Filament slipping

I've done a search but couldn't find anything about this.

I've installed the new wades block but my filament is still slipping, what could cause this? I've cleaned the hobbled bolt, checked it's aligned with the filament correctly and checked that the bolt moves freely.

Could old filament cause a problem? I've not had this problem before.

Perhaps the hot end is blocked. Try feeding it by hand to see how much force is required.

Other possibilities are the filament is too big (or much too small) or the spring tension is enough to squash it so it is too wide.

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[www.hydraraptor.blogspot.com]

It does feel like it needs more force then normal. It will extrude some filament then it starts to slip, could it be clogged? What's the best way to clean the head?

Try the cold pull technique and see if you can empty the barrel. If that fails you might need to push something small up the nozzle. See [hydraraptor.blogspot.co.uk]

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[www.hydraraptor.blogspot.com]

I'll give that a go. Out of interest, how much is new j head? Is there any advantages to adding a e3d hotend?

We sell assembled ones for £50 plus VAT and postage. They are considerably less direct from hotends.com but they don't have as good a thermistor or the silicone tape and don't have the thermistor, resistor, wiring and sleeving fitted.

The E3D can reach higher temperatures but isn't a good fit for Mendel90 as it was designed around the J-head.

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[www.hydraraptor.blogspot.com]

I've been trying the cold pull but the filament still slips when I try to extrude. I've got some new filament, so it can't be that. What else can I do? Can I strip the head?

Edited 1 time(s). Last edit at 04/16/2015 01:48PM by danlad1631.

What sort of filament is it? Perhaps it needs a higher temperature.

Is the temperature reading correct at room temp?

Stripping the hot end is not a good idea as you have to do it hot and you need plumbers PTFE tape to reassemble it. The technique above should fix any blockage.

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[www.hydraraptor.blogspot.com]

I'm printing with PLA but I've also tried ABS and it still slips. It will extrude the first 10mm fine, then it starts to slip and makes a clicking sound.

Have you tried removing the hobbed bolt and feeding it by hand? That is the best way to separate hot end faults from drive faults. Hold the extruder in one hand and feed the filament with the other. You should be able to get a good flow rate without too much effort.

Edited 1 time(s). Last edit at 04/17/2015 01:38PM by nophead.

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[www.hydraraptor.blogspot.com]

Just tried that and it does seem to need some force to push the filament through, almost till my fingers slip down the filament. I've tried doing that at 190 to 220 dec and it feels about the same at both temps.

One thing that it might be is a gap has opened between the bottom of the PTFE tube and the brass. That makes a massive difference. To fix it remove the hot end and heat it to extrusion temperature and then tighten the hex screw in the top.

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[www.hydraraptor.blogspot.com]

How tight should it be? at the moment it's level with the top.

Hard to describe, fairly tight but not tight enough to crush the PTFE. When there is gap it will be easy to turn at first and then get much harder.

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[www.hydraraptor.blogspot.com]

Think I've already crushed the tubing now! Is there any chance if saving it?

Could I take the tube out and trim it a bit? Also does the head need to be hot to take it apart and when I put back together?

The PTFE can be replaced but is probably difficult to remove from the top without further damaging it.

Not sure if you can remove the PTFE when it is cold but it would need to be hot to seat well if the hot end has any PLA in the gap.

It is risky unscrewing the PEEK when it is cold because the PLA acts like glue and it can break. When hot you can unscrew it and then the PTFE can be pushed out. You then need to clean all the PLA from the top of the brass, apply some new plumber's tape to the thread (wrap a few turns anti-clockwise) and you can then re-assemble it cold. You would also need to replace the silicone tape and the cable tie. We can supply those as well as a new PTFE liner.

It is tricky unscrewing the PEEK while hot. I grip the heater block with adjustable pliers like these. Being steel they don't take the heat away very quickly.


I have to say striping it down is a last resort. I solve all my blockage problems with cold pull these days. However, I have known a blockage to create so much pressure it puts a bulge in the PTFE liner and that will make it harder to extrude. It is also probably why your Wades block broke as mine don't. I have only had blockages with ABS and that being softer does not exert as much force before it slips.

Edited 1 time(s). Last edit at 04/18/2015 07:19AM by nophead.

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[www.hydraraptor.blogspot.com]

I've unscrewd it and as you can see in the picture it doesn't look right and I can no longer push the filament through. I think that happened from me crushing the ptfe. Now it's apart I done a cold pull and it worked great, when I was trying it before it felt like it was working but then it would feel as though it was catching as it was coming out.

What's it going to cost me to replace the parts needed? Will it be possible to insert a new PTFE liner?

Thanks

I can't remember replacing one from the top without unscrewing the PEEK. Probably best to try pulling it out and see if the top of the brass looks clean. It needs to be clean to get a good seal, so if it looks like it has PLA on it I think it would be best the strip it down and clean it.

Let me know what you find and I will quote for the parts. As a guide the liners are $2.49 from hotends.com.

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[www.hydraraptor.blogspot.com]

So after stripping it and outing it back together it still slips. When I turn the extruder gear by hand it doesn't seem to need much force, but before I buy a new head, would there be any other possible causes to make it slip?

Springs not tight enough or filament too small so the idler can't close far enough or hobbed bolt teeth clogged up.

The idler screws should be just level with the back of the bearing block. That should give plenty of grip and not be in any way marginal pushing. Mendels have been know to climb up to the ceiling when the filament is suspended from the ceiling and gets tangled. I.e. a Wades can normally push with over 10kg force.

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[www.hydraraptor.blogspot.com]

Does it slip when you turn it by hand?

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[www.hydraraptor.blogspot.com]

Just tried it again by hand and yes it does slip.

We don't seem to be getting anywhere here.

I remove the hobbed bolt and push the filament by hand and I immediately know if the hot end is working or not because I know what the normal force feels like from experience. I also know what a correctly tightened hot end grub screw feels like. It's hard to debug these things remotely.

You should be able to get a good flow rate with about 4kg force. The extruder should easily be able to push with 10kg force. Note that isn't a lot of torque when turning the large gear as it is much bigger than the hobbed bolt so it is not hard to turn it and strip the filament even when the extruder is blocked.

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[www.hydraraptor.blogspot.com]

Related question.
My filament is slipping only when printing , when the head is up high, I can extrude to my heart's content.

is this a matter of not pulling strong enough?

Hi,

Are you saying that with the nozzle away from the bed you are able to extrude without any slipping but placing the nozzle near the bed causes slipping?

If that is the case then perhaps you have set your Z height incorrectly and it is too close to the bed.

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

This also happens in layer 2 and 3 , not just layer 1.

I had a similar problem. My problem was that i did not fasten the brass nozzle tight enough on to the aluminum block.I have the E3D hot end.
When it is warm tighten it and it was good.

i have a j head nozzle, i don't have an aluminum block ,
but thanks