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Wiring up a Paste Extrusion Solenoid

Posted by Cowfingers 
Wiring up a Paste Extrusion Solenoid
March 06, 2012 01:42PM
Hi Guys,
Sorry for cross posting this to the BFB forum - this just seems like a more active place...

I've been following Unfolds design for the Claystruder, to connect to our BFB3000 -I'm working to try extrude UV cure Silicone...
Alas, I'm just having trouble with the wiring of the system.

We bought a DC6012 3/2 valve from Burkert, but I'm not entirely sure which of the wiring that feed the normal ABS filament extruder steppers I should connect up to the solenoid.

Also, I'm not too sure where to insert the differing resistors to tell the controller board the extruder ID - I've measured everything I can from my removed hot end extruder, but haven't found anything corresponding.

Finally, do I still need to keep a hot-end extruder attached somewhere, or can I remove it? (I got the impression from here that Unfold kept his attached initially)

I've been reading as much as I can on this, but unfortunately Unfolds blog is missing a lot of pictures. I'm going to ask him directly too, but I fear he may be pretty busy!

Thanks to anyone who responds!

Re: Wiring up a Paste Extrusion Solenoid
March 25, 2012 04:58PM
Hi Fergal,

Sorry to jump in late, not following the forums daily anymore. Busy indeed smiling smiley But I am writing a new post for the blog.

I never connected the solenoid to the extruder port, there are 2 12v aux ports on the pcb that you can switch with gcode:

M210 AUX 1 off
M211 AUX 1 on
M220 AUX 2 off
M221 AUX 2 on

On early PCBs there used to be a connector soldered to the board, on later ones there is only the holes. I have no idea how it is on the new touchscreen boards but the least I know is that AUX is still there. AUX is never officially used by BFB. This also means that there is no 'standard' way to slice a geode file with support for AUX M-codes. I used to edit the files by hand in a text editor smiling smiley but I am actually not using solenoids anymore and went to the high tech method of just plugging in the pressure line at the start of a print. So I am not switching the pressure during a print... In clay it is to much hassle to switch all the time, gives to much issues with tearing of the model etc. All solvable but we chose to develop methods of printing in one continuous extrusion. But you can probably modify the Makerbot Frostruder scripts to post process the gcode for Bfb AUX.

The ID resistor system is not any more used in recent firmwares. You can safely remove your extruder and stick whatever you want on your machine... You could add a fixed resistor to the terminator pins in order to have your controller report a fixed temperature otherwise it will float between 10 and 20 degrees which can play nasty but most of the time not. I am actually working on new extruders that use a stepper in order to be fully compatible with all machine electronics. Bit tricky with clay but could work nicely with resins because the lower viscosity and its not abrasive.

Btw, never tested this stuff with a 3000, we have one but keep it clean for plastic parts (extruders!!!)


Re: Wiring up a Paste Extrusion Solenoid
June 15, 2012 10:30AM
That's great - thanks Dries!...Sorry for taking so long to reply - i only just noticed there was a reply now!

I've made some progress since I posted that first set of questions.

I ended up having to scrap the Burkert 3/2 valve (unfortunately it got dropped into ceramic slip!) but I have access to a lot of Festo didactic valves and pressure regulators etc, so have starting using them instead.

There's a terrible shortcoming of the BFB 3000 in that their dwell time is in minimum increments of 1 second, so implementing a pre-delay between turning on the pressure, allowing it to pressurise and then moving the needle is difficult.
I ended up adding an Arduino for timing - the BFB switches on its AUX signal and delays for a second. The arduino is then in charge of controlling the switching on of the pressure via relays.

The end time is more difficult to control, but I think what I'll do is buy a pinch valve which will cut off the paste flow as soon as the M211 / M221 codes are received by the arduino.

I started modifying the Frostruder scripts (which unfortunately ended up just too different for the BFB- especially the DXF converter which uses I and J codes for arcs. Alas it seems BFB have removed the arcing code from their firmware)...Instead im now using Axon 2 to convert my STLs into GCode, then I wrote some PHP scripts to flick down through the gcode and replace any commands with what I need. I find Axon to be quite limiting, so will probably look into netfabb (or Kisslicer?) over the weekend.

Little by little I'm branching into Thixotropic Silicones now (I had been practising with tasty tasty Nutella up till now!)
Its all going quite well really, but i'm going to have to remember not to lick the extruders when i'm finished a print!

I'll let you know how it all progresses.
thanks again
Re: Wiring up a Paste Extrusion Solenoid
June 19, 2012 03:32PM
Ah, great sounds like your very dedicated smiling smiley
The Burkert was the one I could easiest find but any valve could do although 12v is fairly non standard but some extra circuitry should overcome that.
Can you set the dwell time on the BFB? I also figured an extra arduino could be a solution, also to detect empty syringes etc. one could wire up the esc key to a reed switch in the syringe to pause the machine. Other option I am thinking off is wiring another controller to my machines so one could actually modify the firmware. Old BFB firmware allowed you to adjust print speed on the fly which was very nice when working with air pressure since you never really know the flow rate, but the feature is scraped and my pleas to add it again are not answered.
Good that you tried the Makerbot scripts, in the end the purpose is the same as what you did, post process the output of the 'standard' geode processors. If you find Axon limiting, try Skeinforge. It will give you all the control (its the open source engine behind Axon and many other slicers).
I am very curious to see how all this works on a bfb3000, would you mind posting a picture? What do you want to print?
Re: Wiring up a Paste Extrusion Solenoid
July 04, 2012 07:47AM
Dedicated indeed! The machine will end up forming a reasonably large section of my PhD research, so I want to get it right! I'm working on Electroactive Polymers (or artificial muscles) and I need an accurate method to print silicone microstructures. In theory the Fab@home would be far better suited to this purpose but my university had bought three BFB3000s last summer, so that's what ended up working with, at least for now.

Since my last post I've moved on a bit again. Attempts at printing thixotropic silicone turned out to be pretty satisfactory now that I've locked down the pre-delay times using an arduino to dwell. The stop time (ooze) is still a bit of a problem - I guess my 100psi takes a moment to de-pressurise. Also, I've got to improve my support material design.

How I got around pre-delay is by using G4 P1.0 to get the BFB to dwell for a second, while signalling a start time to the arduino at the same time. I then get the Arduino control the valves. It's much more controllable I find. Between the two AUX's, and also the "Fan On" signal I can theoretically achieve 8 different binary states for the machine to be in...(I've only been using the two AUXs at the moment, but soon I'll expand)

Next up is implementing a few bits we've just purchased. First is to add a pinch valve on the end of the syringe, which should stop that pesky ooze problem. Again that's going to be controlled by the Arduino. More interestingly perhaps is the proportional air valve we've got. (a Festo VPPE) That will give me instant pressure drops between 1-100 psi, corresponding to 1-10 volts inputted. I'll let you know how that gets on!

There's another guy working with me on this, but coming from in the clay / ceramic side of things. That's a nice situation, as his generative designs are really starting to find the limitations of my implementation. There's another guy starting on this too in September, who will look at methods of delivering static mixes to the nozzle. Quite exciting really.

I was also thinking of looking at getting a new controller/driver board. Not entirely sure which one - I'd be interested in which you were thinking of.. though being honest I don't really feel like recalibrating the whole machine so soon - I'll work with my series of hacks for the moment!..

Here's a pic : of the 'previous' setup (I haven't finished my pinch-valve assembly yet, so i'll put that up later.) I'm using a lot of Festo Didactic valves and things as you see on the left (luckily my Uni has lots of that kind of thing, just sitting around...) Though the PLCs in the top left of the pic are nothing to do with it (yet)!

I'd like to get in contact with you by email soon - I'd love to compare some more technical notes with you, if you're interested? Though I'll progress the design a bit more before I do though - my method is currently still too close to the original design you put up on thingiverse - I'll fork off a little more first!

Re: Wiring up a Paste Extrusion Solenoid
July 04, 2012 08:11AM
... you should receive much less oozing when pushing the pistons with a threaded rod instead of pressurizing them (as done with the fab@home printers).

Look at my paste extruders for an example: [reprap.org]

Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]
Re: Wiring up a Paste Extrusion Solenoid
July 04, 2012 08:26AM
You might take a look at the Universal Paste Extruder for 3D printers from RichRap on Thingiverse.

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
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