Extruder delayed jam

Hello! I'm almost done building a shapercube, but having some problems with the extruder where i can't find much about on the forum.

Before I start to explain, I notice the equipment you use had a lot of influence on the problem solving; so some information about my printer:
Shapercube 2.0
I use a Wade's extruder
PLA filament (3mm).
My hot end was delivered pre-ensembelled: [www.reprapsource.com]
I tried different temperatures and different kind of filament (ABS and 'soft PLA' [www.2printbeta.de])

At first, the extruder runs fine at all speeds. But after some time it jams all of a sudden. The wheel keeps spinning, thus the hobbed bolt starts scratching in the filament. When i put the extruder in reverse, it does come out quit easily. Because i tried this on different temperatures and with different materials I think it is something in the hot end.

If anyone could give me some tips about how to check my extruder I would very much appreciate that!

Mathijs

... i think you jammed the hot end while changing between PLA and ABS - this lets clogg some solidified residues, which won't remelt when reheated again

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Viktor, this is indeed what i did a few times (out of enthusiasm to see wether it would work with PLA as well).

I'll clean it with acetone over night.

thnx for your repsonse!

... it could be that the crystallized residues aren't solvable with Acetone - maybe you can remove it with a drill, but be carefull not to hurt the tube ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

PLA has a very low glass transition temperature. If it warms up to about 50 or 60 degrees Celsius it will tend to swell slightly and will press into the inside walls of your extruder barrel.

I'm not familiar with the design of the extruder that the Shapercube uses, but can you check the temperature at the top of the extruder barrel where the PLA is pushed in? I'll bet that the top of the barrel slowly warming is causing jams once it rises above a certain temperature.

If you can swing it, you should keep separate extruder nozzles for PLA and ABS. What will happen sometimes when switching from ABS to PLA is that the nozzle walls will retain the ABS, the PLA will begin flowing through the center, leaving a solid shell of ABS around it. This restricts the flow severely, and will seem to be a clog in the nozzle.

I regularly switch between the two since printing Prusas. I simply run about a meter of the new plastic through at the correct temperature for ABS, i.e. the higher of the two and then set the correct temperature. I don't have any problems with clogging. It does waste a meter of filament each time though.

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[www.hydraraptor.blogspot.com]

Hi Chris,

which temperatures do you have max. for PLA and ABS?

Maybe the people with clogging nozzles receive some weird chemistry while overheating the mixture?

I read some posts where tey found some hard residues in the nozzle which won't remelt again with the normal used temperature for ABS and will smoke and puff (but not melt) with higher temps ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I run white ABS from reprapsource.com at 250C and PLA from makerbot.com at 220C. I regularly switch between the two when making Prusa's and flush at 250C. The PLA becomes like syrup at 250C, but does not burn.

In my experience ABS does not start to go brown until you get above 280C or if it exposed to air.

The only place I get hard residue is on the outside of the nozzle and at the entrance. Once a month I have to ream the nozzle aperture as it gets smaller in diameter, but I don't get any hard residue inside the extruder.

I have had ABS smoke and produce hard material that blocked the nozzle, but only when the thermistor fell off and the temperature got close to 300C for some time. And yes, burnt plastic will no longer melt, or be dissolved by acetone. I assume it is mainly carbon.

Perhaps some types of ABS degrade at lower temperatures. Possibly coloured ABS, where the pigment cannot handle the same temperature as the base material. [hydraraptor.blogspot.com]

Edited 1 time(s). Last edit at 05/28/2011 08:47PM by nophead.

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[www.hydraraptor.blogspot.com]

I have just had to unblock my first cooked extruder tip when my thermocouple fell off (thermocouple wire snapped).

It had plenty of burnt ABS in the printing tip and on the outside.
I put the tip in an old 50ml acetone bottle from Boots (the largest size they sell).
Filled it up from my 1ltr bottle of Nail varnish remover (acetone with glycerin additive) from Boots and half the price of the 50ml acetone. Acetone must be one of the nasty chemicals that airport security don't like I think.

Shook it left it 24 hours the black ABS deposit flaked off like flaky paint the ABS inside the extruder came out like a gooey paste on a 2.1mm drill again the internal black deposit flaked off with a sewing needle.

I pushed a 0.35 mm drill through the extruder tip not sure that it needed it. washed it in fairy liquid. looks as good as new.

From reading I think there must be several different types of ABS.

By types I mean different polymer mixtures making the ABS, I think it could be a worth while exercise learning a little bit more about the various recipes used in the making of ABS welding rod. Some smell very strong some obviously print better than others some burn or decompose worse than others. Hopefully we have at least one Reprap user who has this kind of Chemistry knowledge who could perhaps help explain or be able to define the best recipe to use for printing.

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Bodge It [reprap.org]
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BIQ Sanguinololu SD LCD board	BIQ Stepcon	BIQ Opto Endstop
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My rep strap: [repstrapbertha.blogspot.com]

Buy the bits from B&Q pipestrap [diyrepstrap.blogspot.com]
How to Build a Darwin without any Rep Rap Parts [repstrapdarwin.blogspot.com]
Web Site [www.takeaway3dtech.com]

Yes the type of ABS is important, but none of the suppliers state what they sell. Also, very few places sell it with the close tolerance diameter required for printing.

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[www.hydraraptor.blogspot.com]

It is possible to define a spec as this must be exactly the way the commercial machine manufactures get their stock.

The RepRap/Makerbot/Ultimaker/TomDick&Harry Open source hobby printing community is be coming big enough to define its own printing material spec. Once that is defined we have enough usage to be able to start specifying our own material definition.

Lets call it 3D hobby printing plastic a simple survey like Erik did nearly two years ago should be able to demonstrate the new buying power and quantity's required. I'm sure defining the formulae for a good ABS polymer for 3D hobby printing plastic would be within the bounds of a PHD project. We seem to see so many requests for PHD ideas here.

Once there is a Spec for us to quote when ordering it will not take long for a manufacturer that has vision to see the world wide sales opportunity. We already can define a material size spec we should be able to define an Ideal melting point, water content etc.

Maybe the concept of specifying the ABS welding rod characteristics is already out there with ISO90002 being a requirement in many manufacturing areas with the primary use of welding ABS structures on cars or industrial mechanics.

Maybe the definition of 3D hobby printing plastic characteristics and specifications is the next Big step forward for the community to make.

Edited 3 time(s). Last edit at 05/29/2011 04:21AM by BodgeIt.

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Bodge It [reprap.org]
=======================================

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BIQ Sanguinololu SD LCD board	BIQ Stepcon	BIQ Opto Endstop
BIQ Heater Block PCB	BIQ Extruder Peek clamp replacement	BIQ Huxley Seedling
BIQ Sanguinololu mounting	BIQ standalone Sanguinololu or Ramps mounting	Print It Stick It Cut it

My rep strap: [repstrapbertha.blogspot.com]

Buy the bits from B&Q pipestrap [diyrepstrap.blogspot.com]
How to Build a Darwin without any Rep Rap Parts [repstrapdarwin.blogspot.com]
Web Site [www.takeaway3dtech.com]