So, I have been playing around with ideas, and this one came up tops (for now)
My first Thingiverse thing!
There are a couple of concerns though, not least of which PTFE creep… apparently Teflon does not have a polymer “memory” and might flow like glass given time and pressure. Will have to do some serious testing – at least there is time for that.
Then there is the issue of the 1mm aperture. The 0.8 refers to the wire that gets fed though it, and not the actual hole size. Found some ancient (2005) reprap hot end literature, and the way they made the hole smaller was quite interesting. They melted some lead-free solder into the hole, while keeping it open with stainless steel wire, chosen for it’s diameter. The solder does not stick to the stainless, and allows the maker to pull the wire out afterwards, leaving a perfect hole.
This is unfortunately not viable with the high speed / high temperature operation people are forcing out of the hot-ends with the latest firmwares, like Sprinter. The solder would just melt out again. Got some ideas from it though… Watch this space.
I have been brainstorming on potential extruder designs for Morgan, keeping in mind the 3+ material design spec I set myself. To make this work it will have to be a Bowden cable setup of sorts with a material selector in the extruder feed mechanism. To keep down costs only one extruder stepper motor should be used.
Looking at current extruder hot-end designs, and at material cost it is very clear why some new designs are shying away from the use of high temperature insulating materials like PTFE and PEEK, although these designs seems to compromise a bit too much. Clearly we need to find a way to successfully implement some lower cost material that will perform the task of keeping the hot end hot, and the cold end cold, while conserving as much energy as possible in order to remain well within the GADA requirement for power use…
Enter (yet another) another new hot-end.
I am going to use a combination of brass, stainless steel and silicone rubber to do the required. My initial checks and calculations makes this look good on paper. Information on the new hot-end should appear here soon, and follow on Thingiverse. It should enable us to place three to four nozzles in relatively close proximity, while still keeping the weight of the print head down to the minimum and keeping heat where it belongs – in the hot end(s).
Now I just need some time in my lab…
Things are progressing much to slowly for me at the moment, with life getting in the way in a serious way.
Well, I have decided to bring the Morgan blog back here. It’s my own space.
Since my last post here I have had a bucket full of great ideas, and spectacular failures. The first frame I built was a base for the Ill fated Sarrus linkage Z-platform that I attempted. I used 45mm PVC piping in the corners, and made a square base using m8 sink-plated rod. On the rod I treaded m8 nuts in clusters, glued to plywood sections that formed the mechanics of the linkage.
- Too much play in the nuts
- Too much flexibility in the structure.
My Sarrus linkage wobbled like jelly… My father visited us, saw the thing, and proclaimed that it was plain nuts. Clearly.
I have abandoned Sarrus, because printed structures would likely have even more play, and would require “living hinges” that would be hard to print (Has to print across the hinge, and not parallel.)
In the mean time I got hold of most of my more expensive vitamins (Arduino, Steppers). I want to use something like the RAMPS shield, but my design calls for four steppers only. The fifth ins a waste of space that could be occupied by other stuff, like an SD card slot.
Started work on a new Darwinesque XY axis, using felt for my linear bearings. Early days – promise to put up some pictures when I get a chance to work on it a bit in the next two weeks. Would be nice if I could print something before the end of the year!
Trying to absorb all the development that has happened in the open hardware 3D printer arena, I find myself veering violently between the different configurations. There is certainly still a lot of merit in the Darwin like machine…
The problem is that I find myself exploring ALL the different parts of RepRap at once.
Time to choose my poison. The frame is an obvious first choice then.
What’s in a name?
Thomas Hunt Morgan did using fruit flies what Gregor Mendel started forty years prior on peas.
My design (or my initial ideas) are loosely based of the current Mendels, but will eventually bear little resemblance to its muse. The idea is to make the design Mendel printable… though it might be a (very) tight fit.
Morgan will be at least 90% printed volume, at least 3 material, automatic unloading with a build area exceeding the 300x300x100 Gada spec. But it will be a while before we get into that. Morgan will have to be printed.
Stumbled across the Gada prize… and some additional stumbling made me decide – I can build that!
Every story needs a beginning, and this one starts a couple of years ago when I bought my first inkjet printer. Wonderful things, except that their print heads did not last more than two cartridge changes…
Three printers later there is enough mechanicals for a nice RepStrap. You have to start somewhere. Only thing is, that to build a Gada compliant RepRapper you will need quite a big RepStrap. This will be a record of the journey halfway there