Meet Phat Freddy

Hi All,

I needed another gMax Dual 1.5XT but I didn't want to wait 8-10 weeks like my first one so I built one from scratch with a few significant features added. Specifically Automatic Bed Leveling & Ditto Printing. I also needed it to run Marlin as the firmware. This was crucial.

I've previously posted my experiences/successes as they related to Ditto Printing and Auto Bed Leveling with a Dual 1.5XT. But that involved switching firmware from Marlin to Repetier since Marlin doesn't easily support Ditto Printing and the current gMax Marlin firmware predates the auto-bed leveling code base.

In short, Repetier's auto leveling proved too unreliable and I can't use it for production purposes. It would simply spaz out, reset ,auto home, etc. in the middle of a print but the issue was not repeatable. It would happen at random times during complex prints. Sometimes the print was successful. Sometimes not. It was absolutely a firmware issue and not a slicer issue because when running the same gCode through Marlin with auto leveling on, I had ZERO issues and it was tested across 4 or 5 different models with the same results. Repetier = fail/ Marlin = pass. And it did not matter what slicing engine I used (Slic3r or Simplify3D). The results were the same. When I ran the gCode through Repetier with Auto leveling OFF the prints finished successfully every time. So IMHO Repetier's auto leveling is not really ready for prime time.

I also originally thought Repetier had superior print quality but after really dialing in my printer, there isn't any noticeable difference quality-wise between Marlin and Repetier. So I switched back to Marlin with the first task being setting up the auto bed leveling. Since I already had Autobed Leveling working in Repetier and had built my servo/z-probe and had all the wiring in place, it was pretty straight forward. Ditto Printing took a little more wrangling but I am happy to say, Auto-bed leveling and Ditto Printing are now merged into one Marlin package. I've had it running on both my Dual 1.5 XTs for several days with zero issues. :p

I will be posting the new firmware and making it available here within the next week. It will be here (gCreate) first and eventually on GitHub but I wanted all my gMax brothers & sisters to be able to upgrade their gMax printers should they want to. These are outstanding printers and they should be extended to their fullest capabilites. Keep in mind, Ditto Printing only works with Dual Extruder printers. It makes the inactive nozzle print whatever the active nozzle is printing. So two simultaneous objects in one print. Ditto Printing is enabled with an M420 S1 command and disabled with an M420 S0 command. If you don't have a Dual Extruder, that's ok. The firmware adapts and Ditto Printing simply won't be available. Auto leveling works for any number of extruders but will use extruder one (left one) as its reference to home.

The intent was always a dual extruder with a full graphics controller. Since this was my first scratch build, I wanted to get it running with a single extruder first, and then upgrade to dual Volcanos. The graphics controller gave me some headaches but in the end it was an outdated library causing issues so the printer now has Dual Volcanos with a full graphics controller. (see second set of pix)

That being said, I am adding a few more tweaks and finishing up some documentation. Mechanically, there are a few differences between Phat Freddy and a stock DUAL gMax1.5XT (i.e. physical dimensions, endstop locations, servo for z-probe,etc., hotends) so I want to make sure the firmware documentation reflects those changes for an easy upgrade.. I will work with gCreate (Gordon & Kyle) to ensure there will be minimal changes required for gMax users to upgrade their printers and I hope to have this to them very soon.

I also want to give special thanks to Kyle for helping with some much needed info during the materials ordering process & his design of the E3D adjustable fan shroud and to Gordon for designing the gMax in the first place. It was a no-brainer that my second (and third and fourth) printers will all be gMaxs (or is it gMaxi?)

And now, here's Freddy..............
A simple filament bracket printed with the Volcano. Really light weight but super strong. 10% infill 2 perimeters. Really glossy finish.


New Member
Hi mate that looks awsome! Looks like a lot of work has gone into this and it has paid off! The auto bed level is something that i am really interested in, i am guessing this works but adjusting values instead of actually leveling the bed physically? (I'm still new to all this :lol: )



Thanks. It was a really fun project and I'm pretty pleased with how it came out. I'm happy with the quality & speed of the prints using the Volcanos. It took a little bit to get them dialed in but now they're doing good. I have not tried two color printing yet but I have done some nice ditto prints and large scale prints using each extruder.

I am relatively new to all of this too. I had never seen a 3D printer until getting my gMax in mid Jan so it's been a little over 4.5 months for me. I knew nothing. Zilch/zero. The point being, ALL the info you want and more is within your fingertips and there is an active community willing to help out so you can get up to speed pretty quick.

You are correct. Auto leveling occurs throughout the print. The firmware dynamically adjusts the Z level on the fly. You can see the Z axis moving in both directions during a print when auto leveling is active. Auto level and ditto printing can be used simultaneously. OF course it helps to have the bed as level as possible especially when ditto printing. The nice thing about the auto level feature is it provides feedback during the initial probing so you know how out of level the bed is and which corner to adjust. My bed is pretty level to within .20 mm throughout (I print on glass) the entire surface so sometimes auto level on small parts in the center of the bed is overkill but on large parts you can really see the Z axis move quite a bit in both directions.

As a heads up you are going to want to get a featherlight 5v micro servo that has NON CONTINOUS ROTATION and a mechanical endstop/limit switch or a proximity sensor to build the auto level Z-probe. Those are the two hardware add ons you will need plus one printed part. I use a mechanical limit switch vs the proximity sensor and it works just fine. It's what I had on hand when I implemented it on my first printer so for the sake of consistency, I did the same on the new printer.

Hope this helps,



New Member
Ah nice so you havn't really been doing this very long, that gives me hope haha. I agree the amount information that is readily available makes it easy to get yourself educated. I will get my new printer im building up and running and then attempt to implement auto leveling!!

Leveling the bed is one of those things that i dont enjoy doing, not because i find it hard but because i know its never truly 100% level.

Have you been on facebook and looked in the group for gmax users?? Theres a guy in there testing the new bed system and it looks much more robust than the current, so i may just skip straight to that system on my new printer.

For what reason is the finish gloss different using those hotends??



I'm a 20+ year IT guy so that helps too :D

I am really happy with my dual gMax 1.5 XT and it's why I built another.

I took a look at the new bed system and it looks awesome. And amazingly rigid. The never having to level it after the first time is great (props to them). I only saw two pix but yeah, it's impressive. And it looks like a very simple upgrade to perform. It rides on the same two 500mm vslot rails and the pulley and motor are in the same locations. And as you pointed out, leveling is not hard but it is time consuming. And manual leveling is far from perfect. Auto leveling is the next improvement over manual, but NEVER having to level the bed after the initial leveling is even better no matter how cool it is to watch the servo probe the bed. Function over form any day. But when it works, you may as well make it James Bond cool. And yes I want one and would love to beta test one (or two).

The high gloss is a result of melting the PLA at a high enough temperature while maintaining the proper flow rate. My stock gMax runs Dual E3V6 hotends and they produce the same high gloss result with PLA. Of course filament quality plays a big part too. I chose the bracket to illustrate that the Volcano can produce really nice glossy parts. It took quite a bit of fussing but I finally have them dialed in. The bracket was printed at 30mm/s @ .6mm layer heights using an .8mm nozzle with a target temp of 199. The cooling fan never exceeding 22%. This is due to the Volcano heaters having a hard time staying @ temp while extruding large volumes of cold plastic and if the fan blew harder it would cool the hotends. It provides sufficient cooling for the molten plastic and I have it override the 22% limit when it needs to bridge but then it dials it back down. @ 22% power to the fan, the hotend will stay within 3 degrees of target and all is well.

I've printed many dual color objects on my stock gMax with the Dual E3Dv6s but today, I tried dual color with the Volcanos for the first time. I used the two color cone from Thingiverse and scaled it to 150%. I was very pleased with the results . See the attached pic. There was really only one noticable trace of ooze and it flaked right off post print. The print is very strong, very lightweight and pretty high quality considering the .6mm heights. Also glossy.


Very awesome, good job!

I am interested in the auto-leveling mod too. I have a 1.5 XT, dual extruder, and it is a PAIN to get level. I swear my bed is not level... always some spots where things don't stick and others where it seems to be REALLY stuck to the bed. Sanded things down a bit, same problems.

In any case, looking forward to your firmware and part to add that feature, when you get to it.

I'm an IT guy too, and software developer, and had thought about looking into the firmware and trying to add some modifications to it, but haven't had the time to investigate it yet. One day, hopefully I will!


New Member
I was having the same problem cncpadawan, after i had done maybe 30 prints or so i started moving to larger prints, and the first layer was really inconsistent in terms of laying it onto the bed, eventually i figured out where i had been printing in the centre all the time and sanding that same area i had created a low spot in the acrylic. Fortunately at work we have massive calibration sander that is really accurate (it can sand writing off of paper!) so i ran the bed through the sander a couple of times and got it perfectly flat. Now i dont have any problems, and if i do i know its because i havn't leveled the bed properly.

Shaq i am going to look into these hotends, are they worth the upgrade for a novice like me? Eventually i want to be able to print in nylon.


New Member
Also Shaq, is there any chance of you posting the files for the Ramps enclosure?? It looks really compact and neat.



Re: Hotends

The stock jhead hot ends that come with the gMax work very well. I never had any problems for the two months or so that I ran them. They never clogged, they heated quickly, and they printed with good quality. I switched to the E3D hotends for the different materials/higher temps they support but you also get higher resolution (assuming your printer is calibrated correctly). So if that's what your after then, yes it's a good upgrade and highly recommended. They are high performance hot ends. Note that on LIRlene (my stock gMax), I am running Dual E3D v6s and Phat Freddy has Dual E3D Volcanos. I am recommending the E3D v6s and not the Volcanos. I like the Volcanos but I wouldn't use them exclusively. I need to print in finer resolutions/greater detail. I can do pretty much the same thing with both printers but Volcanos cut printing times in half and produce stronger thicker parts but obviously sacrifice resolution. LIRlene is a very reliable workhorse that produces high resolution prints.

The printers are complimentary to each other. I haven't had/used the Volcanos long enough to provide a really objective answer but the V6s absolutely rock. It would be nice to use a v6 alongside a Volcano but the Volcano is 10mm longer and E3D to my knowledge doesn't have a 'spacer or a longer heatbreak/heatsink' to lower the V6 so the nozzles are z-level. I have no interest in trying to be the first one to accomplish this with my "Fisher Price Ages 3-5" modeling skills.

The ramps box I used came off of Thingiverse and you can find it here.

I modified it a little after printing by cutting the access slots in the back larger and added the "propeller" top for aesthetics by gluing it to the top. From the start I had planned on having the top half the enclosure "glow" so I printed that part in clear PLA.

For the prop guard, I did a search on Thingiverse for "fan guard" and had a litany of models to choose from. I don't remember the exact .stl I used but this one is very close:

Overall, I like this enclosure vs the stock one as the airflow is MUCH better With all the wires coming off the back in the stock enclosure the airflow is heavily obstructed and you can barely feel the air exiting out the front. I cut a small piece of scotch scouring sponge and put it underneath the fan inside the enclosure to act as a dust filter. I noticed dust gathering on the stepper heatsinks and electronics due to the direct cooling of the fan and strong air intake. Now, everything stays nice and clean and cool. the stepper wires keep the sponge from touching the heat sinks. I'll post pix in a bit.

My aluminum stock enclosure wasn't cut square (it looks trapezoidal) and that detracted from the high quality design of the gMax itself. The printed enclosure blows directly down on the electronics and you can feel the air coming out the front AND back so you know it is being thoroughly cooled. I added an RGB strip inside the enclosure. It can change to any color but now it is left as green. The LED on the power button of my stock gMax never worked so there is no 'power' indicator on LIRlene when the button is pushed. I put adhesive rubber feet on the bottom of the enclosure to dampen all vibration and noise.

Turn Freddy on and the enclosure glows nice and green. Of course, you don't need an illuminated button to know when the printer is on, this was just my tongue-in-cheek answer to that issue. :) Seems like ions ago. Here's the original thread - viewtopic.php?f=8&t=379&p=1617&hilit=power+button&sid=4d3b8c00732c7f7b5ca781f5bb2ca60c#p1617

I'll ultimately have the ramps box display the temp of the hot end via the glow color of the enclosure. When the printer is on and idle it will be green. While heating, it will be blue when cool and gradually ramp to red as the hot ends are heating. It's not an original idea by any means and I think there is base code already in the firmware that I can simply extend. If not, it's pretty straight forward. - during heating read thermistor vals from serial and adjust PWM output to set RGB values (actually from cool to hot you only need RB). But that's purely aesthetic and very low on the priority list.




New Member
Larry, thanks for all that info, i am going to invest in V6 next payday. Thanks for the link to the enclousre, mine was exactly the same when i got it, sort of looks a bit bent! I might model my own based on this design, i have a PSU that is different to the Micro ATX one that comes with the gMax, so i want to try and incorporate them both into one unit. I've also seen your post in another thread about using brackets to connect the printer frame, so im going to be 'borrowing' this idea off you too haha :D

I am still waiting for my aluminium to arrive so i can get started, i will update when it does!

Thanks again