Bananas  

Re: Bananas

Ooops forgot picture

Joan

Re: Bananas

Hi Joan

Did you try ABS juice on the bed and the glue provided by Prusa on your printbed? Long and thin prints often lift with ABS. I have had issues too. I am tweaking my ABS settings and printbed treatment. The banana affect means your layers are shifting in the X or Y direction depending how laid out on the bed. The first few layers are the key, thereafter making sure the filament joins to the previous layers well after. Try upping your ABS temperature.

May I suggest never leave a 3D printer for long unmonitored, something often goes wrong. I monitor my printers with a camera that streams. I never leave home with a 3D printer running. Especially as you seem to doubt the hotend temps. Fire risk!

Re: Bananas

Hi Joan,

Send me your 3D files and I will try to print on my genuine I3 printer.

Re: Bananas

Hi Nigel,
Thanks for the offer...

the models take about 250grams of plastic, which would be an imposition on your generosity. I was unable to attach the .Stl files as they are an unacceptable file format / extension...

the curvature is away from the bed, the tops are pretty much straight, it is the lower layers that have bent up away from the build platform...

the build platform was set to 100C
and the extruder set to 255 C

I am reasonably confident of the temperatures, but note that if the model cooling fan is set to full speed (as default in the Simplify3d Config for the Prusa original,, the extruder has trouble maintaining temperature...

for ABS Adhesion, I am using ABS Juice without Pritt Stick, because that seems to give me the best adhesion.

regards Joan

Re: Bananas

I am reasonably confident of the temperatures, but note that if the model cooling fan is set to full speed (as default in the Simplify3d Config for the Prusa original,, the extruder has trouble maintaining temperature...

The model cooling fan should be disabled for ABS. This would definitely cause the problems you experienced.

Re: Bananas

Hi Joan,

Richard.I is right. The print cooling fan should be disabled with ABS. . I use Joseph Prusa's Slic3r settings on his support site. You can download his ready made Slic3r programs. Look at the support site.

Re: Bananas

Hi Joan

Just to add to what Nigel and Richard have said, over-cooling when printing with ABS does cause the print problems you have experienced.

Firstly, I note that you have the bed set at 100 degrees, which is the correct temperature for printing ABS, however, you have not mentioned whether this temperature is either being achieved or maintained during a print.

Also, drafts can cause problems, so you need to ensure that the printer is isolated and for this some users have built an enclosure for the printer.

A piece of cork tile under the bed can also help to maintain the heat.

Ideally for larger objects, you need to have the bed temperature higher than for smaller items, so try 110 degrees. Pre-heat the bed for 15 minutes and do not start to print until the temperature is reached.

One last point; it may be that dropping your extrude temperature may help. 255 degrees is certainly well over the heat required for my Prusa ABS (specified printing temp 200 to 230 degrees).

Finally, have you tried printing one of the ABS files supplied by PR on the SD card?

Peter

Re: Bananas

Hi Guys,
Taking all the good informations and advices that you are cordially giving, I'm having the following test:

- Ambient temperature = 17°C (my fresh basement).
- Pre heated bed = 100°C (standard for ABS).

Reading on the glass with an IR thermometer (placed at constant height) i find these differences:

Is it normal such non uniform temperatures?
If yes, for large model printed with ABS it is definitively necessary to raise the bed temperature and take care of the speed for the few first layers.
Do you agree?
Paolo

Re: Bananas

Paolo

I think if you want to discuss something other than "bananas" then you should start another thread (or reopen an earlier similar thread to your topic - there are quite a few) rather than hijack this thread...

Peter

Re: Bananas

Hi all,

just a quick comment on ventilation on ABS print.

Globally fan should be switch off for ABS, with exception of very small layer, There, a bit of ventilation is needed (as well as slowdown) to let the ABS getting hard before an additional layer can be built on top on it. On slic3r, there is a conditional fan activation that can help if layer print is estimated below a specific time (something like 1~20 seconds). I was not able to properly print a specific part alone (this one: http://www.thingiverse.com/thing:1406879 ).

Re: Bananas

Paolo

I think if you want to discuss something other than "bananas" then you should start another thread (or reopen an earlier similar thread to your topic - there are quite a few) rather than hijack this thread...

Peter

Ok Peter,
Sorry about that but is not my fault is the subject of this topic started with "bananas" 😆
Paolo

Re: Bananas

@Peter. Paolo's comment is valid. Who made you the main man here? Bed heating distribution may be valid here! It seems that Peter with his many, many comments is the god here. No. He is not. People do not follow Peter slavishly he can be wrong. And often spouts bollocks.

Re: Bananas

Nigel

You are quite obviously correct and I know nothing, so I will leave you to solve this problem.

Peter

Re: Bananas

@Peter. Paolo's comment is valid. Who made you the main man here? Bed heating distribution may be valid here! It seems that Peter with his many, many comments is the god here. No. He is not. People do not follow Peter slavishly he can be wrong. And often spouts bollocks.
What's with the attitude? Drop it.

Peter is correct, Paolo should rather make a thread for his issue than post it in here. He can mention it being the cause for the thread author's issue, but no need to hijack the thread about his own issue.

Re: Bananas

Ok Guys thanks for the Info...

I may have clouded issues here a little...

the reference to the FAN was in respect of holding extruder temperature when I did the PLA Print on the left in the picture... the ABS Print on the right was done with the fan OFF... and a towel draped across the front of the printer to reduce draft potential and maintain ambient temperature.
as far as I can tell the build platform takes a long time to reach 100degrees but then maintains that quite well. I don't have a suitable thermometer to spot analyse the tempersture gradient across the build plate... but do note that it's pretty hot all over after a print.

1 am sure that prusa sets 255 degrees as the extruder temp by default, I will try a sample print and also try a reduced temperature for the box print...

thanks for your suggestions
regards Joan

Re: Bananas

Sorry. Apologies to everyone. I am a bit autistic. I often only see how my posts come across the next day. I am trying I know, but please bear with me.
Thank you.

Re: Bananas

With my Ultimaker 2 + I shrouded the front of the printer with a towel for ABS prints. The problem is the prints start at the top of the printer. The towel does work with some prints. I get perfect ABS prints over a large volume. Mostly. Some stringing today.

Re: Bananas

Sorry if I insist but,
if the first few layers are the key for good ABS printing and the temperature is not uniform on the whole bed surface (like happens on my bed), can it be the cause of such folds? ... I don't say "bananas" 😆
Paolo

Re: Bananas

Yes you are right Paolo. This is an issue that needs addressing.