I made another thing:
Partly I needed a little tray to put screws in partly a learning tool for OpenSCAD – it’s a parametric thing so you can change a few variables at the top of the .scad file and have a single column of 10×100 compartments instead. It’s up on thingieverse in case anyone else finds it useful.
One of the first things I made with Mandy Mendel (oh yeah, I decided she needed a name and that name is “Mandy”) is a set of brackets to mount cold cathode fluorescent tubes on here. They look like this:
I also put them on Thingieverse in case anyone else fancied strapping lights to their mendel.
The motivation for these was mostly that I’m probe to sitting in the dark working on my internet tan but would still like to be able to watch things printing (a large part of my reason for building a 3D printer is I find them fascinating to watch) but there’s also a bit of bling factor in there – I do just like techie stuff that lights up tastelessly.
I’ve been plodding on with mendel assembly. I’ve now got most of the sub assemblies together ready to put the frame together.
X-axis is the most complex of the sub-assemblies. There are 24 bearings in there, not including the ones in the extruder which sits in the carriage.
The extruder is the business end. It pushes the filament into the hot end – a heated tube with the nozzle on the end. Basically a high precision hot glue gun.
The Z-Axis. The X-Axis, is moved up and down by the two threaded rods which are belt driven from the stepper motor. There’s also an optical sensor to tell when it reaches the bottom of it’s travel.
This is the carriage which supports the heated bed on which items are actually printed.
This is the motor that moves the Y-Axis, again with an optical sensor to detect the end of travel.
I’ve started construction on the mendel. First job was a small modification to the heater block. It came with no way of mounting the thermistor (temperature sensor) so I drilled a 1.5mm hole in it and glued it in with the same high temperature sealer used to fix the resistor that functions as a heating element in place.
The thermistor is tiny:
that’s a 1.5mm drill bit next to it.
Here’s the heater block before drilling it:
Heater block being drilled:
After drilling the heater block I crimped the connections to the resistor and thermistor and covered the joins with special high temperature heat shrink – the heater block runs at about 200° C when printing PLA or even hotter for ABS which is too hot to solder or for normal heat shrink.
After glueing the resistor and thermistor in place with high temperature sealent (like normal silicon sealer except black and good to 300°) I put it to one side to set and set to assembling the extruder. This was my first go at assembling printed parts and I discovered I hadn’t cleaned them up as well as I thought I had. Most of the screw holes were actually slightly under-size so I ended up running a drill bit through them in a hand drill. Some of the holes blind holes I very carefully enlarged with the aid of an engraving bit in my mini-drill.
Mostly it was a case of slow careful progress. Nothing too difficult but some bits are a little fiddly and I was glad I have things like a bench grinder, pillar drill, mini drill and mini-vice to hand. For example you have to grind your own flats on the stepper motor shaft. So far then it’s not a job for someone who has difficulty assembling Ikea furniture but isn’t too bad for anyone reasonably practically minded. By the end of Sunday I’d got the extruder and carriage made:
I guess it took me about half a day to get that far taking it slow and gentle. Next time I finish off the X axis.
My medel kit arrived a little while back but I’ve not previously had a chance to start work on it. It turned up in quite a big box which unpacks to a quite impressive (if slightly scary) number of bits:
This should be everything I need to build the reprap mendel – other than time and effort. The 3d printed parts are as they came off the printer:
First job will be to clean up and finish off all the parts. The main build is probably going to take a whole weekend but preping all the parts is something I can get on with on evenings.
This is an origional mendel not a prusa mendel. The difference is this one has a lot more bearings:
The prusa mendel replaces quite a few of the bearings with bushes that are 3D printed. This is a nice idea and lowers the initial cost however I like the greater reliability/longevity of bearings and could afford the extra (I could have beaten the kit price by buying plastics off ebay and shopping around for other parts but I’m time poor more than cash poor right now so the kit seemed a better idea for me).
I’m also not hugely interested in the electronics side so the pre-built single board electronics that came with the kit are a plus for me:
All in all I’m looking forward to building the thing but even more to being able to use it. The ability to 3d print stuff will be useful for all sorts of other projects.