One of the problems that I’ve found with 3D printers is that once they’re capable of producing reasonably decent objects you can very easily become side-tracked into printing all sorts of stuff whilst not actually tidying up all the loose ends and finishing the printer.
In my case this has meant several things…
Firstly for the last year the electronics has been sitting next to the printer on the table with the leads hanging off the edge of the table threatening to drag the whole lot off with one decent tug.
Secondly my fan mount for the cooling fan on the stepper drivers has been a M6 bolt screwed through a small piece of Aluminium, this has sat next to / under the Arduino MEGA, also with a tendency to slide around the table.
Finally the LCD add-on has never had its mounting case printed and so had ended up sitting under the printer where it’s pretty much pointless.
For the last little while, whatever time I had to spend on projects has been eaten up working on the trolley but I’m pretty much at the point now where there’s not much more progress that can be made there until a new set of 12V batteries have been purchased and installed. Consequently it’s been harder and harder to ignore these final small but annoying jobs on the printer front and so this last weekend I got them sorted.
Firstly the electronics are now mounted on a printed sled / clamp deal. One of the pain in the ass parts of this was fitting the mounting screws in / around all the components on the Arduino Mega. There’s two things that are amazingly stupid design decisions on these units, the first being the header spacing (which was apparently a mistake…) the second is that it’s almost impossible to fit the heads of the screws in around the headers / SMD components on the top sides of the board. To get around this I had to stick a couple of screws in a poormans lathe (aka power drill) and turn the head down to a smaller diameter to fit. The ends result is below, The angle is a bit average but there’s a lot of cables blocking the view from above.
Mounting the fan was a bit easier, trawling through the “parts that didn’t print right / werethe wrong size” provided what I believe was a different version of the electronics mount that for whatever reason (maybe I forgot about it, I can’t remember) didn’t get used. Suffice to say it was perfect in that it was designed to clamp to a piece of M8 rod and had a handy hole in the end to which to attach a fan via random section of those “Helping Hands” PCB holders which then clamped onto the fan.
Finally after a quick look through thingiverse for inspiration I made up and printed the below black clips to hold the LCD to one of the top threaded rods of the frame.
As a upgrade I also printed several of the black belt tensioners below. Ideally the belt would be tight without the tensioner but in order to adjust this it would be necessary to remove the heated bed (which would then need to be re-leveled again afterwards). I really couldn’t be bothered doing this and the tensioners turn out to be cheap and easy to print as well as pretty effective.
Since this printer is not marked as finished (apart from upgrades and repairs) I think I can now in good conscience thing about the next one… I3 anyone?
On the shopping trolley front the following has happened;
1) Seatbelt has been attached.
A short section of chain extends the belt down to the body of the trolley where it is attached be a shackle to a decently thick section of the frame.
2) Cover has been printed for the throttle.
This is a massive win for 3D printers aye, it’s amazing what they are able to accomplish in regards to bespoke shapes quickly and cheaply. The amount of filament to print this part is way cheaper than what it would have cost to have it made out of metal. Additionally once the part is designed there isn’t that much interaction on the part of the user until the printer has finished its job. The cover is made up of two sections, the first lower section bolts to two handy (yet randomly) drilled holes in the original metal of the handle bars. The top section then slots over the PCB of the controller and then screws to the bottom with a couple of M3 screws and a couple of captive nuts.
3) Driving lights have been fitted.
Thinking about long missions in low light I realised that I needed some form of front white lighting. I really didn’t want to end up in a position where the flashing LEDs had to be used for this the whole time as it’s a bit of a waste of their potential and functionality really. Scrounging around yielded a couple of LED torches with decent output and small size so these were fitted to the front with a couple of 35mm pipe clamps and some M10 rod. A couple of aluminium plates secured the lot to the frame.
White wheels aren’t much fun so whilst waiting for batteries I decided to bling the kart up a bit. From the parts bin came a whole lot of M10 bolts, nuts and washers, some Perspex sheeting and some bearings. Firstly the Perspex was cut into four circles, these were then drilled firstly with a 3mm pilot hole and then with a 10 mm drill bit in reverse so as to not split the Perspex. Printed hubs then had a washer and bearing fitted before being mounted to the Perspex. I then mounted the wheel horizontally to a block of wood and spun it around whist moving a grinder towards it tangentially to correct any wobble from the center holes and hubs not being dead center. The bolts were then fitted and tightened up.
To mount the rims to the trolley the M6 bolt stopping the wheel from sliding off the end of the axle was removed and a length of M6 rod was put in its place. A nylock nut was then tightened down onto the rod to keep the wheel on. A second nylock nut then gets used as a spacer before the hub is slid onto the rod and held in place with a third nut.
Result = awesome.
It should be noted that as the rear driven axle actually turns as well as the wheel (front axle is fixed and the wheel spins on bearings) it would be possible to fit blades to the rear wheels for a 21st century scythed chariot effect. Perhaps not as public friendly though