So since the last update I’ve not really focused on any one project which now presents an issue with the need to provide updates across a whole range of projects.
The frame is mostly complete now to the point where all that is really remaining is the install of the hot-end and all the wiring… no small job that is going to be.
One interesting thing with the I3 is that most of the install documentation that I’ve been able to find has the vertical frame that the Z axis is mounted on centered on the Y axis.
On the Prusa V2 I find this makes sense as the extruder and the hot-end are mounted down the centreline of the frame vertexes so everything lines up and you are able to access most of the build plate with the hot-end.
On the I3 however the extruder and the hot-end are mounted on the front of the vertical frame and so if the vertical frame is centered on the Y axis then the hot-end isn’t centered on the build plate which reduces the available build area.
I don’t know whether this would end up being an issue simply because I’m not sure whether I would ever need to print a part that was so large in the X and Y dimensions that the offset hot-end means that the build area is too small but I figured I may as well center the hot-end on the Y axis from the start instead of having to shift it later.
The belt for the X axis still needs to be added but the bearings for that arrived this morning so that shouldn’t take too long.
The heated bed arrived a while back and so not that the Y axis is complete I’m able to install that. I opted for the aluminum one with the traces on the reverse side. Some people print directly on the aluminum surface but I’ve had awesome results printing directly onto glass that’s been cleaned with window cleaner so see no reason to change. With that in mind it would have been possible to just use a standard PCB heated bed with the glass on top of that but I figures the aluminum would offer a bit more thermal stability as well as better heat distribution. Awesome coincidence is that the heated bed colors match the color scheme of the rest of the build.
The rest of the body has had the paint stripped from it and is ready for the cracks to be welded with Durafix before repainting.
Something seriously wrong has happened with this mower in a past life, the amount of holes in the deck seem to indicate that it was perhaps used to clear land mines but a decent repair (read not riveted patches and plaster builders bog) should give it a decent further lease on life.
The engine shroud has now also been completely sandblasted, cleaned and sprayed with several coats of ‘Delicious Red’ Wattyl Killrust. The engine still needs to be stripped and cleaned before being reunited with the rest of the mower, part of this will involve an investigation into where the leak is coming from and whether its worth doing anything about.
Kitty litter furnace
Not a furnace for kitty litter, a furnace made of kitty litter! After the ok but energy intensive results from the last smelting session it was decided that a better technique / setup was needed. A scour of the internet revealed a number of people that have had success with a mixture of cement, perlite and crushed kitty litter set between a couple of metal formers to make a furnace. The outer former in my implementation has ended up being an old gas cylinder and the inner an old milo tin. The kitty litter was crushed in a hacked-to-be-always-on blender before being stored until I’ve found a source for some perlite in reasonably small quantity. The gas in the bottle was first used completely before the bottle was filled with water and the valve removed. The inside was then cleaned and left to air before the top was cut off with a cutting disk on an angle grinder.
From here I need to add an air vent pipe on the gas bottle before stripping the paint on the outside and repainting with black furnace paint. The inner former will then be wrapped with a couple of layers of greaseproof paper and corrugated cardboard to ease later removal. A base layer of perlite mixture will then be placed in the gas bottle before the inner former is added and perlite is packed around the outside. After curing for a couple of weeks a test firing will be performed to remove any leftover moisture before the furnace is used to make more aluminium muffins.
Mini CNC mill
Whenever I need to add a multi-pin connector to a project that requires a large number of external connectors I invariably end up settling (read not preferring to use) a D-Sub connector. The massive pain in the butt thing about these is that the cutout is a weird shape that takes ages to cut in the project enclosure and which can very easily end up looking naff. I decided therefore that what was needed was some small CNC router that I could use to do cutouts mainly in project boxes as well as any other small CNC stuff. The idea would be to basically use a semi standard RepRap design but replace the belts with threaded rods, the extruder with a flexible Dremel shaft and the RAMPS board with a CNC interface.
The chosen base design was the OB1.4 RepRap constructed out of OpenBeam aluminum extrusions.
They’re pretty cool as you can use standard m3 hardware to bolt stuff together as opposed to t-nuts etc so that helps keep the cost of fasteners down. Additionally in NZ they are A LOT cheaper than 80-20 extrusions or similar. I’d never played around with these before so wanted to have a go and also the design looked pretty robust and hard wearing. I’m currently building the frame up with only a few more stock parts needed.
The motor mounts on the Y axis need to be redesigned to take a motor parallel with the shaft in-line with the direction of travel as opposed to a perpendicular design required for use with a belt. The Z axis can remain pretty much the same but a similar re-design of the X axis will need to happen to once again allow for the motor shaft being inline to the axis movement. The base design of the OB1.4 also had the Z-axis frame centered on the Y axis so I extended the Y axis out the front of the machine to instead center the spindle of the Dremel on the Y axis of the machine. I think that this is all I’ll manage to get done on this project before heading away, I’d have liked to get the frame complete but am suffering an Out-of-filament error with little time to print more parts even if I did have more filament