So, I think I’m coming close to finalising the Design of the Drakon Extruder. There’s a few small fillets and chamfers to be added, but I’m running them on all my printers, with good results… It is, what is essentially an E3D Titan but on a budget. Currently only available in 1.75mm, but it’ll be converted to 3mm in the future. It should work for direct drive, but is, as yet, untested as all my printers are Bowden.
From the viewpoint of a mechaical engineer, it’s bad to tighten the nut against some not moving parts even if it’s not realy tight. just ad a hole to the cover part to allow the nut to tighten against the bearing should work way better with this kind of adjusted bearing arrangement.
It shouldn’t be bad or something like that in this case, but you have a semi-locating bearing arrangement. That’s not necessary for this application. And since there are two bearing available to fix the screw why not use them?
if you don’t tighten the nut your gear position is only defined by the position of the small gear wich is not realy defined on the motor shaft. The better solution would be to fix the big gearing as mentioned and arrange the location of the small one acoringly.
@Kai11 There’s reason for the arrangement. I did have it that way previously (see attached image), however, I found it was necessary to support the large gear shaft further to take out flex in the body caused by the spring and idler arm. So the lid is actually supporting the assembly. I have tried dropping the nylon bushing into the hole, but it wasn’t as effective at stopping the flex. The lock nut is just there to retain the outer nylon bushing, which also supports the shaft. I know it’s not the most elegant way to do it. As this was designed in FreeCAD, which does have issues and needs work-arounds it’s not that easy to re-shape and add meat without stripping things down totally missing/deleted image from Google+
In that case i would suggest to use a spring with less force to fix the problem. You don’t need a ton of pressure on the filament. Or add some more material to the body, even if it’s a little work. It will run better this way in the long term.
Tbh, the lock nut and top bushing aren’t absolutely necessary and it can be run without. The bearings friction fit well into the seats. For me supporting the whole shaft properly is more important than stopping binding, which can be adjusted by loosening the nut. I do see your point, but in use, I’ve found it’s pretty much a non-issue. If you look at the commits on the github, I’ve been through a whole lot of iterations and uncounted hours of design time to get to this point where I feel it’s usable, I would suggest printing it and trying it before further criticism of the design.
Not having a go, btw, it’s just that in practice some things are not as important as you may think. You do make a good point, but it’s worth trying something before saying oh, that’s bad. I have a fair amount of hours printing with them already across 4 Printers. Also if you look at the Titan, they are doing something similar, admittedly, not as constrained.
Don’t get me wrong it’s not a bad design. It was just a suggestion to improve it a bit. I’m running a very similar extruder with the suggested bearing setup, so I have some experience in the design.
But if you have no problems with it keep it as it is.