The glass bed on the Makerspace’s Taz 3 printer recently did what glass does- it broke. Time for a repair and upgrade!
I started by cutting the under carriage down and modifying it for a three point leveling system instead of the stock four point undercarriage/bed plate bending scheme.
Modified undercarriage mounted on the printer
The original heater was separated from the shards of glass and glued to the 12″ x 12″ x 1/4″ cast aluminum tooling plate using high temperature silicone. 3x #10 countersunk screws and springs support the plate on heat resistant teflon blocks. The whole assembly stands about 1 cm taller than the original bed plate so I printed a small extension for the Z=0 set screw so it would trip the switch from the higher position. I tested the heating time and found that the bed gets up to 110C in about 16 minutes- a little slow, but we probably won’t be printing much ABS with this open frame machine anyway. Next- run PID autotune for the bed heater and adjust acceleration (greater moving mass means lower acceleration and print speeds).
New bed plate and undercarriage mounted on the printer
Some of you might ask why I would replace the glass bed with a piece of cast aluminum tooling plate. Thermal performance is one good reason. Here’s an IR photo of the original glass bed:
IR image of the Taz 3 printer with original glass bed.
Notice the hot and cool spots- 30C temperature variation across the bed.
Here’s what the new aluminum bed plate looks like:
Temperature variation is just a few degrees over the entire surface (the bright almost horizontal lines are not hot spots- they are reflections of the X axis guide rails).
I have run the PID tuning on the new bed and modified the firmware with the new constants. It heats from 25C to 100C in about 9 minutes.
I officially declare the Taz printer ready for action.
MegaMax was a great 3D printer, but it was time for some changes. He was difficult to transport because the electronics were in a separate housing with many cables to disconnect and reconnect, barely fit through doorways, and required a positively gargantuan enclosure to keep the temperature up to control ABS delamination. Though it hurt to do it, I tore him apart and did a complete redesign/build into a form that is more like what I would have done had I known anything at all about 3D printing when I started building MegaMax.
I reused what I could including a lot of the 8020 extrusions in the frame, the Z axis screw assemblies and drive belt, and the X and Z axis motors.
ball screw drive Y axis with high torque motor- precise but noisy
linear guides in X and Y axes instead of 1/2″ round guide rails and linear bearings
SmoothieBoard controller instead of Arduino/RAMPS
BullDog XL extruder and E3D v6 hot end
RepRapDiscount graphic LCD control panel
narrower frame design without giving up print volume- easier fit through doorways!
polycarbonate panels to enclose the print area yet provide a clear view of the print
electronics in a drawer for easy service and transport and neater appearance
DSP motor drivers and 32V power supplies for X and Y axes
Liberal use of screw terminals to make servicing easier
Modular X and Y axes that can be removed for service and replaced in minutes.
SoM will be making his public debut at the Milwaukee Makerspace very soon…
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
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.
Join us for The Greatest Show (& Tell) on Earth at Wisconsin State Faire Park September 24th & 25th, 2016. Admission is free. A joint presentation by Milwaukee Makerspace and the Betty Brinn Children's Museum.
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