.
X-carriage with wider opening to allow E3D hotend to be inserted/removed without taking it's cooling fan off, or detaching it from the extruder block. (one in picture not in my current colour, just test printing it)

One thing leads to another, and if you swap out the j-head (on a Mendel90) for an E3D hotend you'll soon realise the original work cooling fan doesn't fit over the larger heater block of the E3D. So that lead me to Daniel Bull's Fan Duct  which he drew in in Autodesk 123D Draw. A fine job he mad of it too, but it's distance below the x-carriage is set for the E3D fitted to an original (M90) extruder and in a much lower position.
The screenshot above shows my modified version of Daniel's fan duct. I've lowered the mounting points, and adjusted things to make room for the x-belt. It was a struggle but a good way to learn more about 123D Design. Daniel provides a great starting point in his shared fan duct. I added the little cross you'll see in the middle of the duct to help with bed adhesion on this narrow circle. The cross is cut away after printing.


That's it for now! Thanks for viewing.
Ivor.