MakerGear Forum

There was a point in the middle of my "twin extruder" project that I realized that having two extruders running semi-independently on the X axis is exactly what you need to do "ditto printing", or printing multiple copies of the same object at the same time. After some thought, I also realized that the magnetic coupling idea was perfect for ditto printing, since the belt clamp isn't bolted to anything. So you can print a second magnetic belt clamp and slip it over the belt at any point, then slide the right extruder over to magnetically couple to it. That makes the distance between the two extruders for ditto printing completely adjustible, easily and quickly. And just as easy to take the second belt clamp off and go back to normal printing.

There was some firmware coding required, though, which is why it took an extra month to get around to working out how to do the ditto printing (that, and intervening holidays). I am using the Smoothieboard with the Smoothie firmware, so this doesn't immediately translate over to the Marlin firmware, unfortunately, and I don't have the capacity to test the setup with Marlin and the RAMBo. The ditto printing can be done without firmware changes, though, by connecting both extruder stepper motors in parallel (I think they also work connected in series) using a Y-connector cable. But as far as I know, mine is the first ditto printing setup for the M2 using software control to switch to and from the ditto printing mode.

The video can be found here: http://opencircuitdesign.com/~tim/videos/index.html (last video at the bottom of the page). Also, there is a link to the video from my "twin extruder" project page: http://opencircuitdesign.com/~tim/3d_pr ... index.html (also at the bottom).

Nice! Twice the fun in half the time!

Jules wrote:Nice! Twice the fun in half the time!

With twice the opportunity for something to go wrong. Fortunately, nothing did, on my test run. Honestly, I was not expecting first-attempt success, so I'm pretty happy with it.

Wow, another brilliant mod.

Nicely done.

cheers,
c

I've done this under my MB with sailfish firmware which has ditto printing... cool feature... I used it a few times when i was making many copies of a very small print.

it was limited to the size because of the fixed distance between heads...having the ability to have the heads at much wider distances makes this a much more useful feature!

I saw your video for this before the thread. Very cool.

It appears the offset between the two print heads is completely variable, based on where you snap the second magnet on the belt.
How do you protect against banging on the end stop? Or is this completely up to the user?

Levi8than wrote:How do you protect against banging on the end stop? Or is this completely up to the user?

That would have to be up to the user, although if I thought the prints might be kind of marginal on the width, I would probably measure the distance between the nozzles, then make a copy of the object in Simplify3D at the same distance to see if it's going to run into the other object, or off the end of the bed. Because having the second print run into the first or off of the bed is just as much a risk as hitting the end.

Another issue is how to do purging. With the firmware mod, you could do purging of left and right sides in sequence, then switch to ditto printing. But I found it easier just to let both extruders purge at the same time. I kept the right extruder off of the magnetic belt clamp and just held it by hand off the end of the bed while it purged, and then clicked it into place, which effectively did the slow wipe, as they both started printing the skirt outline. Sometimes the hack solution is just way easier. . .

It had been a while since I have been on the forum, but I just wanted to say WOW! Great job on the mods Tim. Very impressive.
That would be a great time saver when printing my wifes crafting 'doodads" they are about 2" diameter would would work perfectly with ditto printing.

thecadman99 wrote:That would be a great time saver when printing my wifes crafting 'doodads" they are about 2" diameter would would work perfectly with ditto printing.

The M2 is such a wonderfully reliable machine that as long as you're printing something that is known to be printable, you're pretty much guaranteed two successful prints with the ditto configuration.

Good. Job Tim. I still think your dual head solution is fantastic. This makes it even more so. You said that you modded it so it was software selectable. Is that tied in to m code to select to output to both extruders ?