As previously promised, MegaMax’s Y-axis has been converted to screw drive along with the addition of a larger motor, DSP based driver, and 32V power supply. The SmoothieBoard arrived and was quickly swapped in to replace the ATMega2560/RAMPS combo. After studying and configuring the Smoothieboard I attempted a few test prints. That’s when the problems started.
Smoothieboard is supposed to read the config.txt file from its uSD card (conveniently accessible via USB) every time it boots. That makes changing configuration very easy and fast – all you do is edit the config.txt file, save it , and reboot the board. Firmware is updated the same way. With the ATMega2560 you have to find the configuration variables by searching through multiple configuration files, make the necessary changes, recompile the firmware, then flash the controller. I said the SmoothieBoard is supposed to read the file every time it boots, but it wasn’t doing it. I’d make changes and they would not appear in the behavior of the printer. Hmmmm.
I attempted some prints and managed to get two decent ones in about a week of screwing around with it. I tried dozens of combinations of speed, acceleration, junction deviation (smoothie-speak for jerk) and even tried different slicers. The machine went completely nuts on two occasions and ignored the Z-axis limit switch and slammed the extruder into the print bed, gouging through the Kapton tape and into the aluminum! I decided I needed some professional help so I got on the #smoothieware IRC channel and discovered that the developers of the board/firmware hang out there quite a lot. After a lot of back and forth Q and A and testing someone suggested it might be the uSD card causing the problem. I picked up a new card at Walmart, put the firmware and config files on it , booted the machine, and attempted a print. PERFECT!
I have made several prints since last night and they have all come out fine. I still have a little tweaking to do and to test the limits of the machine’s performance, but I think the problems are behind me.
Next up: X-axis redesign/build. I’m replacing the two guide rails with a single linear guide. I have also ordered and received a BullDog XL extruder to replace the hacked up QUBD unit I’ve been using. I’ll be adding a DSP driver and 32V power supply for the X-axis motor, too.
After that, I have some ideas for a filament respooling machine and ways to fix the retraction problem in the SnakeBite extruder.
It never ends!
MegaMax has been and continues to be my main project for the last 2+ years. I am currently working on some upgrades that will make him more Mega and even more Max. The Y axis is being converted from belt drive to screw drive and the round guide rails are being replaced with linear guides and bearing blocks. The X-axis will also get converted to linear guide and bearing block and change from 5mm pitch belt to 2 mm pitch belt drive. I feel confident saying that once these modifications are complete the flaws/errors in prints will be due primarily to the nature of liquid plastic squirting through a nozzle, not positioning system errors.
I recently updated my web site with a sort of historical look at the project, including all the mistakes I’ve made along the way and the often failed attempts at correcting them. Here is the page that shows how it all started, how it has ended up, and where it is going. http://mark.rehorst.com/MegaMax_3D_Printer/index.html
Don’t ask me why I do this- I have no choice.
The plan was to take a “Roomba” robot vacuum cleaner that I got for $1.00 at a rummage sale, and covert it into the robot base for a giant spider or some other scary creature that could wander around at a Halloween party.
I started pulling screws out of the bottom to figure out how to remove the brushes and vacuum blower. It took some tinkering to figure out what I could and couldn’t remove and not cause a fault. In the end, it didn’t look like I could remove the blower motor and still have the thing run, so I simply removed the fan blades from the blower.
By that time, I was now thinking about video cameras and how easy it would be to run a 1/4-20 bolt right through the plastic. A bolt and two nuts quickly made a camera mount.
In the other room were some ping-pong balls, and I had a black sharpie. A little hot glue and Roomba-cam has some personality.
Look for Roomba-cam running around the Milwaukee Makerspace and please treat Roomba-cam nice – he is watching you and WILL upload to YouTube!
The video shows the last few layers of the calibration cube “printing” at 414% speed (according to my LCD display).
The Bucketworks 3D printing meet-up on 8/12 paid off big-time! Gary Kramlich helped me debug a problem that was preventing me from flashing the firmware on the controller board for the MegaMax 3D printer. After a few tweaks I was able to get it moving.