Any tips on getting the bowden cut perfectly straight?

[IRobertI 521]

A few nights ago my printer finally stopped working properly and I quickly traced it to the dreaded plug in the PEEK. I had that problem once early on but fixed it by doing Joergen's drill bit trick. Since then it worked for a long time printing beautifully for hours upon hours without issues. This time I had to shorten the bowden though as it was too chewed up to grip (it popped when the plug formed). And now I can't get the #!@n thing to seal again.

I've tried:

Cutting the bowden and re-assembling.

Tried Joergen's trick again.

Changed the bowden retainer clip to a spare.

Installed Owen's bowden clamp (which I had fortunately printed early on and saved for a rainy day).

Bowden clamp + retainer clip.

Bowden clamp without retainer clip.

Unscrewed PEEK to make sure it was clean.

Brass tube is just slightly above the lip (which does look a wee bit chewed up from cleaning).

Having the bowden protrude 8mm, 9mm and something random.

I stopped counting after having had the print head apart ten times and my fingers no longer wanted to keep doing it. After each re-assembly I tried extruding by manually turning the extruder gear and it jams up pretty much immediately. My only conclusion is that I'm not getting the bowden cut straight enough so that it is not sealing properly. Would you concur? And if so, do you have any tips on how to actually get it perfectly square? I have a very limited set of tools at hand unfortunately.

I really wish Ultimaker could come out with a better design for the bowden-hotend interface. It's the weakest point on the machine IMHO and for the past couple of days it has made me want to throw my printer in the trash because it has me so bloody frustrated.

[thedudevt 0]

I put mine in a V-Block and cut it with a razor blade sliding along the face of the block to guide the blade. If you don't have a v-block, maybe a vise?

I have the same problems with jamming though, I think I'm going to thread the end of the bowden tube per viewtopic.php?f=6&t=184.

I agree, if Ultimaker had a solution, I'd buy it. It's frustrating to have prints fail half way through.

Kyle

[owen 19]

You could get something that is 9mm thick and drill a 6mm hole through it, poke your tube through it and use it to guide your knife. When it stops, is there always a plug/blob at the top of the Peek?

[IRobertI 521]

Thanks for the tips guys, I needed to get my brain un-tilted. I have some aluminium profiles lying around that just might work as a sort of jig; put the tube in one of the grooves, pinch it up against the wall and then use the bottom of the profile as a guide. Worth a shot if nothing else. If that doesn't work I guess I'll have to head over to my fathers house and borrow his drill press to create a jig.

Tapping the end of the tube is also tempting, but I still need to get a good seal to start with, so, first things first.

To be honest I'm not sure if the classic "disc blob" formed every time but it did at least a couple of times that I could see. The thing is that I feel straight away if something is wrong or not, with just a turn or two of the drive gear it's immediately obvious that it's not going to work so I just rip it apart again immediately. Everytime I've had it apart there is PLA around the perimeter of the PEEK though which led me to think that it's not sealing properly.

[IRobertI 521]

Ok, I must be retarded or just plain stupid because I can't for the life of me get this thing to print again. I've now cut the end of the tube as flat as I can humanly get it and it still will not extrude. As soon as the filament hits the hot end it just stops and you can see a wee bit of extrusion happening before it stops. I've tried pushing filament through with the hotend detached from the head and while it of course oozes all over the top I can still manage to get some of it to come out through the nozzle so it's obviously not clogged (which as i understand it is extremely uncommon to happen in the first place). The filament can exit the tube just fine as well when I have the thing apart. I even tried cutting the filament at an angle and it still will not extrude. It shouldn't be this hard and I hope the Ultimaker team is listening (even if I do tend to sound whiny and annoying ).

I'm lost... Short of paying one of you guys to take my PEEK and a piece of bowden and threading and testing it for me I don't know what else to do. (I have a tap and die set but at this point I've lost faith in my abilities)

The new SLA type printers that are beginning to show up in the DIY sphere are starting to look mighty tempting, no ends to clog there! I've already added some of the parts to my Ebay surfing habbit.

[owen 19]

First up with it all done up can you push through at a decent rate by hand?

If not is it hot enough?

If yes, can you get the the extruder to push from control panel when not doing a print?

[IRobertI 521]

Nope, it seems to get stuck pretty much immediately.

Yes, I can hear the tell tale high pitched sound that you can hear as the hotend reaches about 185C (at least I can hear that on my machine). It's also apparent by a bit of gravity oozing happening and when holding up a piece of filament to the hotend it starts to melt.

Nope, it'll just start grinding filament (with clean bolt).

Tonight I also tried having the tube extend a bit further down the bottom so I had a ~3mm gap between the aluminium plate and the wood. I adjusted the tightening of the other three bolts to keep the aluminium plate roughly horizontal while doing this. No change. What little extrusion I get is oozing after putting a good amount of tension on the filament (to the point of stripping).

[owen 19]

So you can't push by hand or extruder?

[destroyer2012 0]

Tips for getting the tube straight: Use a small pipe cutter. Just remember to adjust the screw by only partial turns for every revolution. This also helps to not crush the tube as much. Another thing that might help to not crush the tube is to put PLA through the bowden tube then use the pipe cutter so the PLA will support the tubing.

I did this to my bowden tube and it stopped the leaks and plug formation pretty good.

[IRobertI 521]

So you can't push by hand or extruder?

No. A few times after re-assembly I've been able to extrude a few millimeters but then it gets stuck again.

 

Tips for getting the tube straight: Use a small pipe cutter.

Nice one. I actually looked at one at the local hardware store a couple of days ago when trying to come up with a solution but I thought the cutting wheel looked a bit too dull for the soft plastic. But if it worked for you it's worth a shot, they only cost a few bucks so no big deal if it turns out not working for me.

[ddurant 0]

Though I haven't had to cut my bowden tube before, I do think you're looking in the wrong direction.. With some care, you should be able to get it cut straight enough to work. The amount of pain you're expeciencing doesn't seem to match up with this task.

Have you tried heating up, ***carefully*** pulling the nozzle off and seeing if you can push filament through by hand?

(edit: probably don't need to go to your normal heat range.. I'd probably start 15-20C lower than that and see how willing the nozzle is to come off then raise it up a little, if needed)

[IRobertI 521]

Well I'll be... good idea there ddurant, I did what you suggested and tried pushing through filament without the nozzle attached. It worked just fine (and looked hilarious to me for some reason with that big chunky 3mm filament spewing out) and I took the opportunity to clean up the nozzle a bit. I do believe I had an actual clog in the nozzle, there was a small bit of something black mixed in with the red filament I pulled out. Since I haven't used black in the printer for several printing hours it seems unlikely that it would be a remnant of that. Either way, it appears to extrude normally now, I've only tested it by manually turning the gear but it looks fairly normal for now.

I never thought to check the nozzle since I don't think I've seen anyone post about a clog actually forming in the nozzle and since I was also getting a wee bit of "gravity ooze" I figured it was clear. I just hope that was actually the cause and it doesn't end up grinding to a halt again as I try the first print. Just have to re-level and do a bit of clean up before I try a new print.

Thank you all for your input and advice.

[ddurant 0]

Great!!!

 

I never thought to check the nozzle since I don't think I've seen anyone post about a clog actually forming in the nozzle..

I think it's pretty rare to actually clog a nozzle.. The 0.4mm thing sounds really small but it's quite big, compared to dust.

Where did the black filament come from? Someplace reputable?

[IRobertI 521]

The black came from supply3dpla but I believe they have switched suppliers since I bought this roll.

I'm also happy to report that I've printed for 3+ hours so far without any issues. *knocks on wood* hehe

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