Fine-tuning & Increasing Performance of your gMax Printer

#21
Re: Fine-tuning & Increasing Performance of your gMax Printe

"When I print at 20-30mm/s with NGEN and 0.6 layers I cant increase the fan more than to around 30-40% before the temp starting to drop"

In my opinion you should stay below 0.24, 0.32, 0.4mm layer height as the E3D cannot keep up at normal printing speeds (40 to 60 mm/s) with the 0.8mm nozle. You will have to keep the NGEN very hot so that it will not encounter viscosity resistance. However, at that temperature you will be outside of the recommended heat range only to create other printing problems (stringing, blobbing, layer shifting etc). Just to make sure that your extruder thermistor is doing its job right I would do a PID auto-tune in command line. You could have a bad thermistor causing all kinds of issues. I would start from there to make sure there is no mechanical or electrical issues and then focus on printing speeds and layer height. You do not have to go into Marlin to do this, but you can do it live in command prompt and then store all the values in EEPROM with a M500 command. Are you familiar how to do this? If not, I can explain step by step on how to do it.

"I tried to mount the soc but it cant grab the heatblock, I had to modify it a bit, hopefully it will stay.. we'll see"

Yah the sock does not want to stay in place. E3D messed up with the design of this particular part. I used a thin metal wire to wrap it around to keep it in place. Actually if you look closely a the picture above of the first layer adhesion you will notice how I quickly wrapped a wire around the silicone boot that is over the heater block. It worked for me.

"I have some skipping happening but at the exact same two positions during the layers each time, and it has no effect if i print at 220 or 270 degrees, nor if I print at 20mm/s or 50mm/s. "

It is hard to know what is going on without seeing it from up close. I would start by looking at any mechanical issues first. For example, the Z axis lead screw for bends, wobble or misalignment. Can you move now the Z axis by doing a "move axis", select "Z", and then 10mm movement? See if it will go all the way to the top without any stopping, sticking, clicking, skiping or any other mechanical issues. That would be a good place to start.

If the mechanical motion checks out fine then, it could be that the model might have issues, for non manifold surfaces, bad mesh areas etc. Have you tried checking for bad model areas? I have had that happen to me in the past and it drove me insane only to realize it was the model. Have you ever used Netfabb? It is a free for download and use. It has some limitations as a free version, but the free options are good enough to fix and repair models. I use it most of the time to check things prior to using Simplify3D to slice my models.

https://www.netfabb.com/try-netfabb-premium-now

Another issue I have come across in the past was that my model was too tall in respects to its width. That is no problem, but you have to compensate in creating a good fist layer adhesion for rigidity. Otherwise as the model gets taller the center of gravity of the model shifts upwards causing extra wobble only to have the print head miss its intended layer position. The printing results show as layer misalignment, air printing, and in a worst case the head knocks-off the model from the print bed. In cases like that I typically will use two layer of an attached brim and about 15 perimeters. That creates extra adhesion and stability. It has helped me any way.

Check also your belt tension on your heated bed. Some times the Y axis belt can slip one tooth causing layer shifting.
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#22
Re: Fine-tuning & Increasing Performance of your gMax Printe

The new gMax 1.5+ User Guide & Maintenance guide gCreate released is excellent in covering several topics in how to best set up your printer. Pay special attention to the mechanical adjustment setup for the X, Y, and Z axis. Go over that first to make sure that what you are experiencing is not simply a misalignment, or binding of the axis. Also look at the section where it talks about movement binding on the Z axis and the lead screws and how to adjust for play or binding.

I'm glad gCreate came up with this manual. It will help many people solve some of their basic printing issues.

Let me know how it all goes.
 
#23
Re: Fine-tuning & Increasing Performance of your gMax Printe

Thanks again!

Here are some answers, in somewhat the correct order :)

I dont know how to set the values for PID tuning and e steps / mm to save it in EEPROM, I tried the M500 command from Octoprint but it didnt bite... Followed your guide in the first post.

I'll limit myself to 0.4mm layers then, although I'm printing 0.3mm layers with my 0.4mm nozzle printers, so I had hoped for some higher layers with the 0.8mm. Maybe I should look at a Vulcano hotend if I want to reach the high layers.

Sock.. I'll skip it for now, maybe I'll hack something together

My Z axis moves ok up to around 480mm where it binds, my threaded Z rods has always been moving alot.. when the X axis is close to the bed I would say that the top of the right threaded Z rod moves about 1cm back and forth. The left one is more still. I have loosened the screws in the X axis blocks guiding the X rods to accept some more movement.

Im pretty sure the model is fine, I've modeled it myself, and its a pretty simple geometry, I've also used Netfabb for about 5 years and I run all my models through it before printing. I could try slice it with Slic3r instead, just as a test. But I think the first step will be stepping back to 0.4mm layers. If I can do 0.4mm layers at ok speeds, that will mean pretty ok print times anyway.

I would say that the belt tension for the Y axis is ok.

One thing I also looked at (after instructions from Kyle) was the un-concentric nuts holding the wheels for the extruder carriage, when I got the printer and moved the carriage by hand i could feel "bumps" every 4-6 cm, when I loosened the tension on the wheels it got better, but the carriage was too loose so I had to find a middleway there... If I push it by hand I do feel a gentle bumps but also inside acceptable tolerances I would say.

Adding some pictures of my latest test. I had to stop it at 400mm due to wife arriving home :D But I THINK that it would finish.. it felt pretty stable. I printed it with 10mm brim. One thing I was thinking about is the movement of the bed, is it possible to smoothen out the "turn" when the bed changes the movement direction?

First picture shows the position where it skipping, and the second picture shows the "beautiful" parts. I'm aware of the retraction blobs, and the super shiny NGEN is pretty hard to take a photo of, but im ok with how it looks where it looks "ok".

I watched the nozzle closely for a few layers, and strange thing is that when it passes the area the first time it prints just fine, but when it passes it the second time it skips.
 
#24
Re: Fine-tuning & Increasing Performance of your gMax Printe

Are these adjustable corner standoffs available somewhere? Is that the setup before the BL Touch was added?
 
#25
Re: Fine-tuning & Increasing Performance of your gMax Printe

nopick said:
Are these adjustable corner standoffs available somewhere? Is that the setup before the BL Touch was added?

From the pic I did not realize that was my printer. Well I machined the adjustable stand offs at my shop.
 
#26
Re: Fine-tuning & Increasing Performance of your gMax Printe

Where can I buy the 9mm GT2 belt for the bed? I would also like to replace the flimsy factory belt. great article! :D
 
#28
Re: Fine-tuning & Increasing Performance of your gMax Printe

GT2 20T Timing puley

http://www.ebay.com/itm/122015956102?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Wide GT2 Timing Belt

http://www.ebay.com/itm/231231300545?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Please keep in mind that you will have to widen the slots on the Y-axis metal plate otherwise you cannot install the wider 9mm belt. With that said, once you install it, the wringing effects will be substantially reduced and in some cases completely gone on the Y axis. You will also be able to run prints at faster speeds as the Y axis will be have less play, and 90 degree sharp corners come out crispier.
 
#29
Re: Fine-tuning & Increasing Performance of your gMax Printe

What do you mean by print a Z clip and use it to reduce vibrations? Would you care to show us how to install and where to install this clip? Also, please share the stl file for us to print. Thanks for your helpful posts.
 
#30
Re: Fine-tuning & Increasing Performance of your gMax Printe

What do you mean by print a Z clip and use it to reduce vibrations? Would you care to show us how to install and where to install this clip? Also, please share the stl file for us to print. Thanks for your helpful posts.
 
#31
Re: Fine-tuning & Increasing Performance of your gMax Printe

PianoPrint said:
One thing that helped me reduce, and in some cases remove the ringing was to replace the Y print bed belt with a wider one. I went from the original 5mm to a 9mm GT2 belt. Now the bed moves are crisp and solid. I believe that this upgrade is a must for the heavy print bed of this gMax printer. I am vary please with the results.

Just did the same upgrade!

Feels a lot more solid, but I haven't printed with it yet, still waiting on some more upgrade parts!
 
#32
Re: Fine-tuning & Increasing Performance of your gMax Printe

Interesting printed plate. It looks good. I guess you could print it, thus reducing some of the moving weight in compared to the metal plate. GCreate sells the plate for $25, but you have to enlarge the belt slits for the wider belt to work. I assume that you did at least a 90% infill for the print as that plate takes up quite a bit of load during prints. Check for cracks over time of usage. I be very interested to see how your prints do.

I am now in the process of changing the stepper drivers to the Stepstick TMC 2100 for smoother and quieter motion. Once I make the upgrade I will post the results.
 
#34
Re: Fine-tuning & Increasing Performance of your gMax Printe

It has been some time since I have posted as I have been busy with work family and business.

So I have another update for the printer. While back I said that I would try the TMC2100 silent stepper drivers (Chinese version) . Well I manage to install them plus I am working on installing a Thermocouple, the MKS TFT screen and the Full graphics display together. The printer is stunningly silent.

I have everything working.


https://www.youtube.com/watch?v=K_ZwSoTiPDg&feature=youtu.be


You can see a video on YouTube with all of the above in action.
 
#35
Re: Fine-tuning & Increasing Performance of your gMax Printe

So to install the 9mm belt, you just have to size the 3D printer part up by 180%?
 
#36
Re: Fine-tuning & Increasing Performance of your gMax Printe

Great post. I am installing a 9mm belt and want to see if anyone would post a link to download the stl files for the related parts (zclip and back wheel assembly) that need to be printed. Thank you. Awesome stuff!
 
#38
Re: Fine-tuning & Increasing Performance of your gMax Printe

"Make sure your belts are tight and print a “Z” clip that actually helps absorb some of the vibrations."

Pianoprint, could you elaborate on this or maybe provide a link? I've not heard of this and it sounds interesting. Thanks!
 
#39
Re: Fine-tuning & Increasing Performance of your gMax Printe

Keep in mind the circles that you see on the surface of the print were present in the CAD model. So what you see on the model surface is the actual detail as intended. I could never imagine this type of quality when I first put the printer together. Now I am incredibly happy with the results.
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