RE: Printing TPU on the MK4
Part bowed off the sheet. There goes another attempt. Killed the job after 6 hours. It would have never made it to completion as the lift was all around the outer perimeter and extended at least 10mm inward. Hard to make progress that way. Added a 10mm brim and will try again. Running aligned seams in Classic. The random classic started bubbling outwards.
I'm beginning to think the filament needs a lot more drying than my drier can provide. (55C). Might be time to upgrade it to a version that can go hotter and perhaps treat some more silica beads in the toaster oven. The beads aren't showing color change, but it was raining the other day. The filament is stored in vacuum bags with desiccant. Or this run of filament just isn't good.
Wish I knew what was wrong, so I could fix it. Feels like I'm chasing my tail.
RE: Printing TPU on the MK4
Oh man. I use a print dry that will do up to 85C. Can show pictures of how it failed?
Part bowed off the sheet. There goes another attempt. Killed the job after 6 hours. It would have never made it to completion as the lift was all around the outer perimeter and extended at least 10mm inward. Hard to make progress that way. Added a 10mm brim and will try again. Running aligned seams in Classic. The random classic started bubbling outwards.
I'm beginning to think the filament needs a lot more drying than my drier can provide. (55C). Might be time to upgrade it to a version that can go hotter and perhaps treat some more silica beads in the toaster oven. The beads aren't showing color change, but it was raining the other day. The filament is stored in vacuum bags with desiccant. Or this run of filament just isn't good.
Wish I knew what was wrong, so I could fix it. Feels like I'm chasing my tail.
RE: Printing TPU on the MK4
Not much to see. Can't see anything obvious with a photo.
Imagine a cylinder which is only sticking to the sheet near the center of the cylinder, with the lift distance increasing as the radius increases. I could see light all the way around the part at the base. The outer edge is lifted about 0.5mm or so. The 45mm diameter part was being supported by 22mm diameter section that had a 17mm hole in it. So not much to hold to the sheet.
RE: Printing TPU on the MK4
Maybe do a good cleaning on the sheet? Is it satin sheet?
RE: Printing TPU on the MK4
Oh man. I use a print dry that will do up to 85C.
Do you know of a less expensive solution that gets that hot? The Print Dry Pro 3 is $199 these days. It looks ok, but at the moment is a bit too expensive, and more importantly, takes up more room than I have allocated. Wish I had a better setup, but that's what I have to work with.
RE: Printing TPU on the MK4
I don’t. I some esun dryers but I only use the print dry. The esun dryers only do 55 also
RE: Printing TPU on the MK4
Maybe do a good cleaning on the sheet? Is it satin sheet?
Yes, it is satin. Thing is, just before printing I had cleaned it with dish washing detergent, and dried it. Then I used isopropyl 99% to clean the sheet. Finally used AquaMist Unscented hair spray on the sheet. This has worked exceptionally well for me in the past. Good adhesion, but possible to remove. Without Aquamist I had over adhesion with TPU and especially PETG. Still have a couple thin spots of PETG that I can't remove!
RE: Printing TPU on the MK4
If anything, in my hands TPU sticks too well to the bed. But I also dry it at 65 degrees in a PrintDry Pro and run it directly out of the dryer.
RE: Printing TPU on the MK4
Beginning to see a pattern here... Good prints with dry filament. Can't say I'm surprised really, having gone through similar stuff with PETG that was damp. I'll have to search for other (better) driers. If I can't find any other options, may have to get a PrintDry unit.
RE: Printing TPU on the MK4
Another filament jam. 😥 Can't seem to catch a break on this material.
Came upstairs after dinner to hear the click click click of the extruder. Blob on the end and printing with no extrusion. Pretty disappointing. Open up the access door and yes there's a small kink jammed in the back edge of the extruder wheel.
I'm 0 for 3 at this point.
RE: Printing TPU on the MK4
can you show us what the sliced model looks like? While I tend to reduce the mvs when I start getting jams, I think it can also have to do with the how often retractions are occurring. Remember it's reversing the gear and pushing filament back up when a retraction happens. This is why I lowered the retraction speed in my settings. Each time it retracts if there's any bowing in the filament at all inside the extruder there's a chance for it to catch and jam like that. you could try reducing retraction speed to 10 from 20. My general go-to with jams is reduce mvs and or increase the temp slightly. this either reduces the rate the filament is fed into th hot end(to prevent back pressure) or increases temp to make it easier to push the filament through the nozzle. without seeing what the sliced model looks like I'm assuming your jam is being caused by retraction, or as you mentioned, wet filament.
RE: Printing TPU on the MK4
I agree with @fuchsr, tpu tends to stick nearly too well depending on how much of the model is in contact with build plate. I generally put some layerneer bed weld on there when there's a good deal of contact with bed so that when things cool it's slightly easier to peel off.
RE: Printing TPU on the MK4
can you show us what the sliced model looks like? While I tend to reduce the mvs when I start getting jams, I think it can also have to do with the how often retractions are occurring. Remember it's reversing the gear and pushing filament back up when a retraction happens. This is why I lowered the retraction speed in my settings. Each time it retracts if there's any bowing in the filament at all inside the extruder there's a chance for it to catch and jam like that. you could try reducing retraction speed to 10 from 20. My general go-to with jams is reduce mvs and or increase the temp slightly. this either reduces the rate the filament is fed into th hot end(to prevent back pressure) or increases temp to make it easier to push the filament through the nozzle. without seeing what the sliced model looks like I'm assuming your jam is being caused by retraction, or as you mentioned, wet filament.
I will post a section later in the day. I tried my Overture TPU and it jammed as well. It previously had printed ok, but needs more tuning. Maybe have over tightened the idler assembly and would like to know how to adjust it properly. The original instructions were not that clear to me, need to read them again.
The print dry unit has a large footprint so to use it I'd need to make an elevated stand over the printer. The printer is sitting on top of a dresser in a spare bedroom so there's not much space left. Was hoping to avoid high rise stuff, but maybe can come up with something that is workable.
The PrintDry Pro is no longer in production and has been replaced by the PrintDry Pro 3. Not many places have it yet. I looked at making something but it would seem that it would take a bit of time, money and programming to do so. If I factor in the effort it seems I would be ahead to just buy it. Don't need yet another project to get in the way of what I want to do, have to draw the line on expanding scope indefinitely. Two levels of indirection is enough.
RE: Printing TPU on the MK4
As you are learning, tpu can be incredibly frustrating stuff. It's great when it is printing ok. I printed a whole series of these colorado coasters as gifts to give away on our recent cruise. Not only was I doing tpu, I was doing color changes as well. it requires a great deal of patience and often a bit of luck lol
And of course, after printing several I got this on one of the extruders because one of the extruders had jammed. this was quite fun to clean off.
So you mentioned impatience..... TPU will test your patience. If you're in doubt with tpu, slow things down(via mvs).
I will post a section later in the day. I tried my Overture TPU and it jammed as well. It previously had printed ok, but needs more tuning. Maybe have over tightened the idler assembly and would like to know how to adjust it properly. The original instructions were not that clear to me, need to read them again.
The print dry unit has a large footprint so to use it I'd need to make an elevated stand over the printer. The printer is sitting on top of a dresser in a spare bedroom so there's not much space left. Was hoping to avoid high rise stuff, but maybe can come up with something that is workable.
The PrintDry Pro is no longer in production and has been replaced by the PrintDry Pro 3. Not many places have it yet. I looked at making something but it would seem that it would take a bit of time, money and programming to do so. If I factor in the effort it seems I would be ahead to just buy it. Don't need yet another project to get in the way of what I want to do, have to draw the line on expanding scope indefinitely. Two levels of indirection is enough.
RE: Printing TPU on the MK4
Here's a screenshot snippet where the Sainsoft TPU jammed. Seems to be where the max volumetric flow was (and the higher speeds).
I did readjust the tension, the screw ends were sticking out a few threads on the idler nut. The instructions say to make the screw end flush with the surface. However the surface is curved in that region, so I'm not quite sure what surface the screw end is to be flush. In the picture the threads stick out a little. It would be clearer if the orange line wasn't there!
RE: Printing TPU on the MK4
You can clearly see from your picture that the screws are too tight. No wonder the filament got tangled in the extruder.With TPU, you always have to experiment with the adjusting screws. From my experience, I can say that it is better to use a little less than too much.
Another filament jam. 😥 Can't seem to catch a break on this material.
Came upstairs after dinner to hear the click click click of the extruder. Blob on the end and printing with no extrusion. Pretty disappointing. Open up the access door and yes there's a small kink jammed in the back edge of the extruder wheel.
I'm 0 for 3 at this point.
RE: Printing TPU on the MK4
You can clearly see from your picture that the screws are too tight. No wonder the filament got tangled in the extruder.With TPU, you always have to experiment with the adjusting screws. From my experience, I can say that it is better to use a little less than too much.
Another filament jam. 😥 Can't seem to catch a break on this material.
Came upstairs after dinner to hear the click click click of the extruder. Blob on the end and printing with no extrusion. Pretty disappointing. Open up the access door and yes there's a small kink jammed in the back edge of the extruder wheel.
I'm 0 for 3 at this point.
It's not so obvious to me. The views are entirely different. I can't view the printer in the same way as the Prusa supplied picture, I'd need to get up higher on a step ladder. Printer is on top of a dresser, so it is above my eye level.
Maybe I'm off by a thread or two. I don't know where the reference surface is. Perhaps you could tell me? Does the thread just peek out? What surface is it parallel to? Just now, I set it with my fingernail. Don't know if that is ok or not. Will find out tomorrow.
RE: Printing TPU on the MK4
so I went back and looked at the assembly instructions for the MK4. If the tips of the bolts are flush with the surface it's WAY too tight for tpu. I proved this to myself by printing a cylinder and getting a jam. Loosening them back up allowed the same print to finish without issue.
Here's what mine look. The tips are sunken maybe 2-2.5mm. This is with a piece of petg loaded.
RE:
I had the same thing happen with the TPU wrapping around the gear as well, but only with a 0.6 nozzle. It has never happened with my 0.4 nozzle. I used the Amazon Basic TPU profile for Overture TPU without having changed anything.
I am going to try loosening the idlers. If that doesn't work, I'll reduce the flow rate. 🙂
RE: Printing TPU on the MK4
Thanks, @ssill2 that is very helpful. I have backed off the screws by two turns, so 1mm. I'll try again. If needed, I'll back them off some more. I was getting failure within a couple of mm of print the last couple of days, couldn't even complete the bottom shell before it started clicking.
I'm reluctant to back off MVS, right now the estimated print time is at over 17 hours! I suppose that wouldn't be terrible, if it would actually complete.
At 0 for 4 right now, but a little more hopeful. Trying again.