General Category => General stuff => Topic started by: webby2 on March 23, 2020, 10:06:57 am

Title: Petg
Post by: webby2 on March 23, 2020, 10:06:57 am
It has been a while but I am starting back up on some of my stuff,, well I am now only using my latest printer, I gave the other one away to a relative and have switched over to petg.

Problems, problems and more problems,,,, not so much with the petg but with the printer and getting it setup nicely and THEN,, one of the retainers for the bowden tube failed.

These are just small things but when you are trying to get motivated and making things it sure is a damper on the old motivation.
Title: Re: Petg
Post by: webby2 on March 26, 2020, 11:12:29 am
It took a little bit but I think I have the printer setup close enough :)

This one is slower using petg than the other one was,, but it does seem to be doing its thing for me.

Now to print some parts and assemble a testbed!
Title: Re: Petg
Post by: webby2 on March 30, 2020, 09:08:41 am
I am running the printer with the bed set to 70C and the hot end set to 247C,, I increased my print rates a little and things are working fairly well so far with tolerances within +- 0.5%
Title: Re: Petg
Post by: webby2 on March 31, 2020, 10:23:56 am
Some days,,

An interesting thing keeps happening to my bowden tube,, I am guessing it is due to running at 247C,, but at the hot end it is slowly melting (getting soft anyway) and allowing the tube to pull up and out of the retainer leaving a groove in the tube.

I had to clean off a glob of plastic from the nozzle and I guess I hit the very tip with something while doing that.  I did not notice it at first but the feed kept "popping" due to too much pressure,, well in the middle of a print things were looking fairly bad so I stopped the print and pulled out the tube and then ran a drill bit down to make sure the hole size was 0.4mm,, it was not.

It is back to printing as it was.
Title: Re: Petg
Post by: webby2 on April 02, 2020, 06:32:27 am
I tried to speed things up too far,, bummer.

So I can run at 45mm\s prolonged print without running out of extrudite,, petg,, well it stops coming out nicely so it looks like I am underextruding but the problem is that even tho the hot end is showing 247C it is not keeping up so the flow goes down and the pressure on the filament goes up.

Slowing it down means that it takes longer to print,, what is a little more time :)
Title: Re: Petg
Post by: webby2 on April 06, 2020, 07:34:35 am
interesting problem :)

I am using a magnetic build surface, one that lets me pick up the surface with print when I am done and then place it back onto the printer when I have removed the print.

Often a printing issue is with the print NOT sticking to the build surface, well with the surface I am using and the temperature I am printing at the extrudite is sometimes fusing to the surface.  I have made a huge mess of my surface at the moment with holes and whatnot,, not a good thing.

I think I am going to try and use Blue tape on the surface and see if that stops the fusing issue and still allows me to bend the build surface for easy removal.  I will try it with the current surface first, before I put on the new one I have already.
Title: Re: Petg
Post by: webby2 on April 07, 2020, 12:15:57 pm
I have used the blue tape for a few prints and it does stop the fusion issue and still has some flex to it so I can still bend the surface to facilitate removal.
Title: Re: Petg
Post by: webby2 on April 08, 2020, 11:15:31 am
The Blue tape appeared to create issues with the build surface bending up,, so not such a good solution.

I had to change the build surface out with a new one and have been adjusting things to see what I can do to get the print to stick as well as release.
I have set my clearance to 2 sheets of heavy bond paper, then set my slicer to adjust for a Z level error of 0.2mm to raise the first layer height,, I also have turned off the heatbed.

After reading on line that the cheaper magnetic build surfaces will mess up if you run them at 70C and start to warp the edges up, like what I had happening,  I am not so sure which caused the warp so I thought I would try and get things working without the heatbed on.

The sticky tape they use to stick the lower surface to the bed is terrible,, it got all over my hands and made a mess.  Acetone and a lot of wiping with a lot of paper towels cleaned things up.

back to it then.
Title: Re: Petg
Post by: webby2 on April 10, 2020, 04:12:47 am
An issue with the heatbed off is warping.

I loaded up most of my printer with parts to print in one go, things started out really nice and everything came off of the surface really nice,, however the time it took to get back to the first part of the print was way to long and so when the next layer of hot filament hit the now cold prior layers it caused them to shrink a lot.  A large portion of my prints had the bottom curled up at the edges a lot and they almost jumped off of the surface by themselves.

I am trying to print still without the heatbed on but I am going to print a smaller amount and see if that works, it has for some really small parts, I might need to use the heat for some prints, not sure yet.
Title: Re: Petg
Post by: webby2 on April 13, 2020, 05:51:41 am
I have been playing more and it seems that the maximum sustained rate is about 38mm\s that this printer can handle with petg.

When I go faster than that it starts to under-extrude but at the same time it creates too much pressure for the extruder and so it starts to "pop" , I am guessing that the middle of the hot end is not melting the filament completely and that is creating a blockage.
Title: Re: Petg
Post by: webby2 on April 14, 2020, 08:46:20 am
My setup is running fairly well,, well rather slow but doing good.

bed temp is set to 50C
hot end is set to 247C
travel while extruding is limited to 38mm\s

I have put a single layer of blue tape on the build surface leveled to that and then gave a 0.1mm z lift in my slicer.
Title: Re: Petg
Post by: webby2 on May 01, 2020, 07:37:26 pm
Still running with the blue tape to save the magnetic print surface,, there are better surfaces but a simple fix for what I have.

I have increased my print temp up to 250C and my bed up to 55C.

I suffer from a very small case of elephant foot,, very small,, and I could maybe get rid of it but I like how well the setup sticks to the build surface.

With all that I have I am printing some small gears that are working out for me,, I am at a 0.5 module for the gears which I could not do so well with my previous printer,, I think it is more to do with the software and settings with this printer than anything else.
Title: Re: Petg
Post by: webby2 on May 12, 2020, 07:17:15 pm
The blue tape is no longer sticking to the build surface,, it keeps pulling up allowing the print to warp.

I am now trying the build surface sticker that comes with the Overture petg that I am using,, I will see how it works.
Title: Re: Petg
Post by: webby2 on June 07, 2020, 06:30:38 am
A few things of interest,,,

I got rid of the magnetic build surface and am using a sticker from Overture directly on my aluminum heat bed,, it is working a lot better and if I heat the surface up to about 35C the prints come off easy,, hotter and they are harder to get off, colder and they are really difficult to get off.

The first layer is really important, if it is not right it will mess up the print in a few ways.
Lets say that the Z offset is 0.2mm, meaning that the print head is 0.2mm above the surface but you do not put that into your slicer then the first layer may look nice but a little empty, that is the whole of the first layer is not fairly smooth across the face.  This may not be a big thing BUT it also leaves the whole print rather "loosely" connected or fused so it is not very strong.  If you set the offset too much then you get what is called elephant foot, the first layer or 2 will squish out beyond where it supposed to be.  Both of these conditions can also leaves errors throughout the print, stringing, blobbing and stuff like that.

I just happened across a perfect issue within a part I have been trying to print,, it was driving me crazy.  My usual slicer is Kisslicer,, it is easy to use, allows me to place the print center where I want it and without all of those options like with Cura it is not so daunting.
What I had was missing teeth on a gear, another slicer printed all of the teeth but Kisslicer missed some even tho it rendered the 3d view with the teeth the print did not print the teeth,, using the model + path option the print head just did not print some teeth,, go figure.  What I ended up doing is slightly changing that print, I needed to actually close up a tolerance and reduce the overall height of the part,, and then the teeth magically came back.  This reminds me of another small issue with Kisslicer, that is with the fill value, if you set it to 25% it will mess up the print and shift the print in the vertical, 33% is fine.