Has anyone mounted a bowden extruder above a printer with moving x and y axis? Ive only seen them mounted on the side.
You need room for the cable to flex. A large U loop allows it to flex at the minimum and maximum distances without binding. If it were mounted above, it would bind as you reach the minimum distance.
What if you gave it a little extra length so it makes a small loop and extends to the corners? Or would it not be worth the small reduction in bowden length?
To maintain the same bend radius, you would end up with a longer tube with it mounted a U loop is shorter for the same range of motion, plus it provides more convenient places to mount the extruder.
Designing the Bukito, I found that it can be even more efficient (both in terms of the length and of the space the range of space that the tube moves through) with the two ends at 90 degrees to each other and on different planes.
thank you for the answers!
You’ll sometimes see this on deltas, like the new SeeMeCNC Rostocks, as they have the extra vertical space available to not need to worry about the bend radius.
Related question - what is the recommended minimum bend radius for bowden tubes?
Depends on the diameter, wall thickness and shore hardness. Like the filament itself, tubes for 1.75 will be able to bend more than those for 3mm. Best thing to do is to stick a piece of filament in it and bend it, you should be able to tell when it’s bending too far, especially if you try to move the filament while bending it.
In the end, you need to balance the length of the tube with the bend radius to find the optimum. It also seems to do better if you find a way to spread the bend out so that as much of the tube as possible is bent to roughly the same radius, rather than having a long straight part and one that’s tightly kinked. That’s where my idea for the 90-degree angles (tube actually goes though a 270-degree bend) on separate planes idea came from. As the head moves on the Bukito, each point on the tube maintains roughly the same bend radius, it’s just the direction of the bend that changes.
@Whosa_whatsis , using your 90° arrangement, do you ever have trouble with the tube twisting in the fittings?
https://i.cloudup.com/AiSKtQGm2W.jpg My arangement is a 90 degree on a reprap style, not gantry, and I haven’t run into issues so far. I need to try a max height print to see how it performs then but it seems fine then i raise it up.
@Dale_Dunn It does seem to twist in the fittings slightly, but that hasn’t caused any problems.