Pepstrap
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Contents
PepsTrap
On this page i'll keep udpated informationa about my low budget repstrap maiden mostly from junk without loosing anything on quality and features. It has been named PepsTrap from Peps (one of my nicks:) and Trap because it trapped me in developing it, becoming my first activity in the last 2 months :)
I'll also try, while modding and hacking, to develop some concepts that could be applyed on a replicable future version of the printer such as:
- tensostructures substituting heavy metal bar, starting with metal wires and nuts/screws and hopefully ending to printed twisted plastic wires.
- double to triple shaft extruder, hoping to have more strenght and reduce filament's deformation.
- use of replicable plastic wheels instead of metal bearings on all axis.
- kitchen methan gas heated extruder with tungsten nozzle and ceramic/fiber insulators to achive extremely high temperatures.
- cd-rw laser heated extruder.
- 20Mhz sanguinololu electronic based on athmel1284p.
Basic junk, (were) inkjet printers and scanners
Hp-deskjet 7**/9** series, good endstops metal bar with metal bearings (VUP Very Useful Parts) usb, parallel connector.
Lexmark z65, good endstops axes with metal bearings (VUP) usb connector.
Canon bubblejet s5** very good stepper motor nema 17 (VUP) metal axes (no metal bearings) usb connector.
Hoyo (?) flatbed scanner, a very old a3 flatbed scanner, the most intersting thing beside the glass bed (Guess where we can use it :) is the iron wire geared skain and weels.
In all the previous there were a lot of other useful things, such secondary metal and plastic axes, weels, gears and in each printer you can find a very useful gum gears-belt perfect for moving your axis!
Design
The basic design, choosen for it's simplicity and for the few materials needed is an "upside down T" from a Mendel.
- Z axis is maden with the 2 bar+bearing from the hp deskjet.
- Y maden from the Lexamrk bar+bearing+ plastic plane (it was accomodating the printer heads the bearings were already fixed on it) and one of the metal bar from another printer with no bearings, the plastic plane will run on this second bar through a weel system.
- The Extruder is placed on the plastic carriage travelling on the Y axis.
- X axis is maden from 2 metal drawn found in the Deskjets and a carriage with 4 couple of plastic weels.
- Y axis is moved trough the Z axis by a stepper motor and the iron wire motion system from a scanner, they are be placed on the external side of the Y axis to balance the weight of the Y motor on the other side. X and Y axis are moved through a gum belt and a stepper motor each one. The X axis motor will be placed under the printing bed in the middle.
The juntion parts are maiden in wood, merging other metal parts from the printers. The wood parts also are designed to be as small as possible and easy cuttable, so that you can easily borrow a couple of tables for free from your lumberjack friend.
Electronic
This is basically the part that keeps as away from a 0-budget repstrap. I'v searched everything about this topic around, but on the way to be able to have good features and an affordable price, that's been my choose: Sanguinololu. It can be a bit tricky to print out the PCB with your flatiron but not impossible at all. The biggest problem is the ftdi chip which is quite small, but as shown in their wiki page: [...] you can do it! I bought the following from ebay for around 80$:
- 4 x pololu
- ATMEGA1284P
- 20mhz Resonator
- MOSFET
- FTDI chip
- 4 stepper motors nema 17, (i didn't find enough good motors but they where so cheap that i bought 4 of them for 30$)
- SD card reader for Arduino.
- Display 16X2.
All the other parts, resistors, capacitors, pin headers etc. needed can easily be found on old motherboards or printers cpb or in any electronic device.
Then i'm planning to mod a bit the sanguinololu pcb1.3a to be bigger, allowing:
- Bigger traces, easier PCB DIY. - Instead of having a 16mhz ceramic resonator to have a 20mhz crystal + 2 capacitors. - Instead of SSOP 28 PIN i placed a DIP 28 PIN for the FTDI chip, so that with an easily designed DIY SSOP28 to DIP28 PCB, it is possible to plug in/out the chip and reuse it while soldering it just once. If you print from sd card, you can even share just one ftdi chip for all your printers :)
On one printer's pcb [...] i've also found this usefull IC: 74HC125 which comes out to be a really usefull 3state buffer. Thanks to it and other lentils unsticked around i managed to build an AVR programmer as described here: http://avrprogrammers.com/bld-par3.php That makes possible to install arduino/sabguinololu on our fresh ATMEGA1284P as shown here: http://aka47.adsl24.co.uk/serendipity/index.php?/pages/Min644pWarez.html
Extruder
I just bought titanium 0.2-0.5 drill bits a brass threaded bar and some blind bolts on ebay and i'm entering experimentation! Wood and ivory from boar's tusk promise well (no i'm not a poacher, my father is an hunter and boars are legally and commonly killed for food in the south of Italy where i live) Still from the inkjets, there are a couple of extremely important thigs: this two metal rods with wonderfull soldere metal gears and even 3 10mm long gripped trunks on each! YES, we saw something very similar in Wade's Extruder!!
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