Budget Strapped
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Release status: unknown
| Description | A low cost RepStrap
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Contents
Overview
This printer is intended to be a very low cost 3D printer that is still capable of printing useful items. The cost of filament is very significant for a printer in this price bracket. To reduce this cost, BudgetStrapped will print with HDPE filament, which can be created relativly easily from household plastic waste.
Design Goals
- under ~$100 total cost.
- ability to print will filament made from recycled household plastics. Specifically HDPE (#2 plastic).
Remaining Work and Concerns
- The hot end I currently have is a knock-off J-head nozzle. Based on some searching it seems likely it will not work very well.
- SLOW print speed. The X & Y axis print speed of 6.23mm/s is slower than I have seen anyone mentioning printing. (I saw 15mm/s for a first layer.) will the printer still function if it is printing this slowly?
- In an article by someone trying to print HDPE, it was mentioned that printing very slowly (as slow as 0.75mm/s) seemed to cause the HDPE to print better. This is very encuraging
- My household plastic recycler needs to be completed. Until this is completed I have only a few feet of 3mm PLA to work with.
- I have not yet recieved the fishing line. I still need to verify the spooled fishing line drive method will work as planned.
- Additional NiChrome wire may be required to build heated print bed.
- The simplified electronics used do not use stepper boards. I have written a functioning motor test arduino sketch for this setup, but I haven't yet verified that an existing firmware can work with this setup. (I may have to modify the firmware myself.)
Printer Details
Structure And Motion
- Printhead will move on X and Y axes, printbed will move on Z axis
- Frame will be made (primarally) out of 2"x4" lumber
- X and Y axes will use drawer slides (like WolfStrap)
- Positioning on the drawer slides will be done using 70lb test multistrand fishing line.
- Z axis will move on four 10-24 threadded rods
- Multiple 28BYJ-48 stepper motors will be used on each axis instead of NEMA 14 or 17 stepper motors
Electronics
- An Arduino Nano will be the core of the electronics.
- A shift register will be used to increase the number of digital I/O pins
- 1 darlington array driver chip per motor (These come with the motors)
- A bottom-of-the-line PC power supply will be used to provide power.
Extruder
- The current hot end is a knock-off J-head. (hopefully it works...)
- The cold end is a WoodScrew Extruder.
Print Bed
- The print bed will moved by four 10-24 threaded rods.
- The bed support will be made out of 1/4" plywood.
- The heated print will be made from a piece of glass with NiChrome wire taped to the back of it.
- If an additional layer will be added if nessisary to get HDPE to stick.
Printer Specifications
- Cost: ~$85 - $105
- Printed Parts: None
- Electronics: $12
- Extruder: $38
- Motors: $18
- Wood: $6
- Other: ~$10 - $30
- Printing Size: ~ 7"x7"x8"
- Printing Speed: (SLOW) X & Y axis 6.23mm/s, Z axis 0.265mm/s
- Precision: ??? (position), ??? (printing)
Progress
March 19th 2014 Update:
- Progress is being made on completing the SketchUp model before much more mechanical contruction is completed.
March 13th 2014 Update:
- An issue with using T-nuts was uncovered, they pull out of the wood very easily. Also on further examination of the cost of T-nuts, and the 30 odd ~3" machine screws that would be required to make all the axes adjustable (~$20), it was decided, at least for the majority of the upper structure, to move to plywood. Both the top frame and the X-carriage will now be plywood. This should hopefully remove most of the need to have adjustments at the axes connections. The drawer sliders can be mounted in slots if this seems benificial. (Or if someone else is building this, drawer slides with slotted mounting holes could be used.)
- Progress has been made on the WoodScrew Extruder.
- Further research indicates that printing with HDPE will likely prove very difficult. Since a heated bed is already planned, ABS may prove a better inital printing material. On a related note this link [1] seems to have demonstrated that a hair dryer (or hot air gun) may be able to be used to assist in printing HDPE.
March 10th 2014 Update:
- A design for a wood screw based cold end has been developed. This alleviates one of the largest contributors to missing the cost goal. The extruder works by having a 28BYJ-48 stepper motor turn a wood screw with the filament fed along it. A wiki page WoodScrew Extruder has been started.
- Some of the 2x4s have been cut out.
- The new spooled drives should be able to move the X and Y axis at 6.23 mm/s
- A HDPE plastic recycler is being simultaneously developed. It should (hopefully) cost less than $100 to build.
Status as of March 5th 2014:
- Most of design is drawn out on paper (some has been modeled in SketchUp as well).
- A motor testing sketch for an Ardruino Nano has been written and used to verify the ability of the 28BYJ-48 stepper motors to reliably rotate a 10-24 threaded rod through a T-Nut. The sketch makes use of a shift register chip. The rod can be turned at ~15 rpm. This results in an ability to move that axis at 0.625"/min [0.265mm/s] which seems painfully slow for anything other than the Z-Axis. As a result it was decided to switch to a tantillus-like spooled fishing line drive to increase the movement speed.
- T-nuts and machine screws will be used to allow alignment to be adjusted.
