Small Croxy
High Speed Prototyping Printer
Title: Small Croxy
Author: ryan d
Description: A high speed, small form factor, crossed gantry 3d printer on a mostly printed frame
Created: 6-2-2025
6-2-2025 - 3 hours
Planning
I spent today just scetching my idea and getting the main concept down, and getting a rough idea of what materials i could use. I decided on going with rails over rods on the gantry because that has a super high potential for getting way out of alignment and also they are much easier to mount.
Overall today was just a bunch of planning, and figuring out what parts would be suitable.
I decided to go with: - V6 hotend (trianglelab) - BMG extruder (clone) - mgn9 200mm rails (robotdigg) -linear bearings (igus) -steppers from voron trident BOM (never picked these before, and vorons work sooo) - 120mm buildplate (voron 0?) - BTT spyder - a laptop (klipper)
(sorry no pics this was all mental)
6-3-2025 - 9 hours
Structure
A full day of CAD. I started with getting the outer gantry assembled, with the motor mounts comming first, and once i gad those down I added the linear rail supporting pieces, to help them maintain their rigidity. Then I Mirrored everything to the bottom to get the lower structural members done.
The Main side braces are a little small, but they should be plenty, especialy on a bit higher infill, maybe even as high as 50%. Other than that the design is sparse but should be able to handle realitively high speeds, especialy because the plastic structural will have little to no ringing so input shaping may not even be nessisary. Also the design is conviniently modular(besides for the bed) so I can continue development later on if this is sucessful.
Gantry
After the frame, I went on the motion system, and on a cross gantry this works by having two perpendicular linear slides both attached to the toolhead, and individualy attached to another pair of slides of the frame each, so that they each controll one axis of motion but are free on the other for x and y movement.
I love this system because of the simplicity it entails, there are no complex belt paths, and the speeds achevable on these are incredible, reaching hundreds of thousads of mm acceleration and tousands of mm/s speeds. They are also, much more expensive and have more design challenges, such as having more limits on toolhead design.
For my design I am using mgn 9 rails, which should be strong enough, whilst also being very light and easy to fit into my toolhead design. They are attached to some carrage mounts that both hold the gantry rails, and the belts, for the main motion system.
For the belts (not cadded) I am using 6mm gt2 belts, with 20t pulleys, and 3d printed idlers (also 20t). The idea of 3d printing motion parts is confusing to a lot of people, but I have seen them work surprisingly well on countless projects for FTC so I thought that they would work just fine here.
The idler
Printhead
The printhead only has the hotend and partscooling on it to simplify the design and reduce wieght, so to connect a v6 hotend to two linear rails I designed this contraption.
And with the cooling shroud, we also have cooling for the heatbreak in the hotend itself, and a little but of parts cooling since it improves the speeds at which you can print well. The hotend cooler is just a standarsd part that comes with the hotend itself, but the parts cooling was a part that I had to design myself, and all said its not the prettyest part ive designed by a long shot, but will still be functional.
BOM
The budget for this will be a bit tight, but with liberal applications of printed parts it will be managable, so the BOM doesnt need a ton of work after this. The parts are just about as cheap as I could get them, and I think the overall cost is reasonable(esspecialy for cross gantry). I will have to find some filament somewhere else for all of this, and borrow a soldering iron and other such supplies.
I also pitched the project in slack (later found out this was not nessisary but was nonetheless helpful) and I got some great advice on improving the design.
6-4-2025 - 5 hours
Extruder
Polished CAD, got some final parts modeled such as the bowden extruder mount. I just put it at the top on one of the corner motor mounts for simplicities sake because it was as close to the printhead as I could get and realisticaly wont add much weight. It was super important to get it as close to the printhead as possible for the extrusion quality, and also to be as rigid as possible to act as an umbilical cord for all of the other wires that need to run allong to the printhead such as heaters and cooling.
I also decided to Add on some 2020 200mm extrusion after a helpful conversation on slack to help with the riggidity of the printer and to make assembly that much easier. I went with some cheap stuff off amazon as thet was the best price I could find, and precision id not super important here, just making sure that the printer doesnt wobble to much. The riggidity added by the extrusions should be worth the coset, esspecialy after subtracting the cost of the removed linear rods that were supporting the farr side of the printer.
I submitted the projects, so hopefully the concept is good enough.
6-5-2025 - 3 hours
Journaling
Just spent today working of the journal, getting more pictures in and all that. I also beefed up the text portions to the extent of what I can acctually remember doing.
Frame rigidifications
I also spent some time thickening the frame spars, so that there would be less flex in the system. These parts just attach with bolts, but should be plenty rigid on account of three surfaces of contact, they should stay in place plenty well.
All of the parts will be printed in pla which is kinda trash for this but its the only thing im confident in printing on my old ender 3, so its what ill have to work with untill I get an enclosed printer, but all said, it should work well enough for a low temp and small printer such as this one.
Electronics
Also after putting some thought into how to mount the electonics... im gonna worry bout that later cause this cold has killed my abbility to cad pretty much. However, my plan is simply design a case for everything that will fit into the bottom cavity of the printer, and have an external mount for the PSU just to mount it on somthing that isnt PLA.
6/11/2025 - 6 Hours
BOM
I spent sooo long just searching voron, annex, and so many more BOMs. I was searching these for good references for the most important parts, such as a new controller board (BTT octopus or v1.2). then onve I had gotten those I just scoured ali for the beat possible performance and prices I could possibly find. I mannaged to avoid ~$100 in shipping just by using ali and amazon sources for steppers and rails.
More on this tmrw but its 3 in the morning.