This is an adapter plate for the X axis carriage of a Folger Prusa i3 to convert the printer from a single extruder to a dual extruder. It uses the stock Folger complete extruder assembly and does not require any permanent modifications to your mechanical printer hardware.
These instructions are a work in Progress. Details will be updated about bolt lengths, etc, when I get a chance to go back and check what I ended up using.
This build relies on the purchase of a second Folger MK7 Extruder print head (http://goo.gl/OwahWr) which should match the one already installed on your printer.
The mounting is designed to bolt onto the existing X axis carriage and support the 2 extruders side by side, offsetting them.
All of the nuts & bolts required are standard to the Folger kit. Use M3s and the corresponding nuts (don't use Nylocks).
Take 2 M3 nuts and press them into matching hex shaped holes until the are firmly against their backing. I found using a matching size bit driver and genting tapping them with a hammer worked well.
Take an extruder assembly and place it on either the left or right side of the adapter plate with the motor mount holes touching the side of the plate where the nuts are exposed.
Line up the motor mount holes with either the right or left side set of the deeply inset holes.
Run 2 [TBD]mm M3 bolts through the deep inset holes in the adapter plate and into the motor mount holes.
Tighten down the bolts until the heads of the bolts are flush with the adapter. The insets should be just deep enough to get this flush. This is crucial, because that surface will end up sitting flush with the original X carriage.
Repeat this step with the second extruder.
Mount the extruders and plate centered up against the existing X carriage on the printer.
Run 2 [TBD]mm M3 bolts through the holes in the back of the X carriage and into the 2 center holes in the adapter plate where the nuts have been pressed into the opposite side.
Tighten down the nuts.
Congratulations! 2 extruders should now be mounted to a single X axis carriage!
There are plenty of resources online explaining how to do this. Most of this is straightforward. The RAMPS 1.4 board already has a connection for the second extruder motor (E1) and a connection for the extra thermistor.
The tricky part is connecting the hot end. There are a couple of choices here. I chose to disconnect the fan output and connect the second extruder hot end to that output. I then needed a solution for the fan and went the "Fan Extender" route. You can google that.
The firmware will need to be altered to support the second extruder. There are plenty of resources online explaining how to do this. Until I track those down and update this documentaton, please look one up and follow that.
You will have to make some settings changes in Repitier (or your software of choice) as well as you choice of Slicer. There are plenty of resources online explaining how to do this. Until I track those down and update this documentaton, please look one up and follow that.
Most importantly, you need to know the offset of the extruder nozzles. I recommend measuring this with a caliper, entering the values and performing several test prints until you get it dialed in. On my printer I set the right extruder as #1 and the left as #2. I have the X offset set as [TBD] and the Y is just a little off at [TBD]. So those may be a good starting point, but obviously, your build will vary.
There are plenty of good calibration objects out there. I recommend printing them out. Then measure your results with a caliper, adjust the offsets and try again. Lather, Rinse Repeat... Here is a model I put together myself, for just such a test: [TBD].
I would love to see makes and the dual extruded models that resulted. Please leave your comments for anything that is unclear or improvements that should be made.