Spark Bot 3D Printer¶
Small printer with thick layer printing¶
For several years I have wanted to build a small print envelope printer with a large ID print nozzle. Build volume would be on the order of 100 to 140mm cubed. Nozzle should print layers between .6 and 1mm thick. An air knife that cools the entire current layer will be needed. PLA will be the primary material printed. Frame should be open to allow visibility through the machine for workshop facilitation. It would be nice if the printer folded down fold-a-rap style, but that is not an initial requirement. Initially off the shelf circuit boards will be used, but long term scratch built boards will be designed and made. An easy to use intuitive touch screen display with customizable icons is needed. Light up inside reveal cases will be used utilizing 2 way mirrors, à la the Foam Crawler CNC machine. To summarize:
- 0.6 to 1mm layer heights
- .8 to 1.2 mm nozzle ID
- Strong entire layer cooling
- 100 to 140mm cubed build volume
- Fold up?
- Reveal insides enclosures
- Open frame for visual pass through
Impetus¶
On Thursday April 22nd I discussed with Director Manny Juarez, the possibility of the designing and building our own purpose built 3D printers for use at the MSI Chicago Fab Lab. Manny liked the idea, we were also discussing the expansion of our Fab Lab into the larger Spark Fab Lab where we would close the gap between rapid prototyping and factory mass production. In order to help close this gap we want to lead workshops to for people to build their own machines. This concept is not new, the MIT CBA Machines That Make (Machines) and the Rep Rap projects have led people to build their own machines. But being in a museum we are positioned to bring machine building to more people and we may be able to make it more accessible than before.
The ORD Bot Kit, donated to us by Bart Dring, was one of the first 3D printer we built from scratch at the MSI Fab Lab. It was the first rep rap style printer we go working reliably.
Hence the Spark Bot 3D Printer. A small easy to build machine that people would know that it was and that would be easy for me to design and for my team to guide in building. I had attempted other machine designs before, but they were too esoteric for first time machine builders to grasp and they didn’t leverage the deep experience with 3D printers that the MSI fab lab team has built up over a decade.
Spark is a nod to the future expansion of the MSI Fab Lab, the inclusiveness of a DIY machine build and the spark that machine building ignites. It also has a nod to a 3D printer I repaired with my fellow hackers at SSH:C Sparky. May I avoid the sparks of sparky however!
Prusa Mini +¶
At the MSI Fab Lab we have several Prusa printers including 2 Prusa Mini + printers. The Prusa Mini + printers are great and the staff like them quite a bit. The scroll wheel navigation is a bit funky, but the color screen with a jpg preview of what you are printing and the quality of the prints are awesome. We also love the size and the cantilever open frame, that would allow guests to see around and for the printer to be located very closely to a guests design computer. Could we build our own version of this style of printer with modifications for our needs?
Spark Bot 1.0¶
The Spark Bot 1.0 3D Printer will be scratch built except for control boards. It will become the platform for Spark Bot 2.0 which will have fabricated control boards. All parts of the Spark Bot will be open source whenever possible, except possibly a low cost touch screen. For some reason the open source rep rap community doesn’t want to develop a touchscreen. My guess is that Prusa will be the first to develop one.
50mm tall creatures in 15 minutes¶
At the MSI Fab Lab 3D Printed Creature Workshops we want guests to leave with the biggest 3D printed creature possible in a 15 minute print time. Currently we print creatures with a 0.3mm layer height with 0.4mm inside diameter nozzle. This produces a 25mm tall creature in 10 to 15 minutes. A 50mm tall creature in 15 minutes would be amazing, can the Spark Bot do that? I certainly hope so. I think the open source E3D Volcano nozzle system will help meet the goal of printing super sized creatures! As Sanjay says “Volcano enables you to print bigger and stronger parts, faster”
0.4 to 0.8 mm drill out test¶
During the insanity of 3D Printing thousand of PPE Face Shield Frames in 2020 I was wearing out a lot of 0.4mm ID nozzles. So one day I drilled one of these nozzles out to 0.8mm and tried printing a creature at 0.7mm layer heights, it worked surprisingly well. See my photo album here: Big Not So Lucky Cat.
Note the 15 minute print time for a 68mm tall Not So Lucky Cat. At .3 mm layer heights a 25mm tall not so lucky cat takes 15 minutes to print. The new thick layer cat is 2.72 times taller!
The BOM¶
It always great to be the bomb, but making a BOM is a difficult but needed task to control costs and have a list of parts to share so others can build your thing. So let’s so this hot diggidy BOM!:
| Qty | Item | Supplier | P/N | Cost Ea | Ext Cost | Link | Note |
|---|---|---|---|---|---|---|---|
| 3 | Stepper Motor Bracket For NEMA 17 | ||||||
| 4 | Stepper Motor - NEMA 17 | ||||||
| 1 | MakerSlide Aluminum Extrusions 1000mm long | ||||||
| 1 | e3D Volcano Nozzle | ||||||
| 1 | HDPE Sheets | ||||||
| 1 | Acrylic sheets | ||||||
| 2 | Drag Chains | ||||||
| 1 | gShield |
Boy do charts take a long time to make in markdown. I’m going to use google sheets for now:
Low cost materials¶
Aluminum Extrusions¶
Short story for now 20x20mm openbuilds V-Slot linear rail is the lowest cost and versatile extrusion you can get in small quantities. ()[Open builds 20x20 linear rail] is $10.69 per meter.
McMaster Carr has some ok prices for aluminum t-slot extrusion. 20x20 t-slot extrusion for $11.92 per meter.
20x40mm extrusion cut to length is $17.13 per meter.
This is ok price and I can get this extrusion in Chicago in 2 days pre cut to the length I need.
I thought instead of using 20x20 mm t-slot extrusions, aluminum 19mm square tube from the local hardware store could be used to save costs.
Price at Home Depot ends up @ $14.75 per meter, not cheaper than t-slot extrusions!
Buying 1.828m 19mm (3mm wall) square tube from McMaster Carr. Price ends up being $9.21 per meter. Which is little cheaper than 20x20 t-slot extrusion. But with a loss of the awesome t-slots, not really worth it.
Linear rail¶
Open builds 20x20 linear rail is $10.69 per meter. MakerSlide 20x40 is $24.99 per meter. Wide MakerSlide Gantry 44.15 x 40 is $49.00 per meter
8mm rods (ground finish)¶
Left over from Prusa and rep rap printer builds and upgrades, 8mm rod can be found for free.
Brand name 8mm VXB linear rods cost 24.77 per meter.
Off brand 8mm linear rods cost 19.89 per meter