Bogdan Kecman

Links

MySQL Blog (in Serbian)
Electronics Blog (in Serbian)
Picasa RapMan Galery
LinkedIn profile
Skeinforge settings SVN repository http://www.mysql.rs/repos/skeinforge_settings/ NOTE that this is mine personal settings that I experiment with often - use only as example, not as solution

Contact

Phone: +38163243949 (sms capable)
Skype: bogdan.kecman
Email: on gmail

Other

Currently live in Belgrade, Serbia
Work for Oracle as MySQL Cluster consultant/support engineer.
Happy owner of one RapMan v3 from BFB

Why RapMan

In spare time I make robots and I have big problem making parts for them (motor holders, joints, bodies ...). That is the reason I ordered RapMan. I went for BFB version as it offers complete solution with electronics that allows the machine to work as stand alone printer.

Printing

Links

A bunch of links I always chase in history or google so decided to put them all in one place
Forrest made the "pads" system to reduce warping forces on HDPE + mine test with PP
Overhang testing
Spare parts
Heating problem because heater element is 4OHM or less
The problem with electronics - resets mid print - increasing humidity helps
Alibre
Skeinforge installation
No strings firmware
Firmware source / compilation

Software

I use CoCreate running in WinXP under VirtualBox to do the general design of the object I want to print; then Art of Illusion running on Fedora 10 (64bit) to fine tune the object and position it where I want it on the print bed. Fixing and repairing the STL files is done by Netfabb and finally Skeinforge running on Fedora 10 (64bit) to produce the G-Code that I then edit using gedit (just an ordinary text editor) to add few tweaks if I need them.

Print Bed

I use print bed made of

PP 1cm
HDPE 1cm
Acrylic 3mm (the original one that came with RapMan)

I have modified the print bed design so I can use other side to print on when the first side is damaged by making it symetric

PART 10021

DXF 2D drawing of the PART 10021

Mods

I modded my RapMan by

I use 2 fans to cool the object, one on the extruder and second one on the Y motor. Both fan's are equipped with the on/off switch so I can manually turn them off.
I mounted "extra powerfull" 5400 RPM FAN under the PCB and added a grid+gauze under it so it does not suck in the "dirt" from the table
I added on/off switch to the power supply so I do not have to plug/unplug the cable all the time

Z screw

Replaced Z screw with longer one and added a piece of acrylic at and of it so the contact surface with Z switch is larger.

The hole in the acrylic piece is same as screw head so I added some bison epoxy glue to prevent plexy piece from dropping from the screw and added a nut on top of the plexi to assure pressure is constant.

Z micro switch

The Z micro switch had problem passing between top left corner and X drive holder while homing so I had to use Dremel tool to cut part of the acrylic in order for Z micro to pass without obstacles. If you remove leftmost screw from the Z micro holder that would be better solution (but I did not remember it!!! and I like playing with Dremel :D )

X and Y stepper pulleys

I used Dremell tool to file the stepper motor shaft (both X and Y) to D shape so that screw on the pulley can press on the flat surface. This allow much faster movement of the head as well as normal operation of the COMB plugin.

Filament holder

In order to make faster filament change I modified the filament holder a bit. I removed the long M8 screw and replaced it with 19cm long M8 threaded rod. I used two M8 nut's + one washer on either side of the rod in order to attach the rod to the acrylic holder on the machine. Then using 2 nut's and one washer around each side of the acrylic disk (allowing the disk to rotate around the rod) I secured 2 acrylic disks that will allow the filament to rotate easily.

larger photo

The acrylic distancer is then placed between the last nut and the cover that is secured with a butterfly nut.

larger photo

Electronics

Forum Thread about it

The small board on the left is "extruder extension board" and it basically extend all 11 lines of the extruder connector except that all 4 lines for stepper are tapped and brought to the 4pin connector on the side and that heater output is brought to the 2pin connector and gnd from the heater output is also brought to the second 2pin connector. the gnd pin to the heater is not connected to the output extruder pin but the output pin gets gnd from 2pin connector ...

This allow us 1. to add Schottky diodes to stepper lines 2. to use relay to power the heater instead of using FET on the pcb

The right board is fairly simple ... it has 3 sets of 8 big Schottky diodes (1N5822 3;80A) and one set of smaller Schottky diodes (SB260 2;60A). Every set leaves with 4 wires to be connected to stepper lines. The 3 big sections are connected to the mainboard XYZ steppers and the small section is connected to the small board - extruder extender. Board also have a power on/off button, 10000uF capacitor and 2 12V 15A relays. One relay is connected to the heater output for the extruder (on extruder extender board) and it switches the gnd for the heater. The idea was to test if maybe heater will work faster if not going trough FET that is opened with only 3V. Test shown no improvement, probably if the heater was using less resistance the difference would show but attm it is not important. The second relay is connected to the aux port, working contacts are not connected with anything.

What can I say .. the fist print went ok without reset ... but that proves nothing ... we'll c if this helped in any way ... It is ugly, big, and I should of used bit longer cables (seamed long enough when I was cutting them :D ) but .. for now it helps