Jump to content
Ultimaker Community of 3D Printing Experts
Sign in to follow this  
medicalmodeller

PLA stops coming out 1/2 way through the print of a fractured bone

Recommended Posts

I have been successfully printing out models of fractured bones that I have converted from CT scans.

I now have a model of a fracture that I need to print out to help with decision making. The model is quite big when full size in spite of selecting as small a region as possible. The stl file is 16Mb. The print is meant to take about 6 hours

I have tried printing three times now. On each occasion the print seems to go fine for about 1/3 of the print time and then the PLA stops coming out the nozzle and the print head is following its path in mid air. The filament seems to be simple shuttling forwards and back rather than advancing.

I did a material change and the PLA comes out the nozzle and so seems not to be blocked

I have looked at the model with xray in Cura and there are no red lines

Can anyone help me understand what has gone amiss?

I would be ever so grateful if someone could look at the stl file and see if it works for them? I can put it into a dropbox

This is quite important for me as I need to make a clinical decision based on the model - once I get the wretched thing to print

Many thanks

MedicalModeller

 

Share this post


Link to post
Share on other sites

Did the feeder grind into the filament? This would prevent it from moving the material to the extruder. I have no idea what your model looks like, but I am guessing there is a lot of retraction involved. Have you tried printing slower? I print PLA only on a dedicated UM2, anything above 50mm/s and 0.1mm layer thickness is critical. If tolerances are not critical I raise the temperature to 240C which will make the PLA flow much easier. ABS is a different story ;)

Share this post


Link to post
Share on other sites

There is not the grinding as I have had when the print loosens and then the accumulation of PLA around the nozzle blocks it completely. It seems to be stuck retracting and advancing

I am using the "standard" settings of 50mm/s and 0.1mm layer

I will try heating the nozzle to 240C

Thanks

 

Share this post


Link to post
Share on other sites

Have you ever changed the hot end Isolator in your UM2? That's a part which over time, will eventually degrade and will require replacing. It will cause printing problems if it's become worn.

Have you tried the Atomic method to clean out your nozzle?

240C for PLA is very hot at 50mm/s and 0.1mm layer height. Check your isolator. :-)

 

Share this post


Link to post
Share on other sites

It could be that at a certain height of the print, the retraction is more intense and causes the filament to grind,

or also there is a bit too much force on the filament feeder, that deforms the PLA and make it tougher to be pushed through the bowden tube.

try to cut the a section where it goes wrong from the model, and try to print it as a separate piece, so you wont have to test with the complete print again :)

I also have problems with retraction becoming too much for the filament at a certain point during the print.

 

Share this post


Link to post
Share on other sites

I have not changed any part of the UM2. I have had it for a few months

I have cleaned the nozzle with the Atomic method many times when I was having adhesion problems and the PLA accumulated around the nozzle leading to a block

MM

 

If you've thoroughly checked and are happy that your feeder works okay & your filament (2.85mm) isn't being tangled on it's route - which is friction free, the bowden tube is clear & your nozzle is clear... there's little left mechanically that can cause a problem.

Sorry to bang on - but you've not checked your isolator have you? You're certain that's ok then?

The isolator will deform over time and cause you problems. Replace it & I'd put money on that solving your problem. 50p bet? :smile: (I win either way)

 

Share this post


Link to post
Share on other sites

If you've thoroughly checked and are happy that your feeder works okay & your filament (2.85mm) isn't being tangled on it's route - which is friction free, the bowden tube is clear & your nozzle is clear... there's little left mechanically that can cause a problem.

Sorry to bang on - but you've not checked your isolator have you? You're certain that's ok then?

The isolator will deform over time and cause you problems. Replace it & I'd put money on that solving your problem. 50p bet? :smile: (I win either way)

 

Having received the UM2 pre-built, I am not familiar with the parts. I assume that the build instructions are online so that I can work out what the isolator is. What should I look for? Is it easy to change?

MM

 

Share this post


Link to post
Share on other sites

Yes, it's straightforward to do.

These are the steps to remove the nozzle - obviously you may not need to go that far, but handy to know about all the same. The dissasembly shows how to get at the isolator.

 

You may need to order a replacement from UM (it's in their shop) or, if your UM is under warranty they may even send you another.

https://ultimaker.com/en/products/spare-parts

Phoning is the quickest way to get in touch rather than through email.

https://ultimaker.com/en/support

Assembly manual

https://github.com/Ultimaker/Ultimaker2/blob/master/um2%20assembly%20manual%20V1.1%20_english.pdf

 

Share this post


Link to post
Share on other sites

Thanks for the info.

Before going down this route, would you be able to help me by printing out the file and see if it works for you on your machine?

I could share it with by drop box as it is quite big. I would not want to put the link onto the forum as this is a fracture of a real patient!

If you are agreeable, can you send me your email via a private message?

Thanks

MM

 

Share this post


Link to post
Share on other sites

If you've thoroughly checked and are happy that your feeder works okay & your filament (2.85mm) isn't being tangled on it's route - which is friction free, the bowden tube is clear & your nozzle is clear... there's little left mechanically that can cause a problem.

Sorry to bang on - but you've not checked your isolator have you? You're certain that's ok then?

The isolator will deform over time and cause you problems. Replace it & I'd put money on that solving your problem. 50p bet? :smile: (I win either way)

 

About the 50p...................

I think that I have found the cause of the print failure. I have printed out the model completely (7 hours) but with "enable retraction" unchecked.

Due to the nature of the internal structure of bone the filament retraction was in overtime. Somehow, the retraction led to the filament not extruding and then the blockage. Yes there is some stringing, but I can live with this in order to get a complete print

MM

 

Share this post


Link to post
Share on other sites

I had similar problems with a totally different machine/setup (I'm using 1.75mm on UMO+). In the end the solution was to lower just a bit the speed of retraction. But ofc my solution probably isn't usefull. Btw, if you are using the stock feeder, go and print the IRobertI feeder, it's rock solid.

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Our picks

    • How to 3D print with reinforced engineering materials
      Ultimaker is hosting a webinar where we explain how you can achieve and maintain a high print success rate using these new reinforced engineering materials. Learn from Ultimaker's Product Manager of Materials and top chemical engineer Bart van As how you can take your 3D printing to that next level.
      • 2 replies
    • "Back To The Future" using Generative Design & Investment Casting
      Designing for light-weight parts is becoming more important, and I’m a firm believer in the need to produce lighter weight, less over-engineered parts for the future. This is for sustainability reasons because we need to be using less raw materials and, in things like transportation, it impacts the energy usage of the product during it’s service life.
        • Like
      • 12 replies
×

Important Information

Welcome to the Ultimaker Community of 3D printing experts. Visit the following links to read more about our Terms of Use or our Privacy Policy. Thank you!