Your PCB designs sound very encouraging! The ToM's Arduino can translate the G-codes and handle the steppers okay, but that's about it. The extruder control board is a separate entity with its own firmware, and there's another add-on controller board (which I do not have) that serves as a "control panel." There's no reason the Propeller chip couldn't handle the whole schmeer. Plus, with the Spinneret, it could be done over an Ethernet connection, and I could put the ToM in the next room with the laser cutter where its noise wouldn't interrupt my phone calls or train of thought.
I'm interested in the Propeller solution, too.
(I'm building a Prusa Mendel with an Ardunio and RAMPS/Polulu solution rightnow.)
As for moving the unit to another room; you don't need Ethernet for that. You could use an USB-cable with extender electronics(I've used 10meter extender cables with no problems), or stick in an SD-card reader in the electronics package.
(The RAMPS solution has a SDRamps add-on that takes microSD-cards. Unfortunately, it doesn't have an LCD or keypad to select which file to print... And with it being Ardunio, I have no idea how to bodge up a solution. On a Propeller it's easy... )
Thanks Phil. Apart from the software, the only part of the puzzle not done yet (to use a propeller chip) is a Mosfet pcb to drive the extruder and optional heatbed (temp controllers). I have plenty of options for the propeller pcbs, and most others can also be used - I wanted anyone to be able to use this without having to buy new prop boards!
Since you have a working unit, I value your input... So here is my proposed electronics solution(s)...
Stepper Motor control motherboard (1.76"x1.76" or 45x45mm)
Plugs into Prop (or heaven forbid, Arduino) board
Has sockets for 4 Stepper Driver pcbs (Pololu compatible)
My drivers use A4982 or A4984
I use a user soldered resistor for current limit
Pololu use A4983 or A4988
Pololu use pot for current limit (IMHO more complex to setup)
Both 0.6"x0.8"
PCB links to set 1, 1/2, 1/4, 1/8, 1/16 step control (not all available on all A498x chips)
Each driver has STEP and DIR inputs, plus common -ENABLE (and -RESET for my drivers)
Propeller board
I have a few options based on my pluggable boards (mainly 45x45mm)
FTDI/PropPlug USB connection
microSD
TV or VGA
Sound (mono or stereo)
PS2 Keyboard
PS2 Mouse
Optional RamBlade addition (512KB SRAM)
Any other propeller pcb with connections for 10 prop pins, plus 5V & GND
Heater Driver pcb (Extruder and Heatbed)
Most likely 45x45mm
2 channels
P channel MOSFET capable of 24V (typical 12V) up to 15A
Screw connections for V+, Vswitched and GND for each channel
2 wire interface (serial or I2C)
4pin header for (re)programming with the propeller
see discussion below for more details...
Heater Driver PCB:
Here is where I have a few ideas that I would like some input...
I think it would be nicest if this pcb was self-contailed and intelligent. I am thinking of using an ATTiny84 to control the 2 channel P MOSFETs. The feedback would be via Thermistors. I know the prop could do this, but think it would be easier and more beneficial to just be able to set the temperature and forget it. The cost of the ATTiny84 is <$2. This pcb may have other "robotic" uses too.
A 2 wire interface would be used, and I think serial would be the easiest, although I2C is also possible.
The ATTiny84 would also have a 4pin header so that it could be programmed/updated by the prop. This connection would not be a normal connection (saves pins).
The prop would merely send the temperature required for each channel. The ATTiny would control the temperature by PWM and send the temp of each channel back to the prop every xxx (as instructed by the prop).
I see this method as being the easiest, and could be used by the Arduino fans too.
Remember, I am trying to make it easy for the Arduino based solutions to move to a propeller based solution. So, if the two modules (Stepper Control and Temperature Control were seperate pcbs that would work on both micros, then it would only be a substitution of the processor pcb. Of course, we all know that the prop will do this much easier than the ATMega.
The Propeller also brings with it the opportunity to add microSD (to contain the Gcode files) and visual I/O in the form of TV/VGA/LCD and Keyboard/Mouse. This provides the "bait" to switch to a propeller solution I have a Prop pcb with this configuration in the works, all on a 45x45mm pcb.
Although not necessarily required, all my pcbs will fit into Hammond 1551R or S boxes.
I'm afraid you're asking someone who is almost totally ignorant of the way the ToM actually operates. For me, and from an operational standpoint, it's thus far just an appliance. Your best bet would be to obtain the kit and build one yourself so you have something to examine first-hand and experiment with. BTW, the ToM does have an SD card slot from which to read G-code files, but I have not yet used this feature.
I'm curious as to why you're separating the heating and stepper circuits to separate daughter boards.
The ccontrols for the hot bed and the hot-end of the extruder are really pretty simple.
The hot bed only needs a 'ballpark' temperature regulation, and the hot-end really isn't much more demanding.
(It needs to be at a temperature that will melt the plastic used. Anything higher won't matter, unless you ramp it up too much. also, the hot-end and nozzle is made of metal, so will have some 'inertia' and retain heat for a short while.)
Nothing that needs micro-second handling, in other words.
How does the extruder on a ToM operate?
On my(still building) Prusa Mendel, I'm using what's known as a Wade's Geared extruder, basically a NEMA17 size stepper with a small cogwheel, driving a much larger cogwheel mounted on an M8 bolt. On the bolt there's a lots of grooves scored along its length, and the plastic filament is pulled between that scored area and a 'rollerscate bearing'.
I'm going for a J-Head hot-end with .5mm nozzle aperture, but may later switch to a .35mm for precision work.
(There's lots of 'weird' stuff happening with the Mendels; smaller, bigger, multiple hot-ends... )
A Prusa Mendel, or a RepStrap may be a cheaper alternative to the ToM, especially if you can source some of the materials locally. (PSU from old PC, M8 threaded rods, nuts washers, smooth rods. M3 and M4 screws, nuts and washers, 'rollerskate bearings'. Structural parts are printed on other 3D printers, or bodged together in a RepStrap. Sliding bearings for the carriages can be bought, or acceptable substitutes printed of PLA plastics, though thy may not last too long.)
Lots of info over at reprap.org
Note, my Ardunio MEGA2560 and RAMPS(with 4 polulu boards, Mosfets, 3 optical endstops with associated electronics and cabling) came to about $160. (Ardunio was assembled, the RAMPS was a mostly-SMT kit, optos were through-hole kits, and the Polulus needed headers lodered on)
If your kit can beat that price and be easier to solder, you may have a good thing going.
And yes, soldering 0805 is a pain in the... But I only broke one LED and lost a capacitor...
Thanks Phil. I understand its just an appliance for you.
Would you like me to take this discussion to a separate thread or are you happy for it to continue here?
Gadgetman: The reason for a separate pcb for the heater control is mostly from a failure point of view. It is not reasonably possible to replace the smt mosfets so I didn't want them on the same pcb as the stepper driver board or the processor board as a failure could render an expensive board useless. The current is large and therfore the connectors must be on this pcb so a plugin mosfet is not a possible solution. This is the same reason as having the stepper pcbs as individual plugins to a stepper motherboard - a cheap replacement of the driver pcb(s) where the more expensive connectors etc are on the motherboard. Therefore, the heater pcb can be quite a cheap pcb and no doubt would have other uses too. I like multiple-use cheap modules.
So my solution is really 3 pcbs which plug into each other via male/female right-angled pin headers, and limited cable mess. I am aiming at an electronics price <$100 without cables but all connectors included, but excludes endstops. This includes connections for microSD, TV/VGA, Keyboard. The PropPlug or equivalent will most likely be addititional and separate. All smt parts will be preassembled and thruhole will be optional.
Endstops: I think microswitches may be better than optos. I am actually considering if a shorting metal finger could be used.
As for a RepRap unit, I have a prototype micro-mendel of my own simplified design mostly built. I hobbled the frame together with (poorly) cut timber to test out some of my theories. I made a number of simplifications and will also use some of the Prusa simplifications too. IMHO the Prusa has not yet gone far enough, but it is the simplest so far. I have been following the RepRap forums for nearly 2 years now. However, I am only intending on using a single stepper for the Z axis. My rods have been scrounged from old printers and laser cartridges and a few parts from old roller blades. My X & Y carriages move the platform and the extruder only moves in the Z direction. So far, Wade's Extruder seems to be the best choice, together with the lever modification.
Here is a pic of my bodgy prototype. It's an old pic and a couple of horizontal rods are missing near the top. And a pic of the plastic parts I designed to join the rods/bars at the vertices and the mount for the vertical threaded rods for the Z axis.
Cluso99,
BTW, the ToM does have an SD card slot from which to read G-code files, but I have not yet used this feature.
Small correction, the Arduino, as it comes from MakerBot, does not read G-code files, even via the SD card slot. You must first "build" the G-code into a special file for the Arduino to ruin run it. It does not run G-code directly.
I think a Propeller solution should read the G-codes directly. It would make for a far more flexible machine.
Gadgetman: The reason for a separate pcb for the heater control is mostly from a failure point of view. It is not reasonably possible to replace the smt mosfets so I didn't want them on the same pcb as the stepper driver board or the processor board as a failure could render an expensive board useless.
Which is probaly why the RAMPS kit doesn't use SMT MOSFETs...
(They use TO-220 with a heatsink on one)
I am aiming at an electronics price <$100 without cables but all connectors included, but excludes endstops. This includes connections for microSD, TV/VGA, Keyboard. The PropPlug or equivalent will most likely be addititional and separate. All smt parts will be preassembled and thruhole will be optional.
That price difference and the 'extras' will probably make it more attractive, yes.
But a simple UI consisting of a just a few buttons (Up/Down, Select(start) and Pause(cancel)) and a small LCD may be just as effective, as most will only want to select which file to print, maybe pause it if there's a feed-problem developing, and probably read off an estimate of remaining time?
Endstops: I think microswitches may be better than optos. I am actually considering if a shorting metal finger could be used.
The biggest problem with optos is that many forget that a lot of plastics is transparent to the IR light used.
Personally, I like the fact that there's no mechanical parts that can break.
We'll see if mine survives...
And besides, there's a shiny LED on them ;-)
As for a RepRap unit, I have a prototype micro-mendel of my own simplified design mostly built. I hobbled the frame together with (poorly) cut timber to test out some of my theories. I made a number of simplifications and will also use some of the Prusa simplifications too.
Nice.
How big modules will it be able to print?
IMHO the Prusa has not yet gone far enough, but it is the simplest so far.
I agree. There is work going on to replace at least some of the threaded rods with more easily-available materials such as PVC piping or even bamboo. This I consider a 'false trail' as it's the smooth rods that are the most difficult to find cheaply. Some of the screws aren't all that common, either.(Took a while to find M4x60 for the Wade as most stores didn't have longer than 40mm)
However, I am only intending on using a single stepper for the Z axis.
Yeah, that's a redesign that's long overdue.
Anyway, I have a whole stack of Prototype boards with a very bored Propeller stuck in the middle of them.
I might be willing to 'bodge together' some circuitry on them for testing later on.
(I have an SD-card connector on a break-out board, possibly an LCD or ten, and other odds and ends.. )
As for G-code or no G-code, yeah, it really should be able to take them directly. The Ardunio probably doesn't have the extra capacity to both interpret the codes and control the motors at the same time?
Actually the arduino does reads the G-Code directly and has the capability to read from SD, just have a look at a couple of firmwares, here is one example. https://github.com/kliment/Sprinter/
First, thanks Phil for allowing this thread to progress into using the propeller, and for updating the title.
The low Rdson of the newer mosfets makes heatsinks almost redundant and hence the smt parts. I agree that any interface (LCD and a few buttons) would also be fine. That's the beauty of the propeller. We can change that easy without a major rewrite of the software.
I certainly had no problems in finding the threaded rods. The smooth rod (bars) were much more difficult until I found them freely in old printers and laser cartridges.
As for the two Z motors, the Prusa was the first to my knowledge to use 2 motors. It was done to simplify the z axis but I believe at the expense of cost. On my design, the Z axis does not move in the X or Y direction. Therefore, I think I may be able to use a single threaded rod, thereby eliminating both the second motor and any belt/cog design for the Z axis. Time will tell, but I have an idea I will pursue for this. Also, by the extruder only moving vertically (Z) slowly, I hope there will be less strain on the extruder which may help it to perform better. There seems to be two main problems still being encountered with the various reprap designs... the Extruder and the Heated Bed.
Certainly, the Prusa went a long way to simplifying the plastics. However, IMHO there are still too many rods.
Gadgetman: You will be able to use the Prop ProtoBoards simply with my stepper motherboard and this will accept your Pololu pcbs too. This pcb is all t/hole so I will be selling the bare pcb too. I am using the Molex type 4pin connectors to the Nema motors and Molex type 2pin connectors for the power input (two sets). Here is the pcb layout. Sorry, I cannot post a pic of the actual pcb until I get back home
Here is a photo of the pcb. Note I have just placed connections in half the pcb (not soldered). The white motor and power connectors can also be vertical mount (extra mounting holes provided).
Here is a photo of the pcb. Note I have just placed connections in half the pcb (not soldered). The white motor and power connectors can also be vertical mount (extra mounting holes provided).
Cluso99: Any idea what the price will be for the two boards?
The Stepper Baseboard bare pcbs are US$6.50 ea (I only had 3 made and they cost me $5.25ea plus postage). I will be getting more pcbs later.
I can also supply the following parts (not fitted) for US$2.50: 12@ shunts, 4@ 1x6 ST M pins, 8@ 1x9 ST F socket (need to cut/file to 1x8 or 1x7+1x9, and have long tail pins - sockets for stepper pcbs), 1@ 1x14 RA M pins (for processor connector) and includes 1@ 1x14 RA F for other end, and the following pin headers (not polarised) instead of Molex style connectors for the motors 4@ 1x4 RA M, 4@ 1x4 ST M pins (for either vertical or horizontal mount) and 4@ 1x4 F housings for the motor cable end, and for the power supply 2@ 1x2 RA M, 2@ 1x2 ST M pins (vert or horiz) and 2@ 1x2 F housings, plus the 20@ crimp terminal pins for the housings, plus 4@ 100K resistors t/h, 4@ 100uF 35V Electro Caps t/h, 2@ 100nF X7R capacitors t/h (0.2" so you will need to bend pins to 0.1").
The Stepper Driver bare pcbs (pin/size compatible with Pololu A4983/A4988 pcbs) for the A4982 or A4984 are US$1.20ea or US$2.50 with 2@ 1x8 ST M pins, 2@ 0.05R 1/4W 2% 0805, 2@ 10K 0805, 2@ 100K 0805, 3@ 100nF X7R 0805. You still require 2@ 220nF X7R 0805 (I don't have these until I order again) and a t/h resistor to set the current limit, and of course the A4982 or A4984 stepper IC. I have not done the calcs yet to determine the resistor values to set the current limits, nor have I assembled a pcb. So, for now I am not selling them assembled - the A4982/A4984 is not that easy as it has a ground pad underneath. I only have 9 pcbs at present, so really only 2 sets of 4 pcbs.
Unregistered Airmail Postage from Australia is $3-$5 depending on weight.
I did something fun this weekend... I set my MakerBot CupCake on a task to print out a copy of itself. It succeeded with fantastic results! It printed over 150 parts without a single failure nonstop! It printed for over 3 days straight! I've attached a picture of the results. This will be slightly different from any previous CupCake, as it'll have the Mendel's 8" heated build platform installed in it. I'm moving the Y axis to the Z platform and will have a printhead that moves side to side over 8". The X axis will then be used to move the HBP forward and backwards... like a Mendel is. This will allow me to have the CupCake sized "box" but have a much larger print volume.
Oh yeah, I've already modifed my #2 CupCake to have hidden electronics as well as a hidden Z drive. (I moved the pulleys and electronics to the bottom... see attached pic.)
The new "Black Maria" CupCake with the 8" build platform will also not use the standard MakerBot electronics... instead, I've build a Sanguiololu board to drive everything. It's much smaller and will easily hide in the bottom with minimal fuss.
Actually, the black is absolutely beautiful in real life. Especially with the white trim pieces I'm adding to it. I'm planning on building another one in White as well. (I only have white, black, blue and red colored plastic... I also have a bunch of "natural" which is kind of an off white color.)
I can't wait to get a Prop based controller going on this thing! :-)
Bill
Me neither But QuadCopter first.
I have done all the pcbs, and bought the parts, except the mosfet heater driver pcb for the extruder and heated platform. I think this pcb will have a pair of P-channel mosfets and will have the option of an onboard ATTiny84 to control it and sense the temperature feedback via thermistors and I2C or serial I/F (2pins) to the prop. I wanted it to be a separate pcb for easy replacement in case of failure.
Aaaah, I finally got the stepper motors and drivers just now. Now it's off to coding again. But unfortunately a very busy time at work is starting with lots of travelling. I had hoped to receive everything before the National Holidays here in China, so I would have had some time .
I'll keep posting the code in the CNC thread in the Propeller forum.
Discover Channel's new Velocity TV just filmed me using my MakerBot for part of an episode of Inside West Coast Customs show. We're working on a cool car build and I've been commissioned to install some heads up displays in it, and naturally, I was using my MakerBot to make the parts. They loved it and decided to use it as part of the show.
Should be fun to see when it airs in December. I just wish it was prop powered!!! :~)
Discover Channel's new Velocity TV just filmed me using my MakerBot for part of an episode of Inside West Coast Customs show. We're working on a cool car build and I've been commissioned to install some heads up displays in it, and naturally, I was using my MakerBot to make the parts. They loved it and decided to use it as part of the show.
Should be fun to see when it airs in December. I just wish it was prop powered!!! :~)
Hello,
I'm a happy owner of a Thing-O-Matic MakerBot with MK7 stepstruder.
I need your help please, with a problem I have when I build an item on this printer, every time after a few layers the item detached from the base !!!
I use :
ABS, I have the Heated Build Platform,
ReplicatorG 0027 with Machine Type (on ReplicatorG) Thingomatic w/HBP and Stepstruder MK7,
GCode Generator = Skeinforge (35)
Base Profile = 1.75mm ABS MK7
From GCODE I can read Base Temperature S110 and Extruder Temperature 225.
I also put some Kapton tape above the plastic of the base, and the item stayed a little longer.
I use a pressure-sensitive polyester film instead of Kapton. It's adhered to an aluminum heat spreader that's attached to the HBP. The ABS builds stick to the polyester like glue, but they can still be popped off with a little wiggling when done.
Before I installed the heat spreader and polyester, I had the the same problem as you do (using the ABP). At the time, I solved it by adding horizontal stabilizers to the bottom any design that was tall and skinny. This kept the extruder from pulling the build off the base. I don't have to use the stabilizers anymore, though.
Comments
Your PCB designs sound very encouraging! The ToM's Arduino can translate the G-codes and handle the steppers okay, but that's about it. The extruder control board is a separate entity with its own firmware, and there's another add-on controller board (which I do not have) that serves as a "control panel." There's no reason the Propeller chip couldn't handle the whole schmeer. Plus, with the Spinneret, it could be done over an Ethernet connection, and I could put the ToM in the next room with the laser cutter where its noise wouldn't interrupt my phone calls or train of thought.
-Phil
(I'm building a Prusa Mendel with an Ardunio and RAMPS/Polulu solution rightnow.)
As for moving the unit to another room; you don't need Ethernet for that. You could use an USB-cable with extender electronics(I've used 10meter extender cables with no problems), or stick in an SD-card reader in the electronics package.
(The RAMPS solution has a SDRamps add-on that takes microSD-cards. Unfortunately, it doesn't have an LCD or keypad to select which file to print... And with it being Ardunio, I have no idea how to bodge up a solution. On a Propeller it's easy... )
Since you have a working unit, I value your input... So here is my proposed electronics solution(s)...
- Stepper Motor control motherboard (1.76"x1.76" or 45x45mm)
- Plugs into Prop (or heaven forbid, Arduino) board
- Has sockets for 4 Stepper Driver pcbs (Pololu compatible)
- My drivers use A4982 or A4984
- I use a user soldered resistor for current limit
- Pololu use A4983 or A4988
- Pololu use pot for current limit (IMHO more complex to setup)
- Both 0.6"x0.8"
- PCB links to set 1, 1/2, 1/4, 1/8, 1/16 step control (not all available on all A498x chips)
- Each driver has STEP and DIR inputs, plus common -ENABLE (and -RESET for my drivers)
- Propeller board
- I have a few options based on my pluggable boards (mainly 45x45mm)
- FTDI/PropPlug USB connection
- microSD
- TV or VGA
- Sound (mono or stereo)
- PS2 Keyboard
- PS2 Mouse
- Optional RamBlade addition (512KB SRAM)
- Any other propeller pcb with connections for 10 prop pins, plus 5V & GND
- Heater Driver pcb (Extruder and Heatbed)
- Most likely 45x45mm
- 2 channels
- P channel MOSFET capable of 24V (typical 12V) up to 15A
- Screw connections for V+, Vswitched and GND for each channel
- 2 wire interface (serial or I2C)
- 4pin header for (re)programming with the propeller
- see discussion below for more details...
Heater Driver PCB:Here is where I have a few ideas that I would like some input...
I think it would be nicest if this pcb was self-contailed and intelligent. I am thinking of using an ATTiny84 to control the 2 channel P MOSFETs. The feedback would be via Thermistors. I know the prop could do this, but think it would be easier and more beneficial to just be able to set the temperature and forget it. The cost of the ATTiny84 is <$2. This pcb may have other "robotic" uses too.
A 2 wire interface would be used, and I think serial would be the easiest, although I2C is also possible.
The ATTiny84 would also have a 4pin header so that it could be programmed/updated by the prop. This connection would not be a normal connection (saves pins).
The prop would merely send the temperature required for each channel. The ATTiny would control the temperature by PWM and send the temp of each channel back to the prop every xxx (as instructed by the prop).
I see this method as being the easiest, and could be used by the Arduino fans too.
Remember, I am trying to make it easy for the Arduino based solutions to move to a propeller based solution. So, if the two modules (Stepper Control and Temperature Control were seperate pcbs that would work on both micros, then it would only be a substitution of the processor pcb. Of course, we all know that the prop will do this much easier than the ATMega.
The Propeller also brings with it the opportunity to add microSD (to contain the Gcode files) and visual I/O in the form of TV/VGA/LCD and Keyboard/Mouse. This provides the "bait" to switch to a propeller solution
Although not necessarily required, all my pcbs will fit into Hammond 1551R or S boxes.
Does this make sense???
BTW: Apologies for sidetracking your thread.
I'm afraid you're asking someone who is almost totally ignorant of the way the ToM actually operates. For me, and from an operational standpoint, it's thus far just an appliance. Your best bet would be to obtain the kit and build one yourself so you have something to examine first-hand and experiment with. BTW, the ToM does have an SD card slot from which to read G-code files, but I have not yet used this feature.
-Phil
The ccontrols for the hot bed and the hot-end of the extruder are really pretty simple.
The hot bed only needs a 'ballpark' temperature regulation, and the hot-end really isn't much more demanding.
(It needs to be at a temperature that will melt the plastic used. Anything higher won't matter, unless you ramp it up too much. also, the hot-end and nozzle is made of metal, so will have some 'inertia' and retain heat for a short while.)
Nothing that needs micro-second handling, in other words.
How does the extruder on a ToM operate?
On my(still building) Prusa Mendel, I'm using what's known as a Wade's Geared extruder, basically a NEMA17 size stepper with a small cogwheel, driving a much larger cogwheel mounted on an M8 bolt. On the bolt there's a lots of grooves scored along its length, and the plastic filament is pulled between that scored area and a 'rollerscate bearing'.
I'm going for a J-Head hot-end with .5mm nozzle aperture, but may later switch to a .35mm for precision work.
(There's lots of 'weird' stuff happening with the Mendels; smaller, bigger, multiple hot-ends... )
A Prusa Mendel, or a RepStrap may be a cheaper alternative to the ToM, especially if you can source some of the materials locally. (PSU from old PC, M8 threaded rods, nuts washers, smooth rods. M3 and M4 screws, nuts and washers, 'rollerskate bearings'. Structural parts are printed on other 3D printers, or bodged together in a RepStrap. Sliding bearings for the carriages can be bought, or acceptable substitutes printed of PLA plastics, though thy may not last too long.)
Lots of info over at reprap.org
Note, my Ardunio MEGA2560 and RAMPS(with 4 polulu boards, Mosfets, 3 optical endstops with associated electronics and cabling) came to about $160. (Ardunio was assembled, the RAMPS was a mostly-SMT kit, optos were through-hole kits, and the Polulus needed headers lodered on)
If your kit can beat that price and be easier to solder, you may have a good thing going.
And yes, soldering 0805 is a pain in the... But I only broke one LED and lost a capacitor...
Would you like me to take this discussion to a separate thread or are you happy for it to continue here?
Gadgetman: The reason for a separate pcb for the heater control is mostly from a failure point of view. It is not reasonably possible to replace the smt mosfets so I didn't want them on the same pcb as the stepper driver board or the processor board as a failure could render an expensive board useless. The current is large and therfore the connectors must be on this pcb so a plugin mosfet is not a possible solution. This is the same reason as having the stepper pcbs as individual plugins to a stepper motherboard - a cheap replacement of the driver pcb(s) where the more expensive connectors etc are on the motherboard. Therefore, the heater pcb can be quite a cheap pcb and no doubt would have other uses too. I like multiple-use cheap modules.
So my solution is really 3 pcbs which plug into each other via male/female right-angled pin headers, and limited cable mess. I am aiming at an electronics price <$100 without cables but all connectors included, but excludes endstops. This includes connections for microSD, TV/VGA, Keyboard. The PropPlug or equivalent will most likely be addititional and separate. All smt parts will be preassembled and thruhole will be optional.
Endstops: I think microswitches may be better than optos. I am actually considering if a shorting metal finger could be used.
As for a RepRap unit, I have a prototype micro-mendel of my own simplified design mostly built. I hobbled the frame together with (poorly) cut timber to test out some of my theories. I made a number of simplifications and will also use some of the Prusa simplifications too. IMHO the Prusa has not yet gone far enough, but it is the simplest so far. I have been following the RepRap forums for nearly 2 years now. However, I am only intending on using a single stepper for the Z axis. My rods have been scrounged from old printers and laser cartridges and a few parts from old roller blades. My X & Y carriages move the platform and the extruder only moves in the Z direction. So far, Wade's Extruder seems to be the best choice, together with the lever modification.
Here is a pic of my bodgy prototype. It's an old pic and a couple of horizontal rods are missing near the top. And a pic of the plastic parts I designed to join the rods/bars at the vertices and the mount for the vertical threaded rods for the Z axis.
-Phil
Small correction, the Arduino, as it comes from MakerBot, does not read G-code files, even via the SD card slot. You must first "build" the G-code into a special file for the Arduino to ruin run it. It does not run G-code directly.
I think a Propeller solution should read the G-codes directly. It would make for a far more flexible machine.
Which is probaly why the RAMPS kit doesn't use SMT MOSFETs...
(They use TO-220 with a heatsink on one)
That price difference and the 'extras' will probably make it more attractive, yes.
But a simple UI consisting of a just a few buttons (Up/Down, Select(start) and Pause(cancel)) and a small LCD may be just as effective, as most will only want to select which file to print, maybe pause it if there's a feed-problem developing, and probably read off an estimate of remaining time?
The biggest problem with optos is that many forget that a lot of plastics is transparent to the IR light used.
Personally, I like the fact that there's no mechanical parts that can break.
We'll see if mine survives...
And besides, there's a shiny LED on them ;-)
Nice.
How big modules will it be able to print?
I agree. There is work going on to replace at least some of the threaded rods with more easily-available materials such as PVC piping or even bamboo. This I consider a 'false trail' as it's the smooth rods that are the most difficult to find cheaply. Some of the screws aren't all that common, either.(Took a while to find M4x60 for the Wade as most stores didn't have longer than 40mm)
Yeah, that's a redesign that's long overdue.
Anyway, I have a whole stack of Prototype boards with a very bored Propeller stuck in the middle of them.
I might be willing to 'bodge together' some circuitry on them for testing later on.
(I have an SD-card connector on a break-out board, possibly an LCD or ten, and other odds and ends.. )
As for G-code or no G-code, yeah, it really should be able to take them directly. The Ardunio probably doesn't have the extra capacity to both interpret the codes and control the motors at the same time?
https://github.com/kliment/Sprinter/
and some links to G-Code handled by the Arduino
http://linuxcnc.org/handbook/gcode/g-code.html
http://objects.reprap.org/wiki/Mendel_User_Manual:_RepRapGCodes
There are people designing a binary protocol (from what I have read), but I have not yet seen a firmware with it.
In another thread over at the propeller forum I've started with a prop replacement: http://forums.parallax.com/showthread.php?129448-Prop-based-CNC-3D-printer&p=1029389&viewfull=1#post1029389
I've come a bit further, but am waiting for my stepper motors/drivers to be ordered (unfortunately I'm dependant on my wife for this due to the language barrier, and she's been a bit busy lately).
I've already build most of this simple platform: http://www.instructables.com/id/Easy-to-Build-Desk-Top-3-Axis-CNC-Milling-Machine/ to use as a testbed.
Ultimately I'm going for the ultimaker (which I ordered, but will not get my hands on till Xmas)
The low Rdson of the newer mosfets makes heatsinks almost redundant and hence the smt parts. I agree that any interface (LCD and a few buttons) would also be fine. That's the beauty of the propeller. We can change that easy without a major rewrite of the software.
I certainly had no problems in finding the threaded rods. The smooth rod (bars) were much more difficult until I found them freely in old printers and laser cartridges.
As for the two Z motors, the Prusa was the first to my knowledge to use 2 motors. It was done to simplify the z axis but I believe at the expense of cost. On my design, the Z axis does not move in the X or Y direction. Therefore, I think I may be able to use a single threaded rod, thereby eliminating both the second motor and any belt/cog design for the Z axis. Time will tell, but I have an idea I will pursue for this. Also, by the extruder only moving vertically (Z) slowly, I hope there will be less strain on the extruder which may help it to perform better. There seems to be two main problems still being encountered with the various reprap designs... the Extruder and the Heated Bed.
Certainly, the Prusa went a long way to simplifying the plastics. However, IMHO there are still too many rods.
Gadgetman: You will be able to use the Prop ProtoBoards simply with my stepper motherboard and this will accept your Pololu pcbs too. This pcb is all t/hole so I will be selling the bare pcb too. I am using the Molex type 4pin connectors to the Nema motors and Molex type 2pin connectors for the power input (two sets). Here is the pcb layout. Sorry, I cannot post a pic of the actual pcb until I get back home
Yes it does:
http://reprap.org/wiki/Sjfw
Cluso99: Any idea what the price will be for the two boards?
The Stepper Baseboard bare pcbs are US$6.50 ea (I only had 3 made and they cost me $5.25ea plus postage). I will be getting more pcbs later.
I can also supply the following parts (not fitted) for US$2.50: 12@ shunts, 4@ 1x6 ST M pins, 8@ 1x9 ST F socket (need to cut/file to 1x8 or 1x7+1x9, and have long tail pins - sockets for stepper pcbs), 1@ 1x14 RA M pins (for processor connector) and includes 1@ 1x14 RA F for other end, and the following pin headers (not polarised) instead of Molex style connectors for the motors 4@ 1x4 RA M, 4@ 1x4 ST M pins (for either vertical or horizontal mount) and 4@ 1x4 F housings for the motor cable end, and for the power supply 2@ 1x2 RA M, 2@ 1x2 ST M pins (vert or horiz) and 2@ 1x2 F housings, plus the 20@ crimp terminal pins for the housings, plus 4@ 100K resistors t/h, 4@ 100uF 35V Electro Caps t/h, 2@ 100nF X7R capacitors t/h (0.2" so you will need to bend pins to 0.1").
The Stepper Driver bare pcbs (pin/size compatible with Pololu A4983/A4988 pcbs) for the A4982 or A4984 are US$1.20ea or US$2.50 with 2@ 1x8 ST M pins, 2@ 0.05R 1/4W 2% 0805, 2@ 10K 0805, 2@ 100K 0805, 3@ 100nF X7R 0805. You still require 2@ 220nF X7R 0805 (I don't have these until I order again) and a t/h resistor to set the current limit, and of course the A4982 or A4984 stepper IC. I have not done the calcs yet to determine the resistor values to set the current limits, nor have I assembled a pcb. So, for now I am not selling them assembled - the A4982/A4984 is not that easy as it has a ground pad underneath. I only have 9 pcbs at present, so really only 2 sets of 4 pcbs.
Unregistered Airmail Postage from Australia is $3-$5 depending on weight.
http://www.thingiverse.com/joegrand
Oh yeah, I've already modifed my #2 CupCake to have hidden electronics as well as a hidden Z drive. (I moved the pulleys and electronics to the bottom... see attached pic.)
The new "Black Maria" CupCake with the 8" build platform will also not use the standard MakerBot electronics... instead, I've build a Sanguiololu board to drive everything. It's much smaller and will easily hide in the bottom with minimal fuss.
Bill
Bill
I am sure interested to see how your modifications go. Do keep us posted please.
I can't wait to get a Prop based controller going on this thing! :-)
Bill
I have done all the pcbs, and bought the parts, except the mosfet heater driver pcb for the extruder and heated platform. I think this pcb will have a pair of P-channel mosfets and will have the option of an onboard ATTiny84 to control it and sense the temperature feedback via thermistors and I2C or serial I/F (2pins) to the prop. I wanted it to be a separate pcb for easy replacement in case of failure.
I'll keep posting the code in the CNC thread in the Propeller forum.
Should be fun to see when it airs in December. I just wish it was prop powered!!! :~)
Bill
I'm a happy owner of a Thing-O-Matic MakerBot with MK7 stepstruder.
I need your help please, with a problem I have when I build an item on this printer, every time after a few layers the item detached from the base !!!
I use :
ABS, I have the Heated Build Platform,
ReplicatorG 0027 with Machine Type (on ReplicatorG) Thingomatic w/HBP and Stepstruder MK7,
GCode Generator = Skeinforge (35)
Base Profile = 1.75mm ABS MK7
From GCODE I can read Base Temperature S110 and Extruder Temperature 225.
I also put some Kapton tape above the plastic of the base, and the item stayed a little longer.
Thank you all for your time.
Before I installed the heat spreader and polyester, I had the the same problem as you do (using the ABP). At the time, I solved it by adding horizontal stabilizers to the bottom any design that was tall and skinny. This kept the extruder from pulling the build off the base. I don't have to use the stabilizers anymore, though.
-Phil
Thanks for the immidiate answer PhiPi, Can you provide please a link or something for this polyester?