Core One umbilical sagging
I have recently upgraded from Mk3.9 to Core One including the MMU3. With this configuration what strengthens the umbilical such that it desn't sag? I have put a length of PTFE tube along it and secured the PTFE to the umbilical shroud on the Nesxtruder. but it still sags! This becomes a problem when the head moves to the far left, the the umbilical contacts the side of the motor, and is forced down into the belts!!
I imagine that the correct solution will keep the umbilical over the top of the motor. Help please.
RE: Core One umbilical sagging
It should be strapped to the swing arm, assuming we're talking about the same thing
RE: Core One umbilical sagging
Yes - its all strapped to the swing arm, but there is still enough sag to cause issues with the left motor.
RE: Core One umbilical sagging
I have recently upgraded from Mk3.9 to Core One including the MMU3. With this configuration what strengthens the umbilical such that it desn't sag? I have put a length of PTFE tube along it and secured the PTFE to the umbilical shroud on the Nesxtruder. but it still sags! This becomes a problem when the head moves to the far left, the the umbilical contacts the side of the motor, and is forced down into the belts!!
I imagine that the correct solution will keep the umbilical over the top of the motor. Help please.
Had the same thing happen. The PTFE tube is stiff enough to prevent the main cable from sagging but only if the tie wraps after the swing arm are secure and evenly spaced. I had the tie wrap closest to the print head slide closer to it's adjacent tie wrap which caused a sag.
RE: Core One umbilical sagging
I checked that the ties were evenly spaced but still had the problem. I have now temporarily solved the problem by attaching a length of cable chain between the swing arm and the nextruder. This provides enough support to keep the umbilical from sagging, and enables the head to move to all of its extreme positions, without trouble.
Before doing further work on this I'd like to hear whether Prusa think that this is a possible design fault, and any proposed solution.
RE: Core One umbilical sagging
I checked that the ties were evenly spaced but still had the problem. I have now temporarily solved the problem by attaching a length of cable chain between the swing arm and the nextruder. This provides enough support to keep the umbilical from sagging, and enables the head to move to all of its extreme positions, without trouble.
Before doing further work on this I'd like to hear whether Prusa think that this is a possible design fault, and any proposed solution.
Not sure this is a design flaw since I don't see any other threads complaining of this issue. The PTFE tube is rigid enough that after properly attaching the main cable there is zero sag. Again for me this only happened when the tie wrap was too loose and slipped.
RE: Core One umbilical sagging
Pics would help, right now its all speculation and hypothesis. But I agree, this is the first report of an unsolved sag issue - and the solved cases I've only seen here.
RE: Core One umbilical sagging
OK I've added 4 media images. one showing the general arrangement of the umbilical and position of ties. The other three shows what happens when the head moves along the back, to the left trapping the umbilical. It may be that I have constructed this incorrectly, but on the face of it it looks accordance with the instructions.
I don't remember how it looked immediately after construction, but I have now printed a lot of ABS with a chamber temperature of 50 degrees, may be that has had an influence. It looks as though the PTFE is not stiff enough to keep the umbilical lifted.
Adding cable chain to the umbilical and swing arm is currently providing a solution.
RE:
Hey all I actually made a post about this exact thing in the general discussion section of the core one forum. I found even with 2x ptfe tubes acting to stiffen the extruder cable there was always a position or situation where it would still catch or snag, in the end I resolved it on mine and achived a really clean look using a Cable Chain aka linear cable guide as mentioned in the most recent post above mine. But I can confirm it has worked beautifully.
I printed mine in PETG and it has held up to about 38 hours of non stop printing in petg and ABS so far and best of all my issues with prints failing from snags has gone away.
Robin
RE:
I've run across 2 instances (so far) of this being caused by incorrectly routing the umbilical relative to the PTFE tube. Need to make sure it matches (as closely as possible) to this photo. Pay special attention to the spacing of the cable wraps. Also notice how the PTFE tube is to the left of the umbilical closest the X-motor.
RE: Core One umbilical sagging
I'm not sure this detail in the picture is significant: if you click on the next step in the install guide you will see the PTFE tube on top?! In my core one the tube is on top and it works flawlessly. Sure worth trying this position though if it helps avoid the sagging!
RE: Core One umbilical sagging
I'm not sure this detail in the picture is significant: if you click on the next step in the install guide you will see the PTFE tube on top?! In my core one the tube is on top and it works flawlessly. Sure worth trying this position though if it helps avoid the sagging!
Well the exact position probably doesn't matter. The point of it is the PTFE tube acts as a rigid spine for the umbilical. Whatever position prevents the cable from sagging and getting between the print head and the x-motor is sufficient. What I have read on here is that some people ran into sag when the PTFE was on the opposite side versus the photo. I also had this problem when one of the velcro ties slipped down the umbilical and there was too much distance between the successive tie wraps which resulted in sag.
RE: Core One umbilical sagging
good to know, my velcro ties seem to be rather stable but I'll keep an eye on them!
I'm not sure this detail in the picture is significant: if you click on the next step in the install guide you will see the PTFE tube on top?! In my core one the tube is on top and it works flawlessly. Sure worth trying this position though if it helps avoid the sagging!
Well the exact position probably doesn't matter. The point of it is the PTFE tube acts as a rigid spine for the umbilical. Whatever position prevents the cable from sagging and getting between the print head and the x-motor is sufficient. What I have read on here is that some people ran into sag when the PTFE was on the opposite side versus the photo. I also had this problem when one of the velcro ties slipped down the umbilical and there was too much distance between the successive tie wraps which resulted in sag.