I’ve decided that I need a new XY gantry. The old one is fine, if you don’t want to
change nozzles. As this is a very basic requirement of this project, I’ve had
to come up with a solution to a mechanical problem I have while changing nozzles
with the old gantry and carriage.
The Old Gantry
As I said before, the old gantry is fine, if you don’t want to change nozzles. The
thing is, the particular nozzle holder that I have has a really small tolerance.
It has to. Otherwise the negative pressure created by the vacuum pump, would be lost.
So, here we go down the rabbit hole. Bear with me, this is a work in progress, and there will be
more to come.
The problem that I’ve run into, is that the NEMA8 motor is sitting relatively far away
from the aluminium rods, so pushing up on the nozzle holder has a significant amount of
leverage. The aluminum rods themselves aren’t that strong, certainly not when force is applied
to them. When I try to put in a nozzle, the whole carriage bends upwards, creating an angle between
the nozzle holder, and the nozzle. This causes binding, and naturally skipping of Z steps when
it can’t get the nozzle in. The same applies for removing a nozzle, just in reverse.
The New Gantry
I needed something that was more solid, but didn’t add too much weight to the XY axis. After having talked
with a few people, I decided on a 2040 aluminium extrusion profile with V-Wheels on the carriage. The
profile wont bend. Certainly not in the way the aluminum rods did. This was certainly going to be more
challenging, because now I need to design new XY joiners, and a new X carriage. I’m not one to back
down from a challenge. And let me tell you, Fusion360 can sometimes be challenging… In the sense that
on my laptop, it crashes often, and is sometimes very sluggish.
The XY Joiner
Firstly, in order to not have to redesign motor mounts and belt idlers, I’ve kept the belt paths relatively
close to the orignal HyperCube. Naturally not exactly, because now the belts can’t go happily down the middle
of the gantry, there’s now a 2040 extrusion profile in the way. I haven’t designed the belts in Fusion360, because
at this time, this is not supported. Once I have everything printed and built, I’ll certainly be posting some more
pictures of the final setup.
The New Carriage (sort of)
This is essentially a first version of my new X carriage. It’s going in the garbage and I’ll be completely
redesigning it, in the next few weeks, when I can find a bit of time. It uses 4 V-Wheels, two of which will
adjustable with eccentric nuts.
Currently, it is two separate pieces (front and back). My next design will be one solid piece of plastic.
It is possible that I spend a bit more time, and try to fix/finish this carriage, but I think it will honestly
be easier to just start over on it.
More to come
This is where I’m currently at, and I will be writing more on the progress of the redesign.