Okay, so I have less than 3 weeks experience with my gMax 1.5 XL+ dual extruder printer with heated bed. But I have about 250 kg of printing experience over 4 years using many other printer types and brands. Now I’m excited to take full advantage of the relatively massive print volume of the gMax. But as I’ve prepped for designing and printing at gMax scale, I’ve been forced to re-examine many operational challenges that I’d previously mastered at smaller scales. It seems to me that many of the gMax challenges we face relate to the print bed... Its size, certainly. But also how flat it is, how to control temperatures, optimizing first layer adhesion, mastering slicing-related issues, and in some cases surface quality of the printed piece’s bottom.
I spent the months between the day I placed my order and the printer's delivery, and even more intensely in the 20 days or so since it arrived, developing, testing and iteratively refining operational best practices that will enable me to reliably, affordably and efficiently take full advantage of the gMax’s powerful capabilities. After a very concentrated effort, and with Kyle’s invaluable help, I’ve resolved a multitude of assembly-related issues, identified some solutions for improvements to the current design, and put together a set of best practices that fully address all my requirements with few compromises in the printed results. I describe my findings in this discussion.
Just to name it, these are practices and settings that work well for me and my requirements in my operating environment. Your requirements or environment may be so different as to render my conclusions useless — or worse. But it might be worthwhile to at least be aware of what I’ve found even if you have your own best practices that are working well for you in your shop. Take all this for what it’s worth, and ignore what doesn’t fit.
I’ll start with a summary of the requirements I have that are the drivers of these best practices.
* I have no intention at this point of hacking the fully-assembled printer that I received from gCreate. That said, there have been several missteps made in the assembly of my printer that Kyle and I had to think through and fix. I also made numerous changes and additions to evolve a Simplify3D profile for this printer that enabled me to meet my requirements.
* I need to be able to print using any supported filament type from any vendor of reasonable quality within the temperature range of the stock extruder, to include PLA, PETG, ABS, TPU and carbon fiber.
* I need support for dual extrusion using any combination of mutually compatible filaments. Meeting this requirement means that I must be able to slice a single job for fabrication using both materials.
* All jobs must fully adhere to the bed until the print completes. A raft should be necessary only when the surface area of the bottom of the shape being printed is insufficient for the piece to adhere when extruding the higher layers of the print.
* The print bed may be heated if doing so will improve adhesion and not adversely affect the printed object.
* I want to take FULL advantage of the entire gMax print volume. This means every corner high and low. The gantry cable mustn’t bump the object being printed. The extruders must have full freedom of movement across the entire area of the print bed — from the point that it begins printing the first layer until it completes the final layer 530mm above the bed.
* I need to get full fidelity in the first few layers of every print. So the geometry in the first layer of my designs must be represented in the printed object. As such, Simplify3D slices must succeed with a ‘First Layer Height’ ratio setting no higher than 150%.
The Print Bed Surface
My local hardware store here in Berkeley, CA is Orchard Home Supply (OSH) Then I buy a sheet of glass from them they'll custom cut it to my specifications at no extra charge. So I buy single sheets of double strength glass 36 inch X 48 inch, which is 3mm thick. From this sheet they cut six 16 3/4 inch X 16 inch pieces.
I print with a piece of glass clamped on top of the gMax print bed. I have a heated print bed. So the glass is clamped on top of the heated bed. But before installing the heated bed I simply placed the glass directly on top of the metal bed. Either arrangement has worked equally well for me.
I print using a number of different materials. So I keep several pieces of glass prepped and ready for use based on the print surface needed for the filament type being used.
[table][tr][td]Filament Material[/td]
[td]Glass Preparation[/td]
[td]Bed Temperature[/td]
[td]Durability (same print/place)[/td]
[td]Comments[/td][/tr]
[tr][td]PLA[/td]
[td]Blue Painter's Tape[/td]
[td]50ºC[/td]
[td]~20 jobs[/td]
[td]1.88 in. is cheaper, but 2.83 in has fewer seams[/td][/tr]
[tr][td]Ninjaflex[/td]
[td]Blue Painter's Tape[/td]
[td]50ºC[/td]
[td]~10 jobs[/td]
[td]1.88 in. is cheaper, but 2.83 in has fewer seams[/td][/tr]
[tr][td]ABS[/td]
[td]Aqua Net Extra Super Hold Hairspray[/td]
[td]100ºC[/td]
[td]~40 jobs[/td]
[td]1 coat, let dry, then another coat[/td][/tr][/table]
Printing on disposable glass plates optimally fits my needs because custom cut glass is the right size, it’s durable, readily available, inexpensive, VERY flat, and both sides can be used before being cleaned up, then prepared for reuse over and over again. If a piece does break, the shards are at little risk of damaging the machine, though you obviously have to be careful cleaning up the broken glass. Broken glass is 100% recyclable. Just eyeballing it, I find the glass that I buy from OSH to be flat to within +/- 0.2mm across the entire 16 inches in each direction.
Below is a photo of my rig with a piece of blue tape covered glass installed. Note that the glass is sitting on top of a heated bed. Also note that I’m currently using binder clips to secure the glass to the bed. The chrome “handles” of the clips have been removed so that they don’t get caught up on anything while printing. My use of binder clips is temporary, as I plan to hack gCreate’s TPU clips that keep the heated bed in place above, but separate from, the metal bed. You can see these TPU clips in red in the photo below. My hacked version of these clips will be extended vertically so as to clasp the glass to the bed. (I’ll post the STL’s in this discussion.) This is necessary because the binder clips shown below actually do intrude slightly into the print volume, though the hacked TPU-based clips will not.
Placing glass over the printer’s bed (whether heated or otherwise) provides an easy means to level the glass surface simply by using doubly folded Post-It Notes inserted under corners of the glass. Based on my experience, each doubly folder note (so 4 layers thick) raises that corner of the glass by 0.6 - 0.8mm. The glass is rigid enough that it’s not necessary to insert additional shims mid-span. Those in the corners are sufficient. Notice the doubly-folded note in the bottom right corner of the photo.
Using Simplify3D To Slice Jobs
Simplify3D (S3D) is my slicer of choice — by a long shot. It’s been over a year since I had to use Slic3r, though I used to have to use it a lot before S3D arrived on the scene. My opinion when I was using it was that Slic3r is the absolute worst slicer still being worked on — by a long shot. If you care about the quality of your prints, I strongly encourage you to use S3D.
I didn’t find the gMax+ S3D profile that I downloaded from the gCreate website (v. 160520) to be usable when first installed. What would happen is that every job that I sliced using the profile would not progress beyond the initial heating of the extruder(s). However Kyle told me how to get past this hang and get my jobs to print…
[table][tr][td][/td]
[td]I have recently had a customer who used Simplify 3D with his Makerbot prior to using the gMax. When he imported the config files for his gMax 1.5+, an important setting for the printers firmware type was not changed. This is the setting labeled "Update firmware configuration" in the gcode tab.
Normally this is not enabled. Enable it, set firmware type to Reprap (Marlin), and baud rate to 250,000.[/td][/tr][/table]
I was able to generate my first printable job once I made these changes in my factory file.
Sadly, at the time of this writing the download page on the gCreate site for this profile still doesn’t include instructions for changing these settings to overcome this job hanging condition as part of the profile installation process. Unfortunately, I have experienced numerous situations where Kyle and Gordon know how to fix a problem but don’t bother to update the site to inform users of fixes, updates and workarounds.
My S3D factory file can be downloaded from here. It includes processes for printing PLA, Ninjaflex or ABS on the latest version of the gMax 1.5 XL+. Know though that my version differs slightly from the approach taken by the gCreate team…
* The Layer tab for all filament material types has a First Layer Height ratio value of 150%. This setting is essential in order for the first layer of a print to be the same as the geometry in the STL. This is essential when printing pieces where the fidelity of the first few layers is important. In contrast, using the value of 300% as set in the gCreate profile results in a bottom layer of the printed object to be the geometry found around 0.5 mm from the bottom.
I should note that the value of 150% for the first layer height works for me because I print on the very rigid 3mm glass that I’ve described above. I’ve printed 490mm tall jobs in PLA with 0% loss of adhesion found when the job is completed.
Also note that dual extrusion jobs must have the same first layer height ratio values for both extruders, as different values between extruders could cause layers to be misaligned, which could result in the non-printing nozzle to hitting material being laid down in the current layer. This could damage the object, which often snowballs as the job progresses. Layer misalignment could also cause a loss of bed adhesion due to the knocking of an extruder against the printed object.
* My factory file adds support for Ninjaflex.
* Oozing by the non-printing extruder in a dual extrusion job is a significant challenge. Generally speaking, the larger the nozzle opening the greater a problem oozing becomes. TPU filaments ooze much more than ABS or PLA. There’s really no way to completely eliminate oozing using extruders like those found on gMax’s. But my Ninjaflex settings call for 12mm of retraction. The barrel of the stock gMax extruder is fairly tall. This allows for a lot of retraction without “breaking the seal” and introducing air into the barrel when retraction is reversed.
Double-Check, Triple-Check For Assembly Missteps
I bought my gMax pre-assembled rather than build it out myself. I made this decision based on quality assurances on the gCreate website and further assurances in direct email exchanges. But the unit I took delivery of 20 days ago was not up to the promised quality standards. Kyle and I spend literally weeks debugging the problems I was experiencing, which included…
* The install instructions for the S3D profile did not instruct users to confirm the proper Firmware settings in the Advanced tab. So it took 3 days before I was able to print my first job that I’d sliced myself.
* The Create Ticket button on the gCreate support page is non-functional.
* The two screws on the front left side of the gantry that are supposed to hold the belt firmly attached were loose to the point of almost falling out. The very loose belt tension that resulted caused major deformities in tall prints and poor surface qualify (referred to as “ringing”) at 3:00 and 9:00 of all prints. This took almost a week for Kyle, Gordon and I to figure out.
* The 3 screws behind the gantry hood that are used to attach the extruder to the gantry were also VERY loose. (Notice the pattern of problems caused by screws that were insufficiently tightened during assembly?) This resulted in uneven layering in single extruder jobs, and the failure of all initial dual extrusion jobs.
* The gMax is sold as a printer with fully automatic bed leveling. While the probe results in dynamic recognition of bed height, the hardware and firmware don’t currently include a means to actually level the bed. The operator much manually rotate individual Z-axis rods to compensate for different left and right bed heights. There’s no means that I’m aware of to compensate for differences in height between the front and back of the bed. The gMax is NOT a self-leveling machine.
The company’s assembly practices are evolving. Buy my advice for customers taking delivery of pre-assembled gMax units would be to question everything related to assembly. I consider myself very fortunate that the frame of the unit I took delivery of is very straight and rigid. But the state of your machine may be different — for better or worse.
What a GREAT Piece of Gear!
After spending about 100 hours “certifying” my gMax as meeting my requirements, I want to say that I’m very impressed with this rig. There are a lot of new challenges that need to be overcome in order to operate and maintain a rig able to print at this scale. I appreciate Kyle’s help and positive attitude while we debugged the problems I encountered in the unit I received. I’m excited to get started printing at gMax scale.
- Bob
I spent the months between the day I placed my order and the printer's delivery, and even more intensely in the 20 days or so since it arrived, developing, testing and iteratively refining operational best practices that will enable me to reliably, affordably and efficiently take full advantage of the gMax’s powerful capabilities. After a very concentrated effort, and with Kyle’s invaluable help, I’ve resolved a multitude of assembly-related issues, identified some solutions for improvements to the current design, and put together a set of best practices that fully address all my requirements with few compromises in the printed results. I describe my findings in this discussion.
Just to name it, these are practices and settings that work well for me and my requirements in my operating environment. Your requirements or environment may be so different as to render my conclusions useless — or worse. But it might be worthwhile to at least be aware of what I’ve found even if you have your own best practices that are working well for you in your shop. Take all this for what it’s worth, and ignore what doesn’t fit.
I’ll start with a summary of the requirements I have that are the drivers of these best practices.
* I have no intention at this point of hacking the fully-assembled printer that I received from gCreate. That said, there have been several missteps made in the assembly of my printer that Kyle and I had to think through and fix. I also made numerous changes and additions to evolve a Simplify3D profile for this printer that enabled me to meet my requirements.
* I need to be able to print using any supported filament type from any vendor of reasonable quality within the temperature range of the stock extruder, to include PLA, PETG, ABS, TPU and carbon fiber.
* I need support for dual extrusion using any combination of mutually compatible filaments. Meeting this requirement means that I must be able to slice a single job for fabrication using both materials.
* All jobs must fully adhere to the bed until the print completes. A raft should be necessary only when the surface area of the bottom of the shape being printed is insufficient for the piece to adhere when extruding the higher layers of the print.
* The print bed may be heated if doing so will improve adhesion and not adversely affect the printed object.
* I want to take FULL advantage of the entire gMax print volume. This means every corner high and low. The gantry cable mustn’t bump the object being printed. The extruders must have full freedom of movement across the entire area of the print bed — from the point that it begins printing the first layer until it completes the final layer 530mm above the bed.
* I need to get full fidelity in the first few layers of every print. So the geometry in the first layer of my designs must be represented in the printed object. As such, Simplify3D slices must succeed with a ‘First Layer Height’ ratio setting no higher than 150%.
The Print Bed Surface
My local hardware store here in Berkeley, CA is Orchard Home Supply (OSH) Then I buy a sheet of glass from them they'll custom cut it to my specifications at no extra charge. So I buy single sheets of double strength glass 36 inch X 48 inch, which is 3mm thick. From this sheet they cut six 16 3/4 inch X 16 inch pieces.
I print with a piece of glass clamped on top of the gMax print bed. I have a heated print bed. So the glass is clamped on top of the heated bed. But before installing the heated bed I simply placed the glass directly on top of the metal bed. Either arrangement has worked equally well for me.
I print using a number of different materials. So I keep several pieces of glass prepped and ready for use based on the print surface needed for the filament type being used.
[table][tr][td]Filament Material[/td]
[td]Glass Preparation[/td]
[td]Bed Temperature[/td]
[td]Durability (same print/place)[/td]
[td]Comments[/td][/tr]
[tr][td]PLA[/td]
[td]Blue Painter's Tape[/td]
[td]50ºC[/td]
[td]~20 jobs[/td]
[td]1.88 in. is cheaper, but 2.83 in has fewer seams[/td][/tr]
[tr][td]Ninjaflex[/td]
[td]Blue Painter's Tape[/td]
[td]50ºC[/td]
[td]~10 jobs[/td]
[td]1.88 in. is cheaper, but 2.83 in has fewer seams[/td][/tr]
[tr][td]ABS[/td]
[td]Aqua Net Extra Super Hold Hairspray[/td]
[td]100ºC[/td]
[td]~40 jobs[/td]
[td]1 coat, let dry, then another coat[/td][/tr][/table]
Printing on disposable glass plates optimally fits my needs because custom cut glass is the right size, it’s durable, readily available, inexpensive, VERY flat, and both sides can be used before being cleaned up, then prepared for reuse over and over again. If a piece does break, the shards are at little risk of damaging the machine, though you obviously have to be careful cleaning up the broken glass. Broken glass is 100% recyclable. Just eyeballing it, I find the glass that I buy from OSH to be flat to within +/- 0.2mm across the entire 16 inches in each direction.
Below is a photo of my rig with a piece of blue tape covered glass installed. Note that the glass is sitting on top of a heated bed. Also note that I’m currently using binder clips to secure the glass to the bed. The chrome “handles” of the clips have been removed so that they don’t get caught up on anything while printing. My use of binder clips is temporary, as I plan to hack gCreate’s TPU clips that keep the heated bed in place above, but separate from, the metal bed. You can see these TPU clips in red in the photo below. My hacked version of these clips will be extended vertically so as to clasp the glass to the bed. (I’ll post the STL’s in this discussion.) This is necessary because the binder clips shown below actually do intrude slightly into the print volume, though the hacked TPU-based clips will not.
Placing glass over the printer’s bed (whether heated or otherwise) provides an easy means to level the glass surface simply by using doubly folded Post-It Notes inserted under corners of the glass. Based on my experience, each doubly folder note (so 4 layers thick) raises that corner of the glass by 0.6 - 0.8mm. The glass is rigid enough that it’s not necessary to insert additional shims mid-span. Those in the corners are sufficient. Notice the doubly-folded note in the bottom right corner of the photo.
Using Simplify3D To Slice Jobs
Simplify3D (S3D) is my slicer of choice — by a long shot. It’s been over a year since I had to use Slic3r, though I used to have to use it a lot before S3D arrived on the scene. My opinion when I was using it was that Slic3r is the absolute worst slicer still being worked on — by a long shot. If you care about the quality of your prints, I strongly encourage you to use S3D.
I didn’t find the gMax+ S3D profile that I downloaded from the gCreate website (v. 160520) to be usable when first installed. What would happen is that every job that I sliced using the profile would not progress beyond the initial heating of the extruder(s). However Kyle told me how to get past this hang and get my jobs to print…
[table][tr][td][/td]
[td]I have recently had a customer who used Simplify 3D with his Makerbot prior to using the gMax. When he imported the config files for his gMax 1.5+, an important setting for the printers firmware type was not changed. This is the setting labeled "Update firmware configuration" in the gcode tab.
Normally this is not enabled. Enable it, set firmware type to Reprap (Marlin), and baud rate to 250,000.[/td][/tr][/table]
I was able to generate my first printable job once I made these changes in my factory file.
Sadly, at the time of this writing the download page on the gCreate site for this profile still doesn’t include instructions for changing these settings to overcome this job hanging condition as part of the profile installation process. Unfortunately, I have experienced numerous situations where Kyle and Gordon know how to fix a problem but don’t bother to update the site to inform users of fixes, updates and workarounds.
My S3D factory file can be downloaded from here. It includes processes for printing PLA, Ninjaflex or ABS on the latest version of the gMax 1.5 XL+. Know though that my version differs slightly from the approach taken by the gCreate team…
* The Layer tab for all filament material types has a First Layer Height ratio value of 150%. This setting is essential in order for the first layer of a print to be the same as the geometry in the STL. This is essential when printing pieces where the fidelity of the first few layers is important. In contrast, using the value of 300% as set in the gCreate profile results in a bottom layer of the printed object to be the geometry found around 0.5 mm from the bottom.
I should note that the value of 150% for the first layer height works for me because I print on the very rigid 3mm glass that I’ve described above. I’ve printed 490mm tall jobs in PLA with 0% loss of adhesion found when the job is completed.
Also note that dual extrusion jobs must have the same first layer height ratio values for both extruders, as different values between extruders could cause layers to be misaligned, which could result in the non-printing nozzle to hitting material being laid down in the current layer. This could damage the object, which often snowballs as the job progresses. Layer misalignment could also cause a loss of bed adhesion due to the knocking of an extruder against the printed object.
* My factory file adds support for Ninjaflex.
* Oozing by the non-printing extruder in a dual extrusion job is a significant challenge. Generally speaking, the larger the nozzle opening the greater a problem oozing becomes. TPU filaments ooze much more than ABS or PLA. There’s really no way to completely eliminate oozing using extruders like those found on gMax’s. But my Ninjaflex settings call for 12mm of retraction. The barrel of the stock gMax extruder is fairly tall. This allows for a lot of retraction without “breaking the seal” and introducing air into the barrel when retraction is reversed.
Double-Check, Triple-Check For Assembly Missteps
I bought my gMax pre-assembled rather than build it out myself. I made this decision based on quality assurances on the gCreate website and further assurances in direct email exchanges. But the unit I took delivery of 20 days ago was not up to the promised quality standards. Kyle and I spend literally weeks debugging the problems I was experiencing, which included…
* The install instructions for the S3D profile did not instruct users to confirm the proper Firmware settings in the Advanced tab. So it took 3 days before I was able to print my first job that I’d sliced myself.
* The Create Ticket button on the gCreate support page is non-functional.
* The two screws on the front left side of the gantry that are supposed to hold the belt firmly attached were loose to the point of almost falling out. The very loose belt tension that resulted caused major deformities in tall prints and poor surface qualify (referred to as “ringing”) at 3:00 and 9:00 of all prints. This took almost a week for Kyle, Gordon and I to figure out.
* The 3 screws behind the gantry hood that are used to attach the extruder to the gantry were also VERY loose. (Notice the pattern of problems caused by screws that were insufficiently tightened during assembly?) This resulted in uneven layering in single extruder jobs, and the failure of all initial dual extrusion jobs.
* The gMax is sold as a printer with fully automatic bed leveling. While the probe results in dynamic recognition of bed height, the hardware and firmware don’t currently include a means to actually level the bed. The operator much manually rotate individual Z-axis rods to compensate for different left and right bed heights. There’s no means that I’m aware of to compensate for differences in height between the front and back of the bed. The gMax is NOT a self-leveling machine.
The company’s assembly practices are evolving. Buy my advice for customers taking delivery of pre-assembled gMax units would be to question everything related to assembly. I consider myself very fortunate that the frame of the unit I took delivery of is very straight and rigid. But the state of your machine may be different — for better or worse.
What a GREAT Piece of Gear!
After spending about 100 hours “certifying” my gMax as meeting my requirements, I want to say that I’m very impressed with this rig. There are a lot of new challenges that need to be overcome in order to operate and maintain a rig able to print at this scale. I appreciate Kyle’s help and positive attitude while we debugged the problems I encountered in the unit I received. I’m excited to get started printing at gMax scale.
- Bob
