Bowden tube pops out during retractions

[ZenOhSix]

I continue to have non-stop fails. Everything starts fine, but what looks like what is happening is that during a retraction - the filament pulls past the interior ledge of my Prometheus nozzle. When this occurs, I here an audible pop - then the bowden tube pops outwards. I think the Filament is now on the shelf, and as the extractor pushes more filament in - it only pushes the tube further away from the hot-end, causing a spaghetti mess.

Here is an interior example of the nozzle:

[img]https://farm6.staticflickr.com/5742/214 ... ae27_o.jpg[/img]

I have cut the bowden tube's end (making a new contact point). I have done the paperclip trick, pulling the top-hat that sits in the hot-end upwards while inserting the tube into the hot end.

HOW DO I KEEP THE BOWDEN TUBE FROM POPPING OUT?!

This thing is killing me. I cannot print anything as this is occurring.

Finally - the extractor settings I have on retraction are:

[img]https://farm6.staticflickr.com/5791/213 ... 094d_o.jpg[/img]

On the test print (7mm Disk from the A Strategy for Successful (and Great) Prints thread), it makes the outside skirt, then makes two passes around the outside of the disk - then it fails when it tries to filling (as it retracts up and moves). 100% of the time, the bowden tube pops out.

Other prints fail at various retractions as well.

Thoughts?

Thanks,
Mike

[KAS]

Wonder if it's a defective collet? Have you tried increasing the temp?


http://www.dta-labs.com/products/bowden-coupler" onclick="window.open(this.href);return false;

[ZenOhSix]

Thanks KAS.

I will order one overnight and find out.

The default PLA printing temp is 210c. I have followed the various PLA best printing threads, and can print (manually) down to 19x c. I have even tried to raise it to 215 - no luck.

Thanks,
Mike

[ZenOhSix]

I wish DTA was in the US - due to shipping costs/timely. I would have overnight-ed the shipment. The best I could do was pay $33 for a 3 day shipment to me...

Hopefully this fixes the issue. The little collet does not have the strength to hold the bowden tube in place at all. I hope the little flanges inside on the new ones are stronger than the one I have.

Thanks,
Mike

[RP Iron Man]

Hi Mike,

Thanks for pointing me to this thread.

First of all, I am sorry about the shipping fees. There are not many shipping options in Canada and they are all overpriced... There is nothing that I can do about that unfortunately

I have heard of this happening before and there could be a few reasons for it. I will need you to answer a few questions:

- What is the diameter of the tubing you are using, measured with calipers? It should be about 4mm. Please give me an accurate measurement.

- If you insert an undamaged end of tubing into the collet, does it hold the tubing at all when you pull on it? You should be able to pull with significant force without the tubing being pulled out of the collet.

- How much does the collet move in the heat sink? It should only be able to move up and down and side to side about 1mm to 1.5mm.

- Do you have a cooling fan cooling the part? Is it blowing over the nozzle tip? If so this could be a big issue as it could be cooling the nozzle tip resulting in a very high extrusion force. Make sure your cooling fan is not cooling the nozzle tip.

- Can you push the filament through the nozzle by hand when the tubing is pushed out of the nozzle? Does it require a lot of force?

I will ship you an extra 1meter length of tubing for free with your order to replace your current tubing in case that is the issue.

Please answer the questions above and I am sure we can easily fix this issue

Eric

[ZenOhSix]

Hi Mike,

Thanks for pointing me to this thread.

First of all, I am sorry about the shipping fees. There are not many shipping options in Canada and they are all overpriced... There is nothing that I can do about that unfortunately

I have heard of this happening before and there could be a few reasons for it. I will need you to answer a few questions:

- What is the diameter of the tubing you are using, measured with calipers? It should be about 4mm. Please give me an accurate measurement.

- If you insert an undamaged end of tubing into the collet, does it hold the tubing at all when you pull on it? You should be able to pull with significant force without the tubing being pulled out of the collet.

- How much does the collet move in the heat sink? It should only be able to move up and down and side to side about 1mm to 1.5mm.

- Do you have a cooling fan cooling the part? Is it blowing over the nozzle tip? If so this could be a big issue as it could be cooling the nozzle tip resulting in a very high extrusion force. Make sure your cooling fan is not cooling the nozzle tip.

- Can you push the filament through the nozzle by hand when the tubing is pushed out of the nozzle? Does it require a lot of force?

I will ship you an extra 1meter length of tubing for free with your order to replace your current tubing in case that is the issue.

Please answer the questions above and I am sure we can easily fix this issue

Eric

Eric,

Thank you. Here is the answers to your questions:

What is the diameter of the tubing you are using, measured with calipers? It should be about 4mm. Please give me an accurate measurement.

- It is 4mm. The calipers measured 4.01 to 4.04mm throughout the first two inches from the end of the tube.

If you insert an undamaged end of tubing into the collet, does it hold the tubing at all when you pull on it? You should be able to pull with significant force without the tubing being pulled out of the collet.

- It does hold it some, but if I put any force on it, it pops off. It has always done this, and hence where I think all of my issues have come from. It just took me a little bit to realize what was going on. At first, I thought it may have been a jam or something. Yet - immediately after the pop-off, I can put raw filament in the hot-end when heated up, it flows out the bottom fine without any issue. Here is a youtube video of how much it can move outwards, or how much the collet holds it in: https://youtu.be/xhsx-l19k_4

How much does the collet move in the heat sink? It should only be able to move up and down and side to side about 1mm to 1.5mm.

- The collet doesn't move horizontal; it only moves vertical. In the vertical movement, it moves 1/2 a mm.

Do you have a cooling fan cooling the part? Is it blowing over the nozzle tip? If so this could be a big issue as it could be cooling the nozzle tip resulting in a very high extrusion force. Make sure your cooling fan is not cooling the nozzle tip.

- I only use the fan when printing PLA (which is what I am printing), but the fan is OFF for the first three layers. I cannot even get 1/5th a layer printed before the bowden tube pops off..

Can you push the filament through the nozzle by hand when the tubing is pushed out of the nozzle? Does it require a lot of force?

- Yes. It goes through very smoothly, without any force at all. If the bowden tube does not pop out of the end of the Prometheus, then I think I would be off printing some nice pieces...

Thank you,
Mike

[RP Iron Man]

Hi Mike,

Thanks for the very informative video!

It looks like a faulty bowden collet or less likely, a possible machining defect on the heat sink. For good measure I am shipping you an extra replacement heat sink and collets, along with some tubing. I tested this heat sink and collet and it works great so this should solve your problems. First just try replacing the collet. If that doesn't work then replace the heat sink with the one I am sending you.

I will ship out tomorrow via express so I hope you receive it soon!

Regards,
Eric

[KAS]

Sounds like the fix might be on the way. Maybe Trick Laser could stock a few repair parts for the Prometheus?
I've never had any problems with mine, but I guess nothing lasts forever.

[ZenOhSix]

Eric sent me the new parts.

I have thrown them in - and off to print a calibration cube.

I am printing PLA at 210c, along with the bed temp at 68c. I am using the Purple Elmers glue (which seems to work well - as I have a difficult time getting items off the glass).

Notice the picture - it is printing!

First issue I can see while it is printing - front / right corner; it is peeling/separated from the bed.

[img]https://farm6.staticflickr.com/5806/214 ... f275_c.jpg[/img]

I will take more pictures once this cube is completed.

Thanks,
Mike

[ZenOhSix]

Interesting!

Ok.. The back side corners of the cube peeled upwards. Take a look at the photos:

Back:
[img]https://farm1.staticflickr.com/662/2161 ... b146_c.jpg[/img]

Left Side:
[img]https://farm6.staticflickr.com/5733/214 ... bb49_c.jpg[/img]

Right Side:
[img]https://farm6.staticflickr.com/5802/214 ... f2bb_c.jpg[/img]

Front Side:
[img]https://farm6.staticflickr.com/5688/216 ... 0d9b_c.jpg[/img]

From a hot-end perspective, I have a fan on the front side only. Further, I have it set so that the fan doesn't come on until after the 3rd layer. Looking at those pictures, the early layers are the problems from the backside, not the later layers. Yet, the front layers didn't have any issues. I immediately thought this was a fan issue, but those points I just made kind of counter it.

Any thoughts on the print? Why the corner warping in the back? Thoughts on the lines, temp, ???

-- Doing reading while it was printing, I found a few of the standard things to do:
---- Use a Raft.
---- Print the Skirt touching the object.
---- Use corner Mickey Mouse ears, or corner rafts.
---- Potentially lower Hot End temperature?
---- Higher Bed Temperatures?

Thank you,
Mike

[ZenOhSix]

Here is the part with a white background for clarity.

Once I receive some advice to fix the bottom layers which are warped/curled/wacked - I think I will be extremely happy. With the other 65% of the cube (going from top down) - it looks like it printed very well. Just the first few layers are horrid.

Front Corner
[img]https://farm6.staticflickr.com/5630/216 ... bb80_c.jpg[/img]

Back Corner:
[img]https://farm1.staticflickr.com/697/2145 ... 67a6_c.jpg[/img]

Thanks,
Mike

[Earthbound]

My thoughts:

Bed heat seems high (I print PLA with bed no hotter than 60, usually 50)
That seems like an awful lot of glue (but I switched to hairspray a long time ago)


Drop the bed temp to 55
Set layer fan to remain off until Z>2mm
Print speed no higher than 50mm/s
20mm/s for first layer
minimum layer time 12s

[geneb]

I'd cut 10 degrees off the extrusion temperature as well, unless the PLA you're using won't print at 200. Most of the time I run between 190-200, depending on the print speed.

g.

[ZenOhSix]

Thanks for the replies. A few things:

Drop the bed temp to 55

- I will try this next, but my fear was that the first layer didn't immediately stick and was drug all over the print area, messing up the first layer of print. It did that when I had the temp set to 63c. Not only does it mess up the first layer of print, it gets stringy and all over the nozzle.

In regards to the glue, I am just following what the manual says to do with the Purple stuff; horizontal wipe pattern, then once over with a vertical wipe pattern. I will clean it off, and do one swipe of glue + a lower temperature.

Set layer fan to remain off until Z>2mm

- Just for clarification, you are stating that the fan remains off until 3 or MORE layer's have been laid down? Right now, I have it to kick in on the 3rd layer. Hence, I would be meeting this settting.

Print speed no higher than 50mm/s

MatterControl display's their print speeds in a few places, but here is what I have:
- Infil: 40mm/s
- Inside Perimeters: 40mm/s
- Outside Perimeters: 35mm/s
- Support Materials: 40mm/s
- Bridges: 60mm/s
- Non Print Moves: 300mm/s
- First Layer Speed: 15mm/s
- Retraction Speed: 90mm/s

Excluding the Bridges, I am less than 50mm/s.

20mm/s for first layer

See above. I am running at 15mm/s.

minimum layer time 12s

For this setting, I see in the MatterControl cooling area: "Slow down if layer print time is below:" - it is currently 40 seconds. Is this the setting you are recommending to change to 12 seconds?

I'd cut 10 degrees off the extrusion temperature as well, unless the PLA you're using won't print at 200. Most of the time I run between 190-200, depending on the print speed.

- I printed another 1/2 cube at 200c, which is 10o down from 210c. The print still had the back two corners curled/warped, hence I stopped the print about 1/2 way up (after it normalized like the other print did). I will say though, the print looks nicer at 200 rather than 210. Yet, I would have been happy with 210, had I never experimented.

Yet, the back corners still curled and warped on me.

I needed to print a nose from a stuffed animal that I had created, since one of my dog's ate it off my daughters birthday gift. For that print, I created a raft and printed the part on top of it. Overall, the part came out great because the raft was there. Yet, I would rather not use a raft at all. I didn't like having to separate the printed layers where the part was supposed to start.

Thanks,
Mike

[jason128]

check that the nozzle remains level around the print area of the box. (just move it around in mattercontrol and use the feeler guage.)
I chased peeling for ages before realizing it wasn't a printing issue but a leveling one. leveling at the 3 tower positions was perfect, but it was all over the place in between